X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [64.12.137.3] (HELO imo-m22.mail.aol.com) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2604479 for flyrotary@lancaironline.net; Tue, 18 Dec 2007 21:23:54 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.3; envelope-from=Lehanover@aol.com Received: from Lehanover@aol.com by imo-m22.mx.aol.com (mail_out_v38_r9.3.) id q.d3f.1cf614b5 (14457) for ; Tue, 18 Dec 2007 21:23:13 -0500 (EST) From: Lehanover@aol.com Message-ID: Date: Tue, 18 Dec 2007 21:23:13 EST Subject: Re: [FlyRotary] Degrees overlap To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1198030993" X-Mailer: 9.0 Security Edition for Windows sub 5378 X-Spam-Flag: NO -------------------------------1198030993 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 12/18/2007 6:34:15 P.M. Eastern Standard Time, lendich@optusnet.com.au writes: Lynn, I was all over the shop before, but now I think I've got it all sorted. I was trying to see the differences the PP gave in overlap and open ( intake) time. I was confusing myself yet again, until I realized I was looking at the degrees of crank, when I should have been looking at the degrees of the rotor. With IO @ 32 degrees ATDC and IC @ 40 degrees ABDC (12A engine) or IC @ 310 degrees ATDC = 278 degrees/3 = 93 degrees of the rotor I did the same for Exhaust = 415 degrees/3 =131 degrees. Overlap ( standard) =25 degrees/3 = 8 degrees. Overlap PP = 144 degrees/3 = 48 degrees. PP inlet = 430/3 =143 degrees. Inlet time with the PP is an additional 50 degrees (very good) but with a penalty of 40 extra degrees of overlap (bad) but only bad at low RPM's. Interestingly the overlap is 6 times the original - this all varies accordingly with the different models. While doing this exercise it is interesting to see the RX 8 port and why it's placed where it is to eliminate overlap. While it might be nice to have say 180 degree of rotor ( or more) for complete burn of the fuel, realistically the power derived from this exercise would be marginal at best. The power from combustion would (I believe) be totally converted to mechanical power ( to the rotor) by the time it reaches the existing exhaust opening. George ( down under) It is endlessly interesting to turn this thing around slowly and watch the ports open and close. The published open and close events from (for example) Paul Yaw's web page _WWW.yawpower.com_ (http://www.yawpower.com) are at the crank. So being so many (crankshaft degrees) ATDC or BTDC is looking at a very small portion of a cycle that requires 1080 degrees (3 complete revolutions) of crankshaft rotation to complete. One of the many advantages of this engine is that everything is happening in slow motion. In regard to most engine functions this is good news. Sadly this exposes way too much iron and aluminum to the combustion process in each cycle. So you get quenched out flame fronts and unburned hydrocarbons, (HC) and a bit less efficiency compared to a piston engine of the same displacement. It has no squish areas to drive mixture to the flame front or spark plugs. In the Fiat I could run .040" clearance between the head and the piston top and move all of the mixture into the plug and flame ball. So long as the piston didn't touch the head too hard at TDC all was well, and it would run with 14:1 compression ratio. Of the two tube frame cars, the first gen with the factory Pport engine was far easier to drive around in the paddock at below idle speed in first gear. It was not required to declutch and add revs now and again to keep it moving. The exhaust dilution was very bad and this gives you a very slow burn, and a nice long push in each cycle. It was just like a stock car. Very tractable. The third gen car has a bridge port that opens at 110 degrees BTDC and the overlap is way more than the Pport. It is just about not drivable without declutching and adding revs to 4,000, then letting in some clutch (grabby 2 disc metallic) for a lunge, then repeat. Very hard on the clutch. Engine stalls about 20 times on the way to the false grid and so on. So we tow it there with a little tractor. The Pport is very friendly. It is soft in power output until it steps up on the tune at about 5,500 RPM, where the exhaust port closes soon enough to keep a good amount of mixture in the engine. While the porting numbers suggest that the intake port is closing at thus and so degrees, it never actually closes does it? Where the side port gets the flat side of the rotor actually sealing it off, the Pport gets the point of a rotor passing through, valving mixture up or down but never closing the port. Never closed is a lot of intake time. No matter how badly you design your inlet tract, the Pport will provide outstanding power. Should do well from 3,000 RPM to about 14,000 RPM. The Pport intake is open for business 24-7. That is where the power comes from. While the gearing allows the rotor to turn (rotate) one time for three rotations of the crank, the stress on the crank is monumental. At 10,000 RPM the full centrifugal loads of two 9 pound rotors are on the crank and rotor bearings. It happens that the bearing area is well up to the job. Much confusion results from the gearing and speeds involved. The engine is far over-square. And the poor torque (from the short lever arm of the short stroke) is exacerbated by the rotor/crank gearing. So when you gear the reduction unit at 2.78:1 you have not even got back to one to one looking at the rotors. But stick with the degree wheel on the crank. Thinking about the rotor speed will damage your mind. It did mine. Lynn E. Hanover **************************************See AOL's top rated recipes (http://food.aol.com/top-rated-recipes?NCID=aoltop00030000000004) -------------------------------1198030993 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 12/18/2007 6:34:15 P.M. Eastern Standard Time,=20 lendich@optusnet.com.au writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
Lynn,
I was all over the shop before, but now I= think=20 I've got it all sorted. I was trying to see the differences the PP gave in= =20 overlap and open ( intake) time.
 
I was confusing myself yet again, until I= =20 realized I was looking at the degrees of  crank, when I should have b= een=20 looking at the degrees of the rotor.
 
With IO @ 32 degrees ATDC
and IC @ 40 degrees ABDC (12A=20 engine)
or IC @ 310 degrees ATDC =3D 278 degrees/= 3 =3D 93=20 degrees of the rotor
 
I did the same for Exhaust =3D 415 degree= s/3 =3D131=20 degrees.
 
Overlap ( standard)  =3D25 degr= ees/3 =3D 8=20 degrees.
Overlap PP =3D 144 degrees/3 =3D 48=20 degrees.
 
PP inlet =3D 430/3 =3D143 degrees.=
 
Inlet time with the PP is an additional 5= 0=20 degrees (very good) but with a penalty of 40 extra degrees of overlap (bad= )=20 but only bad at low RPM's.
 
Interestingly the overlap is 6 times the=20= original=20 - this all varies accordingly with the different models.
 
While doing this exercise it is interesti= ng to=20 see the RX 8 port and why it's placed where it is to eliminate overlap. Wh= ile=20 it might be nice to have say 180 degree of rotor ( or more) for complete b= urn=20 of the fuel, realistically the power derived from this exercise would be=20 marginal at best. The power from combustion would (I believe) be totally=20 converted to mechanical power ( to the rotor) by the time it reaches=20 the existing exhaust opening.
 
George ( down=20 under)
 
It is endlessly interesting to turn this thing around slowly and watch=20= the=20 ports open and close. The published open and close events from (for example)= =20 Paul Yaw's web page WWW.yawpower.com= are=20 at the crank.
So being so many (crankshaft degrees) ATDC or BTDC is looking at a very= =20 small portion of a cycle that requires 1080 degrees (3 complete revolutions)= of=20 crankshaft rotation to complete. One of the many advantages of this eng= ine=20 is that everything is happening in slow motion. In regard to most engine=20 functions this is good news. Sadly this exposes way too much iron and alumin= um=20 to the combustion process in each cycle. So you get quenched out flame front= s=20 and unburned hydrocarbons, (HC) and a bit less efficiency compared to a pist= on=20 engine of the same displacement. It has no squish areas to drive mixture to=20= the=20 flame front or spark plugs. In the Fiat I could run .040" clearance between=20= the=20 head and the piston top and move all of the mixture into the plug and flame=20 ball. So long as the piston didn't touch the head too hard at TDC all was we= ll,=20 and it would run with 14:1 compression ratio.
 
Of the two tube frame cars, the first gen with the factory Pport engine= was=20 far easier to drive around in the paddock at below idle speed in first gear.= It=20 was not required to declutch and add revs now and again to keep it moving. T= he=20 exhaust dilution was very bad and this gives you a very slow burn, and a nic= e=20 long push in each cycle. It was just like a stock car. Very tractable. The t= hird=20 gen car has a bridge port that opens at 110 degrees BTDC and the overlap is=20= way=20 more than the Pport. It is just about not drivable without declutching and=20 adding revs to 4,000, then letting in some clutch (grabby 2 disc metallic) f= or a=20 lunge, then repeat. Very hard on the clutch. Engine stalls about 20 times on= the=20 way to the false grid and so on. So we tow it there with a little tractor.=20
 
The Pport is very friendly. It is soft in power output until it steps u= p on=20 the tune at about 5,500 RPM, where the exhaust port closes soon enough = to=20 keep a good amount of mixture in the engine. While the porting numbers sugge= st=20 that the intake port is closing at thus and so degrees, it never actually cl= oses=20 does it?
 
Where the side port gets the flat side of the rotor actually sealing it= =20 off, the Pport gets the point of a rotor passing through, valving mixture up= or=20 down but never closing the port. Never closed is a lot of intake time.
 
No matter how badly you design your inlet tract, the Pport will provide= =20 outstanding power. Should do well from 3,000 RPM to about 14,000 RPM.
 
The Pport intake is open for business 24-7. That is where the power com= es=20 from.   
 
While the gearing allows the rotor to turn (rotate) one time for three=20 rotations of the crank, the stress on the crank is monumental. At 10,000 RPM= the=20 full centrifugal loads of two 9 pound rotors are on the crank and rotor=20 bearings. It happens that the bearing area is well up to the job. Much confu= sion=20 results from the gearing and speeds involved.
 
The engine is far over-square. And the poor torque (from the short leve= r=20 arm of the short stroke) is exacerbated by the rotor/crank gearing. So when=20= you=20 gear the reduction unit at 2.78:1 you have not even got back to one to one=20 looking at the rotors. But stick with the degree wheel on the crank. Thinkin= g=20 about the rotor speed will damage your mind. It did mine.
 
Lynn E. Hanover  



See A= OL's top rated recipes and easy ways to stay in shape for winter.
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