question about overbore?

[silvia_ca18det]

so i am sitting here looking at my dissasembled block and i am thinking "**** those are thin cylinder walls" i was planing og going .40 over, basiclly i am asking is it safe to go .40 over and be running 20 psi of boost? anyone else gone .40 over on their block? any little advise would be awsome

thanks

[float_6969]

It's not aluminum. It's cast iron. .040 will be fine. I was going to have mine bored out to that, but they sent me .020 pistons.

[silvia_ca18det]

yeah true.....it is not a sr20, well i will stick with the plan, if anyone else has any more insite to share feel free

[themadscientist]

I don't see all that much merit in overboring. I would prefer to just bore as much is required to clean them up. Not that the CA block isn't bulletproof, I would worry about head gasket failure between cylinders long before the block would give an inch.

[boost_boy]

so i am sitting here looking at my dissasembled block and i am thinking "**** those are thin cylinder walls" i was planing og going .40 over, basiclly i am asking is it safe to go .40 over and be running 20 psi of boost? anyone else gone .40 over on their block? any little advise would be awsome

thanks

Save your money and make your car run good first before you start talking about making the bore bigger. It seems everyone wants a bigger bore! My suggestion to this is to either boost your KA or go buy the famed SR. Some purchased the CA to be different, cost, or it's ability to rev whilst knowing that it has a smaller displacement than it's cheaper counterparts. Just accept you have a small engine and make something out of what you got. I guess it would be like having an extremely small pecker, those were the cards you have been dealt, so play the hand .

Dee

[CA19DET]

i say go for it, more compression, larger displacement, better spooling turbos, more hp, if done right, it will yield positive results..

[nnkfws333]

Save your money and make your car run good first before you start talking about making the bore bigger. It seems everyone wants a bigger bore! My suggestion to this is to either boost your KA or go buy the famed SR. Some purchased the CA to be different, cost, or it's ability to rev whilst knowing that it has a smaller displacement than it's cheaper counterparts. Just accept you have a msall engine and make something out of what you got. I guess it would be like having an extremely small pecker, those were the cards you have been dealt, so play the hand .

Dee

ahhahaha i love that post there.

[silviadrifta]

Some purchased the CA to be different, cost, or it's ability to rev whilst knowing that it has a smaller displacement than it's cheaper counterparts. Just accept you have a small engine and make something out of what you got. I guess it would be like having an extremely small pecker, those were the cards you have been dealt, so play the hand .

Dee

...or some choose it because it was what came in their car

[capwred]

only the lucky ones

[mikesim]

what does .040 overbore yeild in displacement anyway? 1.9L? is the small gain in torque worth the loss of rev-range?

i'd agree with the others here, stick to standard bore.

[boost_boy]

what does .040 overbore yeild in displacement anyway? 1.9L? is the small gain in torque worth the loss of rev-range?

i'd agree with the others here, stick to standard bore.

Exactly!

Dee

[CA19DET]

Quote »is the small gain in torque worth the loss of rev-range?[/quote]please explain?? the bore doesnt change rod ratio drastically or anything, how does it effect rev range?? if anything it would increase torque as displacement increased (minimally of course)

[boost_boy]

please explain?? the bore doesnt change rod ratio drastically or anything, how does it effect rev range?? if anything it would increase torque as displacement increased (minimally of course)

My agreeance is that the small gain in torque is probably not worth the money unless you got a free set of pistons. You may as well go for a stroker kit which woll allow you to enjoy that .040 overbore. The revving stuff I opt to not get into.

Dee

[tyrannix]

speaking of overbore, im getting a nismo full counterweighted crank, it has a longer stroke, i was going to bore out to keep the bore+stroke square (i have to use custom rods, and get forged pistons anyway, so no reason not to in my mind)

so theoretically, i should still be revving the same, but have the little extra torque also? (like a frankenstein stroker kit)

[boost_boy]

speaking of overbore, im getting a nismo full counterweighted crank, it has a longer stroke, i was going to bore out to keep the bore+stroke square (i have to use custom rods, and get forged pistons anyway, so no reason not to in my mind)

so theoretically, i should still be revving the same, but have the little extra torque also? (like a frankenstein stroker kit)

You'll gain your extra torque by installing said components and doing some boring. Go for it............

Dee

[silvia_ca18det]

Save your money and make your car run good first before you start talking about making the bore bigger. It seems everyone wants a bigger bore! My suggestion to this is to either boost your KA or go buy the famed SR. Some purchased the CA to be different, cost, or it's ability to rev whilst knowing that it has a smaller displacement than it's cheaper counterparts. Just accept you have a small engine and make something out of what you got. I guess it would be like having an extremely small pecker, those were the cards you have been dealt, so play the hand . Dee

my car has ran good from day one i have had it to 300PS all year long! no problems no nothing! i am looking for more power though, and i have a silvia, i have also had an sr20, and an rb20, rb25, and rb26, i have used all the motors except for build up a CA, and money is no issue aswell! just looking at the best way to do this efficently!

[silvia_ca18det]

and whats with everyone trying to do it cost effective? u can really half *** a engine build! u do that and once one thing ****s up everything else will!also about head gasket i am getting the custom SCE copper o ringed gasget instead say a greddy/hks etc, the motor right now allready has cams, HKS manifold, HKS wastegate, HKS manifold, GT3071r turbo, the reason i am boreing it .40 over is to try and gain a little quicker spool time out of the turbo without stroking it, i have looked at everything from the tomei stroker kit to just building up my own ca20 crank out of a 200sx, or any other ca20 car and just buying the tomei rod/piston combo, to getting all custom stuff, there is many ways to do it and i am right now looking at ideas and just tossing **** around in my head!

[dattodude]

My engine builder (regularly builds $20k+ GTR RB26 race engines) said on a CA18, it's not worth the risk boring more than 20 thou.

My CA is 20 thou over, copper o-ringed and built for 25psi.

In a 1 month life expectancy race engine 40 thou over is fine.

I don't know about you guys, but my street car doesn't have any sponsors to pay for these kinds of running costs.

Cheers,Chris

[biosehnsucht]

mine is 1mm (0.40) over.. and revs smoothif you have the whole bottom rotating assy (crank+pistons+rods+etc) balanced should be fine.

with the balancing, if a coilpack goes out and its running on 3 cyl's you can't hardly tell. it runs smoother on 3 cyls than the KA ever did on 4!

right now I have stock C/R but when I build the other eventually it'll be time for 9.5:1 (was hesistant to do it on the first one as its my daily) in addition to 84mm (1mm over)bore..