I recently installed crawford headers. We did some dyno runs BEFORE the headers, and then after the headers were installed, we did some more dyno runs as we tuned (this was at Uprev in Austin, TX). Here is the before and after dyno:



For some reason this chart has mph instead of RPM, but you get the idea (I'll try to get another graph if it matters, it'll be the same graph but with different units on the X-axis).

So as you see, the gains are minimal if any - maybe 2 horsepower. Here are the details of my engine mods (it's a 2003 touring 350z):

* JWT pop charger
* Crawford V5 plenum
* Crawford high-flow catalytic converters
* Stillen true dual exhaust
* Uprev reflash & tune


I made sure everything was the same before & after for the dyno - even the temperature and humidity were almost the same (in fact it was a few degrees cooler for the post-headers-install run). For tuning, above 5000 rpms we advanced timing a bit, and tuned the air/fuel, as you can see in the A/F graph at the bottom of the pic above. Does anyone have any ideas? I know some mods are bunk, but I figured crawford headers would have real gains.

 

wow, what a disapointment. Sorry for the outcome.

 

wow that sux, walkert installed my old top speeds and gain 15whp in the mid range with no tune. he over layed the two dynos to prove it. not bad for $150 headers.

 

btw, i think you bought your headers used if im not mistaken. are you 100% sure they are crawfords? i know borla headers make no power and in some cases lose power.

 

I'm pretty certain they are real, they look exactly like the photos of crawfords, the seller has a good reputation here, the quality of the headers looked good, etc. Oh and they were a real pain in the azz to install At least I didn't lose any power eh?

 

yeah but for that much money and effort. damn, i feel terrible for you.

 

i really do too. I wonder what can be the problem? I'm glad you actually have a before and after dyno and not basing it off of the butt dyno.

I got 254hp on the dynojet as well and all i have are test pipes and an intake spacer.

 

That sux

 

I kinda wish you had dynoed staight after the install without tuning. Possible the tune is off?

 

Yeah we did run on the stock fuel map - it runs WAY too lean, it was in the 14:1 A/F range, maybe even higher. The power was also significantly lower above about 4800 RPM... the current tune definitely helps compared to stock. Maybe there's some gains left in more tuning but I dunno. I asked Doug @ crawford what he recommended, he said for 5000 rpm and above, A/F of 12.8 - 13 or so, and timing of 31 degrees.

 

Ok, so the tune didn't take anything away. Sorry to hear about the mod.

 

That really blows!!! I am about to purchase a set of alphawerks headers and install them on an 2006 with Berk HFCs and stillen true dual setup. Now I'm on the fence. I have experience modding mustangs but this is my first nissan. I did discover with mustangs that headers made alot of gains when matched with stock or limited after market exhaust but when matched to a well designed true duals and HFCs; the headers did not make that much of a difference. You could be in the same boat since you already had HFCs and the stillen exhaust on your ride. Just my 2 cents.

 

that really does suck homie. And Crawford is supposed to be top dog. I gained 9hp mid range with my reputation bashed Borla Headers, 0 up top though. Goes to show you, headers just do not work with the VQ, and all the trouble to install the damn things, you could do a turbo

 

you have maximized exaust efficency,work on intake to see the gains

 

OUCH!!! THat does SUCK!!!

 

Damm that sucks. Maybe you should contact Crawford to see what they think.

 

Damn man...sorry to hear that. Only 2whp gain is dreadful...
I only gained about 5whp with my Nismo and I was pretty ticked off about it

 

This is what I dynod with TS headers on stock cats. It put a up/down wave in the curve but the net effect was negligible.

Are you running stock cats? Headers need test pipes to have any significant effect.

 

it's stated in his first post that he has crawford HFC

 

oops missed that.

Go test pipes!