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