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View Full Version : Millling forged pistons to lower CR


ze12o
02-04-2012, 08:11 AM
Is this common practice? or am I stuck with what I got? I want to mill my 8.8 CR arias pistons which I think has a -11cc dish to around -30cc dish. Also balance and coat the top and skirt. Anyone know a good shop that I can send them out to?

Thanks in advance
-Kevin

Def
02-04-2012, 08:57 AM
I've heard of milling valve reliefs, but not an extra 19 cc. I don't think the piston would be very strong after taking that much meat out of it.

Why not also hit the combustion chamber to open that up, and why do you want such a super low CR?

ze12o
02-04-2012, 09:16 AM
Oh sorry I made it a little confusing. It's 8.8 on a ka24e. On a DE it will end up around 10-10.5:1 which is too high for my liking.

On arias site. The pistons is the same specs minus the dish and weight. I'm assuming it is the same piston other then how much they took out in the piston.

I have emailed arias with no responds :/

-Kev

Darren
02-04-2012, 09:39 AM
why not sell them and buy the pistons you actually want?

S@nt0s
02-04-2012, 09:41 AM
You need to speak to Elmer give them a call Monday and he should know but I doubt there is enough meat to mill out and still have enough to handle a beating

Silvia716
02-04-2012, 09:47 AM
why not but a bigger head gasket to lower comp

ze12o
02-04-2012, 09:57 AM
why not sell them and buy the pistons you actually want?

I know I should. I'm just exploring my options lol

You need to speak to Elmer give them a call Monday and he should know but I doubt there is enough meat to mill out and still have enough to handle a beating

No idea who's Elmer. contact? site?

off of arias site

http://desmond.imageshack.us/Himg198/scaled.php?server=198&filename=29489092.jpg&res=medium

Def
02-04-2012, 09:59 AM
Sell current pistons, get correct pistons.

ze12o
02-04-2012, 10:01 AM
why not but a bigger head gasket to lower comp

I did the math does not lower the CR enough. Using the cosworth 90.5mmx1.8mm.

I might get away with it with that some head work and meth. But I'd rather be safe then sorry.

S@nt0s
02-04-2012, 10:03 AM
Elmer is the sport compact rep at arias. Those CC # are based off the head they are used with if I am not mistaken. The E and DE head will yield different comps base off the combustion chamber of the head

ze12o
02-04-2012, 10:13 AM
Elmer is the sport compact rep at arias. Those CC # are based off the head they are used with if I am not mistaken. The E and DE head will yield different comps base off the combustion chamber of the head

Thanks for the info I will contact him on monday and see what he says. Thanks everyone for the insight. I will update the thread if i find anything out.

-Kev

EsChassisLove
02-04-2012, 10:58 AM
thick as hell headgasket will do it.

S@nt0s
02-04-2012, 11:03 AM
I'd rather have 10:5 comp over my 8:5

PoorMans180SX
02-04-2012, 11:05 AM
Run 10:1, you'll love it.

Switch to E85 for big power.

ze12o
02-04-2012, 11:30 AM
I wish I could. Corn is hard to find in my area.

murda-c
02-04-2012, 02:52 PM
I'd try calling reputable machine shops around you.

Or....Instead of increasing the dish, build up the piston, find a high pressure fuel pump, put poppet injectors in the spark plug holes, figure out a way to time the injection, and run diesel. It may not explode!

ze12o
02-04-2012, 02:54 PM
Machine shops is a dying breed in nyc
(╯°□°)╯︵ ┻━┻

murda-c
02-04-2012, 02:58 PM
Machine shops is a dying breed in nyc
(╯°□°)╯︵ ┻━┻

Things like this make me sadder than they probably should.

tunermt
02-04-2012, 11:09 PM
10.5 on pump with boost for the win :) So long as you have full control when it comes to tuning the 10.5 will be fine even if you are stuck with pump gas.

di-devol
02-04-2012, 11:33 PM
^Fuck that shit.

tunermt
02-05-2012, 02:16 AM
^if you're scared go to church (http://www.youtube.com/watch?v=9t41oSMD6vc)
HAHA just joshin my friend, i know high compression and boost can be a bit intimidating however depending on the set up it can also be VERY nice indeed!

ze12o
02-05-2012, 07:38 AM
I'll be running aem series 2 with aem meth kit running 5050 methwater. I have a gt35r trying to push it to 18+ lbs safely

S@nt0s
02-05-2012, 08:01 AM
I'll be running aem series 2 with aem meth kit running 5050 methwater. I have a gt35r trying to push it to 18+ lbs safely


Then you are set I would use what you have there. With the meth injection you will have enough fuel and you will make more power on less boost

ze12o
02-05-2012, 08:38 AM
Then you are set I would use what you have there. With the meth injection you will have enough fuel and you will make more power on less boost

Everywhere i searched people on the thread has said it's going to detonate.
I will talk to my tuner and see what he thinks :bigok:

S@nt0s
02-05-2012, 08:53 AM
You won't need to push as much psi because the motor will make more power then it would with a 8:5 comp. also your torque #s will be higher down low with a more useable powerband as it will spool up the turbo sooner. You could up your a/r and get the same spool while getting more up top. 15-18 psi on 91pump with meth I don't see any issues you will be running roughly 100oct fuel if using 100% meth?

Check out the Evo forums for info on meth it was used a lot and pushed to its limits

AdamR
02-05-2012, 10:58 AM
The compression ratio is not going to change the rpm the Turbo spools at.

ze12o
02-05-2012, 11:01 AM
Yup, it's actually widely debated. But science points to higher CR does NOT increase spool time. Just feels like it because you're making more power down low.

waxball88
02-05-2012, 11:17 AM
For what it's worth I'm running 8.6:1 pistons in my DE. I love it. t3/t4 8PSI @ 2500rpms. And the extra piece of mind is nice too.

I'd sell the arias because i would imagine getting them milled would be non cost efficient. Sell the arias, buy what you need. I'm running supertechs, few K on my ka-t and i beat it like a dog and it loves it.

tunermt
02-06-2012, 02:33 AM
what is the AR of the turbine housing on your GT35? what waste gate and what manifold?

if you run a decent tubular manifold, .82 AR and an external waste gate that high compression wont be an issue at all! Chat with your tuner for sure see if he is comfortable with it :)

Really sounds like you've got most everything needed to make this work very very well.