Curious if there are big enough improvents with aftermarket intake & exhaust manifolds over ported stock versions? (I know there is supposed to be)

Anyone had big gains all things being equal before and after? I have been content with my oem ported and coated manifolds. But, researching has stirred my interest in better flow dynamics. The AMS F1 intake appears good. As for exhaust manifolds, I have always been told to shy away b/c they all eventually crack.

Anyone got a wide body kit lying around or aero splitter/wing?

Welcome any input from proven racers.

Thanks. Cheers.
AA

 

Lol, you've been around long enough to know. But I wouldn't until they break or another "while your in there" moment. The small gains can be made in the tune until then. As far as exhaust mani's - the cast will eventually warp, the tubular will eventually crack. But you 'should' likely be rebuilding your turbo before that happens.

 

ive seen plenty of tubular mani crack or warped flange and blow out gasket at the track. so i tend to stay away from tubular mani, even though there are gains to be had, i'm HP limited for my class anyways. i had to go back to stock everything when i switched to e85 to try to keep power down. i do have the FP cast manifold, it's been working good so far. i got in home of reducing back pressure and gain some spool. never did back to back test, so don't know if there was any gains or not.

 

On an 8/9 i think there's plenty of evidence out there that an aftermarket intake mani is helpful.

As far as exhaust manifolds, i'd also say yes, but whatever you get make sure there's a lifetime warranty. Tubular mani's CAN crack, but if there's a lifetime warranty, **** it.

 

^ even with warranty, you still have to remove it, wait for it to come back and install it. also could crew up your weekend at the track, which is where it will most likely happen. unless you bring a spare mani with you all the time.

 

On the intake manifold doing the AMS F1i would not be good for road racing, unless you want to give up a fatter mid section.


With the exhaust manifold, I have been running a JMF manifold that was coated. I have not had any issues yet, but I do check my car every few months just to make sure there are not obvious issues.


So if was upgrading, I would make sure to get a good well made tubular manifold, and stick with a stock ported intake manifold.

 

Great feedback. Thank you all.

 

I did same-day dyno testing with a JMF and a ported stocker. The difference was...
1 more peak hp for the JMF.
1 more peak tq for the ported stocker.

The JMF was cheap (well, it was used, it still wasn't cheap, lol) and it's a work of art, so I didn't feel too bad, and I didn't lose much on it since everyone wants them. But so many manifolds get built, and everyone thinks they're pretty, and people buy them without seeing anything vaguely resembling proven gains.

Caveat: this is on a stock engine, stock turbo, stock injectors, stock boost management, and minor bolt-ons (SCCA STU autocross), so you may see different results in the higher HP ranges. Just sharing my experience.

 

peak numbers is not the whole picture. did the JMF mani gain more power below peak, or increase spool ect.