Which size headerwould be better for a supercharged engine with 460hp and 500 ft lbs?
Longtubes 1 3/4 with 3'' or 1 7/8 with3.5"

 

Are those numbers at the crank or the flywheel. A stepped header combination of the two would be perfect but either or would be fine. What size engine is this? and what rpm range does it make that power?

 

1 7/8" headers are insane unless you are making some serious HP

 

I have seen a set of 1 7/8" Kooks headers make a 15 rwhp difference on a 402 LS1 putting out 480 to the wheels...

I like the stepped header idea. Kooks makes custom stainless headers and can probably do a stepped 1 3/4" to 1 7/8" header.

You would more than likely be fine w/ 1 3/4" headers w/ a 450 rwhp supercharged motor.

 

1 3/4 are more than enough for motors pushing up to the 500+ range, if you run 1 7/8" primaries, you need flange adapters to bolt them up to small block heads. And if you ran the 1 7/8" headers your going to lose some velocity on the low end, hurting your low end torque, and you'll probably gain some on the top end, but they are probably over kill for that motor. I believe car craft or hotrod did an issue, that tested each type of headers, shorties, equal length, long tubes, tri y's, and anything in between, including different primary sizes, you may want to look for that one.

 

Yeah I saw that article and the 1 7/8" compared to the 1 3/4" picked more hp up top than it lost down low. Why would you need flange adapters to bolt them up??

What the article did prove about the added 1/4" was that it moved peak power up in the powerband by about 150 RPM. But the difference in the high end hp and low end torque was negligable IMO. What is 8 ft/lbs when you pick up 12 hp up top while moving the peaks up in the powerband? To me nothing.

The main issues is going to be finding a company that produces a set of 1 7/8" header, if the decision is made to go that way.

I am not going to argue w/ the overkill arguement though. I doubt the 1 3/4" would be that much of a restriciton. My point is that if he is referring to 460-500 rwhp, then I am pretty sure that he might net a few more hp out of the 1 7/8".

 

hooker supercomps, baby. I almost got a pair, until i got a great deal on my hedman 1 3/4".

 

Supercharged, turbocharged and nitrous injected cars benefit from an overkill exhaust setup. Cylinder heads with 1:1 I/E ratio, 1.6 ratio rocker arms on the exhaust side and camshafts with 13* more duration on the exhaust side @.050 than on the intake. Go with the 1 7/8" headers, especially since you wont have to worry about any loss of low end torque. David Vizzard says that 100 hp nitrous jetting on an NOS kit came make as much as 190 horsepower with the right camshaft and exhaust setup .

 

Exactly. I have personally seen a car pick up closer to 300 rwhp w/ a 250 shot of N20 b/c they had the right cam and 1 7/8" headers. You need the free flowing exhaust for a supercharger/N20 application.

 

The engine is fuel injected 355 with 8psi of boost it is making
460 hp and 500 ft lbs at the crank.

 

You need an adapter for the 1 7/8" headers, because the primaries are too large, and the bolts would be smashing into the primary tubes. When you step up to a 1 7/8" primary over a 1 3/4", theres a flange adapater required, which relocates the bolt holes, to a more staggered fashion.