Ross pistons

[kc95sc400]

Hey guys,

Need some help. I've been searching and have found nothing despite the fact that there are quite a few on here with Ross pistons. Question is about the 8.5 compression 3.465 bore pistons, part number 99733.

Have those with 20 over pistons overbored the block or installed new sleeves?

The sleeves are scary thin and I just want to be sure they can be bored 20 over as I do not intend to do sleeves. Way more than I can afford.

Thanks,

KC

 

[Lextreme II]

You are ok to bore 20 over. Resleeving will run you at least $1,000.

 

[kc95sc400]

You are ok to bore 20 over. Resleeving will run you at least $1,000.

Isn't it somewhat of a catch 22? The sleeve is only 2mm thick to start. Then to go 20 over one has to remove .5mm. So the sleeve is down to 1.5mm.

25% loss on the sleeve for stronger pistons.

I'm kind of paranoid about cracked sleeves after boring..

Any more input?

KC

 

[Lextreme II]

I think your rods will break before the sleeves. If you think that is bad, you should see the new 3UR motor.

 

[kc95sc400]

I think your rods will break before the sleeves. If you think that is bad, you should see the new 3UR motor.

Ok, thanks.

Just need to find a machine shop willing to do it I guess.

FYI, if you don't already know, the 3uz sleeves are 1.5mm to start with so I guess Toyota thought it was ok to be smaller.

KC

 

[stevechumo]

Isn't it somewhat of a catch 22? The sleeve is only 2mm thick to start. Then to go 20 over one has to remove .5mm. So the sleeve is down to 1.5mm.

25% loss on the sleeve for stronger pistons.

I'm kind of paranoid about cracked sleeves after boring..

Any more input?

KC

If the OEM sleeve is 2mm thick and the piston is 0.5mm thicker than standard, then you only bore out .25mm on each side of the sleeve. That means the bore is only 0.25mm thinner. Still a lot of room to play around. lol.

 

[Lextreme II]

Question is about the 8.5 compression 3.465 bore pistons, part number 99733.KC

FYI... by lower your compression you will loss some boost. You might loose about 4-4.5 psi....from the boost gauge...

 

[XR8tt]

With lower comp the turbo/blower will make more power when ON SONG but under that ?? Yes too low compression can lead to slow throttle response..
Which isn't necessary spool..

Another part to consider ??
The bores are specific steel cylinders designed to do what they do.. A full on bore with integrated sleeve as part of the block is much weaker in "most cases" being cast iron...
Higher carbon, nickel etc is added for better durability..
Serious engines have there blocks at least 1/4 grouted for strength..

 

[Brad Bedell]

I've been driving one of Lex's 5.2 stroker motors with Ross pistons daily for about 15 months now. I use about 1 quart of oil per 3000/miles. Considering it's a boosted(6psi) car and I rarely let it warm up longer than 2-3 minutes, I'm happy with them. In the cold, they do rattle a little, but once warm, it's not an issue.

Personally, I wouldn't bore any of the aluminum engines, I'd only hone them true for final piston fit. Toyota manual states to not bore the 3uz and has a .010 or .020 limit on the 1uz (I forget, but it's worth consulting the manual)

 

[stevechumo]

Have you dynoed the car?

 

[ash]

You are ok to bore 20 over. Resleeving will run you at least $1,000.

yes,
we have a part number for Darton sleeves now.
there was 50 odd sleeve made.
The block requires extensive machining, but the end product is pretty good.
the wall thickness is now .250 + inch, iron not alloy