has anyone thought about boreing out ur sho engine like .30 over???

[taurusshoguy89]

ok ive got a 89 sho and i just found out that im going to have to rebulid the motor. and the question is does anyone know how much it would help on power or would it or would it hurt my sho engine plzz post me some answer if u want. thanks fellow sho owners

 

[Yamaha V6]

If you're over-boring the engine, consider moving from a 3.0L in your 89 to a stock 3.2L SHO engine from a 93-95 Automatic. Basically, same block, larger pistons, different rods, same crank, etc.

Probably a lot cheaper to find a used 3.2L than to go through & do a complete rebuild. Also, if you do decide to go complete rebuild, that's the time to consider bumping up the compression ratio to something like 10.5:1 for additional power. Aftermarket pistons, etc are available, you can visit www.shonutperformance.com (among others) for more info & pricing.

 

[Slo-Sho]

Page 03-01B-40 of the Bible (helms) lists a .25 and .50 O/S piston size.

Riddle me this....what would the total ci of the 3.0 be, bored over .50"?

 

[Cobraii976]

I can give you the formula to figure it out.

Pi x bore x bore x stroke x 6 divide by 4

 

[Hack]

Page 03-01B-40 of the Bible (helms) lists a .25 and .50 O/S piston size.

Riddle me this....what would the total ci of the 3.0 be, bored over .50"?

Are you sure it is inches, and not millimeters? The most you can overbore a 3.2L is 1mm (for a total bore of 93mm and a total displacement of 3.26L) due to the diameter of the fire rings on the head gaskets. 93-95 3.0L motors can also be bored to 93mm if 3.2 headgaskets are used, but 4mm is a far cry from even 0.25" let alone 0.5". (25.4mm to an inch)

A slightly larger bore can be achieved if you are willing to spend the money on custom head gaskets. If memory serves, 94.5mm was the magic number provided that the bore spacing was perfect, or something along those lines. Any more and you would risk hot spots in the cylinder walls and premature engine failure. A forum member that goes by the screen name JEM is/was building a motor utilizing a set of custom headgaskets. A search for his posts should reveal more details.