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References: <list-4509376@logan.com>
Date: Sun, 17 Oct 2010 10:59:16 -0700 (PDT)
From: Kelly Troyer <keltro@att.net>
Subject: Re: The Case For Turbocharging
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-4509376@logan.com>
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Sorry guys..........Did not think about my "Open Office" files not opening =
for =0Aeveryone !!=0AHope this is not too big for the forum !!.............=
......=0A=0ATurbocharging Automotive Engines for Aircraft Applications=0AAp=
ril 27/98 =0AWith automotive engines finding increasing use powering homebu=
ilt aircraft, we =0Afind many people entertaining the idea of turbocharging=
 to boost the power to =0Aweight ratios and altitude performance of these e=
ngines. We will examine the =0Avarious facts and myths regarding turbocharg=
ing as applied to light aircraft =0Ause.=0AHistory=0ATurbos in aircraft wer=
e first successfully applied in mass numbers during WWII. =0AThe P-38 and P=
-47 were the best known turbocharged fighter types and both had =0Aexcellen=
t high altitude performance.=0AIn general aviation use as applied to air co=
oled opposed engines, turbocharging =0Ahas a less revered reputation. Much =
of this has to do with the air cooled engine =0Aitself and the fact that mo=
st of these engines were never designed to be boosted =0Ato begin with. The=
y may have been modified a bit for the turbo but with power to =0Aweight ra=
tios being a major concern, many are structurally and thermally not up =0At=
o the task. Other concerns such as turbo cooling and lubrication by inferio=
r =0Aaviation type oils also led to premature turbo failures.=0AWhat is a T=
urbocharger?=0AA turbo consists of a centrifugal compressor connected to a =
turbine wheel which =0Ais spun at high rpm by the energy of the engine exha=
ust gasses. It is a very =0Asimple device, but the high temperatures and st=
resses acting on it require =0Aexotic materials in the turbine section whic=
h are somewhat expensive. A turbo =0Awill cost in the neighborhood of $800 =
to $1300 with the wastegate assembly.=0A=0ATurbine wheels come in many shap=
es and sizes. Constructed of high temperature =0Aalloys such as Inconel or =
Hastaloy. This is the hot end. =0A=0A=0ATurbine housings are cast from a hi=
gh nickel/iron alloy. =0AThe compressor pressurizes the intake manifold to =
achieve higher hp or maintains =0Asea level pressure as the aircraft climbs=
. This permits higher climb rates at =0Aaltitude and increased cruise speed=
s.=0A=0ACompressor wheels are cast from aluminum alloy and come in many siz=
es or trims. =0AThis is the cold end. =0A=0A=0ACompressor housing is cast f=
rom aluminum alloy. Shape is designed to slow the =0Aair, thus compressing =
it. =0A=0A=0ACast iron center section or bearing housing contains floating =
sleeve bearings or =0Amore recently ceramic ball bearings. High pressure oi=
l from engine feeds the =0Abearing and is drained out the bottom of the hou=
sing back into the engine. Some =0Ahousings are water cooled to prevent cok=
ing of oil deposits leading to bearing =0Afailure. =0A=0AElegant Simplicity=
=0ATurbocharging is the most efficient method of boosting hp with the least=
 weight =0Apenalty known. A typical turbo installation on a light aircraft =
including =0Aintercooler and exhaust is around 35-50 pounds. Such an instal=
lation is capable =0Aof tripling hp at sea level or adding 50% to the natur=
ally aspirated output up =0Ato 15,000 feet. Sea level manifold pressures ca=
n be maintained to 25,000 feet in =0Asome cases. An aircraft capable of 200=
 knots at sea level would true out at =0Anearly 300 knots with a good turbo=
 system at high altitude.=0ASpinning the compressor with an exhaust driven =
turbine is a much better way than =0Aby the mechanical means as in a superc=
harger. It is lighter, more reliable and =0Amore efficient and has the adde=
d advantage of having more drive energy available =0Aas the aircraft climbs=
 due to lower backpresure, which is exactly what is =0Aneeded. =0A=0AFuel F=
low vs. Power=0AThere is a common misconception that turbocharging increase=
s fuel flows because =0Aof the backpressure of the turbine. This may be tru=
e in air cooled engines using =0Aa poorly matched turbo without intercoolin=
g because the air cooled engine cannot =0Amaintain temperature stability wi=
thout adding fuel for cooling purposes. Reduced =0Afuel flows at altitude i=
n naturally aspirated and turbine engines is not due to =0Asome magic proce=
ss, it is due to the fact that as altitude is increased, less =0Apower is p=
roduced thus less fuel is required. Many people also don't seem to =0Areali=
ze that fuel flow is related to hp developed and that a turbo engine will =
=0Adevelop more power at altitude than a naturally aspirated engine, obviou=
sly =0Arequiring more fuel and delivering higher speeds at the same time. =
=0A=0ATesting done back in the '40s and '50s on turbo engines actually conf=
irm that =0Afuel flows were LOWER at the same BMEP with turbocharging than =
in a naturally =0Aaspirated engine developing the same power. This suggests=
 that when properly =0Aapplied, the turbo actually recovers more energy fro=
m the exhaust to be applied =0Ato reduce pumping losses during the compress=
ion stroke than is consumed during =0Athe exhaust stroke working against hi=
gher backpressure. With approximately 50% =0Aof the energy in the fuel goin=
g out the exhaust in the form of heat and =0Apressure, turbocharging can re=
cover some of this waste and put it to good use.=0AIt was shown that turbos=
 could achieve fuel flows 3-6% lower and =0Aturbocompounding could achieve =
up to 15% lower fuel flows. Cylinder head and =0Apiston cooling were shown =
to be the primary limitations to achieving lower BMSFC =0Afigures. We can c=
onclude from this that as applied to liquid cooled engines with =0Atheir su=
perior thermal rejection rates, turbocharging really has few =0Adisadvantag=
es compared to the many advantages it offers.=0AIt should be no surprise th=
at the latest certified liquid cooled engines from =0AToyota and Orenda are=
 turbocharged. People also should remember the awesome =0Aturbocompound rad=
ials of the '50s. These engines offered extremely low BSFC and =0Ahigh powe=
r. It seems foolish not to turbocharge most good aircraft engines used =0Aa=
t any kind of altitude as you are throwing away performance without it.=0AT=
urbocharged Air Cooled Engines=0AAs mentioned earlier, turbocharged , conve=
ntional opposed air cooled engines =0Ahave a less than stellar track record=
 and many lay people blame the turbo. In =0Afact, the fault lies with the e=
ngines it is applied to. The average Lycoming or =0AContinental has a lot o=
f things not going for them. Many of these engines suffer =0Apremature fail=
ure of crankcases, cylinders, heads and valves in their =0Aturbocharged ite=
rations. Let's examine why.=0AProbably the leading cause of case and barrel=
 cracking is the lack of rigidity =0Athese engines have in the cylinder/ ca=
se area. For ease of barrel replacement I =0Aassume, the designers of these=
 engines chose to bolt the cylinders individually =0Ato the crankcase at th=
e bottom of the cylinder using a flange. This arrangement =0Acreates a very=
 willowy structure and with each firing impulse, combined with the =0Asheer=
 mass of the huge reciprocating parts used in these engines, a definite =0A=
high amplitude, cyclic stress is put on these parts eventually leading to =
=0Acracking. The increased gas pressures associated with turbocharging comp=
ound =0Athis problem. This design problem is actually the cause of a major =
portion of =0Athe high vibration levels associated with conventional aircra=
ft engines.=0AThe flange method puts the barrel under a tension load with e=
very firing impulse =0Atoo which is just plain stupid given the thickness o=
f the cylinders. Modern =0Aautomotive racing practice would use through stu=
ds to retain the barrels, thus =0Aputting the barrels under compression.=0A=
Cylinder head cracking and exhaust valve burning and sticking are primarily=
 due =0Ato insufficient cooling in these areas which is exaggerated by the =
extra heat =0Aintroduced by turbocharging. Air cooling is relatively ineffi=
cient at sinking =0Aheat off around the exhaust port and valve seat area. T=
his problem is compounded =0Aby the use of very low compression ratios resu=
lting in higher EGTs thus even =0Ahigher heat flux in the critical exhaust =
port area. Typical air cooled aircraft =0Aengines run cylinder head tempera=
tures in excess of 400 degrees on a regular =0Abasis. With aluminum alloys =
losing roughly 50% of their strength at this =0Atemperature it is easy to s=
ee why cracking is all too common here. The high =0AEGT's are also detrimen=
tal to the life of the turbo's turbine section.=0AValve problems are due to=
 the same cause, temperatures being too high from =0Ainefficient heat trans=
fer. Many factory turbo aircraft are forced to either open =0Acowl flaps or=
 richen the mixture at high altitude to keep temperatures within =0Alimits.=
 With power being maintained at altitude and air density falling off, =0Ath=
ere is often insufficient mass flow available for cooling. This is rarely a=
 =0Aproblem on naturally aspirated engines as power and cooling requirement=
s are =0Adropping off with increasing altitude.=0ANot a lot of design went =
into the induction system on many of these engines =0Ahence fuel distributi=
on is usually not the greatest. This contributes to engine =0Aroughness and=
 problems with leaning. Leaning is limited by the mixture in the =0Ahottest=
 cylinder with the others running richer than desired.=0AThe oils used in a=
ircraft engines are relatively crude by modern synthetic =0Aautomotive stan=
dards and consequently not the best for the turbocharger. The use =0Aof the=
se oils appears to be a result of the very loose tolerances required in an =
=0Aair cooled engines because of the high operating temperatures which also=
 leads =0Ato the high oil consumption characteristic of these engines.=0AFi=
nally, many certified installations never used intercooling which is simply=
 =0Aamazing. The advantages and necessity of it was clearly understood in W=
WII. High =0Acharge temperatures at altitude required even more fuel for co=
oling and yet more =0Acowl flap opening to control head temperatures.=0ATur=
bocharged Liquid Cooled Engines=0ALiquid cooled engines are a natural for t=
urbocharging because of their higher =0Aheat rejection capabilities. Water =
cooling also enables the turbo center section =0Ato be water cooled which a=
lleviates a primary cause of turbo failure- coked =0Abearing holes from hig=
h heat and fried oil. Water cooled engines can use modern =0Asynthetic oils=
 because of their tighter clearances. Synthetic oils with their =0Amuch hig=
her temperature capabilities are more suitable to lubricate the turbo =0Ath=
an old fashioned, aircraft oils derived from natural base stocks. The popul=
ar =0AMobil 1 synthetic oil, common in the racing world, can withstand temp=
eratures of =0A350 degrees continuously and even 450 degrees intermittently=
 without significant =0Adegradation. With proper lubrication and cooling, t=
urbochargers will easily last =0Athe life of the engine.=0AIf we compare th=
e Popular Subaru EJ22 and EJ25 horizontally opposed 4 cylinder =0Aengines t=
o their certified counterparts we find many advantages especially in =0Atur=
bocharged trim. The Subaru has 5 main bearings instead of 3 which means tha=
t =0Athe crank is better supported. The Subaru has a higher compression rat=
io for =0Ahigher thermal efficency. Its overhead cam, 4 valve per cylinder =
arrangement =0Aprovides lower friction and higher volumetric efficiency tha=
n a 2 valve pushrod =0Asetup. Finally, the integrated block and head design=
 is many times stiffer and =0Astronger than the aircraft engine.=0AAs long =
as the radiator and ducting are properly designed, cooling problems are =0A=
not a concern on the liquid cooled engine.=0AThe induction system on the Su=
baru has proper runner lengths to boost torque, =0Arelatively equal airflow=
 to each cylinder and can easily use a modern digital, =0Aelectronic fuel i=
njection system to precisely meter fuel. All of these things =0Aaid in prod=
ucing more power with less fuel.=0APower vs. Weight vs. Manifold Pressure v=
s. Life vs. Cost=0AThe EJ engines when turbocharged and equipped with a rad=
iator, PSRU and =0Acomposite propeller are slightly heavier than the popula=
r Lycoming and =0AContinental 360 cubic inch engines which are rated at 180=
- 200 hp for takeoff =0Aand around 135- 150 hp for maximum cruise. The Suba=
ru can easily attain 200- 250 =0Ahp at 50 inches for takeoff and reliably d=
eliver 140 to 170hp at 35-38 inches =0Afor cruise. The 3.3L EG33 six cylind=
er is capable of 300+ hp for takeoff and =0A200-250 hp in cruise making it =
a viable alternative to the O-540 engines. These =0Apower levels can be mai=
ntained during climb and cruise at altitude thanks to =0Aturbocharging and =
liquid cooling.=0AProjected TBO is in the 1000-1200 hour range at this time=
. Most people flying =0Athe EJ engines are confident that no interim work w=
ill be required during this =0Aperiod such as cylinder barrel replacement a=
nd valve grinding operations which =0Aare quite common on aircraft engines =
before reaching their stated TBO. In other =0Awords, if you change the oil =
and check the water, that is about all that is =0Arequired during those 100=
0 hours. There are no magneto or even valve adjustments =0Ato worry about. =
Expect spark plug replacement every 100- 250 hours or so at $3 =0Aeach. Ove=
rhaul costs will range from about $500 to $1500 for parts and machine =0Awo=
rk depending on condition. Labor would be in the $500 to $1200 range. We ar=
e =0Aall familiar with the costs to overhaul a certified aircraft engine. =
=0A=0AMatching a Turbocharger=0AAs applied to the popular Subaru EJ22 and E=
J25 engines for general purpose use =0Abelow 15,000 feet we can narrow the =
choice of turbos down a bit. Garrett T3 =0Aturbos are recommended as they a=
re relatively cheap, reliable and easy to fix =0Awith a vast array of combi=
nations available. The compressor side may be either a =0A-50, -60 or super=
 60 wheel with a stage 3 turbine wheel in a .82 A/R housing, =0Adepending o=
n the exact use and hp. These may be ordered with an integral =0Awastegate =
and a water cooled bearing housing which are both highly recommended. =0ATh=
ese turbos are quite capable of producing enough boost to extract 250 hp at=
 =0Asea level and still have 175+ hp available at 15,000 feet.=0AThe integr=
al wastegates are generally more reliable than an external type =0Aespecial=
ly on an aircraft application in which it is almost constantly bypassing =
=0Aexhaust. The wastegate is simply a valve used to bypass exhaust gasses a=
round =0Athe turbine to control turbine and compressor speed and thus boost=
 pressure. It =0Ais usually actuated automatically by a diaphragm sensing m=
anifold pressure.=0AMany people have tried to use the OE turbo on auto airc=
raft conversions, often =0Awith limited success. The turbos on cars were no=
t matched to operate at high =0Aaltitude and continuous high power settings=
 so they are mismatched and =0Ainefficient when used on aircraft. High exha=
ust back pressures and overspeeds =0Awith consequent catastrophic failure a=
re not uncommon. In extreme cases, =0Acompressor or turbine wheel bursts ca=
n cause engine damage and failure due to =0Apart ingestion or oil loss. Thi=
s is not a good idea. Use a turbo which is =0Aprofessionally matched for yo=
ur engine and intended use by someone familiar with =0Ahigh altitude turboc=
harging. =0A=0AIntercooling=0AIntercoolers are heat exchangers placed betwe=
en the compressor and intake =0Amanifold. Their purpose is to reduce the te=
mperature of the compressed air =0Abefore it enters the engine. Whenever ai=
r is compressed, its temperature =0Aincreases. In the case of a high boost =
turbo at high altitude, the air exiting =0Athe compressor may reach 300-350=
 degrees F. This lowers the mass flow of air =0Ainto the engine and reduces=
 power. It also raises EGTs and lowers the detonation =0Alimits. All of the=
se things are detrimental to performance and engine longevity. =0A=0AAn eff=
ective intercooler will lower the charge temperature to within a few =0Adeg=
rees of the ambient temperature.=0AExhaust Systems=0AThe exhaust system on =
turbocharged engines is critically important. High =0Atemperature materials=
 such as stainless steel or Inconel should be used for =0Atheir constructio=
n to ensure longevity. Tubing thickness should be a minimum of =0A.060 inch=
 to withstand the constant 1500 degree temperatures. Careful attention =0At=
o thermal expansion is necessary so that cracking possibilities are minimiz=
ed. =0ABellows or slip joints are often required at junctions. The turbo it=
self should =0Anever be supported by the headers. A strong, triangulated st=
ructure should =0Asupport the weight of the turbo on the engine.=0AIf possi=
ble, the primary header tubes should be equal length and mandrel bent =0Afo=
r low restriction and maximum pulse energy with equal pulse spacing. The =
=0Aturbine discharge pipe should be 2.25 to 2.5 inches to minimize backpres=
sure. A =0Amuffler is often unnecessary to reduce exhaust noise as the turb=
o usually does a =0Agood job of this. This helps to offset the weight of th=
e turbo installation to =0Asome degree.=0AFuture Developments=0AWatch the A=
ircraft section for pictures and updates on turbo installations as =0Athey =
become available. We are currently flying our turbocharged EJ22 powered =0A=
RV6A seen elsewhere on this site.=0AR.F.=0A=0AFuel Octane vs. HP=0A03/13/98=
=0AIn turbocharged engines there is a fine balancing act when it comes to m=
aking a =0Alot of power on low octane fuel. In most cases, ignition timing =
must be retarded =0Aas the boost pressure rises above a critical point and =
finally there reaches a =0Afurther point where the engine simply loses powe=
r. If the timing was not =0Aretarded with increasing boost, destructive pre=
ignition or detonation would =0Aoccur. Normal combustion is characterized b=
y smooth, even burning of the =0Afuel/air mixture. Detonation is characteri=
zed by rapid, uncontrolled temperature =0Aand pressure rises more closely a=
kin to an explosion. It's effects are similar =0Ato taking a hammer to the =
top of your pistons. =0A=0AMost engines make maximum power when peak cylind=
er pressures are obtained with =0Athe crankshaft around 15 degrees after TD=
C. Experimentation with increasing =0Aboost and decreasing timing basically=
 alters where and how much force is =0Aproduced on the crankshaft. Severely=
 retarded timing causes high exhaust gas =0Atemperatures which can lead to =
preignition and exhaust valve and turbo damage.=0AWe have a hypothetical en=
gine. It's a 2.0L, 4 valve per cylinder, 4 cylinder =0Atype with a 9.0 to 1=
 compression ratio and it's turbocharged. On the dyno, the =0Amotor puts ou=
t 200hp at 4psi boost with the timing at the stock setting of 35 =0Adegrees=
 on 92 octane pump gas with an air/fuel ratio of 14 to 1. We retard the =0A=
timing to 30 degrees and can now run 7psi and make 225hp before detonation =
=0Aoccurs. Now we richen the mixture to 12 to 1 AFR and find we can get 8ps=
i and =0A235 hp before detonation occurs. The last thing we can consider is=
 to lower the =0Acompression ratio to 7 to1. Back on the dyno, we can now r=
un 10psi with 33 =0Adegrees of timing with an AFR of 12 to 1 and we get 270=
 hp on the best pull.=0AWe decide to do a test with our 9 to 1 compression =
ratio using some 118 octane =0Aleaded race gas. The best pull is 490 hp wit=
h 35 degrees of timing at 21 psi. On =0Athe 7 to 1 engine, we manage 560 hp=
 with 35 degrees of timing at 25psi. To get =0Atotally stupid, we fit some =
larger injectors and remap the EFI system for126 =0Aoctane methanol. At 30p=
si we get 700hp with 35 degrees of timing!=0AWhile all of these figures are=
 hypothetical, they are very representative of the =0Agains to be had using=
 high octane fuel. Simply by changing fuel we took the 7 to =0A1 engine fro=
m 270 to 700 hp.=0AFrom all of the changes made, we can deduce the effect c=
ertain changes on hp;=0ARetarding the ignition timing allows slightly more =
boost to be run and gain of =0A12.5%.=0ARichening the mixture allows slight=
ly more boost to be run for a small hp gain =0Ahowever, past about 11.5 to =
1 AFR most engines will start to lose power and even =0Aencounter rich misf=
ire.=0ALowering the compression ratio allows more boost to be run with less=
 retard for =0Aa substantial hp gain.=0AIncreasing the octane rating of the=
 fuel has a massive effect on maximum =0Aobtainable hp.=0AWe have seen that=
 there are limits on what can be done running pump gas on an =0Aengine with=
 a relatively high compression ratio. High compression engines are =0Athere=
fore poor candidates for high boost pressures on pump fuel. On high octane =
=0Afuels, the compression ratio becomes relatively unimportant. Ultimate hp=
 levels =0Aon high octane fuel are mainly determined by the physical streng=
th of the =0Aengine. This was clearly demonstrated in the turbo Formula 1 e=
ra of a decade ago =0Awhere 1.5L engines were producing up to 1100 hp at 60=
psi on a witches brew of =0Aaromatics. Most fully prepared street engines o=
f this displacement would have =0Atrouble producing half of this power for =
a short time, even with many racing =0Aparts fitted.=0AMost factory turboch=
arged engines rely on a mix of relatively low compression =0Aratios, mild b=
oost and a dose of ignition retard under boost to avoid =0Adetonation. Powe=
r outputs on these engines are not stellar but these motors can =0Ausually =
be seriously thrashed without damage. Trying to exceed the factory =0Aoutpu=
ts by any appreciable margins without higher octane fuel usually results in=
 =0Asome type of engine failure. Remember, the factory spent many millions =
=0Aengineering a reasonable compromise in power, emissions, fuel economy an=
d =0Areliability for the readily available pump fuel. Despite what many peo=
ple think, =0Athey probably don't know as much about this topic as the engi=
neers do.=0AOne last method of increasing power on turbo engines running on=
 low octane fuel =0Ais water injection. This method was evaluated scientifi=
cally by H. Ricardo in =0Athe 1930s on a dyno and showed considerable promi=
se. He was able to double power =0Aoutput on the same fuel with the aid of =
water injection. =0A=0AFirst widespread use of water injection was in WW2 o=
n supercharged and =0Aturbocharged aircraft engines for takeoff and emergen=
cy power increases. The =0Awater was usually mixed with 50% methanol and en=
ough was on hand for 10-20 =0Aminutes use. Water/methanol injection was wid=
ely used on the mighty =0Aturbocompound engines of the '50s and '60s before=
 the advent of the jet engine. =0AIn the automotive world, it was used in t=
he '70s and '80s when turbos suddenly =0Abecame cool again and where EFI an=
d computer controlled ignitions were still a =0Abit crude. Some Formula 1 t=
eams experimented with water injection for qualifying =0Awith success until=
 banned. =0A=0AMy personal experience with water injection is considerable.=
 I had several turbo =0Acars fitted with it. One 2.2 liter Celica with a Ra=
jay turbo, Weber carb and no =0Aintercooler or internal engine mods ran 13.=
3 at 103 on street rubber on pump gas =0Aback in 1987. This was accomplishe=
d at 15psi. With the water injection switched =0Aoff, I could only run abou=
t 5 psi before the engine started to ping. I think you =0Amight see water i=
njection controlled by microchips, catch on again in the coming =0Ayears on=
 aftermarket street turbo installations. It works.=0A=0A=A0=0AKelly Troyer=
=0A"DYKE DELTA JD2" (Eventually)=0A"13B ROTARY"_ Engine=0A"RWS"_RD1C/EC2/EM=
2=0A"MISTRAL"_Backplate/Oil Manifold=0A"TURBONETICS"_TO4E50 Turbo=0A=0A=0A=
=0A=0A________________________________=0AFrom: "shipchief@aol.com" <shipchi=
ef@aol.com>=0ATo: Rotary motors in aircraft <flyrotary@lancaironline.net>=
=0ASent: Sun, October 17, 2010 12:40:28 PM=0ASubject: [FlyRotary] Re: The C=
ase For Turbocharging=0A=0AKelly:=0AMaybe I'm a bonehead, but those zip fil=
es didn't include anything readable for =0Ame....=0AOn the other hand, I'm =
using a Turbo on my RV-8 prject, so I'm in as far as =0Aselecting a turbo.=
=0AI finally decided to use a turbo because of Tracy's muffler experiments.=
 I have =0Aa Turbo engine, with the open exhaust ports, so the sound pressu=
re is very high =0Aand would require an extra strong and tough exhaust syst=
em (heavy). So I decided =0Ato use that weight in the form of a Turbo to kn=
ock the most vicious element form =0Athe exhaust noise. I=A0hope for=A0a hi=
gher rate of climb as a result of the =0Aincreased power potential. =0A=0AI=
 realize that all engines have a sweet spot that would be best for cruise a=
nd =0Arange, which would co-incide with the engine torque peak RPM=A0and an=
 airspeed =0Aless than Vne, so sustained high turbo boost is not practical =
or desired unless =0A25 gallons per hour fuel flow is expected! That's a pr=
etty short flight with 42 =0Agallons total fuel aboard.=0AI set my goals to=
 a more attainable level, with a=A0prop that should draw about =0A200 HP at=
=A06500 RPM. It's a left hand turning equivalent of the prop for RV-8s =0Aw=
ith a 180 HP O-360=A0Lycoming. I have Tracy's RD-1 2.19:1 4 planet gear, so=
 I =0Adon't plan to abuse it past the 200 HP limit he has established.=A0I =
simply =0Acalculated the prop power draw 180HP / 2700RPM =3D 200HP / 3000 R=
PM.=0ABy the way, for you prop chord measuring guys, it's a=A0CATTO 2 blade=
 68x74 prop, =0Awith the greatest chord about 6-3/16" falling from 16" thru=
 20" in from the tip, =0Awhich is right in front of the cowl cheek edge.=0A=
This last week I put the wings on and set the incidence, made the fuel tank=
 =0Aattach brackets and fit the flaps &=A0fairings. Now the wings are back =
off, =0Agetting the fairing platenuts etc. =0A=0AI'm not that far from taki=
ng the whole caboodle to the airport!!=0A-----Original Message-----=0AFrom:=
 Kelly Troyer <keltro@att.net>=0ATo: Rotary motors in aircraft <flyrotary@l=
ancaironline.net>=0ASent: Sun, Oct 17, 2010 9:50 am=0ASubject: [FlyRotary] =
The Case For Turbocharging=0A=0A=0AGroup,=0A=A0=A0=A0 Perhaps of interest t=
o those=A0us interested in Turbocharging our =0Aprojects..........It=0Ais f=
rom the "SDS" website.............=0A=A0=0AKelly Troyer=0A"DYKE DELTA JD2" =
(Eventually)=0A"13B ROTARY"_ Engine=0A"RWS"_RD1C/EC2/EM2=0A"MISTRAL"_Backpl=
ate/Oil Manifold=0A"TURBONETICS"_TO4E50 Turbo=0A-- Homepage:  http://www.fl=
yrotary.com/ Archive and UnSub:   =0Ahttp://mail.lancaironline.net:81/lists=
/flyrotary/List.html  =0A
--0-409484142-1287338356=:4681
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<html><head><style type=3D"text/css"><!-- DIV {margin:0px;} --></style></he=
ad><body><div style=3D"font-family:arial, helvetica, sans-serif;font-size:1=
4pt"><DIV style=3D"FONT-FAMILY: arial, helvetica, sans-serif; FONT-SIZE: 14=
pt">=0A<DIV style=3D"FONT-FAMILY: arial, helvetica, sans-serif; FONT-SIZE: =
14pt">=0A<DIV></DIV>=0A<DIV>Sorry guys..........Did not think about my "Ope=
n Office" files not opening for everyone !!</DIV>=0A<DIV>Hope this is not t=
oo big for the forum !!...................</DIV>=0A<DIV>&nbsp;</DIV>=0A<DIV=
>=0A<H2>Turbocharging Automotive Engines for Aircraft Applications</H2>=0A<=
P></P>=0A<P>April 27/98 =0A<P>With automotive engines finding increasing us=
e powering homebuilt aircraft, we find many people entertaining the idea of=
 turbocharging to boost the power to weight ratios and altitude performance=
 of these engines. We will examine the various facts and myths regarding tu=
rbocharging as applied to light aircraft use.</P>=0A<P><STRONG>History</STR=
ONG></P>=0A<P>Turbos in aircraft were first successfully applied in mass nu=
mbers during WWII. The P-38 and P-47 were the best known turbocharged fight=
er types and both had excellent high altitude performance.</P>=0A<P>In gene=
ral aviation use as applied to air cooled opposed engines, turbocharging ha=
s a less revered reputation. Much of this has to do with the air cooled eng=
ine itself and the fact that most of these engines were never designed to b=
e boosted to begin with. They may have been modified a bit for the turbo bu=
t with power to weight ratios being a major concern, many are structurally =
and thermally not up to the task. Other concerns such as turbo cooling and =
lubrication by inferior aviation type oils also led to premature turbo fail=
ures.</P>=0A<P><STRONG>What is a Turbocharger?</STRONG></P>=0A<P>A turbo co=
nsists of a centrifugal compressor connected to a turbine wheel which is sp=
un at high rpm by the energy of the engine exhaust gasses. It is a very sim=
ple device, but the high temperatures and stresses acting on it require exo=
tic materials in the turbine section which are somewhat expensive. A turbo =
will cost in the neighborhood of $800 to $1300 with the wastegate assembly.=
</P>=0A<P><BR>Turbine wheels come in many shapes and sizes. Constructed of =
high temperature alloys such as Inconel or Hastaloy. This is the hot end. =
=0A<P><BR>Turbine housings are cast from a high nickel/iron alloy. =0A<P>Th=
e compressor pressurizes the intake manifold to achieve higher hp or mainta=
ins sea level pressure as the aircraft climbs. This permits higher climb ra=
tes at altitude and increased cruise speeds.</P>=0A<P><BR>Compressor wheels=
 are cast from aluminum alloy and come in many sizes or trims. This is the =
cold end. =0A<P><BR>Compressor housing is cast from aluminum alloy. Shape i=
s designed to slow the air, thus compressing it. =0A<P><BR>Cast iron center=
 section or bearing housing contains floating sleeve bearings or more recen=
tly ceramic ball bearings. High pressure oil from engine feeds the bearing =
and is drained out the bottom of the housing back into the engine. Some hou=
sings are water cooled to prevent coking of oil deposits leading to bearing=
 failure. =0A<P><STRONG>Elegant Simplicity</STRONG></P>=0A<P>Turbocharging =
is the most efficient method of boosting hp with the least weight penalty k=
nown. A typical turbo installation on a light aircraft including intercoole=
r and exhaust is around 35-50 pounds. Such an installation is capable of tr=
ipling hp at sea level or adding 50% to the naturally aspirated output up t=
o 15,000 feet. Sea level manifold pressures can be maintained to 25,000 fee=
t in some cases. An aircraft capable of 200 knots at sea level would true o=
ut at nearly 300 knots with a good turbo system at high altitude.</P>=0A<P>=
Spinning the compressor with an exhaust driven turbine is a much better way=
 than by the mechanical means as in a supercharger. It is lighter, more rel=
iable and more efficient and has the added advantage of having more drive e=
nergy available as the aircraft climbs due to lower backpresure, which is e=
xactly what is needed. </P>=0A<P><STRONG>Fuel Flow vs. Power</STRONG></P>=
=0A<P>There is a common misconception that turbocharging increases fuel flo=
ws because of the backpressure of the turbine. This may be true in air cool=
ed engines using a poorly matched turbo without intercooling because the ai=
r cooled engine cannot maintain temperature stability without adding fuel f=
or cooling purposes. Reduced fuel flows at altitude in naturally aspirated =
and turbine engines is not due to some magic process, it is due to the fact=
 that as altitude is increased, less power is produced thus less fuel is re=
quired. Many people also don't seem to realize that fuel flow is related to=
 hp developed and that a turbo engine will develop more power at altitude t=
han a naturally aspirated engine, obviously requiring more fuel and deliver=
ing higher speeds at the same time. </P>=0A<P>Testing done back in the '40s=
 and '50s on turbo engines actually confirm that fuel flows were LOWER at t=
he same BMEP with turbocharging than in a naturally aspirated engine develo=
ping the same power. This suggests that when properly applied, the turbo ac=
tually recovers more energy from the exhaust to be applied to reduce pumpin=
g losses during the compression stroke than is consumed during the exhaust =
stroke working against higher backpressure. With approximately 50% of the e=
nergy in the fuel going out the exhaust in the form of heat and pressure, t=
urbocharging can recover some of this waste and put it to good use.</P>=0A<=
P>It was shown that turbos could achieve fuel flows 3-6% lower and turbocom=
pounding could achieve up to 15% lower fuel flows. Cylinder head and piston=
 cooling were shown to be the primary limitations to achieving lower BMSFC =
figures. We can conclude from this that as applied to liquid cooled engines=
 with their superior thermal rejection rates, turbocharging really has few =
disadvantages compared to the many advantages it offers.</P>=0A<P>It should=
 be no surprise that the latest certified liquid cooled engines from Toyota=
 and Orenda are turbocharged. People also should remember the awesome turbo=
compound radials of the '50s. These engines offered extremely low BSFC and =
high power. It seems foolish not to turbocharge most good aircraft engines =
used at any kind of altitude as you are throwing away performance without i=
t.</P>=0A<P><STRONG>Turbocharged Air Cooled Engines</STRONG></P>=0A<P>As me=
ntioned earlier, turbocharged , conventional opposed air cooled engines hav=
e a less than stellar track record and many lay people blame the turbo. In =
fact, the fault lies with the engines it is applied to. The average Lycomin=
g or Continental has a lot of things not going for them. Many of these engi=
nes suffer premature failure of crankcases, cylinders, heads and valves in =
their turbocharged iterations. Let's examine why.</P>=0A<P>Probably the lea=
ding cause of case and barrel cracking is the lack of rigidity these engine=
s have in the cylinder/ case area. For ease of barrel replacement I assume,=
 the designers of these engines chose to bolt the cylinders individually to=
 the crankcase at the bottom of the cylinder using a flange. This arrangeme=
nt creates a very willowy structure and with each firing impulse, combined =
with the sheer mass of the huge reciprocating parts used in these engines, =
a definite high amplitude, cyclic stress is put on these parts eventually l=
eading to cracking. The increased gas pressures associated with turbochargi=
ng compound this problem. This design problem is actually the cause of a ma=
jor portion of the high vibration levels associated with conventional aircr=
aft engines.</P>=0A<P>The flange method puts the barrel under a tension loa=
d with every firing impulse too which is just plain stupid given the thickn=
ess of the cylinders. Modern automotive racing practice would use through s=
tuds to retain the barrels, thus putting the barrels under compression.</P>=
=0A<P>Cylinder head cracking and exhaust valve burning and sticking are pri=
marily due to insufficient cooling in these areas which is exaggerated by t=
he extra heat introduced by turbocharging. Air cooling is relatively ineffi=
cient at sinking heat off around the exhaust port and valve seat area. This=
 problem is compounded by the use of very low compression ratios resulting =
in higher EGTs thus even higher heat flux in the critical exhaust port area=
. Typical air cooled aircraft engines run cylinder head temperatures in exc=
ess of 400 degrees on a regular basis. With aluminum alloys losing roughly =
50% of their strength at this temperature it is easy to see why cracking is=
 all too common here. The high EGT's are also detrimental to the life of th=
e turbo's turbine section.</P>=0A<P>Valve problems are due to the same caus=
e, temperatures being too high from inefficient heat transfer. Many factory=
 turbo aircraft are forced to either open cowl flaps or richen the mixture =
at high altitude to keep temperatures within limits. With power being maint=
ained at altitude and air density falling off, there is often insufficient =
mass flow available for cooling. This is rarely a problem on naturally aspi=
rated engines as power and cooling requirements are dropping off with incre=
asing altitude.</P>=0A<P>Not a lot of design went into the induction system=
 on many of these engines hence fuel distribution is usually not the greate=
st. This contributes to engine roughness and problems with leaning. Leaning=
 is limited by the mixture in the hottest cylinder with the others running =
richer than desired.</P>=0A<P>The oils used in aircraft engines are relativ=
ely crude by modern synthetic automotive standards and consequently not the=
 best for the turbocharger. The use of these oils appears to be a result of=
 the very loose tolerances required in an air cooled engines because of the=
 high operating temperatures which also leads to the high oil consumption c=
haracteristic of these engines.</P>=0A<P>Finally, many certified installati=
ons never used intercooling which is simply amazing. The advantages and nec=
essity of it was clearly understood in WWII. High charge temperatures at al=
titude required even more fuel for cooling and yet more cowl flap opening t=
o control head temperatures.</P>=0A<P><STRONG>Turbocharged Liquid Cooled En=
gines</STRONG></P>=0A<P>Liquid cooled engines are a natural for turbochargi=
ng because of their higher heat rejection capabilities. Water cooling also =
enables the turbo center section to be water cooled which alleviates a prim=
ary cause of turbo failure- coked bearing holes from high heat and fried oi=
l. Water cooled engines can use modern synthetic oils because of their tigh=
ter clearances. Synthetic oils with their much higher temperature capabilit=
ies are more suitable to lubricate the turbo than old fashioned, aircraft o=
ils derived from natural base stocks. The popular Mobil 1 synthetic oil, co=
mmon in the racing world, can withstand temperatures of 350 degrees continu=
ously and even 450 degrees intermittently without significant degradation. =
With proper lubrication and cooling, turbochargers will easily last the lif=
e of the engine.</P>=0A<P>If we compare the Popular Subaru EJ22 and EJ25 ho=
rizontally opposed 4 cylinder engines to their certified counterparts we fi=
nd many advantages especially in turbocharged trim. The Subaru has 5 main b=
earings instead of 3 which means that the crank is better supported. The Su=
baru has a higher compression ratio for higher thermal efficency. Its overh=
ead cam, 4 valve per cylinder arrangement provides lower friction and highe=
r volumetric efficiency than a 2 valve pushrod setup. Finally, the integrat=
ed block and head design is many times stiffer and stronger than the aircra=
ft engine.</P>=0A<P>As long as the radiator and ducting are properly design=
ed, cooling problems are not a concern on the liquid cooled engine.</P>=0A<=
P>The induction system on the Subaru has proper runner lengths to boost tor=
que, relatively equal airflow to each cylinder and can easily use a modern =
digital, electronic fuel injection system to precisely meter fuel. All of t=
hese things aid in producing more power with less fuel.</P>=0A<P><STRONG>Po=
wer vs. Weight vs. Manifold Pressure vs. Life vs. Cost</STRONG></P>=0A<P>Th=
e EJ engines when turbocharged and equipped with a radiator, PSRU and compo=
site propeller are slightly heavier than the popular Lycoming and Continent=
al 360 cubic inch engines which are rated at 180- 200 hp for takeoff and ar=
ound 135- 150 hp for maximum cruise. The Subaru can easily attain 200- 250 =
hp at 50 inches for takeoff and reliably deliver 140 to 170hp at 35-38 inch=
es for cruise. The 3.3L EG33 six cylinder is capable of 300+ hp for takeoff=
 and 200-250 hp in cruise making it a viable alternative to the O-540 engin=
es. These power levels can be maintained during climb and cruise at altitud=
e thanks to turbocharging and liquid cooling.</P>=0A<P>Projected TBO is in =
the 1000-1200 hour range at this time. Most people flying the EJ engines ar=
e confident that no interim work will be required during this period such a=
s cylinder barrel replacement and valve grinding operations which are quite=
 common on aircraft engines before reaching their stated TBO. In other word=
s, if you change the oil and check the water, that is about all that is req=
uired during those 1000 hours. There are no magneto or even valve adjustmen=
ts to worry about. Expect spark plug replacement every 100- 250 hours or so=
 at $3 each. Overhaul costs will range from about $500 to $1500 for parts a=
nd machine work depending on condition. Labor would be in the $500 to $1200=
 range. We are all familiar with the costs to overhaul a certified aircraft=
 engine. =0A<CENTER></CENTER>=0A<P></P>=0A<P><STRONG>Matching a Turbocharge=
r</STRONG></P>=0A<P>As applied to the popular Subaru EJ22 and EJ25 engines =
for general purpose use below 15,000 feet we can narrow the choice of turbo=
s down a bit. Garrett T3 turbos are recommended as they are relatively chea=
p, reliable and easy to fix with a vast array of combinations available. Th=
e compressor side may be either a -50, -60 or super 60 wheel with a stage 3=
 turbine wheel in a .82 A/R housing, depending on the exact use and hp. The=
se may be ordered with an integral wastegate and a water cooled bearing hou=
sing which are both highly recommended. These turbos are quite capable of p=
roducing enough boost to extract 250 hp at sea level and still have 175+ hp=
 available at 15,000 feet.</P>=0A<P>The integral wastegates are generally m=
ore reliable than an external type especially on an aircraft application in=
 which it is almost constantly bypassing exhaust. The wastegate is simply a=
 valve used to bypass exhaust gasses around the turbine to control turbine =
and compressor speed and thus boost pressure. It is usually actuated automa=
tically by a diaphragm sensing manifold pressure.</P>=0A<P>Many people have=
 tried to use the OE turbo on auto aircraft conversions, often with limited=
 success. The turbos on cars were not matched to operate at high altitude a=
nd continuous high power settings so they are mismatched and inefficient wh=
en used on aircraft. High exhaust back pressures and overspeeds with conseq=
uent catastrophic failure are not uncommon. In extreme cases, compressor or=
 turbine wheel bursts can cause engine damage and failure due to part inges=
tion or oil loss. This is not a good idea. Use a turbo which is professiona=
lly matched for your engine and intended use by someone familiar with high =
altitude turbocharging. =0A<P><STRONG>Intercooling</STRONG></P>=0A<P>Interc=
oolers are heat exchangers placed between the compressor and intake manifol=
d. Their purpose is to reduce the temperature of the compressed air before =
it enters the engine. Whenever air is compressed, its temperature increases=
. In the case of a high boost turbo at high altitude, the air exiting the c=
ompressor may reach 300-350 degrees F. This lowers the mass flow of air int=
o the engine and reduces power. It also raises EGTs and lowers the detonati=
on limits. All of these things are detrimental to performance and engine lo=
ngevity. </P>=0A<P>An effective intercooler will lower the charge temperatu=
re to within a few degrees of the ambient temperature.</P>=0A<P><STRONG>Exh=
aust Systems</STRONG></P>=0A<P>The exhaust system on turbocharged engines i=
s critically important. High temperature materials such as stainless steel =
or Inconel should be used for their construction to ensure longevity. Tubin=
g thickness should be a minimum of .060 inch to withstand the constant 1500=
 degree temperatures. Careful attention to thermal expansion is necessary s=
o that cracking possibilities are minimized. Bellows or slip joints are oft=
en required at junctions. The turbo itself should never be supported by the=
 headers. A strong, triangulated structure should support the weight of the=
 turbo on the engine.</P>=0A<P>If possible, the primary header tubes should=
 be equal length and mandrel bent for low restriction and maximum pulse ene=
rgy with equal pulse spacing. The turbine discharge pipe should be 2.25 to =
2.5 inches to minimize backpressure. A muffler is often unnecessary to redu=
ce exhaust noise as the turbo usually does a good job of this. This helps t=
o offset the weight of the turbo installation to some degree.</P>=0A<P><STR=
ONG>Future Developments</STRONG></P>=0A<P>Watch the Aircraft section for pi=
ctures and updates on turbo installations as they become available. We are =
currently flying our turbocharged EJ22 powered RV6A seen elsewhere on this =
site.</P>=0A<P>R.F.</P></DIV>=0A<DIV>&nbsp;</DIV>=0A<DIV>=0A<H2>Fuel Octane=
 vs. HP</H2>=0A<P></P>=0A<P>03/13/98</P>=0A<P>In turbocharged engines there=
 is a fine balancing act when it comes to making a lot of power on low octa=
ne fuel. In most cases, ignition timing must be retarded as the boost press=
ure rises above a critical point and finally there reaches a further point =
where the engine simply loses power. If the timing was not retarded with in=
creasing boost, destructive preignition or detonation would occur. Normal c=
ombustion is characterized by smooth, even burning of the fuel/air mixture.=
 Detonation is characterized by rapid, uncontrolled temperature and pressur=
e rises more closely akin to an explosion. It's effects are similar to taki=
ng a hammer to the top of your pistons. </P>=0A<P>Most engines make maximum=
 power when peak cylinder pressures are obtained with the crankshaft around=
 15 degrees after TDC. Experimentation with increasing boost and decreasing=
 timing basically alters where and how much force is produced on the cranks=
haft. Severely retarded timing causes high exhaust gas temperatures which c=
an lead to preignition and exhaust valve and turbo damage.</P>=0A<P>We have=
 a hypothetical engine. It's a 2.0L, 4 valve per cylinder, 4 cylinder type =
with a 9.0 to 1 compression ratio and it's turbocharged. On the dyno, the m=
otor puts out 200hp at 4psi boost with the timing at the stock setting of 3=
5 degrees on 92 octane pump gas with an air/fuel ratio of 14 to 1. We retar=
d the timing to 30 degrees and can now run 7psi and make 225hp before deton=
ation occurs. Now we richen the mixture to 12 to 1 AFR and find we can get =
8psi and 235 hp before detonation occurs. The last thing we can consider is=
 to lower the compression ratio to 7 to1. Back on the dyno, we can now run =
10psi with 33 degrees of timing with an AFR of 12 to 1 and we get 270 hp on=
 the best pull.</P>=0A<P>We decide to do a test with our 9 to 1 compression=
 ratio using some 118 octane leaded race gas. The best pull is 490 hp with =
35 degrees of timing at 21 psi. On the 7 to 1 engine, we manage 560 hp with=
 35 degrees of timing at 25psi. To get totally stupid, we fit some larger i=
njectors and remap the EFI system for126 octane methanol. At 30psi we get 7=
00hp with 35 degrees of timing!</P>=0A<P>While all of these figures are hyp=
othetical, they are very representative of the gains to be had using high o=
ctane fuel. Simply by changing fuel we took the 7 to 1 engine from 270 to 7=
00 hp.</P>=0A<P>From all of the changes made, we can deduce the effect cert=
ain changes on hp;</P>=0A<P>Retarding the ignition timing allows slightly m=
ore boost to be run and gain of 12.5%.</P>=0A<P>Richening the mixture allow=
s slightly more boost to be run for a small hp gain however, past about 11.=
5 to 1 AFR most engines will start to lose power and even encounter rich mi=
sfire.</P>=0A<P>Lowering the compression ratio allows more boost to be run =
with less retard for a substantial hp gain.</P>=0A<P>Increasing the octane =
rating of the fuel has a massive effect on maximum obtainable hp.</P>=0A<P>=
We have seen that there are limits on what can be done running pump gas on =
an engine with a relatively high compression ratio. High compression engine=
s are therefore poor candidates for high boost pressures on pump fuel. On h=
igh octane fuels, the compression ratio becomes relatively unimportant. Ult=
imate hp levels on high octane fuel are mainly determined by the physical s=
trength of the engine. This was clearly demonstrated in the turbo Formula 1=
 era of a decade ago where 1.5L engines were producing up to 1100 hp at 60p=
si on a witches brew of aromatics. Most fully prepared street engines of th=
is displacement would have trouble producing half of this power for a short=
 time, even with many racing parts fitted.</P>=0A<P>Most factory turbocharg=
ed engines rely on a mix of relatively low compression ratios, mild boost a=
nd a dose of ignition retard under boost to avoid detonation. Power outputs=
 on these engines are not stellar but these motors can usually be seriously=
 thrashed without damage. Trying to exceed the factory outputs by any appre=
ciable margins without higher octane fuel usually results in some type of e=
ngine failure. Remember, the factory spent many millions engineering a reas=
onable compromise in power, emissions, fuel economy and reliability for the=
 readily available pump fuel. Despite what many people think, they probably=
 don't know as much about this topic as the engineers do.</P>=0A<P>One last=
 method of increasing power on turbo engines running on low octane fuel is =
water injection. This method was evaluated scientifically by H. Ricardo in =
the 1930s on a dyno and showed considerable promise. He was able to double =
power output on the same fuel with the aid of water injection. </P>=0A<P>Fi=
rst widespread use of water injection was in WW2 on supercharged and turboc=
harged aircraft engines for takeoff and emergency power increases. The wate=
r was usually mixed with 50% methanol and enough was on hand for 10-20 minu=
tes use. Water/methanol injection was widely used on the mighty turbocompou=
nd engines of the '50s and '60s before the advent of the jet engine. In the=
 automotive world, it was used in the '70s and '80s when turbos suddenly be=
came cool again and where EFI and computer controlled ignitions were still =
a bit crude. Some Formula 1 teams experimented with water injection for qua=
lifying with success until banned. </P>=0A<P>My personal experience with wa=
ter injection is considerable. I had several turbo cars fitted with it. One=
 2.2 liter Celica with a Rajay turbo, Weber carb and no intercooler or inte=
rnal engine mods ran 13.3 at 103 on street rubber on pump gas back in 1987.=
 This was accomplished at 15psi. With the water injection switched off, I c=
ould only run about 5 psi before the engine started to ping. I think you mi=
ght see water injection controlled by microchips, catch on again in the com=
ing years on aftermarket street turbo installations. It works.</P></DIV>=0A=
<DIV><BR>&nbsp;</DIV>=0A<P>Kelly Troyer<BR><STRONG><FONT size=3D4>"DYKE DEL=
TA JD2"</FONT> <FONT size=3D1>(Eventually)</FONT></STRONG></P>=0A<P>"13B RO=
TARY"_ Engine<BR>"RWS"_RD1C/EC2/EM2<BR>"MISTRAL"_Backplate/Oil Manifold</P>=
=0A<P>"TURBONETICS"_TO4E50 Turbo</P>=0A<DIV><BR></DIV>=0A<DIV style=3D"FONT=
-FAMILY: arial, helvetica, sans-serif; FONT-SIZE: 14pt"><BR>=0A<DIV style=
=3D"FONT-FAMILY: times new roman, new york, times, serif; FONT-SIZE: 12pt">=
<FONT size=3D2 face=3DTahoma>=0A<HR SIZE=3D1>=0A<B><SPAN style=3D"FONT-WEIG=
HT: bold">From:</SPAN></B> "shipchief@aol.com" &lt;shipchief@aol.com&gt;<BR=
><B><SPAN style=3D"FONT-WEIGHT: bold">To:</SPAN></B> Rotary motors in aircr=
aft &lt;flyrotary@lancaironline.net&gt;<BR><B><SPAN style=3D"FONT-WEIGHT: b=
old">Sent:</SPAN></B> Sun, October 17, 2010 12:40:28 PM<BR><B><SPAN style=
=3D"FONT-WEIGHT: bold">Subject:</SPAN></B> [FlyRotary] Re: The Case For Tur=
bocharging<BR></FONT><BR><FONT color=3Dblack size=3D2 face=3Darial>=0A<DIV>=
Kelly:</DIV>=0A<DIV>Maybe I'm a bonehead, but those zip files didn't includ=
e anything readable for me....</DIV>=0A<DIV>On the other hand, I'm using a =
Turbo on my RV-8 prject, so I'm in as far as selecting a turbo.</DIV>=0A<DI=
V>I finally decided to use a turbo because of Tracy's muffler experiments. =
I have a Turbo engine, with the open exhaust ports, so the sound pressure i=
s very high and would require an extra strong and tough exhaust system (hea=
vy). So I decided to use that weight in the form of a Turbo to knock the mo=
st vicious element form the exhaust noise. I&nbsp;hope for&nbsp;a higher ra=
te of climb as a result of the increased power potential. </DIV>=0A<DIV>I r=
ealize that all engines have a sweet spot that would be best for cruise and=
 range, which would co-incide with the engine torque peak RPM&nbsp;and an a=
irspeed less than Vne, so sustained high turbo boost is not practical or de=
sired unless 25 gallons per hour fuel flow is expected! That's a pretty sho=
rt flight with 42 gallons total fuel aboard.</DIV>=0A<DIV>I set my goals to=
 a more attainable level, with a&nbsp;prop that should draw about 200 HP at=
&nbsp;6500 RPM. It's a left hand turning equivalent of the prop for RV-8s w=
ith a 180 HP O-360&nbsp;Lycoming. I have Tracy's RD-1 2.19:1 4 planet gear,=
 so I don't plan to abuse it past the 200 HP limit he has established.&nbsp=
;I simply calculated the prop power draw 180HP / 2700RPM =3D 200HP / 3000 R=
PM.</DIV>=0A<DIV>By the way, for you prop chord measuring guys, it's a&nbsp=
;CATTO 2 blade 68x74 prop, with the greatest chord about 6-3/16" falling fr=
om 16" thru 20" in from the tip, which is right in front of the cowl cheek =
edge.</DIV>=0A<DIV>This last week I put the wings on and set the incidence,=
 made the fuel tank attach brackets and fit the flaps &amp;&nbsp;fairings. =
Now the wings are back off, getting the fairing platenuts etc. </DIV>=0A<DI=
V>I'm not that far from taking the whole caboodle to the airport!!</DIV>=0A=
<DIV style=3D"FONT-FAMILY: arial, helvetica; COLOR: black; FONT-SIZE: 10pt"=
>-----Original Message-----<BR>From: Kelly Troyer &lt;keltro@att.net&gt;<BR=
>To: Rotary motors in aircraft &lt;flyrotary@lancaironline.net&gt;<BR>Sent:=
 Sun, Oct 17, 2010 9:50 am<BR>Subject: [FlyRotary] The Case For Turbochargi=
ng<BR><BR>=0A<DIV id=3DAOLMsgPart_2_a4531c23-5030-4356-b4cb-13178de8d1ce>=
=0A<STYLE type=3Dtext/css>#AOLMsgPart_2_a4531c23-5030-4356-b4cb-13178de8d1c=
e td{color:black;}#AOLMsgPart_2_a4531c23-5030-4356-b4cb-13178de8d1ce DIV {m=
argin:0px;}</STYLE>=0A=0A<DIV style=3D"FONT-FAMILY: arial, helvetica, sans-=
serif; FONT-SIZE: 14pt">=0A<DIV style=3D"FONT-FAMILY: arial, helvetica, san=
s-serif; COLOR: #000000; FONT-SIZE: 14pt">=0A<DIV></DIV>=0A<DIV>Group,</DIV=
>=0A<DIV>&nbsp;&nbsp;&nbsp; Perhaps of interest to those&nbsp;us interested=
 in Turbocharging our projects..........It</DIV>=0A<DIV>is from the "SDS" w=
ebsite.............<BR>&nbsp;</DIV>=0A<DIV>Kelly Troyer<BR><STRONG><FONT si=
ze=3D4>"DYKE DELTA JD2"</FONT> <FONT size=3D1>(Eventually)</FONT></STRONG><=
/DIV>=0A<DIV>"13B ROTARY"_ Engine<BR>"RWS"_RD1C/EC2/EM2<BR>"MISTRAL"_Backpl=
ate/Oil Manifold</DIV>=0A<DIV>"TURBONETICS"_TO4E50 Turbo</DIV>=0A<DIV></DIV=
></DIV></DIV></DIV>=0A<DIV style=3D"BACKGROUND-COLOR: #fff; MARGIN: 0px; FO=
NT-FAMILY: Tahoma, Verdana, Arial, Sans-Serif; COLOR: #000; FONT-SIZE: 12px=
" id=3DAOLMsgPart_5_a4531c23-5030-4356-b4cb-13178de8d1ce><PRE style=3D"FONT=
-SIZE: 9pt"><TT>--=0AHomepage:  http://www.flyrotary.com/=0AArchive and UnS=
ub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html=0A=0A</TT>=
</PRE></DIV></DIV></FONT></DIV></DIV></DIV></DIV></div></body></html>
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