Headers 1 5/8 vs 1 3/4
Thread Starter
Race Director
Joined: Dec 1999
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From: Forked River NJ
Headers 1 5/8 vs 1 3/4
Is it worth it to go from a 1 5/8 tube to a 1 3/4 tube header on a 500 HP 383. Engine builder says I will lose maybe 8 to 10 HP. I have the 1 5/8 Hookers on mine now and it would cost about 600+ dollars to upgrade to 1 3/4 Jet hot coated.
Thread Starter
Race Director
Joined: Dec 1999
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From: Forked River NJ
Maybe I worded it wrong. If I stay with the 1 5/8 I would lose 8 to 10 HP over going with a 1 3/4. So the 1 3/4 will make 8 to 10 more HP than the 1 5/8. What will it do in the midrange though?
Le Mans Master
Joined: Oct 2004
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From: Orlando Florida
St. Jude Donor '05
1 5/8 is more or less the standard header size for a 350 (long tube headers). I have 1 7/8 primary tubes on my Hooker sidepipe headers and I was told many times that that's too big for a 350... well, I'll soon have a 383 so that will be taken care of 
Your 383 should be happier with the 1 3/4 tubes, I would expect more than 10 HP gain. Not sure how noticeable the difference between 495 and 510 HP is.... not worth $600 IMO....
Your 383 should be happier with the 1 3/4 tubes, I would expect more than 10 HP gain. Not sure how noticeable the difference between 495 and 510 HP is.... not worth $600 IMO....
Team Owner
Joined: Sep 2003
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From: eville in
Originally Posted by RedBad1979
1 5/8 is more or less the standard header size for a 350 (long tube headers). I have 1 7/8 primary tubes on my Hooker sidepipe headers and I was told many times that that's too big for a 350... well, I'll soon have a 383 so that will be taken care of
Your 383 should be happier with the 1 3/4 tubes, I would expect more than 10 HP gain. Not sure how noticeable the difference between 495 and 510 HP is.... not worth $600 IMO....
Your 383 should be happier with the 1 3/4 tubes, I would expect more than 10 HP gain. Not sure how noticeable the difference between 495 and 510 HP is.... not worth $600 IMO....
Race Director
Joined: Dec 1999
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From: Sierra Foothills CA
I've been running 1 3/4" on my 70 Z28 forever & it's just a built 355. It's strong right from off idle- not bigblock strong of course but not at all soft in spite of a healthy solid lifter cam. The 4.10s help but I also have the Muncie close ratio, which only has a 2.20 1st gear. If your 383 will make 500 HP I think it would like the 1 3/4" headers & I'd guess a gain of 15-20 HP. I'd go for it but I like to get everything I can out of my combo. 
Thread Starter
Race Director
Joined: Dec 1999
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From: Forked River NJ
Originally Posted by PRNDL
Gordon, you must be well over 400 hp at the flywheel right now. How much more power are you expecting from this new engine?
Anybody looking for a set of 1 5/8 Jet hot coated Hooker Comps. Might be looking to sell mine if I go to the 1 3/4
What is the chance of the 1 3/4 Hookers bolting up in the same location as the 1 5/8 at the collecter. Probably not much
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Burning Brakes
Joined: Aug 2002
Posts: 1,146
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From: Scottsboro Alabama
Here's some info on headers........
http://www.chevyhiperformance.com/te...8_0404_header/
http://www.chevyhiperformance.com/te...8_0404_header/
Last edited by Older Than Dirt; Jan 10, 2006 at 09:06 PM. Reason: typo
Thread Starter
Race Director
Joined: Dec 1999
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From: Forked River NJ
Originally Posted by Older Than Dirt
Here's some info on headers........
http://www.chevyhiperformance.com/te...8_0404_header/
http://www.chevyhiperformance.com/te...8_0404_header/
Thread Starter
Race Director
Joined: Dec 1999
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From: Forked River NJ
Originally Posted by Redshark6974
whats this about a new 500hp 383?? specs?! I'm hoping to have my roller 383 fired up this weekend.
Taking my upper end of AFR 190 heads Victor Jr and 750 DP and my cam 294S (might change this) and putting it on top of a 383. Forged 4340 Eagle crank, Eagle H beam rods and SRP forged pistons with 10.5:1 comp ratio. Block is at the machine shop right now. Bottom end is stron enough for a lot more but I have to keep some type of budget wit hall the other mods to the car. The roller cam is just not in the budget for now.
Race Director
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Using the same parts and just increasing the motor displacement form 350 to 383 ci will not increase HP any, it is possible it could drop a few. It will increase torque at the lower RPMs which will make it alot more fun to drive on the street. I would stay with 1 5/8 in. headers for the extra torque they will deliver
Team Owner
Joined: Apr 1999
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
You need to read a book on header science. It's a combination of primary diameter and length that determines the operational range.
The head exhaust port size is a consideration.
Your better off spending the $600 on a super free flowing three inch exhaust system and let your 1 5/8th do their work for now. I'll also keep you in mind when I remove my 1 3/4 Hooker S/C's I've been looking at adapters and running 2 or 2 1/8. My head ports are larger than 1 3/4 so I had to grind out the pipes to kind of match
The head exhaust port size is a consideration.
Your better off spending the $600 on a super free flowing three inch exhaust system and let your 1 5/8th do their work for now. I'll also keep you in mind when I remove my 1 3/4 Hooker S/C's I've been looking at adapters and running 2 or 2 1/8. My head ports are larger than 1 3/4 so I had to grind out the pipes to kind of match
Burning Brakes
Joined: Feb 2004
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From: shawnee ks
Keep your headers you have,like moterhead said bigger cubes more tq at lower rpms,We thought about bigger headers than 1 5/8 on this 1000hp camaro I have been building but all the engine gurus around here said no benifit unless going to spreadport heads.As long as the rest of your exhaust flows well your in great shape.This engine is a 427 and it works very well.