Header Sizing Questions - Opinions?

[86Cutlass383SR]

First of all, if this a beaten horse already I'm sorry. But I'll ask anyway.

I just recently had a new 383 built and was pondering if my current headers would be good or if I needed to upgrade what I have, or if I'd really see much differance in upgrading.

I presently have the Hedman 1 5/8" shorty headers. Total length is unknown. Will probably be running 2.5" true duals all the way out to rear bumper.

My engine: 383 with 10-1 compression, AFR 190 (older non-Eliminator unported) with 2.02/1.60, 230/236 .540"/.534" 113* lsa (Comp 280 XFI hyd roller on 1.5 instead of the recommended 1.6) Cam oper range 2000-5000 per Comp Cams. Daily driver with no more than 6000 rpm, more likely 5700-5800 max rpm.

Induction will be TPI based with Accel SuperRam base, runners and plenum, 58mm tb, 30# injectors with adj press regulator, modified MAF and custom chip.

It'll be lucky to even see a chassis dyno in it's lifetime but estimates are between 450-500 hp and torque. Most it's life will be between 2000-4000 rpm cruising down the highway.

Driveline will be 3.42 gears and Aftermarket T56 (.62 6th gear) and 25.7" tire.

Stock weight body (86 Cutlass)

I noticed alot of Schoenfeld's headers don't fit the stock a/c box which I'll retain. Must also fit mechanical clutch linkage.

Would moving up to a long tube header really be beneficial for my usage? Better to go with 1 5/8" or 1 3/4"? I imagine the 1 5/8" but I may be wrong.

I would really need to keep these under the $400 level. If I can get coated for that price, fine. Size, fitment, and function is more priorty than a *purty* finish.

Here's a few long tubes I've been looking at. If anyone has had any experience with these either good or bad, please comment !!!

Hooker Headers 2451 1 5/8" x 30" length painted $159.95 coated $369.95
Patriot Exhaust H8047 1 5/8" x ??? painted $156.95 coated $305.95
Dynatech 01-22000 - Dynatech Stock Clip Headers (?) 1 3/4" x ??? painted $276.95
PaceSetter Performance 72C2100 1 5/8" coated $363.39

Would it be worth going from 1 5/8" shorty headers to 1 5/8" long tubes for a daily-driven cruiser with a bit of playful driving thrown in on occasion?

Any and all thoughts/opinions appreciated. If any vendors deal with any of these, PM me.

[osdmike]

https://www.pro-touring.com/forum/sh...ad.php?t=52681



I´ve read somewhere ,that the size of the primary tubes don´t have to be larger than the size of the exhaust valve.
It makes sense to me.
Any opinions?



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[86Cutlass383SR]

Thanks for that link Mike.

I do have some observations though. They say the short tube and long tube headers produce the same power in a street motor. Yet in the second chart it starts at 3500 rpm and it appears the torque of the short tube surpases the long tube. I'm curious what that chart would look like in the 2000 - 3500 rpm range. It's also interesting they used a 433 big block with a 250/259 solid cam. I wonder what the chart would look like with a more streetable smallblock in the 1500 - 6000 rpm range.

[osdmike]

I enjoy reading HOT ROD/ CHP /POPULAR HOTRODDING -dyno tests.
Many tests shows that 1 5/8" long tubes works very well for a small block street engine,even a 383ci.
See this "Twister" dyno test!

http://www.chevyhiperformance.com/te...est/index.html

See The Twister, Part III and IV.

Maybe You´ll find something here.

[86Cutlass383SR]

Well Mike, if that don't answer my question nothing will. Thanks!

As a quick recap of that article, they took a HT383 and added TFS 215 heads and a Comp Cams XE282 (230*/236* 110*lsa) hyd roller cam and pulled 491hp @ 5700 rpm & 500 lbs/ft torq with 1 5/8" long tubes. 1 3/4" long tubes hurt performance.

My combo is very simular. 383 with 10-1 comp ratio and 190 AFR heads with an XFI 280 Comp hyd roller (230*236* 113* lsa). I've got 1 5/8" shorty headers.

Should make for a fun daily driver with close to 500hp/500tq.

Sorry if I sound a wee bit excited...

[osdmike]

Also, since You have a big cubic inch smallblock for the street, You are looking for torque.
Check out/Google, test results for "Tri-Y" headers.
Very popular in the 60´s.
Yunick,Lingenfelter,.. speak well of the Tri-Y´s.

Maybe it will solve Your clearance problems.

http://www.superchevy.com/technical/...er/index1.html

I made a pair of Tri-Y out of "Patriot Clipster" headers.
I don´t know if it did any big difference,but now I have clearence to the steering box and they are easy to remove.
I also improved My 1/4 mile ET!

[86Cutlass383SR]

I've thought about using a Tri-Y design. I may just stay with my shorty headers until I can afford some of the Tri-y's. Looking at Doug's Headers website and StrokerEngines.com who sells Doug's headers I can get them from Summit for $429.95. No listing in Summit specifically for my car but it shows the same part numbers for the 68 Chevelle as mine on the other websites. I may just have to call Doug's headers.

I wish I had fabrication skills like that. Those are nice looking headers Mike!

Thanks for the info.

[osdmike]

Check out FlowTech Afterburner Headers !

http://www.summitracing.com/search/?...0Headers&dds=1

http://www.jegs.com/p/Flowtech/Flowt...44859/10002/-1

http://performanceparts.com/part.php?partID=81732

[wmhjr]

One thing for consideration. I've used a bunch of different headers, and for build quality and fitment the Dougs are excellent. In my experience, far better than Hookers, Hedmans, etc.

OTOH, if you're planning to do ceramic coatings, I was very unsatisfied with the coating from Dougs. I actually returned mine, and purchased some Dougs from Thermal Tech. The coating was far superior to what I got from Dougs (Petronix).

[86Cutlass383SR]

Unfortunately the Flowtech Afterburners won't fit my application. 86 Cutlass 383 with a mechanical linkage T56. For search purposes I usually go with a simpler 79 Malibu 305 or 350 with standard manual floor shift.

I imagine I'll just save up for the Doug's Tri-Y's. Thanks for the tip on getting them from Thermal Tech. Prices dictate whether I get them coated or uncoated. I've actually thought about finding someone who does the hi-heat powdercoating if I can't swing the cost of the coated ones.

I just use my shorty headers for now I guess. I've got a bunch of other parts to get before I have to make a final header selection and running shorty headers now I can always cut some pipe to install the full length Tri-Y's later.

Thanks a bunch for the ideas and tips!