Why headers?

[CharlesBrown]

I've seen any number of posts extoling the bennies of replacing the factory headers as the easiest and simplest was to improve performance. Okay, if they say so, I suspect there's something to it. However, what does this say about the good folks at Chevrolet? They designed a, "World-class sports car" with just average (or worse) headers? Maybe headers aren't the first place the average bear should look for more ponies.:confused

 

[stang-etr96]

Headers are a proven power adder. GM does what they do to compromise between cost, noise abatement regs, fuel regs and a host of different laws and regs in 50 different states plus the federal boys and the big guy in the glass office at the top that puts the OK rubber stamp on the deal. Politics bite. Once the warrenty runs out.... god bless the aftermarket.

 

[svoch]

I just put long tubes on my 96 LT4 CE. I already have noisy 3" triflow exhaust. Now w/ headers..yikes, very loud but very cool. WE dyno at 20 more ponies at rear wheels with headers. GM would not sell one vette with noise like that.

 

[geekinavette]

The early C4 factory "headers" are so poorly built it is not even funny. Sure they're stainless steel...but beyond that they really are pure crap. (I can only speak for 84 "headers", no idea how or if they improved in later years).

 

[Sunstroked]

Recently our corvette club had a dyno day at a local shop. A fellow enthusiasts 94 corvette, supposedly stock with the exception of longtube headers, and an aftermarket ignition system produced 307 hp at the rear wheel, I dont recall the torque. My 92, has a catback only exhaust with a thermomaster chip, produced 273 hp, 315 torque at the rear wheel. Both are Lt 1 engines with no internal mods, my engine had just turned 105k, his has over 200k. Talking it over, last weekend with the 94 owner and we joked about his engine being looser internally must have accounted for the wide h.p. gain. Hard to say, but it could be that the headers flow that much better. Also he's not the original owner, so maybe someone else did something internally, cam? rockers? performance tune? Dont really know for sure.

 

[svoch]

Sunstroked, My son works in an autobody shop that recently open a performance joint with Dyno. I have have had the long tubes laying around and i was dreading installing them. My son 25 took them to the shop and they Dyno before and after headers. before 321 321 rwhp and 312 tq. Now keep in mind this is a LT4 with only bolt on stuff.(no internal work)
Cold air
Granatelli mass aif flow
4.10 gears
Stage 2 jet perf chip
hi pressure f/regulator
triflow cat back
aluminum Flywheel
48K miles
So we remove the cats and add the headers...341 RWHP and 340 torque. That is roughly 400 HP at flywheel and as you know it was rated 330 stock.+70 ponies.

I posted Dyno on Grand Sport web site...best regards

 

[CharlesBrown]

Sunstroked, My son works in an autobody shop that recently open a performance joint with Dyno. I have have had the long tubes laying around and i was dreading installing them. My son 25 took them to the shop and they Dyno before and after headers. before 321 321 rwhp and 312 tq. Now keep in mind this is a LT4 with only bolt on stuff.(no internal work)
Cold air
Granatelli mass aif flow
4.10 gears
Stage 2 jet perf chip
hi pressure f/regulator
triflow cat back
aluminum Flywheel
48K miles
So we remove the cats and add the headers...341 RWHP and 340 torque. That is roughly 400 HP at flywheel and as you know it was rated 330 stock.+70 ponies.

I posted Dyno on Grand Sport web site...best regards

Would it be correct, then, in thinking that you could not be sure which of the mods (converters out or headers on) were responsible for the additional HP?

 

[Toms007]

Going back to my younger days of hotrodding, my biggest con on headers is that most headers do their best at higher RPM's. I've had headers on three of my past vehicles and after the installation of the 4 tube headers, my low end power suffered, you know, the place where street driven cars (or pick-ups) are 80% of the time. Tri-Y headers (vs 4 long tube) are the only ones which really help the low end power and yet they flow nearly as well as long tubes at the upper end. My question is why aren't there more Tri-Y on the market? None of the major manufacturers make Tri-Y's for our cars. My guess is that the 4 tube ("equal length") headers are less expensive to produce??

 

[ZumZum]

Going back to my younger days of hotrodding, my biggest con on headers is that most headers do their best at higher RPM's. I've had headers on three of my past vehicles and after the installation of the 4 tube headers, my low end power suffered, you know, the place where street driven cars (or pick-ups) are 80% of the time. Tri-Y headers (vs 4 long tube) are the only ones which really help the low end power and yet they flow nearly as well as long tubes at the upper end. My question is why aren't there more Tri-Y on the market? None of the major manufacturers make Tri-Y's for our cars. My guess is that the 4 tube ("equal length") headers are less expensive to produce??

A lot of header buyers make the mistake of buying headers with too large primary tubing. 1 3/4" tubing is not needed for a stock or nearly stock small block Chevy motor. While you will see high rpm improvement it will be at the cost of low end power. Save the 1 3/4" tubing for big cube, high rpm, cammed up motors.

A 1 5/8" primary is more than adequate. You will see an improvement in bottom end power (although the range may move up just a tad) and high end power.

1 5/8" primaries feeding into a 3" exhaust or a 2 1/2" dual exhaust (with a x-pipe) will definitely give you a seat of the pants improvement in your entire power range.

 

[aboatguy]

I love my 1 3/4" primary tube headers (they were the size recommended by my head porter/cam supplier) Now he is telling me to scrap the 2 3/4" factory cat back and go to 3" duals with an X pipe. But I have an LT1 not an L98 and my engine likes to BREATHE. (Cam 23X 23X with .6XX lift)

MIke