bored 4g63

[97 turbo talon]

I need some help im kinda new to the turbo engines. i was looking to buy a 4g63 that is bored .20. but someone told me that with a bored engine you cant run as much boost. I'm not sure i have never heard this before.

 

[gorf]

I need some help im kinda new to the turbo engines. i was looking to buy a 4g63 that is bored .20. but someone told me that with a bored engine you cant run as much boost. I'm not sure i have never heard this before.

better check your source - boring an engine gives the engine brand new cylinders and pistons to work with.

 

[Jeff@Slowboy]

better check your source - boring an engine gives the engine brand new cylinders and pistons to work with.

True. However if you are more than .040 over I would start getting a little sketchy on the wall thickness. I see no problems with a .020 or even .040 block. My personal block is .040.

Oliver
[email protected]

 

[kahl23]

Engines get bored out when the machinist needs a fresh surface to work with, it's normal and fine. I think that you mean .02" over, not .2, but I know what you mean and you really shouldn't have any issues with the overbore, just make sure that the machinist who did the work has correct piston to wall clearances and you should be good to go. I'm not sure I would listen to whoever told you that much anymore, there's absolutely no reason why getting a block freshened up should effect your ability to run a certain psi, so long as the correct pistons are used.

 

[knochgoon24]

Why do you want one bored .020" already? Do you already have 20-over pistons to go in it? That little bit of extra volume in the cylinders doesn't add any extra power.

If you just need motor, a standard bore will perform just as good as one bored .020"

 

[kahl23]

You're missing the point. When the surface of the cylinder walls needs to be refreshed, a machinist will bore it out .02" over so that he has a fresh surface to hone. It's not so much to increase performance over stock bore, but to restore performance levels to that of a fresh engine without getting a new block.

 

[nlzn]

Why do you want one bored .020" already? Do you already have 20-over pistons to go in it? That little bit of extra volume in the cylinders doesn't add any extra power.

If you just need motor, a standard bore will perform just as good as one bored .020"

Untrue. Bored pistons .020 or .040 will ALWAYS net a performance gain assuming the control motor tested against is tuned EXACTLY the same has the same parts/compression etc..

 

[kahl23]

Eh, a .02 overbore nets a bump in displacement from 1997cc to around 2021cc (rough math), so yes, it will increase the amount of air that goes into the engine per revolution, but we're talking negligible gains.

 

[mitsu-luver]

when ever your boring the cylinders of an engine your weakening it PERIOD.
but not that much, sure you cant run as much boost but i dont think your planing on running
40-50 psi WTF , and im sure you dont have a turbo that can (no offense, either do i haha)
you shouldn't worry plus its cast iron pretty strong material.

 

[knochgoon24]

Untrue. Bored pistons .020 or .040 will ALWAYS net a performance gain assuming the control motor tested against is tuned EXACTLY the same has the same parts/compression etc..

Ok, we're splitting hairs here. The OP doesn't have the mods to have to resort to boring to get more power. We're talking a 1.2% gain in displacement (if the previous number were correct. So I doubt you'd get anything more than 1-2hp. If you're looking for that much, do a boost leak test.

 

[BoredDSM]

Ok, we're splitting hairs here. The OP doesn't have the mods to have to resort to boring to get more power. We're talking a 1.2% gain in displacement (if the previous number were correct. So I doubt you'd get anything more than 1-2hp. If you're looking for that much, do a boost leak test.

Boring isn't used to gain power in our case. V8 guys use it because they 8 cylinders and boring it slightly will increase displacement a notable amount. On our cars the main purpose is to provide a good sealing surface for the rings.

 

[dsm-onster]

4g64 blocks are .060" over-bore 4g63 blocks with a taller deck. . . You can research the many, many VERY high horsepower 4g64 blocks out there.

 

[MaNGiNa24]

As long as it's bored .020" over and not .2" over you'll be fine. It's very common to bore .020" or .040" over & I've personally seen engines bored .060" over run 30psi + without a problem.

 

[dsm-onster]

I thought that was a typo too

 

[97 turbo talon]

yea, sorry it is 0.02 my bad. but the the reason im getting the engine is because mine is blow and this engine is the cheapest i have found. and should my car be tuned after i put this engine in. thank you for all the replies

 

[tkelly27]

You'll be fine. If I remember right, every high performance DSM has had some amount moved from the cylinder walls to accommodate forged pistons. Even if you use standard sized forged units you need to machine the block an amount to allow for the higher rate of thermal expansion. Which is why you'll typically get piston slap on a cold engine with forged pistons.