overboring

[Cypher]

last night while me and my mechanic were kicking back and talking we were talking about my car and somehow overboring came up... he has a buddy that owes a favor apparently and could bore my cylinders out to whatever i wanted for like 200$... what i want to know is how much power is to be gained from going from stock which is 82mm i believe to something like 83.5??? just like to add that i don't plan on doing this anytime but i'm just curious

[labmixz]

My block got bored out by a NHRA Shop for $50...

10k mi later no probs... lol...

so $200... eh, well, you get where I'm going with this... It's not hard to overbore and match the piston size on a 4cyl esspecially the beta II block, it's so friggin small... I was suprised that I could carry it by myself...

[Cypher]

oh well maybe his numbers were messed up because we were drinking lol... what kind of gains could be had?

[VTElantra]

Depends how much. if you go 30 over than you just need bigger rings. If you go 60 over than you need new bigger pistons.

[Cypher]

well i'm talking new rings, and new pistons i'm just curious on the gains going from 82mm to 83 or so

[01elantra4dr]

More displacement means more power. Always have and always will. A small gain of displacement means a small gain in hp. I know how to estimate the power gain but right now i dont feal like doing math. So i'm saying at the most 1whp gain. Also, since you have a larger engine mean you will benefit more from your modifications. I'm occupaid right now so i cant really alaburate on it more (or spell check) sorry.

[Cypher]

only 1whp gain for boring it out 1.5mm??? wow....

[2001GLS]

Save your money.

[Cypher]

i had no intention of doing it i just didn't know so i asked...

[KeWLKaT]

I dont think it would be only 1whp... Why would so many people do it?

[tharptroy]

all other thing constant, you'd pick up about 6 horsepower at the crank simply by increasing the displacement.

your cylinder head is going to flow more on a larger bore as well.

[KeWLKaT]

there you go, that's more like it.

[CTele02]

Since youre "shaving" the inside wall of the engine block to increase displacement would this significantly reduce the strenght of the block? For instance (theoritically) a 4mm wide sheet of iron can withstand more pressure (hp) than a 2.5mm wide sheet of iron... will this reduce the overall "max hp" an engine could handle? will this reduce the longevity of the block as well?
So in other words, if you are going to turbo/supercharge.. you dont want to bore out the block and reduce its resistance/strenght to the extra hp, but if youre going to go N/A and dont expect to gain much hp this is safer.

[KeWLKaT]

It does reduce it. That's why it is recommended to forge the internals for high hp applications.

You have to be careful with the way you do it. And consider all of the factors.

[Estopatitiana]

well i had my van bored out 30 over when the engine was completely rebuilt and now it has 113k on the motor with a 670 cfm holley 502-6 tbi unit...its not exaclty forced induction but its running just fine..and honestly, i felt no difference after boring it out, but every car is different

[labmixz]

Overboring won't really give you any wHP gian because it is so signifigant... So, it's not going to be anything you will notice..

Main reason is just to allow a bigger low compression pistion, mainly for F/I reasons, like I have the 82.5mm Wiseco Forged Low Compression 9:1 Pistions in my engine... So, thats a .5 overbore... which is something like 1/1000th of a liter... or some crazy shyt... you get my point... to actually get .1 of a liter you would have to go insane on the bore size... and really I don't think you could go that big on this small of a block... soo ;)

[KeWLKaT]

Actually there is a beta accent that is bored/stroked to 2.1 liters

[Cypher]

gotcha... not worth it to overbore reduces amount of power the engine can handle awesome thanks guys

[01elantra4dr]

I have problems explaining things, but i'll give it a try.

Your boring it out your gaining 1/100 more displacment (2.02L). Meaning that if everything is stock your going to multiply your hp by 1.01. So if you have a 135hp and you bore it out youll end up with 136.35 hp.

[Cypher]

but you lose some longegivity(sp??) on the block right??

[01elantra4dr]

Not anything significant. If you spray boost or even add some basic bolt ons your lessining the logevity of the motor.