ok just like the title says,,,,,,,, is there a big difference from tubular in flow and back pressure given the same size turbo, T4? there they are

 

There is not a clear answer to your question but there are a couple people with log manifolds making 1000+ hp. I believe tubular headers will flow more than logs but the real question is how much power are you wanting to make?

Where is A-town Texas? I'm in Austin..

Who did the headers? They look pretty good!

 

Equal length turbo headers for equal timing of exhaust pulses seems more applicable when you only have 4 cylinders firing, rather than 8. Probably wouldn't notice a huge difference.

Those manifolds are very cool btw, the best part is the thick v-band flange. Did you make em?

 

Power level makes a difference. Like they said, what are you shooting for? Headers will make more... but it depends at what power level.

 

i live near waco,

ya i made them,,,

and im looking to run consistent low 9's, so maybe make round 900 thru a th400! think thats possible?

 

Those will be good for your goals.

I'd be more concerned about cracking with that design. Logs are inherently stiff so thermal expansion isn't nice to them. Take a look at the stock log on Buick GN's - they have expansion joints built in between cylinders. You'll probably have to cut the single head flange into 3 flanges, then use a solid copper gasket and stage 8 bolts to continue to seal as the front and rear flanges slide back and forth across the head during thermal cycles.

 

ok cool, i didnt know if it would be better to leave them this way or to cut the flange!

 

trouse, where did you get that transition for the ?1 5/8? to the actual log?

 

Yeah, I would definitely slot the flange to seperate the ports into 3 flanges.

Also I Would drill out the very outside 2 bolt holes 1/8" oversize, the next 2 inward 1/16", and leave the center 2 bolt holes normal sized. ESPECIALLY is the flangeis stainless steel. This allows for thermal expansion outward from the center. You can expect about .1" of expansion per foot... This can sheer bolts in the head with log manifolds.

 

Funny...that's close to what I calculated a couple years ago.