Who hates messing with long tube headers?

[olds307 and 403]

I went with Sanderson shorties because they had thick 3/8" flanges that only need RTV to seal and smaller 1 5/8" primary tubes. The passenger side went in from above. The driver's side would have, except the steering shaft was tight, might have scratched the ceramic coating. They cleared everything too. How much flow advantage do full length headers have with big dents? I saw comparision to factory 318 manifolds, terrible just like SBO manifolds to 340, 360 manifolds, shorty and full ength stepped headers. On a 300 hp 318 the HO bigger manifolds were worth 11 and 14 hp. The headers 21 hp and 28 hp, shorty and full length. Similar torque gains too. If factory HO manifolds are avialable, they may be worth it over headers on a pure street motor. The SBO only has the Thornton manifolds as an option, never seen dyno proof. A 10 hp would be max with them.

 

[Chickenbone]

I forgot to mention the Doug Thorley Tri-Y's that I had on the Malibu. They were only mid-length headers, but they ran really nice with the 305 sbc. The install wasn't so bad either. I did everything backwards though. I did the exhaust two years prior to installing the headers. So fitting the new cat and mid-pipe to the supplied Y pipe took a little time. That install was totally worth it. The increase in MPG alone was worth it, let alone the sound. I wish I had gotten another engine to use those headers on, to see their true potential. I also wish Doug Thorley had long tube versions of those headers for the G-body platform.



Chickenbone

 

[Intragration]

Headers may only be worth 10 horsepower over good factory manifolds, if you can find those good manifolds, but to me the point is that every little bit helps. 10 horsepower isn't going to win a race, but 10 here, and 7 there, and 12 there and then you're starting to talk.

 

[Chickenbone]

I think a good place to start mods to any engine is the exhaust. Especially with the older sbc and bbc engines with their log manifolds. Then afterwards, you start matching engine components to work with your plan for that car/truck. All in all, good/fun stuff



Chickenbone

 

[ElCamMan515]

After Seeing This Post, I Have A Set Of Shorties That Wont Clear My Mechanical Clutch Linkage So I Am Thinking About Modifying Them Into Some Log Type Manifolds. Good Thread!

 

[DoubleV]

Headers may only be worth 10 horsepower over good factory manifolds,

It really depends on the engine. Headers may only give you a modest gain on a weenie build but can provide a massive gain on a real beefy build. Of course the gains from headers are also determined by how good/bad the exhaust manifolds are to begin with and proper sizing of the headers themselves.

If everyone had the luxury of having custom made headers made specifically for their engines, the gains could be substantial even on weenie builds. Unfortunately due to cost and space limitations, the vast majority of us will never experience what a set of 'perfect' headers can really do.

 

[PGLM]

Headers may only be worth 10 horsepower over good factory manifolds,

It really depends on the engine. Headers may only give you a modest gain on a weenie build but can provide a massive gain on a real beefy build. Of course the gains from headers are also determined by how good/bad the exhaust manifolds are to begin with and proper sizing of the headers themselves.

If everyone had the luxury of having custom made headers made specifically for their engines, the gains could be substantial even on weenie builds. Unfortunately due to cost and space limitations, the vast majority of us will never experience what a set of 'perfect' headers can really do.

yep, I have seen 50horsepower gains between 4-1 and 4-2-1 headers... Although it was 350cid race engine..

 

[bigalturk1]

I hate headers!
They leak, they're hot (Especially Fenderwell headers).
However....You can buy exhaust manifolds (Small-blocks) from Speedway that have 2 1/2 inch outlets...they work very well.

 

[1SlowBu]

I don't know but I don't think I want to try exhaust manifolds on a motor that makes 1100+ hp on N20. I'm just sayin.