boreing .20 over

[twizdt]

Will boreing your motor increase performance at all?

 

[my4ATEurV8]

yes it will. when you bore block, you are in a nutshell getting more displacement than what you previously had. ie, a 1.5 will make less power than a 2.0 liter assuming that the tunes are similar.

 

[Burnett03]

You are wrong. Going .020 over is not going to make any more power because the amount is so small and insignificant.

 

[my4ATEurV8]

do you have anything to back that up? just saying that I'm wrong does not mean that you are right. a
.02 overbore yes is a small change none the less, but is still considered a mod and does add displacement to your motor. more displacement. that extra space will help suck more air thus require more fuel netting more power. and I'm sure a slight tuning would be in order to fully utilize this. ......... so yes. i say it will give more power. a small amount but still, an increase. that is my reasoning, what is yours burnett03?

 

[Burnett03]

You ever heard of using the shift key to make some "real" sentences? You seriously think that .020 is going to make more power man? .020 Over bore wont even make a 2.0 a 2.1, hell it won't even make it near a 2.1 liter. I think you are getting confused with changing the stroke of the motor. Just if you don't know what you are talking about...

 

[my4ATEurV8]

lets not get into an argument about it and just state reasoning. no use getting offended. tHAt BEtTeR. i still say yes. and no I'm not getting it mixed up. I'm actually doing a 2.4 stroker with magnus internals, and i got the .02 overbore. I'm not arguing the fact that .02 is a small change because it is. you are still getting a little more displacement. and the power would be noticed on the dyno wether it be 0.5 or 2 hp. it will be noticed. not to mention that it would also clean up the cylinder walls and help compression. so lets not atack each other and play nice.

 

[jrohner]

yes it will. when you bore block, you are in a nutshell getting more displacement than what you previously had. ie, a 1.5 will make less power than a 2.0 liter assuming that the tunes are similar.

.020 over does almost nothing for displacement increase, so no that alone will not increase your power (oh, 1 hp, wow). You're only gaining like 1.4 cubic inches / or about 23 cc's.

Going with higher compression ratio pistons at the same time will increase your power though, but it still will have nothing to do with the slight overbore.

 

[my4ATEurV8]

to some people 1hp is still 1hp. ill bet that shep doesn't skip things because its only a 1hp increase

 

[jrohner]

lets not get into an argument about it and just state reasoning. no use getting offended. tHAt BEtTeR. i still say yes. and no I'm not getting it mixed up. I'm actually doing a 2.4 stroker with magnus internals, and i got the .02 overbore. I'm not arguing the fact that .02 is a small change because it is. you are still getting a little more displacement. and the power would be noticed on the dyno wether it be 0.5 or 2 hp. it will be noticed. not to mention that it would also clean up the cylinder walls and help compression. so lets not atack each other and play nice.

Well, I'd have to agree with the other poster that your first answer was...
He wasn't going from a 1.5 to a 2.0 like you were referring to, he was going from a 1.997L to a 2.020L.

I also agree that you should start using the shift key and making your posts more readable; if you have a post that way that's more than a couple lines long, most of us will quit reading it.

Plus he was asking if it increased performance, is 1hp a real performance increase? Your first post was saying that it definitely is.

lets not get into an argument about it and just state reasoning. no use getting offended.

You were the one starting the arguing, in my opinion. You were also the one acting offended.

 

[my4ATEurV8]

I was just using the 1.5 -2.0 for a dramatization. Not to be taken literal

 

[Johnny123]

I'm actually rebuilding my motor .20 overbore with 8.5:1 pistons. Anything?

 

[jrohner]

Every 1 increase (like 8:1 to 9:1) in compression, is said to increase power by about 4%. So 8.5:1 instead of 7.8:1 would be a .7:1 increase, so 2.8% increase / 2.8hp per 100hp. The 3-angle valve job you're going for (according to your profile) may increase the flow of your ports slightly, gaining you a couple HP.

You might have to adjust your timing back a bit (for knock control) because of the extra compression though.

 

[Demon33]

To answer the OP's question-

Will boreing your motor increase performance at all?

Yes, all other things being equal, an increase in displacement from overboring will technically increase power output, small as it may be. Now, does the power increase justify the work and money involved in the 0.020" overbore? Probably not, at least in my opinion.

.020 over does almost nothing for displacement increase, so no that alone will not increase your power (oh, 1 hp, wow). You're only gaining like 1.4 cubic inches / or about 23 cc's. Going with higher compression ratio pistons at the same time will increase your power though, but it still will have nothing to do with the slight overbore.

1 hp more is technically an increase. So yes, there will be a gain, but not worth it in my opinion.

do you have anything to back that up? just saying that I'm wrong does not mean that you are right. a
.02 overbore yes is a small change none the less, but is still considered a mod and does add displacement to your motor. more displacement. that extra space will help suck more air thus require more fuel netting more power. and I'm sure a slight tuning would be in order to fully utilize this. ......... so yes. i say it will give more power. a small amount but still, an increase. that is my reasoning, what is yours burnett03?

I agree with you here. 0.020" is small and the increase will be small, but it's an increase none the less.

 

[Johnny123]

Every 1 increase (like 8:1 to 9:1) in compression, is said to increase power by about 4%. So 8.5:1 instead of 7.8:1 would be a .7:1 increase, so 2.8% increase -- adds 2.8hp per 100hp. The 3-angle valve job you're going for (according to your profile) may increase the flow of your ports slightly, gaining you a couple HP.

Oh ok, well its my DD and it needed to be done anyways. Thanks though.

 

[jrohner]

HP is not really performance, acceleration (and/or handling) is.

 

[rstare]

Every 1 increase (like 8:1 to 9:1) in compression, is said to increase power by about 4%. So 8.5:1 instead of 7.8:1 would be a .7:1 increase, so 2.8% increase / 2.8hp per 100hp. The 3-angle valve job you're going for (according to your profile) may increase the flow of your ports slightly, gaining you a couple HP.

You might have to adjust your timing back a bit (for knock control) because of the extra compression though.

Just to clear up a few things, stock compression on the 420a is 9.6:1, so going with 8.5:1 would actually cause a loss.
And the timing on the 420a is pretty mild so I doubt you would have to adjust the timing. Most people that turbo the 420a don't even adjust the timing.

 

[Locke]

Pssst, Ryan - jrohner was replying to Johnny123, who has a '93 TSi AWD.


On our little 4 cylinder motors, boring shouldn't be done to increase power, but only to fix cylinder walls. The gain in displacement is not worth the cost of the machine work.

 

[toofast82]

On our little 4 cylinder motors, boring shouldn't be done to increase power, but only to fix cylinder walls. The gain in displacement is not worth the cost of the machine work.

Exactly, i wouldn't bother unless out of spec. It's not going to gain anything worthwhile, but will keep a block going safely. My 454 in my camaro is .060"+ and bumps it to 468 which isnt probably worth more than 10hp, but was used to fix the walls

 

[JusMX141]

You will see more gains from having fresh, straight bores and rings / pistons that fit perfectly than you would see from just boring .020" over.

If you compared two new engines, one standard bore and one .020" over, the horsepower difference would be null....but going from ovaled standard bores to straight .020" bores will definitely show a horsepower increase.

 

[stevestevesteve]

is it worth it? considering if i want rebuild my engine? buy forged internals.... all that jazz

and then all i would need is piston's that are .020 oversized?

sorry im a n00b at this.... this is my first eclipse

 

[delta448]

Yes and no.

How far are you willing to go to make your N/T fast? What's your budget? Will you be installing a power adder (turbo, nitrous, supercharger)?

If you expect a major performance improvement from just cleaning up the cylinders and dropping in forged internals, you will likely be disappointed. You might see a small gain from using lighter parts and if you increase the compression ratio with the new pistons, but the car will also require a means of tuning to optimize any CR change.

Bottom line, do plenty of research and choose your parts carefully if you're on a strict budget. While forged internals are always good, do you really need them to make the power you're looking for? How poor is the health of your engine right now? Have you performed a proper compression test?

 

[stevestevesteve]

Yes and no.

How far are you willing to go to make your N/T fast? What's your budget? Will you be installing a power adder (turbo, nitrous, supercharger)?

If you expect a major performance improvement from just cleaning up the cylinders and dropping in forged internals, you will likely be disappointed. You might see a small gain from using lighter parts and if you increase the compression ratio with the new pistons, but the car will also require a means of tuning to optimize any CR change.

Bottom line, do plenty of research and choose your parts carefully if you're on a strict budget. While forged internals are always good, do you really need them to make the power you're looking for? How poor is the health of your engine right now? Have you performed a proper compression test?

Just bought a new fully rebuilt engine. but its all stock. budget doesnt matter, but keep it cheap. I want to turbo my car in the future.

 

[SweetLeaf]

I'm doing a rebuild too... so, I guess I'm understanding, do what's needed/required and save your extra cash for turbo (in the hopefully near future) because that'll make all the difference! Correct?
fyi, I'm a girl, and I'm here to learn... I think maybe this post has changed some of my plans and probably saved me unnecessary work & spending for what I want. Thanks 2 all!

 

[VETTE_50_TH]

Stroke and compression ratio are the big factors for our cars.

James

 

[twizdt]

wow i wasnt expecting this topic to get so many replies. What kind of bore would i need to notice an increase in power? Thanks for all the responses.