I had a version of my 428 with a fairly short duration cam and 10.4:1 compression. The cam was a 270/276 degree advertised (@0.020") solid flat tappet. Installed on a 107 degree intake centerline the DCR was about 8.47:1. It ran fine on high octane pump gas. That is usually 91 octane and 93 when I could get it. I didn't run vacuum advance.frnkeore wrote: ↑Mon Jun 14, 2021 7:46 pmRandy and Paul. Temp and Elev are as above. Loaded is loaded, no matter the weight. Consider it a steady dyno pull at 160 deg engine temp. The 80 deg is assuming air intake, out side the engine compartment.
I know by application, there are things that work. Such as 6.8 DC but, I would like a upper end number to build a engine to.
Will 7.5 do it, in those exacting numbers, supplied above?
I still think the "load" matters, if only because it increases the time in the danger zone. However on the dyno the rate is steady anyway, as you noted.
For me personally a DCR of 8.0-8.25:1 is safe on good pump gas with a sane combination.
paul
edit: I see you are stipulating 87 octane. I was assuming around 91 octane in my response above. I think your 7.5:1 would do okay given your stated conditions, maybe even a little more.