Exhaust Sleeves
Thread Starter
Senior Member
Joined: Oct 2007
Posts: 115
From: IDAHO
this year will be large street 6-port n/a, and will run that unless i can do a PP! that is if the mill we have will cut the opening. runing stock ecu and stock intake this year, next year custom intake and megasquirt!
Member
Joined: Apr 2008
Posts: 33
A std S4 opens at 75ºBBDC and closes 48ºATDC
The old comp manual says 73º and 65º
I don't know if things have changed but the openings don't change much the closing change a lot
In the SAE paper 900032, Prediction of Power Output Performance of the Rotary Engine by Gas Exchange Process Simulation
They simulated and tested different port timings and areas of a PP
Std PP IO 100ºBTDC, IC 75ºABDC, 20cm²
EO 73ºBBDC, EC 65ºATDC, 9.2cm²
Optimised IO 80ºBTDC, IC 80ºABDC, 25cm²
EO 73ºBBDC, EC 55ºATDC, 12.5cm²
The ports had less timing but more area, you would think the power curve would be better below peak power(more drivable) but the HP curves show loss of power below peak power and more HP up high. This make sense , the larger port area has a lower velocity so you have to rev it higher to get the velocity back to where is was. Large areas for high rpm power, small areas for more driveability
The old comp manual says 73º and 65º
I don't know if things have changed but the openings don't change much the closing change a lot
In the SAE paper 900032, Prediction of Power Output Performance of the Rotary Engine by Gas Exchange Process Simulation
They simulated and tested different port timings and areas of a PP
Std PP IO 100ºBTDC, IC 75ºABDC, 20cm²
EO 73ºBBDC, EC 65ºATDC, 9.2cm²
Optimised IO 80ºBTDC, IC 80ºABDC, 25cm²
EO 73ºBBDC, EC 55ºATDC, 12.5cm²
The ports had less timing but more area, you would think the power curve would be better below peak power(more drivable) but the HP curves show loss of power below peak power and more HP up high. This make sense , the larger port area has a lower velocity so you have to rev it higher to get the velocity back to where is was. Large areas for high rpm power, small areas for more driveability
Member
Joined: Nov 2005
Posts: 93
Old Grey what country are you in? Lately I've discovered different markets (countries) got different exhaust port timing and different spark plug position. Some housing have both, some have one or the other. From memory there are 5 or 6 different part numbers for S4 turbo housings alone. I have a S4 turbo housing sitting on the bench with the same spark plug position as the MFR housings. At the moment I'm looking for comparisons from Australia.
Senior Member
Joined: May 2002
Posts: 22,465
From: California
ive seen 2 different s4 t2 housings, the us one (n332) and the jdm one (n318). interestingly n318 is the s5 part number, but the part is different from the jdm s4. jdm s4 has the moved plugs, and its got n318 cast into it, by the metering nozzles