header tube size
 

Small block Chevy stocker engine, is there any advantage to using a1 3/4 to 17/8 inch step header over the smaller 1 5/8 to 1 3/4 inch step?

Re: header tube size
 

Probably going to need more information. Displacement? Carbureted or EFI? Compression ratio? RPM range? Car type & weight, etc., etc., etc.,

Re: header tube size
 

That would be a question for PipeMax software, Jere Stahl, or Calvin Elston (who will tell you that you need 4-2-1 or tri-y headers). I'd need a detailed sheet on the engine to give you a good idea what it wants.

Re: header tube size
 

The engine is .040 over 350, 10.5 comp. 750 dbl pump on victor jr, car weight 3100. running in IHRA Crate Motor class. Trap RPM 7200. I have always thought the pipe at head should be approx. the same size as exhaust valve but have gotten some opinions that the larger 1 3/4 inch pipe at head works better. The 4-2-1 collector is pricey but have heard well worth the investment. Thanks for your input gentleman.

Re: header tube size
 

That motor is comparable to the motor in my car and my stahl headers are1 3/4 to 1 7/8 with a 3" collector. With a tri Y it's a whole different deal.

Re: header tube size
 

Dave I have had the 4-2-1 collectors & Merge both on my car......Same E.T. out of both. I would go with the 1 5/8 step to 1 3/4........unless your running the Fast Burn heads.

Re: header tube size
 

1 5/8...............

Re: header tube size
 

Several IHRA and NHRA 360 Stockers, including myself, use off the shelf TTI 1 5/8"-1 3/4" step headers with good results. But they only manufacture Mopar applications.

Re: header tube size
 

Whatever Greg Hill is running.

Re: header tube size
 

Either size will work well on a 350. Don't fall into the "equal length" trap. Just buy a merge collector from Performance Welding. The larger header may want to be shorter on the primaries. If you don't buy a merge collector, consider buying or building a header that fires in rotation into the old style collector. But, the bottom line is, it's all theory until you get an ET slip........

Wade O

Re: header tube size
 

Wow, Wade you sound like a real header builder......lol...but you forgot to tell him about the steps in the header and what purpose they serve....

1.625 is the way to go and when you measure that exhaust port, I bet it is really close to that size.....

Chassis1

Re: header tube size
 

Myron, agree but cut the collector off and put on Mark Lelchook's merge collector. Think you'll be very satisfied.

Re: header tube size
 

Lol, I've wasted enough money on headers and hardly ever see a gain. Use the KISS method.........

Wade O

Re: header tube size
 

for the combination you run, there are very interesting ways that are not simple to make the small engines move more air then ever thought. Believe it or not, it is done with the 4 into 1 and not the tri-y because of the cfm of the smaller heads......sometimes you can speed the air up too fast and the smaller engines do not like it.....

Chassis1

Re: header tube size
 

Thank you for the feed back gentlemen, I was pretty well sold on 1 5/8 to 1 3/4 tube size, based on what I had observed around the pits, that apeared to be the most popular small block set up. I will let the manufacturer sell me on collector style. Happy Holidays to all of you.

Re: header tube size
 

;)

Re: header tube size
 

Here is what we got; 360 motor wedge 1 5/8 to 1 3/4 to 1 7/8 with merge collector, 370 motor hemi; same size one runs to 7k, the other past 8k, the 370 liked a 1 3/4 to 1 7/8 about 5 better one made 540, one made 660.

Re: header tube size
 

Strangely, mine doesn't appear to like step headers. Been running them (1 3/4" to 1 7/8") since last year, but I have never even had the thing on a dyno until recently. Bought them on the recomendation of someone I really respect. The step headers only appear to help down around 5000 RPM. Past that straight 1 7/8" picked it up everywhere. If I were foot braking they might be worth more. Wonder what I'm doing wrong, that it doesn't appear to like them, when everybody else runs them?

Thinking about trying a set of 2" primaries? My old, original-1975-rules-292" C/SM Camaro loved 2" headers. But, it was a stick car leaving over 8000. This is a 358" LT1 trans brake car, the converter hits about 6000.

Re: header tube size
 

1.750 is way too big for the lt1 first step.......measure the ports one of the heads, I think they are more D shaped and barely over an 1.500.....

and remember, just because it is a step header does not mean the steps are correct......

Chassis1

Re: header tube size
 

The 1 7/8" are even bigger, yet made more power 5500 + up.

Re: header tube size
 

BOY! You said it !
I've got a bunch of expensive stuff I'm gonna make into wind chimes and try to sell on E-BAY.
"Tune around what you have" is the best advice I ever got.
KISS method.........

Re: header tube size
 

everyone seems to forget that the cam is still the brain of this deal when it comes to headers. most of the time, off the shelf STOCKER cams are still very old designs and are not made to be as efficient as some headers are built or bought, no matter what your engine guys chooses.....truth is most engine guys miss on the cam and go to what they call, " ol' reliable cams...." but yet the racer seems to think better than the engine builder sometimes...and looks at his WHOLE combination......

Chassis1

Re: header tube size
 

I know a racer that ran a 69 Camaro 350/255 auto stocker. He had a set of Kromer (sp?) step headers that were 1/12 - 1/58 - 13/4. He blew out a tube at a race and put on a straight 13/4 on that side and did not affect performance one bit. He ran it like this for a couple of years and won class many times including Indy. Like Wade said, unless you are way out in left field there is probably not a big performance difference in them.

Re: header tube size
 

Not for nothin', Dave.. but I would be looking to talk to Billy Nees on this issue.. he will put you in the right direction, and/or build you a set..

Re: header tube size
 

I would just call this guy.! :)
http://www.perfweldheaders.com/

Take a look at the E/SA & F/SA RECORDS!

He builds nice quality stuff and he is not a liar & HIS stuff fits and WORKS!

Re: header tube size
 

X2, If he can help, he will. If he cant improve upon what you have, he will tell you that also.

and his car is bad fast!

Wade O

Re: header tube size
 

Lots of great advise guys, thank you. I'll talk to all the recommended sources for sure. I plan on installing a new cam, so the header change can be done after a new base line is established. I was pretty sure the first pipe should be close to exhaust port size but had not considered a three step header. My combination runs under the index everywhere and I'm usually in the late rounds but you know how it is in Stock Eliminator, there is always room for improvement.

Re: header tube size
 

Step headers offer a small gain, mostly what they do is increase average HP and torque. It is critical that the length of the primary and collector tubes is correct. You can actually get away with as large or larger an error in diameter than you can in length. A two step header (3 diameters) is worth just a few percent in peak power, but can be worth more in average power.

Re: header tube size
 

Mark builds the best header I have used. They are a work of art. They fit without having to bust out the hammer. His customer service is second to none.

Keep in mind, there is a common denominator in our cars besides the headers. There is a gentleman in Missouri that seems to know his way around stock eliminator engines. I wish my car was as quick as his.

Re: header tube size
 

You are so right. Brad is aces on those small block Mopars!