Header diameter for 406ci 500hp engine?
10-18-2004, 02:30 PM
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Header diameter for 406ci 500hp engine?
I ordered and received a ~500hp 406ci engine from AR Racing on EBAY.
They said they dyno'd it with 1 3/4" diameter headers.
The engine has a large cam with lots of overlap (108 LSA, ~248 duration at 50).
Wouldn't that high a horsepower engine, with so much overlap, like 1 7/8" primaries? My understanding is that backpressure is the enemy of overlap.
Thanks.
They said they dyno'd it with 1 3/4" diameter headers.
The engine has a large cam with lots of overlap (108 LSA, ~248 duration at 50).
Wouldn't that high a horsepower engine, with so much overlap, like 1 7/8" primaries? My understanding is that backpressure is the enemy of overlap.
Thanks.
10-18-2004, 05:28 PM
#2
they dyno the 357hp TPI vortec Crate motor with 1 3/4 headers.
That 406 motor would be better off with 1 7/8 primaries to help that motor breathe. 1 3/4 would be sufficient especially good set of long tubes, but 1 7/8 would probly see an increase in power. It may be slight, or alot, i not sure.
That 406 motor would be better off with 1 7/8 primaries to help that motor breathe. 1 3/4 would be sufficient especially good set of long tubes, but 1 7/8 would probly see an increase in power. It may be slight, or alot, i not sure.
10-18-2004, 09:49 PM
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Car: One of 5
Engine: LB9
Transmission: 700R4
1 3/4 longtube headers should be enough, I have seen guys wilt 600fwhp use 1 3/4 lt's. I'd be more worried about buying a engine off ebay. Most of those guys use desktop dyno for their buildups HP claims. I am just a little more partial to using a local builder for engines.
10-18-2004, 11:20 PM
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Car: 1989 Trans Am
Engine: 355 HSR
Transmission: Pro-Built 700r4 w/ 3400 converter
Axle/Gears: 10 bolt w/ 3.42 gears
I would go w/ 1 7/8" personally. I have seen LS1 346s w/ 1 7/8" on h/c motors...
10-19-2004, 02:27 AM
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Car: NCC-1701-D (docked in AZ)
Engine: impulse drive
Transmission: fusion reactors
Axle/Gears: Rescued from the Borg by my crew
I have a 406/500hp motor in my 85Z28...I use the 1 3/4" long tubes and they are fine. Having 1 7/8" certainly wouldn't hurt either.
10-19-2004, 10:38 PM
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Car: 89' T/A, 00' Firehawk
Engine: 406 Roller
Transmission: TH700R4 w/2800 stall
Axle/Gears: 3.23 Posi
I think 1 3/4 and a true dual 3inch system would be enough. I have an estimated 500hp 406, 
won't know till it hits the dyno and I have 1 3/4 and 2.5 true dual system right now, thinking about going to 3 inch. I think you have to run an adapter to use 1 7/8 header, I think, and finding a set of headers that big to fit a third gen has to be expensive.
won't know till it hits the dyno and I have 1 3/4 and 2.5 true dual system right now, thinking about going to 3 inch. I think you have to run an adapter to use 1 7/8 header, I think, and finding a set of headers that big to fit a third gen has to be expensive. Trending Topics
10-25-2004, 08:50 PM
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Car: 1984 Camaro on steroids/ 1987 iroc-z28 5 speed.
Engine: 383 nitrous motor / poindexter 305
Transmission: Th350
10-26-2004, 11:23 AM
#9
Hedman makes some headers for our cars. 1 7/8 and 2" headers! 
Thats big for small block!!
But a good set of hooker super comps in 1 3/4 size will be enough for sure.
http://www.hedman.com/pages/hedmanmain.html
Thats big for small block!!But a good set of hooker super comps in 1 3/4 size will be enough for sure.
http://www.hedman.com/pages/hedmanmain.html
10-26-2004, 07:00 PM
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Car: 82 TRANS AM
Engine: BIG BLOCK
Transmission: TURBO 400
11.0's @123 in a 3750 lbs. 82 TA
I had a .030 over 400 SB in my firebird with the 1 3/4" super comp. headers that ran on pump gas. You figure up that horse power @3750 lbs. with driver.
PS: I had an Isky roller hyd. 246 degrees @ .050 with a 110 degree lobe sep.
PS: I had an Isky roller hyd. 246 degrees @ .050 with a 110 degree lobe sep. Last edited by 10 SECONDS; 10-26-2004 at 07:04 PM.
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