If a 351w is bored to a 357, how much power does that increase?

 

just adding 6 cubic inches you would never no it was there, if your building a motor with a block then it would be silly to bore a motor that didnt need it unless it a hard core all out competion race motor. hope this answers you question. DW

 

If the piston to bore fit was good, I would rather have a stock bore engine. I tire of people thinking a 30 over 302 is now somehow a magical performance "306" engine.

 

A stock engine if your lucky will yeild 7 tenths of a horse power per cubic inch. a serious built motor if your lucky will yeild 1.25 horse power per cubic inch

302 - 0.030 = 4-6 hp increase

351 - 0.030 = 4-8 hp increase

unless you have excesive wear, scoring,, it not worth boring a block for power.

 

"I tire of people thinking a 30 over 302 is now somehow a magical performance "306" engine."
Haha so true, I understand that something like thats not going to give you monumental power increases. Just wondering because I had my motor done a while ago and they bored it out, and just was wondering what exactly it does. Thanks for the info.

 

the only praticlew reason to bore a engine is to clean up the bores, and bring the cylinders back to a uniform size, so when you put new piston and rings in, your tollerences will be within spec. but there is no significant power gain just from boreing one 0.030. DW

 

DW is on point Bluetorpedo. It is common to bore the cylinder 30 over when rebuilding an engine.

 

What's even funnier with the "306" is alot of mustang guys buy a 306 "stroker kit" and think its the answer to all there power needs. Look in the catalogs, some even list a 306 stroker kit. I just want to die laughin when I hear of people paying over a grand for this "kit"

Stryder

 

If you bore it .030" over you'll gain a little compression, unless the oversize pistons are destroked to compensate. Some piston manufacturers destroke, others don't. You'd get more benefit from the increased compression than the extra cubes.

 

I'm sorry, but simply boreing out the dia of the cylinder bore DOES NOT INCREASE the compresion ratio, in order to do that you must reduce volume, and boreing the motor increases volume. DW

 

You're confusing swept volume with clearance volume.

Boring a block increases swept volume, which would increase compression. If you increase clearance volume like a cylinder head, you would decrease compression. Ask any machinist. That's also why many aftermarket piston manufacturers destroke their oversize pistons.

 

YEA, YEA, WHAT EVER MAN! all i know is if you take a stock motor bore it 0.030 put a stock 0.030 over piston back in it its not gona raise the compresion. DW

 

Hey DW, in his defence, I think you actually will raise compression........by about .0000001%. I'm with you all the way. The ONLY reason you would bore an engine is because it is out of specs and you want to bring it back, PERIOD.

 

All i know is i've been there and done that, I build small blocks i tell the machinist what i want done they do it i build'em and they scream! So Whatever? DW

 

Well, you can look at it as you are gaining about .5 cu. in. per cylinder. That would mean you are compressing .5 CI of air-fuel in the same chambered head. I believe if you do the math you are increasing the compression ratio by about 1.4%