One test I want to do before engine comes out at end of year is go back to the 1 5/8" tri-y headers that are port matched to these cast iron heads.skinny z wrote: ↑Sat Aug 13, 2022 5:11 pmI think that last sentence is key to my question.steve cowan wrote: ↑Sat Aug 13, 2022 3:57 pm
Kevin,
My opinion is it is to hard to lock in a definite answer to your question.
This is where Larry's program gives a really good starting point on induction size including headers etc.
I wanted to test open headers this weekend compared to full 3" exhaust but we got rained out.
Certainly changes in the tune would be expected especially if scavenging is improved regardless of the shape of your combustion chamber But as suggested, improvements in chamber shape have shown improvements in VE by way increased high lift flow (as in Vortecs).
Regarding the induction, yes most definitely. That side of the cylinder head is every bit as important in tuning as witnessed by your extensive testing with spacers. I'll be going there as well however my immediate interest, once I'm back on track, is to get into this exhaust. It's always been crippling and there certainly are better results to come.
Anyway, hoping for sunny skies down under and some testing and analysis from you.
Thanks as always Steve.
I ran those headers against my 1 3/4" 4 into 1 headers when combo was running 11.7s @ 114.
No difference was found.
I would like to see if the smaller header kills top end power
I run from 6000rpm- 7500rpm at the track,does not fall under 6000rpm on the shift.
At a guess I think they might help in the first 330ft but fall off after that.
The 4 into 1 is 1 3/4" to a 3" collector 19" long with bolt on extensions.
I have a set of 1 3/4" tri-y but got to get them to fit in the car.