Would someone please explain the corking effect of the Nismo headers when mated with the Nismo cams? Do the Crawford headers not exhibit this? Are there quantitative evidence to this (dynos, timeslips) or is this based on qualitative butt dyno's?

I would really like to know since I am looking to have a set of headers installed. Then perhaps a set of cams, either Tomei or Nismo in the next 30 days.

I'd like to get it done while I'm on leave here in MD (perhaps at AAM), and before I head down to Pensacola, FL. Thanks.

 

I don't mean to sound ignorant...what do you mean "corking effect"?
I'm running the Crawford headers and plenum.
Thanks

 

I've heard of people switching over to Crawford headers because some have said that the Nismo headers are demonstrating some torque restriction at the low end.

Which raises another question, are the Nismo headers showing lower torque readings at low rpms compared to the stock manifolds? Or only compared to Crawford's?

Please help!

 

On a car running the Tomei 268s and NISMO headers... he was EXTREMELY corked. i.e. BOTTLENECK!

When he went to the Crawfords HUGE gains were made down low.

The NISMO headers are VERY nice. Just weren't thought out... they were designed to make gains on a stock car. Not something with cams, supercharger, etc.

 

What size primary tubes are used in the crawford headers?

I know the nismos use a combination 1.75" and 1.625"

 

I would not call it a bottle neck (or corking). . . it just so happens that the Nismo Headers did not make as much power as the Crawford headers. I am sure the Nismo headers make better gains with the cams over the stock headers. Its all about the best performance. I dont think that anyone has built 350Z headers(even Crawford) thinking . . . oh this design will be a benefit to a car with cams. I could be wrong, I just know what the ideals were for the Crawford headers . . .there was a goal from the beginning. X primary length, equal length, tube size, collector design, etc. All specs determined by years of experience and teamwork from VQ engine specialists. They were not just thrown together, it truly is a science.

 

Your cat's are the biggest problem. No matter what brand you go with, you can't go wrong by replacing them with high flow units!!

 

True true...

Cats do okay on their own.
Headers do pretty good on their own.

Headers and Cats - Do GREAT on their on.

Headers, Cats, and Exhaust do STELLAR on their own.

You have to remove bottlenecks to do it right!