Vacuum Secondary Conversion
Sorry, i will post a link next time. Whenever I try screen shots, they tend to come out blurry.
Unless some company starts producing modern cast iron sbm heads, I doubt I would ever build with iron now except for a basically stock rebuild.
I have no doubt people are building 11.5 cr iron headed street motors, but not sure if that is a function of cam events and SCR.
If you have a build that you have done that used iron heads and 195-200 psi on pump gas, I would love to see those specs and run it through wallace every which way.
Anyway, like I said, I don't want to hijack the op's thread
That’s ok. I went to Hughes and found it. Usually I can’t find anything on that site but I did find it.
I’ve already said when I put my junk back together I’ll make some videos to cover it.
It will be 12:1 or a bit more. Who knows? When I build the W2 headed engine I may try for 12.75:1 just for fun.
And really, cam timing doesn’t play into how much compression you can run. At least within reason. 11:1 is so easy to do (if you can find pistons any more) I can’t believe guys still struggle with it.
And you’re right. Not many iron heads left out there (THANK GOD for that!!) but the W2 is still the best inline valve, 18 degree, standard port head out there. There’s not a 23 degree Chevy head (in iron) that would touch it.
And even if you never build another iron headed engine, do you really think that if I switched to an aluminum head I could be at 13.1 plus on pump gas? No chance.
I’m thinking the limit of pump fuel is 12:1 or a bit more, regardless of cam timing or any thing else.
As to cam timing, it makes little difference in how much compression you can run, except we both know more compression allows you to run more cam timing IF you need it.
The two biggest factors in using higher than orthodox compression ratios are the cooling system and the timing curve.
