2.0" to 2.125" in about 14.0" down the tube for the stepped header effect, adjust the 14.0" distance depending on cam grind and RPM for optimum results.
Reason I ask is I've got some 2in hooker super comps the over the rail style but I seen where Rick Martinez and Hecker saw 30hp Goin to 2.125 header on the stage 1 head,...now I haven't got the heads yet so it's either get some TE stage1s are TE stage 2s and then build a set of 2.125,...either will have a merge collector with probably a 3in choke
What I'm thinking too Gary,...I'm all but positive I'll end up with a stage2 head more I think about it the more I want a crazy looking header to compliment the tunnel ram,...like something that goes up and over the rails,.. clearance the cowl back to accommodate the tubes whatever's needed I guess
Motor in the stude made 703hp with 2” t/a stage 2’s. Bolted on my homemade 2 1/8” noisemakers and it made 679hp. It’s fun watching people cringe when I fire the stude off, good for frightening pets and small children. lol Big, ugly noisemakers…
Well not that it should matter , but with a Pontiac 505 cid in a 3300 lb car with 2" tubes the best time was a 9.13 1/4 mile. Seem's to work out to 740 hp.
9.55@140 3860-3880 lbs. off foot brake. 2” comp headers to 3” exhaust to rear end w down spouts. Has a 2.5” h pipe.
Hey gang, lets look at things purely by numbers/ math. In a perfect world so to speak a 2" header could handle the Exh from a Exh valve bowl with a 2" throat. If you go with the accepted max of 91% for the valve to throat ratio then a 2" throat would be being fed by a massive 2.360" Exh valve. How many full out race heads does anyone know of that uses a 2.360" Exh valve ? In my book once you get up above making 760 hp then it's time for 2.250" header tubes, especially if the motor is being run way way up high and with a narrow 1500 rpm wide power band.
I will have a custom set made,which will likely be a step header. 2” to 2 1/8”,and 2 1/4” if needed,then a merge collector. I’ve made some satisfying gains with a custom header. This is also 800+.
I'm gonna try the 2in on the 494 with the tunnel ram and a flat tappet,...9s are probably optimistic,...the 475 aluminum rod that will go in later on will see more rpm for sure,..it I feel like will go 9s
What length should the 2” be before going up in size on stepped headers? Didn’t know if there is a magical number.
I believe I read on Calvin Elston site steps at 8”. He also mentioned to start with the size of the exhaust port opening or just over if need be. And step up. Mine is a Chevrolet but in reality they are all air pumps.
I’ve never tried anything but the exhaust that’s on my car over 20 years. It would be an interesting test but costly so I work with what I have now. I do believe there is power just like you say left on the table. I’d do the step if I were to invest in new headers.