ColinRX7

[quote name='BLUE TII' date='Jul 28 2005, 03:53 PM']Edit- Mazda did try cross/combo ports in the preproduction Cosmo Sport 10A, but there were no real gains over sideport in production trim (legal exhaust ect.).


[/quote]





I guess this is where we figure out what "streetable" means to the end user...



My idea of streetable is driving on the street without too much drama as far as driveability is concerned... Good applied powerband, Idles without stalling (which seems easily attainable, brappy bouncy idle is still an idle).. For streetability to me, noise level, emissions, fuel consumption, etc are not issues.



Could be louder than a freight train and have absolutely no emissions and I would still call it "streetable"







The original poster might have a concern with noise level or emissions functions..

heretic

Some people think "idle" means "to run glass smooth at zero load". Which is probably where the "bridge/peripheral won't idle below 3500" type bollocks comes from. But if it will sit left alone at 1100 all day long without fouling plugs or what have you, and when you let off the throttle it doesn't sag down and die, then it can be said to idle at 1100. Even if it still crackles and raps and generally carries on stumbling like a drunk!

j9fd3s

i ve never driven a pp car, but the full bridge car i drove would fire right up and idle at 1100ish rpms all day. the idle is rough enough to shake the whole car though, and then it ran great and had more under 2000rpms than my gsl-se but it did no like cruising under 4500rpms without wanting to brap brap brap. could it be driven everyday? yes. was it quiet? yes. would you want to drive it everyday? no it would get old.

heretic

[quote name='j9fd3s' date='Jul 30 2005, 09:25 AM']i ve never driven a pp car, but the full bridge car i drove would fire right up and idle at 1100ish rpms all day. the idle is rough enough to shake the whole car though, and then it ran great and had more under 2000rpms than my gsl-se but it did no like cruising under 4500rpms without wanting to brap brap brap. could it be driven everyday? yes. was it quiet? yes. would you want to drive it everyday? no it would get old.


[/quote]



So he should have stepped up to a peripheral port, with its reduced timing. And that's for the huge MFR ports, a peripheral port doesn't necessarily have to be "HUGE". After all NSU didn't go huge did they?

j9fd3s

[quote name='heretic' date='Jul 30 2005, 05:21 PM']So he should have stepped up to a peripheral port, with its reduced timing. And that's for the huge MFR ports, a peripheral port doesn't necessarily have to be "HUGE". After all NSU didn't go huge did they?


[/quote]



i'll bring the camera to work, nsu is small

ColinRX7

[quote name='heretic' date='Jul 30 2005, 09:21 PM']a peripheral port doesn't necessarily have to be "HUGE".
[/quote]



That's exactly what I'm getting at





Seems like if people bother to go PPort in the first place, they go all out and have huge ports, peak power at over 9k RPM type of huge.

ColinRX7

[quote name='j9fd3s' date='Jul 30 2005, 01:25 PM']but it did no like cruising under 4500rpms without wanting to brap brap brap.
[/quote]





FYI I think that's awesome





Did the car start bucking when it did that or?



There must be a way to tune that out.. Be it stepping the throttle plates so the overlap isn't there so much or.. There's got to be something..

heretic

There's a guy on a different RX-7 forum that did a moderate port. Still waiting to see what the results are, but given that it's all been done before by Mazda engineers in the 80's, it should work just fine.

j9fd3s

[quote name='ColinRX7' date='Jul 31 2005, 01:32 PM']FYI I think that's awesome

Did the car start bucking when it did that or?



There must be a way to tune that out.. Be it stepping the throttle plates so the overlap isn't there so much or.. There's got to be something..


[/quote]



car would buck in the lower gears. if you were accelerating or decelerating at all it was fine. it was streetable, but little too intense to drive everyday, i'm old though

ColinRX7

[quote name='j9fd3s' date='Aug 1 2005, 01:23 AM']car would buck in the lower gears. if you were accelerating or decelerating at all it was fine. it was streetable, but little too intense to drive everyday, i'm old though


[/quote]





You're 32, shut up.





JK





Well that being considered, we will see if that's something that I can avoid after I put mine together..



I'm really up in the air however on designing an intake manifold... I went from custom LIM to now I just want to fab an entire manifold from block to TB..



I'm thinking NO dynamic chamber, have the secondary runners goto each throttle plate, and use a stock FC3S TB (Mainly because I already modified one for a full range TPS and I have a good TB elbow and piping and stuff).



Any input from anyone? If I go with no dynamic chamber how should I set up the runners?



I really need to read that book.. Bible of intake and exhaust timing or something it's called?