The overbore from 77 to 77.5 gives you 1.3% more cc's, ie 1598 to 1619cc, assuming the stroke is unchanged. It is hardly worth it just for the cc's to be honest. There are other advantages, ie allows better ideal match of pistons, as the existing bore will probably be slightly worn, scoured etc. Fitting new pistons to a newly bored block will allow an ideal fit. However, it will also make the run in period somewhat longer.

 

Yeah, the CC change is about 5cc per cylinder, it wont do much. Using basic math it would be a 3 HP gain. The real power gains will be from the turbo and head (once I get it). As you said the real benefit will be bore matched pistons; with the added benefit of knock protection.

R53 Warrior, still have not received the turbo back. Since it is the holidays it will be about 10 business days as apposed to 7.

 

Where's the added benefit of knock protection coming from ?

 

It comes from the proprieties of 2618 aluminum alloy. Contrary to popular belief forged pistons are not stronger than cast ones. The metal is actually softer. The reason they are considered to be stronger is because they can deal with high pressures and knock better. They are able to do this because the metal is softer. Where a cast piston may crack the forged one would not.

 

Contrary to what you've written, if you've a detonation (knock) problem, your aftermarket pistons regardless of % metallurgy blends, will still fail from uncontrolled detonation (knock)

 

Obviously they will fail if you get a bad enough knock event. The fact of the matter is, cast pistons will fail with a smaller knock event then forged pistons. That being said, any amount of knock is bad. Cast pistons are more brittle and can break easier than forged ones.

 

We could discuss this for quite some time, as you have rightly mentioned, the fact remains any uncontrolled (knock) detonation will give cause to piston/ring failure.

 

We are agreeing knock is bad. I don't get why you keep trying to make this point. I know this, and you know this. Ill try to clarify what I am saying.

This will be a somewhat bad example but you will be able to understand it. You can look at knock like hitting a piston with a hammer. If you have two pistons one cast and one forged and hit them both with equal force the cast piston will sustain more damage then the forged one. The forged one will also be damaged just not as bad as the cast one.

 

I wish I had known you were looking for an OS Giken Clutch I could have made you a good deal on mine. ALso is turbo work in your future? Oh yeah where are you in the world?

 

My turbo has been at G-pop for about a week.

 

Oh cool., I am mailing mine out today maybe.

 

This isnt much of an update. G-pop called and said my turbo will be going out tomorrow, and I dropped off everything at the machine shop. Block willl be bored out tomorrow.

 

What are you going to tune your car with in the end, and how much HP do you expect?

 

I will have RMW re tune my car. I expect at least 240

 

How old are you? I was 26 when I got my '12 JCW clubbie. I cant wait to blow a ring so I can also rebuild the engine. I came into this having done 0 work on cars in the past and so far I have replaced my exhaust manifold (sucked, took me a long time as I just started taking stuff apart), had to helicoil my turbo as an engine stud broke off in the top most eye, done all of my mods myself (all of the common bolt-on's). The only thing I have left to do is put my suspension on (KW variant 3's with Vorcshlag plates and all that) and then wait for a ring to blow. I cant wait!

 

My problem isn't age or knowledge, it's the fact that I'm only in my second year of college and my finances are atrocious.

 

Meh lets not compare age or anything because us young folk will always be trumped by some older ladies and gents with more experience.

 

Working on car-wise not so much, Porthos. You and MNIPWR have me beat hands down and I have both of you guys by a couple of decades (damn that makes me feel old saying that!).

 

haha, I wasn't insinuating age was a problem, just asking since you mentioned that you thought you were vastly younger than people on NAM =) If anything, I am jealous of how much knowledge you have being so young (I am guessing early 20's).

 

Thought I'd mention--love this thread!

 

Something like that. I didn't mean to imply you were insinuating age was an issue. I said that in the sense that I wouldn't of minded if my engine waited a bit longer till I had a real job and was not in college. If that was the case I probably would of sleeved my block and gone stroker. But hey Ill just save that for another day.

 

No disrespect, but you are doing upgraded rods and pistons to make the same power as a JCW with software? Seems a bit overkill IMO.

Are you lightening the crank to match the weight of the rods/pistons?

Have you considered ceramic piston coatings rather than water/meth?

What intercooler are you using?

Please don't take any of my questions as being abrasive, I am just trying to understand more of the direction of your build.

 

I was basically already making JCW numbers.

I am not doing any of the internal engine work. The machine shop that is working on it is very reputable and builds drag car engines. They will be building mine as a high performance motor. Balancing and lighting the crank is included.

Meth and ceramic coated pistons do not do the same job. Meth cools the combustion temperatures while the ceramic coating raises them. I don't feel like explaining in detail but if you would like to know just reply and I will.

Basically ceramic coated pistons prevent the piston from stealing heat from combustion. The extra heat in combustion is then turned into rotational force. This can actually increase the chance of detonation.

I have a helix cooler.

Almost forgot to explain why I got upgraded pistons and rods. I could of got a new long block but I figured for a couple grand more I could build a motor that I could trow nitrous through if I wanted. So piece of mind really.

 

My understanding was that the ceramic coatings deflect heat evenly, preventing hot spots on the pistons where detonation may occur. I've disassembled many engines with pockmarks around broken ring lands which I suspected were areas of high temp within the combustion chamber.

Instead of meth, do you have E85 in your area? That would give you a cooling effect similar to water/meth in addition to higher octane.

Also I am waiting for the day that someone runs an N12 head without DI (back to pulsed injectors on a fuel rail). Might be more tuning potential that way, as well as eliminating the carbon problem altogether. Just a side thought that came to mind looking over this thread.

Will be following to see how it turns out!

 

I don't have E85 in my area. Your understanding is correct. You really have to have the head and valves coated as well to increase detonation potential. A lot of people will have everything coated and then run w/m. It increases efficiency and performance.