marky mark

I was wondering what is the longest header collector that will fit in a 'vette. I was thinking of Hooker Super comps with a 12" to 24" (3") collector for additional torque. Any thoughts?

Regards, Mark :chevy

427V8

I think if you look in websters dictionary under oxymoron you will find 'Hooker supercomps and low end torque' Supercomps are made for high RPM not for torque.

marky mark

427V8,

Yes,you are right about the header making high rpm horsepower.

But, the longer the collector the more torque you get. I've done a bunch of research on this very subject and read the "white paper" on headers/collectors from "Headers by Ed" who has got to be one of the most knowledgeable guys on this subject. This is precisely the reason that "shorty headers" come up "short" (so to speak) in the power making dept. Thanks for your comments, but I think you miss the point that headers improve both hp & torque.

Regards, mark :flag :chevy

73 LS-4

I'm running the 1-7/8 primary tube super comps. I wanted to stay with a fairly small tube to keep as much low end as possible. This is one of the first mods I did, I don't really think they hurt my bottom end at all and deffinitly helped the mid and higher RPM,s. I'd run as much collector length as you can if your looking for low end torque.

:cheers:
Pat Kunz

427Hotrod

A lot of the header science becomes academic once you cap it up with pipes etc. Yes, there will be some trends, but the exhaust pipes are going to act as one long collector.

I went from 1 3/4" to 2" primaries on my 427 when it was in a Camaro and it made no difference. I was expecting some improvement since it was running 11.70's at the time. The collector length was within 3/4" of each other. Over the years I found the 427 not to be super sensitive to header changes. Any of the good ones can take care of it in the 10-12 sec range.

Once the engine size gets larger the whole thing changes. I'm using 2" on my 540 but really need to step up to 2 1/8". I did find on the dyno the 3" pipes were killing 45+ rwhp but adding about 40 ft lbs at lower rpm.

I tend to lean toward larger primary tubes and collectors when running capped up is in the plan.

If you can fit them in I'd run the 2" or 2 1/8" primaries and whatever you can do for collectors. There ain't much room on Vette's for them and most end up relatively short or awful low to the ground.

Jim

63Banshee

What rpm are you running and what is the estimated HP of you motor?

marky mark

Dave, I'm guessing around 375 hp and 450 ftlbs. torque (flywheel) and cam's power range is 2000 to 5000. Engine has low rise stock intake w/Quadrajet and is pretty much done by 5200 rpm. I am looking for more torque as this is a week-end type street cruiser, not a dragstrip car, (not that I am afraid to abuse it every now and again).

Thanks to all who replied.

Regards, mark :flag :chevy

63Banshee

In that case I wouldn't run a primary larger then 1 3/4" in diameter with a length of around 26” or longer. The only compromise you will have is in the collector. Headers with primary diameters usually come with a 2 ½” collector, I’d prefer a 3” collector. I’d also extend the collector with 3” pipe just before the point where the crossover is optimally positioned and run 2 ½” pipe from there back.

I’ve never build an exhaust for a Vette before so I’m not sure how much room there is for all this. Main point is to not oversize the primary diameter. With your motor you will kill the bottom end while gaining nothing at top end if you use a larger diameter. My $.02


[Modified by 63Banshee, 10:13 AM 11/30/2001]