X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from poplet2.per.eftel.com ([203.24.100.45] verified) by logan.com (CommuniGate Pro SMTP 5.3.4) with ESMTP id 4181751 for flyrotary@lancaironline.net; Sun, 28 Mar 2010 17:04:44 -0400 Received-SPF: none receiver=logan.com; client-ip=203.24.100.45; envelope-from=lendich@aanet.com.au Received: from sv1-1.aanet.com.au (mail.aanet.com.au [203.24.100.34]) by poplet2.per.eftel.com (Postfix) with ESMTP id 0B73917356E for ; Mon, 29 Mar 2010 05:04:06 +0800 (WST) Received: from ownerf1fc517b8 (203.171.92.134.static.rev.aanet.com.au [203.171.92.134]) by sv1-1.aanet.com.au (Postfix) with SMTP id A9D51BEC00D for ; Mon, 29 Mar 2010 05:04:04 +0800 (WST) Message-ID: <6EFF3904ED704E23AC8D9A93540C6F99@ownerf1fc517b8> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: P-Port performance Date: Mon, 29 Mar 2010 07:04:06 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000F_01CACF0E.0564BBE0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Antivirus: avast! (VPS 100328-1, 03/28/2010), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_000F_01CACF0E.0564BBE0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Thanks Tracy, I agree these are average and ball park figures. The numbers which were = interesting to me were the difference between large and smaller inlets = and how much that affected the velocities. It is nice to know that = velocities might peak at .6 mach or more, I wasn't aware of that, I = thought maybe 200 mph would be peak - I will tuck that bit of info away. For me working these figures helped me to understand what to expect from = the engine. I just thought it might help others as well. George ( down under) George, your numbers look reasonable. Only thing I would add is that = the calculated runner speed is an average. The actual velocity in a = running engine varies radically (it even reverses). The significant = speed is peek velocity which is so high it is measured in Mach. Mach .6 = or more is not uncommon in a well tuned engine. It is the energy in = this peek velocity which allows better volumetric efficiency at the = tuned rpm. Tracy On Sat, Mar 27, 2010 at 10:43 PM, George Lendich = wrote: Naturally I take on board all Lynn and Ed say, as they have helped = me understand how things work and Ed with the maths to give a ball park = figure rather than a WAG, on performance. So I have condensed the figures Ed gave me a tried to make it as = simple as possible to show others - see attached. I hope this helps = those willing to look into the maths. You will notice that the results strongly agree with what Lynn has = stated (in general terms). This in turn strongly agrees with what = powersport was using i.e. 40mm up to 6,000 rpm and 44mm up to 7,500rpm = (checked this with Bill). What Lynn has suggested is 50mm reduced 15% = 42.5mm - hello! I've seen that figure before - dia required at 7,200 = rpm. I also agree with what Lynn suggests on P-port shapes - I just find = round easier to do, so round is probably not optimum, but good enough = for some. Some of the Renesis figures I've increased hp in line with = compression increase and rounded off some end result figures. Hope it helps - it sure helped me. George ( down under) =93that things that work in one application (like Rx-7 racing) = just great - may well suck in another application.=94 Or not suck enough=85. ;) Neilk Here is some more stuff to read, since none of you are building = right now.=20 http://mototuneusa.com/think_fast_intake_porting.htm This fellow fills in some cross section on the intake runners of = big engine street and road race bikes. Even the factory people fall in love with maximum HP numbers to = sell bikes. The big numbers at the top RPM require big intake runners. = Big intake runners means high flow velocity will be at astoundingly high = RPM. This means the reverse will be available at mid and lower RPM. So, = the rider is beaten silly on the road course by some weekend nitwit with = a smaller engine, that appears to be stock. He obviously has less = maximum HP, but seems to be doing quite well with his setup.=20 Because....... The smaller engine has good torque and HP at lower and mid range = RPM. Maybe he is not as fast at the end of the long straightaway, but he = seems to get to his top speed much sooner than the new bike with the = bigger engine. And in road racing and drag racing, it is the first = person to his top speed that wins, not always the highest top speed.=20 Think gear ratio spreads, and area under the curve when you graph = HP.=20 Racing engines and airplane engines are the same engines. Some = racing organizations even use rev limiters to equalize competition = between car brands to keep the racing interesting. So you have to = imagine that your club, be it hair club for men or the home built = airplane club has a rule about top RPM.=20 Of course the club has no such rule, but Mother nature does have = such a rule. It has to do with the tip speed of propellers. So once you = calculate the ratio of your reduction unit, you know how fast you can = turn up your engine. And it isn't very much RPM.=20 So now you are unhappy with the torque of the car engine that had = good torque at 2,500 RPM in the street car, and now you want the best = torque to be where? 5,000 RPM with best HP at 5,800 or 6,000 RPM?=20 Note that the car engine has short runners for high RPM and = valving to lengthen the runners for low RPM. You might even say that low = RPM is where the airplane engine runs all of the time. This should be = easy. That length thing has to do with tuned length, or a pipe organ = effect.=20 And our motorcycle friend above shows us that in order to fill out = the mid range,(right where airplane engines run) you need to fill in = part of the intake runners.=20 So folks are making errors at both ends of the runner. The = Throttle body is so big that the last 1/3 to 1/4 of opening has no = affect on RPM. Fortunately this has nearly no affect on HP. At the = engine end of the runner just as in the stock intake manifold the runner = needs to be smaller just as it mates with the block. So the highest flow = velocity is right at the port face.=20 The rotary has a problem that involves the bowl shape below the = opening into the engine, valved by the sides of the rotor. In order to = get the valve timing we need, that bowl is too big (Too much volume). = Some folks fill this in a bit with epoxy products. Some folks make it = worse by increasing the port timing but that makes the bowl volume = increase. The bowl volume causes the velocity to drop right where we = want the highest velocity.=20 Some folks make Periphery port engines with 2" tubing run from = some distance that seems to make sense. This is a big help at RPM above = where you can use it for anything. So at RPM lower than the ideal to = take advantage of the Pport, there is less HP than a side port engine.=20 The opening into the housing with a Pport is usually a round hole. = Not ideal. Later intake opening and earlier closing give you more mid = range. The 2 inch pipe flattened slightly, or a dart removed to reduce = the ID about 15% or a bit more. would keep the velocity high, where it = needs to be high. The best HP should be just before the top speed, so = you can lean away power and heat to get down to cruise RPM.=20 Like the racer you want to be first to your top speed. If you have = to pull off throttle to stay at cruise RPM, add some prop and test = again. The engine will make power to well past 9,000 RPM in street trim, = if the breathing is available.=20 If you want to go real fast, cool the oil. A 12-A can do 310 HP at 10,700 RPM breathing through two 44MM = holes. My side port 12-As can do 250 HP at 9,400 RPM breathing through = two 38MM holes. My intake manifold gasket is stock. The runners at the = port face are the street diameter and shape. A 12-A is 2,292 CCs, a 13-B = is 2,606CCs. These engines are not dynoed below 7,000 RPM, because they = have no power at all below that RPM it is pointless to test there. They = are towed to the false grid with little tractors because they have no = torque at all and they idle at 2,200 RPM. So if you keep building racing engines and puting them into = airplanes that operate below the bottom of the power band of the engine, = why do you do that? Doctor, Doctor, it hurts when I do that. Quit doing = that. Of course I could be completely wrong. Lynn E. Hanover =20 -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_000F_01CACF0E.0564BBE0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
 Thanks Tracy,
I agree these are average and ball = park=20 figures. The numbers which were interesting to me were the = difference=20 between large and smaller inlets and how much that affected = the velocities.=20 It is nice to know that velocities might peak at .6 mach or more, = I  wasn't=20 aware of that, I thought maybe 200 mph would be peak - I = will=20 tuck that bit of info away.
For me working these figures helped me = to=20 understand what to expect from the engine. I just thought it might = help=20 others as well.
George ( down under)
 
George, your numbers look reasonable.  Only thing I would add = is that=20 the calculated runner speed is an average.  The actual velocity in = a=20 running engine varies radically (it even reverses). The significant = speed is=20 peek velocity which is so high it is measured in Mach.  Mach .6 or = more is=20 not uncommon in a well tuned engine.  It is the energy in this peek = velocity which allows better volumetric efficiency at the tuned=20 rpm.

Tracy

On Sat, Mar 27, 2010 at 10:43 PM, George = Lendich <lendich@aanet.com.au> = wrote:
Naturally I take on board all Lynn and Ed say, as they have = helped me=20 understand how things work and Ed with the maths to give a ball = park=20 figure rather than a WAG, on performance.
 
So I have condensed the figures Ed gave me a tried to make it = as simple=20 as possible to show others - see attached. I hope this helps = those=20 willing to look into the maths.
 
You will notice that the results strongly agree with what = Lynn has=20 stated (in general terms). This in turn strongly agrees with=20 what powersport was using i.e. 40mm up to 6,000 rpm and 44mm up = to=20 7,500rpm (checked this with Bill). What Lynn has suggested is 50mm = reduced=20 15% 42.5mm - hello! I've seen that figure before - dia required at = 7,200=20 rpm. I also agree with what Lynn suggests on P-port shapes - I just = find=20 round easier to do, so round is probably not optimum, but good = enough for=20 some.
 
Some of the Renesis figures I've increased hp in line with = compression=20 increase and rounded off some end result figures.
Hope it helps - it sure helped me.
George ( down under)
=93that = things that=20 work in one application (like Rx-7 racing) just great - may well = suck in=20 another application.=94

 

Or = not suck=20 enough=85.  ;)

 

Neilk

Here is some more stuff to read, since none of you are = building=20 right now.
 
 
This fellow fills in some cross section on the intake = runners of=20 big engine street and road race bikes.
 
Even the factory people fall in love with maximum HP = numbers to=20 sell bikes. The big numbers at the top RPM require big intake = runners. Big=20 intake runners means high flow velocity will be at astoundingly = high RPM.=20 This means the reverse will be available at mid and lower RPM. So, = the=20 rider is beaten silly on the road course by some weekend nitwit = with a=20 smaller engine, that appears to be stock. He obviously has less = maximum=20 HP, but seems to be doing quite well with his setup.
 
Because.......
 
The smaller engine has good torque and HP at lower and mid = range=20 RPM. Maybe he is not as fast at the end of the long straightaway, = but he=20 seems to get to  his top speed much sooner than the new bike = with the=20 bigger engine. And in road racing and drag racing, it is the first = person=20 to his top speed that wins, not always the highest top speed. =
 
Think gear ratio spreads, and area under the curve when = you graph=20 HP.
 
Racing engines and airplane engines are the same engines. = Some=20 racing organizations even use rev limiters to equalize competition = between=20 car brands to keep the racing interesting. So you have to imagine = that=20 your club, be it hair club for men or the home built airplane club = has a=20 rule about top RPM.
 
Of course the club has no such rule, but Mother nature = does have=20 such a rule. It has to do with the tip speed of propellers. So = once you=20 calculate the ratio of your reduction unit, you know how fast you = can turn=20 up your engine. And it isn't very much RPM.
 
So now you are unhappy with the torque of the car engine = that had=20 good torque at 2,500 RPM in the street car, and now you want the = best=20 torque to be where? 5,000 RPM with best HP at 5,800 or 6,000 RPM?=20
 
Note that the car engine has short runners for high RPM = and=20 valving to lengthen the runners for low RPM. You might even say = that low=20 RPM is where the airplane engine runs all of the time. This should = be=20 easy. That length thing has to do with tuned length, or a pipe = organ=20 effect.
 
And our motorcycle friend above shows us that in order to = fill out=20 the mid range,(right where airplane engines run) you need to fill = in part=20 of the intake runners.
 
So folks are making errors at both ends of the runner. The = Throttle body is so big that the last 1/3 to 1/4 of opening has no = affect=20 on RPM. Fortunately this has nearly no affect on HP. At the = engine=20 end of the runner just as in the stock intake manifold the runner = needs to=20 be smaller just as it mates with the block. So the highest flow = velocity=20 is right at the port face.
 
The rotary has a problem that involves the bowl shape = below the=20 opening into the engine, valved by the sides of the rotor. In = order to get=20 the valve timing we need, that bowl is too big (Too much volume). = Some=20 folks fill this in a bit with epoxy products. Some folks make it = worse by=20 increasing the port timing but that makes the bowl volume = increase. The=20 bowl volume causes the velocity to drop right where we want the = highest=20 velocity.
 
Some folks make Periphery port engines with 2" tubing run = from=20 some distance that seems to make sense. This is a big help at RPM = above=20 where you can use it for anything. So at RPM lower than the ideal = to take=20 advantage of the Pport, there is less HP than a side port engine.=20
 
The opening into the housing with a Pport is usually a = round hole.=20 Not ideal. Later intake opening and earlier closing give you more = mid=20 range. The 2 inch pipe flattened slightly, or a dart removed to = reduce the=20 ID about 15% or a bit more. would keep the velocity high, where it = needs=20 to be high. The best HP should be just before the top speed, so = you can=20 lean away power and heat to get down to cruise RPM.
 
Like the racer you want to be first to your top speed. If = you have=20 to pull off throttle to stay at cruise RPM, add some prop and test = again.=20 The engine will make power to well past 9,000 RPM in street trim, = if the=20 breathing is available.
 
If you want to go real fast, cool the oil.
 
A 12-A can do 310 HP at 10,700 RPM breathing through two = 44MM=20 holes. My side port 12-As can do 250 HP at 9,400 RPM breathing = through two=20 38MM holes. My intake manifold gasket is stock. The runners at the = port=20 face are the street diameter and shape. A 12-A is 2,292 CCs, a = 13-B is=20 2,606CCs. These engines are not dynoed below 7,000 RPM, because = they have=20 no power at all below that RPM it is pointless to test there. They = are=20 towed to the false grid with little tractors because they have no=20 torque  at all and they idle at 2,200 RPM.
 
So if you keep building racing engines and puting = them into=20 airplanes that operate below the bottom of the power band of the = engine,=20 why do you do that? Doctor, Doctor, it hurts when I do that. Quit = doing=20 that. Of course I could be completely wrong.
 
Lynn E.=20 = Hanover   

--
Homepage:= =20  http://www.flyrotary.com/
Archive and UnSub: =   http://mail.lancaironline.net:81/lists/flyrotary/List.htm= l


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