I know this is a subject with many opinions and I welcome any comments:

What I was wondering was this: To those of you who have added a set of headers to your Big Block, what performance gains did you see? Were the increases subtle or more obvious? More on the top end or bottom end? Did your performance get worse?

Finally, you've tried both, would you recommend headers???

Regards, mark :flag :chevy

 

Can't say on a big block but a small block YES. You will see more torque and horsepower on any engine. It allows the engine to breath better. Any increase in breathing will help HP. Just don't go overboard on tube size and your torque will increase. Large tubes are good for more rpm and huge motors. I would say it is a good addition.

 

I picked up 60 hp and 100 ft-lbs of torque. I have some dyno graph on my webpage. Only downside to headers is slightly less ground clearance.

 

I put a set on mine recently, did make some difference at least it was noticeable. I tmostly picked up in the mid to high rpm range with the bottom end being pretty much the same with 1 7/8 primaries. Ground clearance will be slightly reduced to about 4" or a little better, but this seems to vary with brand and car a bit, I went with hookers on mine. Would i recommend them? Well if you plan to put the car into any sort of performance workout they are a definite plus.

:cheers:
Pat Kunz

 

I first put side-mount headers on my '67 435 in 1969.

No comparison - impressive horsepower gains - not to mention the weight loss of cast iron exhaust manifolds!

With side-mounts (and slip-in mufflers) there are no ground clearance problems either - nice bonus!

When you're racing, it's easy to slip off the side-mount pipes leaving the header collector just below the side fender gills exiting four inches of impressive noise! That's when the engine really comes into its own...free flowing out of a four-inch collector....momma!

The below photo shows the white headers minus the slip-ons.
:smash: :crazy:

 

Thanks for the info and replys everyone!! I DO appreciate it!!

Regards, mark :chevy

 

Mark,

If you have a mild i.e. 390 horse BB, I would make sure I had 2.5 inch pipes and low restriction mufflers before I would be tempted to change to headers. I believe muffles and pipes will make as much or more power and easier to get.

Now, If you have a hipo version, even a 435 horse motor, yes I would certainly go for headers too. Much more is gained with headers if your motor is a really hot one (like Zwede's). Otherwise, the factory Corvette exhaust manifolds are actually quite good.

Chuck

 

Yes Chuck, it's a 390 hp version that I've done a little head work to and am running a Crane H-272 cam which has .216/.228 duration and .515/.510 lift at a 112 LSA. I have a custom made 2&1/2" true duals exhaust with a Dr.Gas "X" pipe installed just aft of the crossmember. Mufflers are Dynomax Super Turbo's (2&1/2" inlet/outlet) with custom 2&1/2" od polished stainless tips.

I will have Lars tweak and fine tune the Quadrajet soon and that's about it unless I want to try and tweak the distributor curve and/or add headers. Other things to increase power, such as a roller cam or aluminum heads are out of the question right now (financially).

Car is very powerful as is and the cam's advertised power band of 2000-5000 with peak torque at around 3500 is accurate from what I can tell. I wanted a more torquey motor than what the previous owner had done (camwise). I won't push past 5000 rpm very often and since the cam is somewhat mild I wonder if headers would add a whole lot of power given the limitations of my heads and cam combo.

Thanks for your thoughts.

Regards, mark :flag :chevy

 

Mark,

It sounds like you really have a nice engine setup now. I think you would get more fun for your buck if you put the cost of headers into suspension parts that will really make the car more pleasurable to drive. Regardless of the show quality paint and huge power numbers, if a car rides as loose as a kid's "Little Red Wagon" I am generally quite unimpressed. I could live without big power much longer in a car with a tight, solid, well tuned suspension than a high powered car that with sloppy suspension. You can only really use the power when the suspension is in good shape!

Get the car low. For me (I'm 5',10") the front bumper strikes me just below the knee cap. The back bumper at about the knee cap. With good springs, shock, bushings, and tires the car corners like its on rails and looks the part. If you put the underneath exhaust style headers, you will be scraping and denting them up in no time at this suggested ride height. A big plus for the factory manifolds. Shorty headers would clear better, but not perform much better than yours anyway. A rock steady steering wheel, centered and precise gives me more joy than an extra 100 horsepower. It is this quality that sets so many of the fine European cars apart from ours. Most modest Vettes boast more hp than a Porsche for instance, but it is the precise and nimble feeling of the Porsche that brings the raves. Don't think you can't narrow this gap quite a bit!

Mark, as I reread this reply, I know I'm coming off sermonizing again. Not my intention. I just think so many people get so wrapped up in horsepower wars, that they don't really get to know the other side of what makes the Vette such a great car to drive. You don't have to go with a full kidney bruising racing suspension to get that great road feel. It's been the long road trips that were the most memorable. I have had to catch myself and realign my priorities more than a few times.

Chuck

 

Hey Mark, how much low end did you loose with the 272 cam? I've been thinking about that one.

-Joe

 

Chuck, I'm fortunate that the previous owner re-did the suspension before I bought it. This would include the entire 'Vette Brakes "Steet & Slalom" set-up. This includes new front springs that lowered the car, as well as heavy duty sway bars and composite leaf spring in back. He wisely went with rubber bushings instead of poly. It rides stiff now and with poly it might have been too much. I replaced the rag joint also. I do need some cosmetic work that will have to wait.

Flareside, The Crane H-272 is best suited to 3:08 to 3:55 rear gears. The recommended cruise rpm (what rpm you turn at 60 to 65 mph) is 2600-3000 & peak torque is at 3500. This is what they said it would be and they were spot on. I have a 4 spd with 3:36 gears and the previous owner had put in a more aggresive cam that had a mean idle and all, but it had very little low-end. I don't know how aggresive that cam's #'s were but the Crane H-272 has improved my bottom end power dramatically.

I used to have to rev to around 3500 and feather the clutch on standing starts to light up the tires (this is a ragtop which is slightly heavier than a coupe). Now I get more power at around 2700 rpm and I can literally go sideways with both wheels spinning until I let off the gas. That's what I was hoping for when I rebuilt the motor and picked out this cam. It doesn't have that aggressive and lumpy idle that many equate with powerful motors and it's pretty much done at 5000 rpm. But, if you are looking for an overall streetable cam I would recommend it. If you have 3:55 to 3:73 gears You may want to consider the next step up which is the H-278 I believe.

Regards, Mark :flag :chevy