360 Advice Needed - Autocross / Street Engine Build

nm9stheham said

OK, actually I did get your SCR.....?? And nearly the same DCR, with an ICA of 65.5; pretty close agreement. I have gotten consistently good agreement with computations and measurements of cranking pressures, so that took me by surprise. But field measurement variations are there for sure, as you say. (And I don't think for a moment that the cam is 15 degrees out!)

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I dunno. I mean, my gauge might be a little out. I've used it awhile and the readings it gives have always "made sense", but that's not to say it couldn't be off a bit. Less than 10 psi I would think, otherwise the readings its given me on other engines wouldn't make sense. But if it's close to 10 psi the numbers on this start making more sense don't they? :p

And yeah, 175 psi is a little high. But then again if the cranking pressure was much lower, or if the DCR was less than 8 I probably wouldn't have to pull a few degrees of timing either. So I just look at it go, yeah well, it makes sense I have to pull a few degrees of timing and push the timing curve back a little because the cranking pressure is 175, and that's a little higher than expected/calculated. But it fits with what I'm seeing during tuning, so, maybe the calculations were a bit off.

I should probably stop de-railing this poor guys thread. :rolleyes: Moral is, for 91 octane my combination is a little borderline with open chamber iron heads, and that Lunati cam is a little big for street use and 3.55's.