Porting
 

How much of a difference does top end porting really make? Can you feel it or will it?

Re: P & IH & TB porting
 

I had to go to a less restrictive exhaust to feel the benefit of P & P the IH and Plenum. I didn't do the heads.

Re: Porting
 

Can you feel it? No. The proof is in the dyno about 15Hp Max with the Plenum, IHs and Heads ported to match. However combined with an open Air filter and Headers expect that number to go to 25-30Hp with a chip reburn to optimize the improvements. Haibeck and others like Jeffvette say its so. I have a set of Jeals to install next but am holding off on that mod until I can work out all the IM74 potential issues with emissions here in AZ.

Is it worth doing while you there? Yes especailly when you getting some P&C work done at the same time. Also the work cannot be seen and does not affect the value of the ZR-1!!! It just makes sense. Just my thoughts and Jeffvette and locobob do some great work. And stand behind that work (voice of experience) Id rather have someone like them (experts) do the work as im not a brave as Dominic S but he can tell you how much his labor of love cost him time and equipment wise to do his self porting. GC

Re: P & IH & TB porting
 

corey henderson of HPT. did my car .when i brought it into him he ran it on the dyno car made 373rwhp after the porting and him retunning the prom it made 409.9. tq also went from 355 to 373.3 his ph is 210 867 6286. he is very fair price wise and is a well known zr1 builder . loco bob also does excellent work as does mark haibeck .i would choose one of those 3 if it were me.

Re: P & IH & TB porting
 

Oops, GC is correct. A Marc Haibeck chip for me helped maximize the other mods.

Re: P & IH & TB porting
 

I feel it, especially since it has warmed up and when I run the AC...it still feels strong.

B&B
Haibeck Chip
PORTED
K&N

Re: P & IH & TB porting
 

You may notice some seat-of-the-pants difference, especially so in the 90-92 cars. Port work on the 405 horse later models doesn't make as much of a difference as it does in the 375 horse earlier models. The great equalizer in both is port work to the plenum and injector housings coupled with a set of long tube headers and a tune. :wink:

Re: P & IH & TB porting
 

I could easily feel it on my car. Marc H ported it and included a chip. It was noticeable the improvement, as well as how the power didn't drop at higher rpm. Stock it seemed to drop off around 6,500 or so, resulting in a natural inclination to shift. With the top end ported, I hit the limiter a lot until I got used to it.

I think having a ported top end is what made my exhaust change so noticeable too. I gained about 22whp on a Superflow just from a cat-back change. I suspect the number was that high because the exhaust was choking the porting a bit.

Re: P & IH & TB porting
 

On my 92 Z , went from 325rwhp to 396rwhp. 100% stock to ported with headers and corsa (no head work). Night and Day difference. The power never dropped, it was still pulling at the rpm limiter. I think every Z should have this done (top end port work). They are so far off stock, and it makes the motor just pull to redline.

DO IT:mrgreen:

Re: P & IH & TB porting
 

Getting more air in is good as long as it can get out. All adds up at the end of the day.