Engine Engine Block Question

Zbanks1

New Member
Sep 16, 2012
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I recently bought a 5.0 block out of a 97 GT. I have a 89 GT as well. I am going to have the block bored out. I have been told not to go more than 30 or 40 over. We are aiming to have a 450 whp car when we get done. So how much should I bore out the cylinders and not have to worry about them being too thin and maybe cracking under a heavy load.
 
I recently bought a 5.0 block out of a 97 GT. I have a 89 GT as well. I am going to have the block bored out. I have been told not to go more than 30 or 40 over. We are aiming to have a 450 whp car when we get done. So how much should I bore out the cylinders and not have to worry about them being too thin and maybe cracking under a heavy load.

Well that would depend if you are trying to get that kind of power naturally aspirated. If not then I would suggest keeping the boring to a minimum. if so then 30 is a common choice
 
450rwhp is probably not going to happen with an N/A hydraulic roller small block setup. You would rev that thing to 7,500 rpm to get those kind of numbers out of it. Even at that rpm, 420-430 is probably best case out of a 4.030 block with a 3.25 stroke (331 ci). RPM kills the late-model 5.0 blocks, so your best bet is to source out a Mexican block or something equivalent.

If you're going power adder, ignore everything above.
 
Are the cylinder walls worn? Ive always been told that boring s motor out doesnt really help performance too much. Just raises compression due to larger pistons. If they are worn have the shop try 20 over and if theyre not cleaned up go 30. Most shops do this anyways. Either way its still a 306.....oh and its a stock block 5.0....that mustang wasnt a 97