Machining down stock cast 4g64 pistons to lower compression?

Robert Venable · Post by **Robert Venable** » Mon Jan 29, 2007 3:02 am

Let me know how it goes. I don't think it will reliably work, but I would like to know either way. W/E you do, make sure you don't use it in a block you want to keep for very long.

Old Colt · Post by **Old Colt** » Mon Jan 29, 2007 7:16 am

Try opening up the diameter as much as possible before going deeper, leave all the squish area you can.

Bill Hincher · Post by **Bill Hincher** » Mon Jan 29, 2007 9:31 am

is there a way of changing the compression ratio in removing materail in the head? instead of the piston? or a balance of both?

GRNDSM · Post by **GRNDSM** » Mon Jan 29, 2007 10:29 am

First of all, a set of forged 4G63 pistons of just about ANY compression ratio that you could possibly want, with a nice set of rings, runs around $400. Why go through any of these games when you can have the “real thing” for not much more money?

Stock pistons are around $160 and rings are around $120, so we are not talking about a huge difference here.

Second, I saw what can happen to a stock Mitsu pistons when they are weakened by having material removed from them for balancing purposes (they crack!) and I would advise against it!

Bill Hincher · Post by **Bill Hincher** » Mon Jan 29, 2007 11:12 am

maybe we could get some custom headgaskets from one of the suppliers, the pistons i saw was $700.00 from Wisco
I donno, $400.00 bucks or $700.00 bucks, it's money that could be used in a lot of other places for a guy on a budget

Post by **DJpowerHaus** » Mon Jan 29, 2007 6:18 pm

Too bad that link you posted is for a 2.0L block with a 2.4L crank (2.3L "stroker"). Wiseco only offers 1 6 bolt 4G64 piston P/N: K564M87. It has a .020" overbore with around 8.5:1 compression ratio. Only 1 choice but at least there is an off the shelf piston available.

Summit Racing has them for around the same price though. Its usually special order though which takes under a month.

Robert Venable · Post by **Robert Venable** » Tue Jan 30, 2007 1:18 pm

Yes, this is my reasoning also. I have a 2.4 block and would like to try an NA 4G63 Head swap on to my 4g64 before boosting it, but with 11.5ish:1 after the swap keeping the stock pistons it's a little too much compression for me to run on a daily driver. Then if you step down to 8.5:1 that is offered by wiseco it kills quite a bit of torque. If the stock pistons and combustion chamber could be machined down to a 10:1 ratio I would feel alot better about running this daily.

Old Colt · Post by **Old Colt** » Tue Jan 30, 2007 2:31 pm

Umm, it comes out to 11.5:1 or so. I need to build one. My 6G72 DOHC engines with 10:1 run on 87 octane so 11.5 is just what I want.
If they are about 11.5 you won't find enough material to get down to turbo range.
I was thinking it was in the 9.5 range to start with. To low for NA and too high for boost.

Robert Venable · Post by **Robert Venable** » Tue Jan 30, 2007 9:14 pm

I know I can run 93 octane and tune around it, but I'm more comfortable around 10-10.5 for street use. More so, because I plan on using this motor in my Truck, and trying to keep the revs low. I've found that you are more prone to detonation under lower rpms than higher ones.

tonydanzah · Post by **tonydanzah** » Wed Jan 31, 2007 2:19 am

hey robert are you using a eugo or other type of wideband to check F/A ratio?
also anyone on here running an egt guage?

Bill Hincher · Post by **Bill Hincher** » Wed Jan 31, 2007 9:12 am

smog wrote:

430 bucks is too much for me. I can rebuild a g54b for less... I'm not building a monster engine or anything. I'd just like to use it, for cheap. I'm cheap, give me a nickel and I will give you 5 pennies.

I did the math on this smog and if you snd me the 5 pennies, your out the nickel..........

better refigure your that one

GRNDSM · Post by **GRNDSM** » Wed Jan 31, 2007 9:24 am

430 bucks is too much for me. I can rebuild a g54b for less...

And you will end up with something much less...

Let me reiterate: machining stock pistons is a bad idea! I have seen them crack on a 400hp engine with very minor removed material for balancing. I hate to see just how weak they will become if you actually remove some significant material!

So if you are looking to build a cheap engine, I would recommend looking at other ways to save money!

But using 4G64 block requires an engine rebuild, so why are using it if you can’t afford to properly rebuild one? As someone suggested earlier, using at turbo 4G63 will be much cheaper. Personally, I still prefer 2.0 to 2.4, performance wise…

Bill Hincher · Post by **Bill Hincher** » Wed Jan 31, 2007 11:34 am

Leon is right about the pistons, its false economy, after you put all that work into it, its too much to risk.
a thicker headgasket makes sense but the 2.4L will not perform as well as the 2.0 4g63

If you want a 2.4L bore out athe 2.0 and leave the stock stroke in there

the power from the extra stroke is negated by the fricton losses because of the increase in piston speed

Post by **DJpowerHaus** » Wed Jan 31, 2007 3:56 pm

Bill Hincher wrote:

Leon is right about the pistons, its false economy, after you put all that work into it, its too much to risk.
a thicker headgasket makes sense but the 2.4L will not perform as well as the 2.0 4g63

If you want a 2.4L bore out athe 2.0 and leave the stock stroke in there

the power from the extra stroke is negated by the fricton losses because of the increase in piston speed

Try and tell that to my tires

Video coming soon...

Bill Hincher · Post by **Bill Hincher** » Wed Jan 31, 2007 6:27 pm

yeah, you can make a few passes and spin the tires, but I am talking about something you can depend on, how many runs do you get between headgasket repairs?
I still think thats why your headgasket failed on the dyno and you had to set out that event you wanted to go to

carguyf545 · Post by **carguyf545** » Wed Jan 31, 2007 6:52 pm

when i finaly get the money and get off my ass im going to use stock pistons, thick head gasget. arp rod bolts, arp head studs, and a small t3. i really dont see a reason why this wont make 250 hp and run every day.
if a honda can do it i dont see why a motor that is in a turbo family cant do it.

Bill Hincher · Post by **Bill Hincher** » Wed Jan 31, 2007 8:03 pm

finally! Carguy! somebody is sane !!!!!

77amc · Post by **77amc** » Mon Apr 21, 2008 11:10 am

Why do most people here jsut deal with Wiseco??
How about Venolia? I think they were only asking around 80ea for some custom pistons for some older Honda 1200's

And since Lunati sold out to Holley, they made a 'Lunati-Talor' piston shop about 5 miles from me. I can go ask them today if I get the 'free pass' from the warden..

E

Post by **DJpowerHaus** » Tue Apr 22, 2008 3:20 pm

Price and convenience are the main reasons we've stuck with Wiseco for so long. No need to specify the details, we just order a part proven to work. If any of those companies offer something similar for cheaper I'm sure we'd all give them a shot.

quest4power · Post by **quest4power** » Tue Apr 22, 2008 7:05 pm

I can rebuild a g54b for less...

but when you have to rebuild it 2-3 times...what's that equal out to?