Question about headers...

[TRAU 82]

Hey guys...feel a bit like a noob, but i need a little help from all my truck enthusiasts out there. SITUATION: im restoring my 82 short bed chevy...i've taken out the ole stock 305 and am replacing it with a rebuilt '94 vortec motor bored .20 over(vortec heads), edelbrock intake with a 770 Holley carb. i'm now at the stage of purchasing a set of headers and thats where you guys may be able to help me out...will i be purchasing headers for a 94 model motor? or an 82 model chevy?? i think i've looked at so many pair of headers i've simply confused myself but...perhaps you guys can be of help. also, what brand have you guys had luck with/would opt to stay away from? Shortys or full-length?? your help is much appreciated..

[codydubb]

Quality headers come at a price, IMO the bigger the tubes the better for performance anyways, longtube headers all the way, you get very little advantage running shorties over stock manifolds, my favorite brand would have to be hooker headers but there are a ton of other great companies out there, but like i said quality comes at a price!

[Cue-Ball]

Originally Posted by codydubb

the bigger the tubes the better for performance anyways, longtube headers all the way, you get very little advantage running shorties over stock manifolds

None of those things are true.

Making power is all about velocity. Bigger is NOT always better. If you want to make power at 10K RPM then you need big headers to prevent restriction and keep the exhaust velocity high. If you're mostly driving around town and are using an engine built to make power under 6K RPM (which Vortecs are perfect for, and most trucks are used in this way), then you don't need large tubes and are better off with smaller tubes. That's right, *smaller* headers make more power in these circumstances.

Longtube headers often make more power than shorties, but not always. And the installation and clearance issues often make them not worth the hassle. That's part of the reason that Tri-Y headers became so popular. They offered most of the performance of long tubes but were easier to package than longtubes or equal length shorties.

Shorty headers can be a huge advantage over stock headers. They are more uniform in size and shape so the exhaust gases don't have to constantly speed up and slow down in the tube. Look at most any SBC exhaust manifold and you'll see that the exhaust gas has to take a sharp 90 degree turn as soon as it exits the port. Headers smooth out this turn with a larger radius which aids velocity. Additionally, because they are made of formed steel and not cast iron they are smoother and less turbulent inside. Also, many of the headers from the 60's to 80's are "log style" which cram gasses from multiple cylinders a single small tube. The different pulses hit the collector at irregular intervals and cause issues with flow. Even a crappy shorty header is going to be more efficient than most older stock cast iron manifolds.

Here's an excerpt from a Chevy High Performance header test that was conducted a few years ago:
"As for the smallest of the headers tested, we meant to provide a baseline number but instead netted the best overall power curve for a street/strip vehicle. We feel comfortable concluding that the shortest and smallest tube design held true to our initial theories by promoting as much upper-end horsepower as possible with a short tube while building an impressive amount of torque with a small diameter."

Keep in mind that the headers they're talking about are Flowtechs with only 1.5" primaries. And this is on a fairly stout 383 making over 430 hp! They'd certainly be large enough for a milder 350 or 305.

[benoit454]

do long tubes, and as far as I know they all should bolt up to vortec heads, buy them for the truck NOT the heads. Buy them for an 82 chevy 2wd or 4wd whatever it is and stick shift or auto whatever it is.

I've run dynomax before and they fit 2wd or 4wd auto or stick. I have a set of the summit brand on an 84 right now 2wd and not that impressed due to them hitting a plug and had to dimple and tube and they angle down. Not much of a problem though.

IMO maybe the stainless ones on ebay, they are long tube and about $158 a set. stainless doesn't rust like the others and at that price it's cheaper then coated ones.

[Prerunner1982]

You will need to look for headers for a 94 motor.. as the exhaust ports/mounting/plug angle etc.. may be different.

But someone with a vortec motor in a square may be better to answer this.

Disregard my statement........ most likely wrong.

[benoit454]

they won't fit, 88-98 truck headers don't fit a squarebody truck from what I've seen and as far as I know the bolts are the same, the ports and plugs too I think, maybe they have angled plugs though not sure.

[TRAU 82]

Thanks for the help so far guys...i'll continue my research before shelling out the cash, but if you happen to discuss the issue with a buddy or come across anymore findings please let me know..

[benoit454]

very true I heard the sae thing. it also applies to pipe size for the whole system, which in short means it's easier for velocity to move gasses out of a 2-1/4 or 2-1/2 pipes then it is to have a huge 3 inch pipes that's not really needed. Velocity is gonna be lower and not help to pull the exhaust out faster as it would with smaller pipes.

The larger pipes do sound deeper, but unless you got some big power maker or something it's not really needed.