Looking for an educated as guess on a buddies motor build.
It's a gen vi 454 bottom end with flat top pistons, 781 iron heads with 2.19 and 1.88 valves. Running a 500 efi cam and induction setup.
Just thought someone might have a good educated guess or desktop dyno. To run it through. Running on pump gas

423.75

Whats the compression with the flat tops and those heads?

Using .018 in the hole, 118 cc chambers and a .038 head gasket I come up with 8.1:1. So really low! Could be even lower if he used a standard thickness head gasket , chambers are bigger than 118,and the pistons are in more than .02.

I'd say 400-415

No dome on a 454 and open chamber heads = what happened with the parts selection process ?

Or, does he only have 82 octane available near him ?

89 octane. Was told the 781 were 114 cc chambers

He ran the same setup but with cheap 320 119 pro comp heads made good top end but no low end so since the 781 ovals.are smaller.runners he was thinking should make same hp but better low end torque. But I take it from your thoughts that his information and thought was wrong.

781's can be a little inconsistant chamber volume wise but im gonna ask the hp500 cam in a 454 question....what exhaust ? That cam gets bigger per se when it goes from a 502 to a 454

Yes but seems to run ok in the setup with the larger pro comp heads