Pro Stock John

iTrader: (34)

I would in most cases get 1.75 full length headers.

I would get 1.875 full length headers if I had 382ci or bigger engine, or I had heads, cam and was running 9 - 15 lbs of boost with a supercharger.

I have a set of 1.875 full lengths on order from QTP, with 3.5" collectors. On motor, with my 9:1 348ci they will hurt low - mid range but when the blower is on and we see (hopefully) 20 lbs of boost I will really need the bigger headers. NMRA Mustangs run 2" headers with 306ci motor but 23 lbs of boost to run flat 9's...

Got Me SOM

iTrader: (2)

I looked at the graphs on the thread i posted psj, there is no indication of a loss of power anywhere in his powerband. he gained 45 rwhp!! <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

the loss of power theory has not been proven and it looks like there are a few people on this board running the bigger header with great results.

in your application i sure would hope you run 1 7/8 headers..

Got Me SOM

iTrader: (2)

<img src="http://www.derty.org/images/performance/dynoruns/stock11242001/SD11242001.jpg" alt=" - " /> STOCK

<img src="http://www.derty.org/images/performance/dynoruns/exhaust05212002/SD-5-21-2002-HPTQ3.gif" alt=" - " /> 1 7/8 grotts with cats

Colonel

You'll lose some power down low and in the midrange. Topend power will likely be about the same.

If I were planning on a stroker soon, I'd go ahead and get the 1 7/8". If it's going to be awhile, the 1 3/4" headers will be easy to sell if you ever decide to go stroker later on down the road.

BTW, 1 3/4" will still do well for a moderate powered stroker...say a 382ci with a hydraulic cam. For 400ci and up, I'd definitely want 1 7/8".

PWRTRIP, me thinks you've been eating too many cajun mushrooms. Maybe drinkin' a little first class H2O will help to dilute the effects? <img border="0" alt="[jester]" title="" src="graemlins/gr_jest.gif" />

Kaveman42

Damn you got 45 HP just from headers? Tell me you did some other mods.

o0Dan0o

iTrader: (1)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Kaveman42:
<strong> Damn you got 45 HP just from headers? Tell me you did some other mods. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I believe he got a y-pipe, high flow cats, and a cat back at the same time. Other then that, I think it is pretty much stock.
Dan

Ian

What has the greatest bearing on what size header you should run; cubic inches, or power output?
The main reason I ask, is that with some of the newer H/C packages hitting the 460rwhp range, and the possibility of a new intake (Vararam) on the horizon, H/C cars could be putting 480+ to the wheels. If I'm planning on a 346cid engine with S2 LS6 heads, a G5x2 cam, and N20, should I go ahead and get 1 7/8" headers, or stick with the 1 3/4"?

Thanks!

Kaveman42

TTT Im curious too.

whatever

It all comes down to how much air your pushing through the motor. Again this is oversimplified so nobody kill me. On a NA 346 you can only move as much air as the motor breathes in. Under these circumstances 1 3/4 is more than adequate(did not take into account custom intakes and extreme high horsepower situations). When going to a blower/nitrous/bigger cubes you are bringing in more air and most are going with a cam with duration leaning heavily to the exhaust side to move that air out. This is were we begin to see the deffinate advantages of a 1 7/8 or larger exhaust. Hope this helps. Please rebuke me if i'm wrong.

jeffrey G

I just installed my hooker coated lt's..if I add a 100 shot..whenever that nxl comes out..will that be plenty of flow with those headers?..im excited ive never been in a nitrous car...