So im reading the latest Engine Masters magaine and reading the article of the Ultimate SB. His set up was in a nutshell was a 396ci,brodix 18*stx heads,and a 258/266-595/558 on a 108. This motor made 600hp@6500rpm with some rusty old 1 3/4 no name long tubes. No merge collector,no stepped headers, no big 1.75-1.85 primaries. Big exaust is overrated

In an other article. Another EM Contestant tested several sets of headers on a heads and cam SBF. Although he didnt give what his combo of parts. He testes several sets of headers rangeing from, kooks,Bassani,Macs,and Hooker. He tested one after the other including those headers that had merged collectors and headers that were stepped. All of them produced different peak numbers but all of them averaged out the same hp and tq numbers. So I guess the moral of the article was not to be seduced by peak numbers?. BTW if you havent read the articles Mike Petralia wrights you need to do so. Good stuff........

 

1-3/4" by 30-34" is pretty standard for a SBC. 1-1/2"--1-5/8" is considered small for that HP level. It depends on the HP and RPM's and the way the exhaust is ported and the exhaust valve size. The length has a big part also.
If ya got a blower or NO2 the size goes up.

 

Your statement is very general and you may be a bit skewed in your thinking. Exhaust design isn't just a bunch of tubes in different sizes and different lengths. When you step into the relm of actual racing and not just street car stuff than you'll see why exhaust design is important in making the motor do exactly what they need it to do. Calling it "overrated" is not valid.

 

I didnt, Steve Petralia did. I guess i should have quoted that part.

 

No it's Mike. I know him well. FWIW he moved to Tenn and now works for RTM on HP Television.

I also think Mikey over cammed that puppy and a 1 7/8 header probably would have helped, he never tried that on his motor.

Bret

 

Tell ya what......... I hope to put an end to this arguement pretty quick. Got a set of 1 7/8 stepped down to 1 3/4th ready to install as soon as I get some new springs/retainers from Bret. We'll see what the dyno says.

I don't know either but about to find out.

 

Ya may have to retune to get the full effect.
Do you mean 1-3/4 to 1-7/8 Kooks where the first step is 10" from the flange? What collector do they have?

 

All depends on the setup what set of headers will work the best.

I don't think on yours you are going to see huge gains but there are a lot of setups that have too small of headers for the RPM range they are going.

Bret

 

Nope, these come from Exotic Muscle and are basically hand made as they get the orders turn them over to whomever they have make them. Took me about six weeks to get them. The headers are 1 7/8th, flair down to 1 3/4ths and don't have a clue as to who makes the collectors.

Whoever did them did an exceptional job on the headers and frankly it is a roll of the dice so we'll see if they work or not. This learning with your wallet stuff can at times take a toll but if you don't grow ya go. Just got back from LA and hopefully everything is hear so the headers can go on and be dynoed this week.

We'll see..... what we see.

Happy New Year everyone!

 

1-7/8 to 1-3/4 is totally *** backwards to the common thinking of these days??????????

 

That's what I was thinking?

 

Flair:


Flare:

 

Wouldnt a reducer in the collector do the same job?.

 

A bit of a back half fan with a very good local “King of the Hill” circuit that I follow. Been checking out headers for some time and I see mostly larger to smaller on their cars so I’m a bit clueless as to which way is better. These start out large, get a tiny bit smaller and have a mild reducer in the merge collector going to bigger again. ???

Love the sound the big inch high compression cars make and you can always tell a high compression stepped header motor because they “squeak" when they idle. Don’t think 12.5 to 1 will give the same effect as a 16 to 1 motor.

Not holding my breath till I turn blue waiting for big gains, but at this point I’ve got to try every trick I know and if it doesn’t work…… hey, that’s unfortunately one way of learning.

Still haven’t gotten the springs so it time to bug Bret as to where they are at. Easier to do headers and springs together or I’d have those puppies on way before now.

 

OK, take a step back and clear your mind. That's it, just let it all go......

Think about the exhaust on a 2 stroke engine.... a high performance dirt bike or ATV...... do you see a pipe with a constantly varying diameter? Small at the exhaust port, getting bigger as it goes and then out near the end it necks down again? Good. You're seeing clearly now.

2 strokes LIVE on exhaust. The guys who engineer them spend zillions of hours modeling the exhaust. They KNOW how to make an exhaust work. Without their work the engine wouldn't make as much power or do so over as broad an RPM range. At least not on a 2 stroke.

That kind of knowlege and technology hasn't filtered down to the street performance V8 guys yet. Maybe someday it will, but at present the average guy doesn't know what he's doing with that kind of stuff. I certainly don't. Guys who build NASCAR motors certainly do. Somewhere in the middle are guys who are beginning to pay more attention to stuff like that. Currently, I'd say it's in the realm of "black art" for the average Joe. Might work on your engine, might not. No way to know without trying it.