I am currently evaluating the use of larger than 1 3/4" headers for my N/A 383 buildup. The setup consists of a set of competition ported AFR 220's and Cam Motion custom grind solid roller ~25x duration and .650-.670 lift.

I have set a goal of making 500rwhp with it and was wondering what experiences have been or even opinions on using a 1 3/4" to 1 7/8" stepped header design on the LT1?

Would this setup be advantageous over a standard 1 7/8" header? ie, would the step be even better than the larger primary throughout?

I realize the 1 3/4" longtube offerings that are readily available are decent for those making up to this power level N/A but if there is some HP to be gained (which I think there is), I would be willing to spend the extra money on it.

Lastly, does anyone know who sells these headers other than having them custom made?

I know that dynatech offers them for LS1's but it seems they don't offer that size for LT1's at least according to their site but I have not called them directly to verify. There is no A/C on my car and they will be used with a tubular K-member so clearances should not be a problem, though the alternator is relocated to where the A/C is.

Any insight appreciated.

 

What's up man?

Sounds like you're trying to compete with Madhu.

 

i think your barking up the wrong tree, try putting your money elsewhere...biggest things with running N/A is compression, air volume and velocity. i doubt the headers are causing a problem. look into your heads, intake,and tb.

 

Well, Hedman makes 1 3/4 to 1 7/8 step headers, and just 1 7/8 headers for 4th gen LT1's.

Not sure if the step headers would be better than the 1 7/8 but I can say that we picked up about 18rwhp switching from 1 3/4 to 1 7/8 headers on our 427 ZO6 (which makes 527rwhp through the stock mufflers).

 

Thanks for the insight so far guys.

As far as looking at the heads/intake/TB...well, it is an AS&M monoblade rated at 1300cfm, the heads are flowing right at 300cfm on Thunder Racings flowbench (which according to them is fairly conservative), and the intake is a fully ported LT4. So that kind of leaves me with getting exhaust out. This is a weekend track/street car.

INTMD8-thanks for the info. I'll give them a call to find out info/pricing/fitment.

KRAEST-Good to hear from you. Competition is what makes you fast!

 

Hey All,

I was searching for similar and found this thread. Did you find some headers Turbo6? I also thought that with similar top mods, 383, and nitrous I should look to larger (1 7/8 or 2) headers. I was told my 4000-4200 stall would go to 5000 with nitrous off the line. I do not think low end torque will be a concern. So far it looks like weld up Dynatech or Headers by Ed.

Thanks,

Rick

 

Rick,
I spoke to a few people and like you mentioned above, both those companies can do a 1 7/8". Also I spoke w/ Jason Short and he suggested the Hedman 1 7/8" headers, though it requires some modification to the heater box and possible power steering line rerouting.

I am currently putting the 1 3/4" hooker headers on my car for my initial startup, break-in, and tuning period and seeing what kind of power it makes, at that point, when all the bugs are worked out and if power isn't what I want, I may switch to the 1 7/8". If you do go 1 7/8", let us know how it works out.

Ron

 

Thanks Ron

My biggest concern was blocking the exhaust port which I know my 1 5/8 shorty did on stock heads. I sure wish I'd never let the last engine builder and Hooker talk me into the shorty over the long tube now that I am converting from street use. I have removed the A/C and heatbox, the power brakes and ABS and the power steering. I don't have lots of room but I have more than I started with. The inner fenders better look out

Thanks again,

Rick

 

I'm running custom 1-7/8" headers on my engine... making in excess of 650 hp at the flywheel. Most dyno results I've seen seem to indicate nice gains going from 1-3/4 to 1-7/8 at anything over 600 hp.
For all intents and purposes, they should at least match up to the exhaust port.

-Mindgame

 

Yep, what MG said.

You might be able to get a little anti-reversion action if you (mis)align them correctly.

 

Well I am hoping to get near 600 but this is still the (extensively worked) LT4 intake and I have spent more on the exhaust head flow then the intake. The engine is primarily intended to work well with 300 nitrous shot so the exhaust should be key. It looks like the Dynatech weld ups will give me the best fit for the price.


I wish I could weld!

 

I have a masters in computer science a minor in mathematics/science and I went back to school to learn how to weld.

Check with your local community college! Welding courses are cheap and you meet some really neato folks. We had everything from artsy welding folks to pipe welders. It was a very neat experience for me.
I don't consider myself a pro by any means but I did learn a great deal (hands on) in a short time. Plan on taking the advanced courses next semester... time allowing. So yeah, sign up for some courses.

-Mindgame