X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-m14.mx.aol.com ([64.12.138.204] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2573391 for flyrotary@lancaironline.net; Sun, 09 Dec 2007 11:31:37 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.138.204; envelope-from=Lehanover@aol.com Received: from Lehanover@aol.com by imo-m14.mx.aol.com (mail_out_v38_r9.3.) id q.d00.1e78d5b4 (29673) for ; Sun, 9 Dec 2007 11:30:40 -0500 (EST) From: Lehanover@aol.com Message-ID: Date: Sun, 9 Dec 2007 11:30:39 EST Subject: Re: [FlyRotary] PP Timing To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_d00.1e78d5b4.348d722f_boundary" X-Mailer: 8.0 for Windows sub 6808 X-Spam-Flag: NO --part1_d00.1e78d5b4.348d722f_boundary Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable In a message dated 12/9/2007 4:32:22 AM Eastern Standard Time,=20 lendich@optusnet.com.au writes: > The inlet timing would be the same ( 85 degrees) - but later, but not so=20 > late as to get into the compression stage, which might cause further issue= s. > =20 > I remember discussing this with someone (it might have been Lynn) but I=20 > can't remember what the negatives are with such a late PP. > =20 > Can someone put me straight on this again! > I hope I got those degrees right! > George (down under) >=20 Port Timing IO =3D Intake opens IC =3D Intake closes EO =3D Exhaust opens EC =3D Exhaust closes US Model First Generation RX-7 IO 32=B0 ATDC IC 40=B0 ABDC EO 75=B0 BBDC EC 38=B0 ATDC European Model Model First Generation RX-7 IO 32=B0 ATDC IC 50=B0 ABDC EO 75=B0 BBDC EC 48=B0 ATDC First and Second Generation 6-Port 13BPrimary intake (Part throttle/cruise) IO 32=B0 ATDC IC 40=B0 ABDC Secondary intake (Part to full throttle) IO 32=B0 ATDC IC 30=B0 ABDC Auxiliary high speed ports (Full throttle above approximately 4000 rpm) IO 45=B0 ATDC IC 70=B0 ABDC EO 71=B0 BBDC EC 48=B0 ATDC Second and Third Generation Turbo 13B IO 32=B0 ATDC IC 50=B0 ABDC EO 71=B0 BBDC EC 48=B0 ATDC Racing Beat "Street Port" IO 25=B0 ATDC IC 60=B0 ABDC EO 84=B0 BBDC EC 48=B0 ATDC Racing Beat "J-Bridge Port" IO 115=B0 BTDC IC 72=B0 ABDC EO 88=B0 BBDC EC 57=B0 ATDC Mazda Factory Peripheral Port IO 86=B0 BTDC IC 75=B0 ABDC EO 73=B0 BBDC EC 65=B0 ATDC This information was copied from Paul Yaws very informative web site at: WWW.Yawpower.com.=20 You cannot spend too much time reading on this site. I could not get my mind around some of the numbers you cited. I am setting u= p=20 a new house in Zephyrhills Florida, and will be building a new shop here as=20 money becomes available. I have none of my stuff here, and had to refer to=20 Paul's web page to see the open and close numbers. This is my wife's compute= r, and=20 she has nothing about rotaries on it. We will be in Ohio for Christmas and we will keep that house for summer time= .=20 Of the 4 events called out in both piston and rotary engines, the intake por= t=20 (or valve) in the piston case, closing point have the greatest effect on=20 lower to middle range power. This also applies to the Pport engine. =20 Note: that even the exotic high speed ports on the 6 port engine close at 70= =20 degrees ABDC. So even with red lines at or above 8,000 RPM this modest port closing is mor= e=20 than adequate. If I remember correctly (this becomes less likely with time)=20 My Bridgeported engine closes at 80 degrees, techically, but is flowing very= =20 little at that point. (big radius and polish job on the closing line). Exten= ding=20 the closing point to gain HP higher up the RPM range is fine for a car, or a= n=20 application where torque can be mulitplied by some sort of transmission, but= =20 the fixed loading of a propeller may not allow you to wind up to your ideal=20= or=20 near to your ideal power RPM. So a robust mid range is a must.=20 The side ported engines (even street ported) open the intake port After BDC.= =20 So exhaust dilution is nil. In the Pport engine, this is not possible. The b= ig=20 hole in the housing will be opening long before the exhaust port is closed=20 off to any extent, and dilution is going to happen.=20 From this fact alone I deduce that the intake port should close just after 7= 0=20 degrees. That the intake port should open as late as it is possible to build= .=20 The intake port would have a near rectangular shape, not far removed from a=20 tall looking exhaust port. Even so, the round port may be flowing so poorly=20 near the open and close points that very little affect may be noticed. The=20= top=20 of the exhaust port I would leave stock. I would widen and radius the sides=20= of=20 the port. I would open the port just a bit early with a slight bow to the=20 centerline, and a generous radius.=20 The idea here is to minimize overlap.=20 The Pport engine has the pointed rotor tip to open and close the port /vice=20 the flat side of the rotor. The flow is uninteruped in effect, with the down= =20 side being that the flow is directed right out the exhaust port, producing t= he=20 giant fireballs the racers love to generate. The RPM where this shuts off is controlled by the overlap period.=20 Airplane engines operate in the low to middle of the RPM range of the engine= .=20 My bridgeport idles at 2,200 RPM. The hint here is that automotive like=20 closing points will produce the best airplane engines. A poorly done Pport engine will massively outperform a side port engine. The= =20 Pport will be less happy with exhaust system problems. More thought to heade= r=20 lengths and muffler design. A function of overlap. Smaller header tubes rath= er=20 than larger. Same exact length a must. Same angle into a collector. Longer=20 rather than shorter.=20 The idea here is to have the port close before a reflected wave can get back= =20 to it. The port numbers I could give you from home are from Mandeville modified=20 housings that were used up to 10,700 RPM, and that data would probably be of= no=20 value. Sorry. Lynn E. Hanover=20 =20 ************************************** Check out AOL's list of 2007's hottest=20 products. (http://money.aol.com/special/hot-products-2007?NCID=3Daoltop00030000000001) --part1_d00.1e78d5b4.348d722f_boundary Content-Type: text/html; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable In a message dated 12/9/2007 4:32:2= 2 AM Eastern Standard Time, lendich@optusnet.com.au writes:

The inlet timing would be the s= ame ( 85 degrees) - but later, but not so late as to get into the compressio= n stage, which might cause further issues.
 
I remember discussing this with someone (it might have been Lynn) but I can= 't remember what the negatives are with such a late PP.
 
Can someone put me straight on this again!
I hope I got those degrees right!
George (down under)





Port Timing






IO =3D Intake opens
IC =3D Intake closes
EO =3D Exhaust opens
EC =3D Exhaust closes

US Model First Generation RX-7
IO 32=B0 ATDC
IC 40=B0 ABDC
EO 75=B0 BBDC
EC 38=B0 ATDC

European Model Model First Generation RX-7
IO 32=B0 ATDC
IC 50=B0 ABDC
EO 75=B0 BBDC
EC 48=B0 ATDC

First and Second Generation 6-Port 13BPrimary intake (Part throttle/cruis= e)
IO 32=B0 ATDC
IC 40=B0 ABDC
Secondary intake (Part to full throttle)
IO 32=B0 ATDC
IC 30=B0 ABDC
Auxiliary high speed ports (Full throttle above approximately 4000 rpm)
IO 45=B0 ATDC
IC 70=B0 ABDC
EO 71=B0 BBDC
EC 48=B0 ATDC

Second and Third Generation Turbo 13B
IO 32=B0 ATDC
IC 50=B0 ABDC
EO 71=B0 BBDC
EC 48=B0 ATDC

Racing Beat "Street Port"
IO 25=B0 ATDC
IC 60=B0 ABDC
EO 84=B0 BBDC
EC 48=B0 ATDC

Racing Beat "J-Bridge Port"
IO 115=B0 BTDC
IC 72=B0 ABDC
EO 88=B0 BBDC
EC 57=B0 ATDC

Mazda Factory Peripheral Port
IO 86=B0 BTDC
IC 75=B0 ABDC
EO 73=B0 BBDC
EC 65=B0 ATDC

This information was copied from Paul Yaws very informative web site at:

WWW.Yawpower.com.

You cannot spend too much time reading on this site.

I could not get my mind around some of the numbers you cited. I am setti= ng up a new house in Zephyrhills Florida, and will be building a new shop he= re as money becomes available. I have none of my stuff here, and had to refe= r to Paul's web page to see the open and close numbers. This is my wife's co= mputer, and she has nothing about rotaries on it.
We will be in Ohio for Christmas and we will keep that house for summer time= .

Of the 4 events called out in both piston and rotary engines, the intake por= t (or valve) in the piston case, closing point have the greatest effect on l= ower to middle range power. This also applies to the Pport engine. 
Note: that even the exotic high speed ports on the 6 port engine close at 70= degrees ABDC.
So even with red lines at or above 8,000 RPM this modest port closing is mor= e than adequate. If I remember correctly (this becomes less likely with time= ) My Bridgeported engine closes at 80 degrees, techically, but is flowing ve= ry little at that point. (big radius and polish job on the closing line). Ex= tending the closing point to gain HP higher up the RPM range is fine for a c= ar, or an application where torque can be mulitplied by some sort of transmi= ssion, but the fixed loading of a propeller may not allow you to wind up to=20= your ideal or near to your ideal power RPM. So a robust mid range is a must.=

The side ported engines (even street ported) open the intake port After BDC.= So exhaust dilution is nil. In the Pport engine, this is not possible. The=20= big hole in the housing will be opening long before the exhaust port is clos= ed off to any extent, and dilution is going to happen.

From this fact alone I deduce that the intake port should close just after 7= 0 degrees. That the intake port should open as late as it is possible to bui= ld. The intake port would have a near rectangular shape, not far removed fro= m a tall looking exhaust port. Even so, the round port may be flowing so poo= rly near the open and close points that very little  affect may be noti= ced. The top of the exhaust port I would leave stock. I would widen and radi= us the sides of the port. I would open the port just a bit early with a slig= ht bow to the centerline, and a generous radius.

The idea here is to minimize overlap.

The Pport engine has the pointed rotor tip to open and close the port /vice=20= the flat side of the rotor. The flow is uninteruped in effect, with the down= side being that the flow is directed right out the exhaust port, producing=20= the giant fireballs the racers love to generate.

The RPM where this shuts off is controlled by the overlap period.

Airplane engines operate in the low to middle of the RPM range of the engine= .  My bridgeport idles at 2,200 RPM. The hint here is that automotive l= ike closing points will produce the best airplane engines.

A poorly done Pport engine will massively outperform a side port engine. The= Pport will be less happy with exhaust system problems. More thought to head= er lengths and muffler design. A function of overlap. Smaller header tubes r= ather than larger. Same exact length a must. Same angle into a collector. Lo= nger rather than shorter.

The idea here is to have the port close before a reflected wave can get back= to it.

The port numbers I could give you from home are from Mandeville modified hou= sings that were used up to 10,700 RPM, and that data would probably be of no= value.

Sorry.

Lynn E. Hanover









**************************************
Check o= ut AOL's list of 2007's hottest products.
(http://money.aol.com/special/h= ot-products-2007?NCID=3Daoltop00030000000001) --part1_d00.1e78d5b4.348d722f_boundary--