DonMan

Does Mercruiser`s 496 Mag have the same bore stroke as a custom-built 496? (4.25 X 4.25)

bajadude

4.25 x 4.38

Here are the specs

DonMan

I guess I`ve killed off too many brain cells.
If you have a 454, how do you make it a 496?
What exactly is the new bore / stroke?

FindMe

Click here for complete 496 engine specs

CigDaze

A factory 496(8.1L) is 4.25" Bore X 4.375" Stroke.

A factory 454(7.4L) is 4.250" Bore X 4.000" Stroke.
If you bore it out by 0.030 and Stroke it 0.250" You'll also get 496.
4.250+ (0.030 X 2) = 4.31 Bore.

bajadude

thanks Daze, beat me to it

Here's a neat calculator for displacement and compression

DonMan

I`m not even gonna go there....

Thanks for clearing up this bore/stroke thing.

mcollinstn

Daze,

Don't you mean bore it .060" over?

My .030" over pistons have always measured .030" total, not .030" per side.



DonMan:

(Bore/2)squared x pi (3.141) x stroke = cylinder displacement

cylinder displacement x no. of cylinders = engine displacement.

CigDaze

Yes, that's exactly what I meant...0.030 on the radius, 0.060 on the diameter...Note my formula. Thanks for clearing that up!