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From: "Mike Wills" <rv-4mike@cox.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Throttle limits was  Re: N.A. Renesis to turbo
Date: Mon, 8 Feb 2010 19:36:19 -0800
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Thanks Ed. Mentioned this a few months ago and was convinced at least for 
the moment, to just fly the plane as is. So that's what I have been doing.

To recap, my engine is an NA 13B built by Bruce Turrentine. It is a second 
gen engine with Turbo rotor housings (no exhaust splitter) and high 
compression NA rotors. The exhaust uses 1 3/4" x 32" primaries into a Burns 
merge collector, 2 1/2" outlet directly into my "muffler". My "muffler" is 
essentially a 4 1/2" x 30" tube with some spiral baffles and 2 1/2" 
inlet/outlet. The intake uses a modified 87 lower manifold casting port 
matched to the engine. The upper manifold uses 4 tubes (1 1/2" and 1 1/4" 
dia) over the top of the engine to a small dynamic chamber/plenum directly 
over the oil filler port in the center iron housing. The throttle body 
copies Tracy's original - a stock second gen 3 throat TB cut down to just 2 
ports.

The gearbox is Tracy's first RD-1 with 2.17 gears. Prop is a Warnke 68 x 80 
(not sure the pitch number is meaningful - everyone seems to measure it 
differently). On the ground static RPM is about 5350 and is reached at about 
2/3 throttle opening. In flight max RPM I've seen is about 5750.

The Warnke prop is unique due to the shape. The appearance gets a lot of 
comments. I'm really hesitant to mess with it and screw it up unless/until I 
can say with certainty that there isnt something else I can do with tweaking 
(I'm thinking on the intake side) to improve airflow through the engine.

Hard to believe that there isnt more HP to be had when a hacked 2 barrel TB 
is only 2/3 open and I've hit the limit. But like you say there are a lot of 
variables.

Mike

--------------------------------------------------
From: "Ed Anderson" <eanderson@carolina.rr.com>
Sent: Monday, February 08, 2010 5:06 AM
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: [FlyRotary] Throttle limits was  Re: N.A. Renesis to turbo

> Hi Mike,
>
> Several things could be causing the situation you see in advancing your
> throttle but getting no increased engine rpm.  This is not an uncommon
> situation. Ok assuming we are talking naturally aspired engine (no forced
> induction), fixed pitch prop and assuming your engine is basically OK (not
> weak on compression, etc),
>
> then the most  likely cause is you have simply reach the point at which
> where the engine is producing all the power it can - given the prop load 
> it
> sees at that moment.  Once that point is reached, then advancing the
> throttle more does not result in more air flow through the engine and
> therefore no increase in power nor rpm.  In fact, it can cause the engine 
> to
> run leaner and actually produce less power than a partial closed throttle.
>
> It's sort of the chicken and the egg in that you need more power to 
> produce
> more rpm, but power is dependent on air flow - which is dependent on rpm
> which dependent on power produced, etc. {:>).  But to try to be a bit more
> helpful, look at it this way.
>
>
> Basically for every throttle position (at a constant altitude, temp, air
> density, etc) there is one associated manifold pressure(air density). 
> This
> manifold pressure is a product of a number of variables, but the most
> dominating ones involving the engine are volumetric efficiency,  throttle
> position and engine rpm.  Now your volumetric efficiency is more or less
> fixed by the intake/exhaust design so we'll eliminate that for the moment.
> That leaves throttle position and rpm as controllable variables and your
> ambient air density as a fixed (for this discussion).
>
>
> We know the engine is a positive displacement pump which displaces the 
> same
> volume once each engine cycle. The power the engine produces in that cycle
> is limited by the density of the air in the combustion chamber as the 
> volume
> is always a constant (fixed by size of your combustion chamber).  The air
> density into the combustion chamber is dependent on the air density in the
> intake manifold.
>
> So that leaves us with:  More throttle = higher manifold air density =
>  = more oxygen + More fuel(permits more fuel to be burnt) = more power =
> more rpm.  That is until you hit the limit - what limit you say?
>
> The limit is that once you have opened the throttle plate sufficiently 
> that
> the air density in the intake manifold is equal to ambient air density (or
> as close as its going to get- given intake losses) - then it will not make
> any difference (in power) to advance the throttle further.  Once you have
> reached that limit, then advancing the throttle further does not further
> increase the air density in the manifold and therefore limits the amount 
> of
> fuel you can burn/power you can make.
>
> Clearly if you have a large throttle body you can reach that point with a
> smaller opening of the throttle plate than if you have a small throttle
> body.
>
> As I said - there can be other causes, but this is the one I think most
> folks run into. You can find the same situation even on the ground, where
> again once the manifold air density = ambient air density (or as close as
> your engine Ve will permit) you stop producing power increase even if you
> have throttle travel left.
>
> Therefore if your throttle body is sized so you get max power at 100%
> throttle opening a sea level, then with every increase in altitude, you 
> will
> find you have additional throttle travel that produces no increase in 
> power.
> The higher you go in altitude the more throttle travel will be available
> that results in no power increase.  This is because the ultimate limit is
> based on the ambient air density.
>
> Hope this helped.
>
> Ed
>
>
>
>
> Ed Anderson
>
> Rv-6A N494BW Rotary Powered
>
> Matthews, NC
>
> eanderson@carolina.rr.com
>
> http://www.andersonee.com
>
> http://www.dmack.net/mazda/index.html
>
> http://www.flyrotary.com/
>
> http://members.cox.net/rogersda/rotary/configs.htm#N494BW
>
> http://www.rotaryaviation.com/Rotorhead%20Truth.htm
>
> -----Original Message-----
> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
> Behalf Of Mike Wills
> Sent: Sunday, February 07, 2010 12:51 PM
> To: Rotary motors in aircraft
> Subject: [FlyRotary] Re: N.A. Renesis to turbo
>
> Don,
>
> I'm at about 23 hours and am seeing roughly the same performance on my 
> RV-4
> with a Bruce T built gen 2 13B. My temps are a little cooler. I'm pretty
> happy with the performance, but like you say, its not possible to have too
> much power. But I don't have room for a turbo and intercooler.
>
> I think there's more power in my NA engine. I'm still a little mystified 
> by
> the fact that at about 1/2 - 2/3 throttle the engine stops making any more
> power. But I decided to take several people's advice and just fly it for a
> while. I also think there's more speed in it via some drag reduction. A
> turbo would be nice to tame the noise though.
>
> I'll be interested in seeing how the Burns muffler works out for you. I'm
> not willing to dive into any more muffler experiments for the moment since
> my failed trial with the DNA muffler. But sooner or later, and one way or
> another I have to quiet this thing down.
>
> Mike Wills
> RV-4 N144MW
>
> --------------------------------------------------
> From: "Don Wallker" <drwalker@gbis.com>
> Sent: Saturday, February 06, 2010 6:21 PM
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Subject: [FlyRotary] N.A. Renesis to turbo
>
>> Dear list, Turbo flyers and especially David Leonard,
>>    I've 16 flying hours on my RV-8 with a Renesis and all of Tracy's 
>> stuff
>
>> and a Catto 76/88.  The airplane flys great, just like an RV, no gliding
>> time, and about 36 hours on the ground. SPECS
>> Full throttle 8,000'   174 mph indicated, 2450 on the prop, water 185, 
>> oil
>
>> 205,
>> Climb out 110 mph, rate of climb, 1250'/min.  Field elevation 5046.
>>
>> These are not bad numbers, but I would like better.  I've been influenced
>> by some of the the local jet jocks who say that there is no such thing as
>> too much horsepower and they are right!   N113BR seems to be performing
>> about like a 160-170 HP RV.  So I am investigating turboing it!  The idea
>> is to have a little better than sea level performance on take off
>> (designed for 210HP N.A.) and turbo normalizing at cruise.  Up to 12000'
>> would be nice.
>> During the air races this year, Dave Leonard showed up and I was very
>> impressed by his airplane.  He was able to turbo and inter cool it and
>> have it all inside an RV cowl, so I'll  likely base my installation on
>> his.  Plus, he has been through the learning curve of 3 or so turbos so 
>> he
>
>> knows what to do, what not to do and what would be better if he were to 
>> do
>
>> it all over again.
>>
>> I've spent the afternoon looking through the archives, reading as much as
>> I can find about turbos, and downloading all the photos I can.  Here is
>> what I am tentatively planning  on doing.
>> Get one of Techwelding's Renesis exhaust flanges made from 304 SS and 
>> have
>
>> my local waterjet guy copy it and make one out of 321SS.  I'll weld 321 
>> SS
>
>> and  manifold it together and run it into the bottom of the turbo that
>> will sit right in front of the exhaust.  The turbo will have additional
>> support.  Run the turbo outlet air from it through a stock RX-7 inter
>> cooler sitting in front of the left cheek opening and then out to the
>> right side of the engine, probably routing it under the PSRU and then up
>> to a throttle body and manifold.  Then four al tubes over the top of the
>> engine into a cut down and welded up stock RX-8  intake manifold.  The
>> exhaust out of the turbo will run down and out in the usual center of the
>> back of the cowl opening.  I am thinking of trying one of Burns Stainless
>> all SS mufflers.  It is basically a glass pack, but instead of glass, 
>> they
>
>> are using stainless steel wool and they say it is holding up for the
>> rotary racers.  They make it any length you want and is about 4 lbs with
>> their SS vs 9 lbs with the hushpower 2 I'm using now.  The combustion air
>> intake to the turbo will be on the aft left side of the cowl via an NACA
>> duct opening as Dave's is.
>> The oil cooler will have to be moved to under the engine.  I will build 
>> up
>
>> a fiberglass scoop, probably based on Van's scoop and modify it to have a
>> bigger opening and be farther forward, closer to the prop.  I will
>> probably  have the oil cooler made a little larger (Techwelding) than the
>> one I have now.
>>
>> That's the basic idea at this point.  I'll finalize my plan, prebuild as
>> much as possible before tearing the airplane apart and try for as little
>> down time as possible.  I'm looking for the list's critique here, plus
>> questions that I will have missed.  The following are a list of questions
>> that I have.
>> 1. Which turbo should I use, which orientation and who should I use to do
>> the work, plus what is the approximate price?   TO4 hybrid?  Dave and
>> Steve Brooks mention BNR turbo as a modifier.  Who manufactures the 
>> turbo?
>> 2. What is the ideal situation with a waste gate?  Full open or not, or,
>> or?
>> 3. I read about a N.O.oil line solenoid to the turbo bearings.  I assume
>> that if the Turbo fails, you turn it on to the N.C. position to prevent
>> oil from being pumped down your exhaust?  I assume the oil that is used 
>> is
>
>> routed back to the sump.
>> 4. What size exhaust is optimum?  It seems Dave is running 2.5 inch.
>> 5.  What size throttle body should I use and what would be a good one? 
>> One
>
>> throttle body or two? 4.  What size injectors should I use, and where
>> should the secondaries be placed?   Dave is using 480cc and staging is at
>> 32 inches.  Are you using the same for the primaries and is there an idle
>> problem with the larger injectors?
>> 5.  Anyone out there turboing a Renesis?  Anyone flying one?
>> 6.  My compression is 9.7 to 1.   Any problems with this higher
>> compression ratio as long as I use an inter cooler and keep the boost no
>> higher than 35"?
>> And lot more questions, but that's all I can think of now.
>> So If any of you can add any thought, let me know.
>>
>> Don Walker
>>
>> --
>> Homepage:  http://www.flyrotary.com/
>> Archive and UnSub:
>> http://mail.lancaironline.net:81/lists/flyrotary/List.html
>>
>
>
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