Switching from 1 7/8 headers back to 1 3/4" on H/C car?
03-23-2007, 11:38 PM
#1
Switching from 1 7/8 headers back to 1 3/4" on H/C car? As title says, trying to decide if it's worth the trouble to switch from 1 7/8" primaries (currently on car) back down to 1 3/4"........mods are F13 112LSA, TEA Stg 2.5 LS6s, full bolt ons, including FAST 90/90, making ~450rwhp thru a 9" w/ 4.10s and a very rich tune. I'm expecting the usual response of a loss down low, but what about the rest of the powerband?
Also, is there a noticeable sound difference just by changing the primary size? I absolutely LOVE the way it sounds at the moment (ORY into Magnaflow).
Also, is there a noticeable sound difference just by changing the primary size? I absolutely LOVE the way it sounds at the moment (ORY into Magnaflow).
03-24-2007, 12:05 AM
#2
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I don't think going from 1 7/8" down to 1 3/4" will gain anything except maybe a little under the curve. 1 7/8" are usually for 408ci + motors or high HP and high reving 347's. You may see some throttle response but probably 0 HP gain. On a 347ci motor a 1 7/8" primary header is only needed in 700rwhp applications and above to see a gain. Other's will chime in I'm sure but I just don't see it.
03-24-2007, 12:17 AM
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Personally id stick with the 1 7/8s. im running them on my bolt on car and have no problems, lost a bit of torque but gained 2 mph up top with them, so really no loss or gain
03-26-2007, 09:33 AM
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Has anyone actually proved that you will not gain with 1 7/8 or stepped 1 3/4 - 1 7/8 headers over 1 3/4 headers on a 346????
All I keep reading on this site is that 1 7/8 headers are for bigger cubed engines. Where is the proof????
I switched from 1 3/4 Hooker LT's w/ 3" X-pipe duals to stepped 1 7/8 Eddlebrock LT's w/ 3" mufflers off the headers and picked up E.T. & MPH. I will have dyno #'s on the new setup within the next 2 weeks.
All I keep reading on this site is that 1 7/8 headers are for bigger cubed engines. Where is the proof????
I switched from 1 3/4 Hooker LT's w/ 3" X-pipe duals to stepped 1 7/8 Eddlebrock LT's w/ 3" mufflers off the headers and picked up E.T. & MPH. I will have dyno #'s on the new setup within the next 2 weeks.
03-26-2007, 09:33 AM
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It's funny, on a SBC a 1 3/4" header is uncommon and more of a race piece. You'd be hard pressed to find a 1 7/8" header unless it's a dragster, but on 'tech people daily drive the big tubes. 
Ben T.
Ben T.
03-26-2007, 09:37 AM
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There's a lot of people out there that still think backpressure is a good thing and true duals are too big for a bolt on car too. How many of those naysayers are actually going fast though?.....EXACTLY!
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03-26-2007, 03:05 PM
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I don't think it's worth the swap. You have a large cam and big setup as it sits. You *might* gain some tq down low, because of better exhaust gas velocity at low rpms, but prob not enough to be worth the cost.