I currently have a set of FabShop headers on my SBC powered dragster. 2in to 2 1/8 with a 3.5 in merge collector. The engine is 429 cid that makes peak HP at 8400 rpm. Is shifted at 8600 rpm. My engine guy says the headers are killing this engine with the small collectors. I called about welding a set of 4 in collectors on the headers. They want me to go with a set of 2 1/8 to 2.25 with a 4 in merge collector. Question is, would headers of this size be too big and kill the low end? Or would they be just too big? Bob J

Reher Morrison recommends a 2 3/8 primary, 4" collector for their 665" BBC..... Your engine builder is recommending a damned big header...I've seen big blocks with smaller headers than that run very well.....Merged headers are intentionally made smaller at the entry to the collector to increase exhaust velocity and scavenging.....I'd stay with what you have..but that's just me....

I'm with Mark on this one. A lot of people don't realize how small a header they can get away with.

Before you drop any money you may not need to, I'd suggest getting a copy of PipeMax from Larry Meaux.

Was the topic brought up because it wasn’t performing to your expectations or just talking in general

I run a 2.25 straight out to 4” merge fab shops on my 600” engine shifting at 7400. 4.70 at 148 in the heat @ 2000 lbs, no idea what hp it makes.

quote:

Originally posted by nomad:
I'm with Mark on this one. A lot of people don't realize how small a header they can get away with.

Before you drop any money you may not need to, I'd suggest getting a copy of PipeMax from Larry Meaux.

I already ran my engine specs on PipeMax. It said 2 in to 2 1/8 in to 2.25 in with a 4 in collector. I thinking about going with that combination. Bob J

Exhaust port size to 2 to 2 1/8 to a 3 1/2 merge to a 3 1/8 choke* to a 3 1/2 exit.

Call Calvin Elston to double check that though.

This message has been edited. Last edited by: Mike Rietow,

I would be surprised to see a big difference. How much power is it making? It's certainly high strung! How low do you run it in the power band during a run? If you are never loaded under 7000 rpm, I don't know that a bigger header would hurt you anywhere.

I'm surprised no mention of power, it's gotta be a 18 degree 850 - 875 - 900 hp.

I'd call Calvin Elston, it might take him a week to call back, but he will call back if he doesn't answer. He can easily tell ya exactly what ya need.

This would be a guess from the brief education he gave me on the phone. I definitely wouldn't do pipe max after talking with this man and seeing the results first hand, of his suggestions.

Exhaust port size to 2 to 2 1/8 to a 3 1/2 merge to a 3 1/8 choke* to a 3 1/2 exit.

Realistically you won't gain much on the timeslip going 2-1/8 or even 2-1/8 stepped 2-1/4... Gotta decide if the amount of money for new headers is worth the little gain or not. I know a guy with 2-1/4 straight headers on his BBC 632, approx. 1150 hp, that runs low 4.50's everywhere in Ohio, even quicker at sea level. So take that for what it's worth.

I never look at like what do I gain from bolting any part on. I look at it from the perspective what do I gain with the capacity to gain once everything on the combo is optimized. Especially headers, you're looking for the slightest edge on the competition.

If I had 30 - 40k wrapped up in a sbc, I'd definitely want resonance appealing to the ear, as well as the capacity for optimized performance.

I bolted the configuration that was suggested to me with the Idea of mufflers. When I fired it first time uncapped, my first thought was there's no way in hell I'm putting mufflers on this. No way.

People think you need to have the pipes outside the car with methanol, for the fumes - doorslammer. I pointed the collector extensions slightly to the ground and cut the pipe at a slight angle (long on floor board side). No fumes on the driver seat at all, none.

Try that next go around.

If you do make the change recommended by Pipemax come back and let us know the results. I for one would be interested in knowing how well it worked.

quote:

Originally posted by scoop:
My engine guy says the headers are killing this engine with the small collectors.

Find a new engine guy. Guys like him will always every other component except their engine when it don't make the power it should and/or don't run the ETs it should.

quote:

Originally posted by scoop:
I already ran my engine specs on PipeMax. It said 2 in to 2 1/8 in to 2.25 in with a 4 in collector. I thinking about going with that combination.

be prepared to run slower ETs.

quote:

Originally posted by Mike Rietow:
Exhaust port size to 2 to 2 1/8 to a 3 1/2 merge to a 3 1/8 choke* to a 3 1/2 exit.

Call Calvin Elston to double check that though.

The current headers are 2 in to 2 1/8 in with a 3.5 in collector that 3 in at the merge and 4 in at the exit.

The engine has 18 degree heads and a sheetmetal intake with 2 Dominator carbs. Made right around 900 HP on the dyno with a 2 in to 2 1/8 in headers with a 4 in collector. It goes to 7300 on the hit shift at 8600 and it should see 8700 to 8800 in the quarter. I have only been to the 1/8 mile so far this year.

quote:

Originally posted by scoop:
The engine has 18 degree heads and a sheetmetal intake with 2 Dominator carbs. Made right around 900 HP on the dyno with a 2 in to 2 1/8 in headers with a 4 in collector. It goes to 7300 on the hit shift at 8600 and it should see 8700 to 8800 in the quarter. I have only been to the 1/8 mile so far this year.

Ok, well my guess is there's nothing to be gained spending 2 or 3k on a set of headers but I can imagine how this went. This is a guess now.

You run it on the dyno it makes good power, you put it in the car, make a few licks and you're not quite happy with it, so you call the engine builder and he suggests bigger headers?

You gotta take into consideration what you're running isn't cookie cutter as a BBC dragster where there's so many of them out there what works is easier to hit on from the transmission to the converter to the gearing and fastest tire for any given torque.

It could be a lot of different things causing it not to run up to snuff but the fact there's not a bunch of people going this route kinda makes you on your own.

I'm kinda in the same boat sbc heavy doorslammer so I focused on the gearing, number of clutches in the transmission, transmission pressure, converter. These sbc gotta 60ft to run exceptional.

If you're shifting this thing 8600 you may need a 7" converter dunno, but I do know the drop back at the shift needs to be 7600 minimum.

These are just some thoughts, I could be a mile off, you'd need to tell us more about it. I'd definitely not spend the money on headers though, the engine builder most likely isn't well versed with gears, transmissions and converters.

I could definitely help ya but I'd have to have more info. I don't see any problem running exceptional though, sounds like you have some good stuff.

quote:

Originally posted by scoop:
The engine has 18 degree heads and a sheetmetal intake with 2 Dominator carbs. Made right around 900 HP on the dyno with a 2 in to 2 1/8 in headers with a 4 in collector. It goes to 7300 on the hit shift at 8600 and it should see 8700 to 8800 in the quarter. I have only been to the 1/8 mile so far this year.

Ok, so the converter is a little tight 7300. That won't help. Ya probably have a Transmission more suited a BBC too - number of clutches and pressure. All this combined kills the 60 ft.

Not the headers. If it'll 60ft, it'll be a rocket ride for what it is. Typical for sbc chit.

If it has a transmission cooler, bypass it, loop the line, see if that does anything to the drop back rpm.

If you get out there, shift and it drops back 7100 that'll knock the wind out of the sails too, especially two carbs.

Loop the cooler, see if that does anything.

As far as transmission cooler lines etc., if you do have one and it has the Jiffy Tite quick disconnect fittings, it has been confirmed that they will tighten your stall up a few hundred RPM. Just something to consider, but as mentioned above I do not know what you have, so I'm just throwing this out there.

quote:

Originally posted by NC3x58:
As far as transmission cooler lines etc., if you do have one and it has the Jiffy Tite quick disconnect fittings, it has been confirmed that they will tighten your stall up a few hundred RPM. Just something to consider, but as mentioned above I do not know what you have, so I'm just throwing this out there.

That's a fact.