Toyota Piston Codes

[mxr]

I have a 20v and I am going to be buying a set of 4agze 8.9-1 pistons for it. What is the difference between the mark 1/2/3 pistons listed from toyota? I assume this is a letter designating tolerances but what are the differences if anyone knows?
Any idea where I can find the stamped letter on the block to match them up to, if I need to?
Ive done a dozen swaps and have re-ringed motors, but never swapped pistons before.
Any help is appreciated.

[GTSSportCoupe]

From the MR2 Owners Club Message Board:

USDM 8.0:1 4AGZE Pistons & Rings
Pistons:
STD:
13101-16100-01 4AGZE, AW11 STD MARK1
13101-16100-02 4AGZE, AW11 STD MARK1
13101-16100-03 4AGZE, AW11 STD MARK1

OVERSIZE:
13103-16100 4AGZE, AW11 O/S .50mm

Rings:
OVERSIZE:
13013-16090 4AGZE, AW11 O/S .50mm

JDM 8.9:1 4AGZE Pistons & Rings
Pistons:
STD:
13101-16131-01 4AGZE, AE101 STD MARK1
13101-16131-02 4AGZE, AE101 STD MARK2
13101-16131-03 4AGZE, AE101 STD MARK3
OVERSIZE:
13103-16131 4AGZE, AE101 O/S .50mm

Rings:
STD:
13011-16210 4AGZE, AE101
OVERSIZE:
13013-16210 4AGZE, AE101 O/S .50mm

[Jeff Lange]

GTSSportCoupe, that information doesn't tell you anything.

MXR, the numbers stamped on the pistons are the diameter of the piston. What you need to order will depend on the bore size of your block and how much oil clearance you want to run.

After you hone the block, accurately measure the bore, find out what the oil clearance should be, then go from there.

I'll check what the numbers correspond to when I have a chance. The factory bore sizes will be stamped on the block as well.

Jeff

[sunray]

I don't know about toyota for sure but I do know that sometimes when they manufacture domestics, they will have a 1, 2, or 3 thousands of an inch piston tighter or looser to mate a hole that is not perfectly in spec. They do the same with bearings too.

[Jeff Lange]

Yes, that is what the numbering is for, but what the numbers actually mean can vary from engine to engine. For example a #1 4A-FE piston is not the same diameter as a 4A-GE piston, because they have different oil clearance specs.

Jeff

[mxr]

Thats exactly what I was wondering about. Im wanting to use the Jdm 8.9:1 pistons but I assume the oil tolerances will be the same if not very similar for the 8.0:1 motor.

Thanks Jeff, much appreciated.

[sunray]

Thats exactly what I was wondering about. Im wanting to use the Jdm 8.9:1 pistons but I assume the oil tolerances will be the same if not very similar for the 8.0:1 motor.

Thanks Jeff, much appreciated.

I would always just buy a set of oversize pistons, bore the engine out based on a target piston-to-wall clearance. You get the taper out and therefore the best result for ring and compression longevity.

[mxr]

Yeah... It is supposed to be a budget build but I don't know if I can pull it off. Ill find out tomorrow what a few shops want to bore out the motor, I just am afraid of the cost.

[sunray]

I know for me I apways save a lot of money by doing my own measurements and assembly. I tell the machine shop what I want, I never let them tell me what I need. Good measuring tools like micrometers and a good dial bore gauge have reaped many rewards in engine building for me.

[Brian]

I don't know about toyota for sure but I do know that sometimes when they manufacture domestics, they will have a 1, 2, or 3 thousands of an inch piston tighter or looser to mate a hole that is not perfectly in spec. They do the same with bearings too.

5/10thou is usually the size difference between 1/2/3 sizes on Toyota stuff.

0.0005" or half-thou.

Look for a stamping on the oil pan gasket surface that says 2212 or 2222 or whatever, and that is your original bore size. After a VERY light hone, you can re-install new pistons of the same size and not have problems.

Cheers.

[mxr]

Well then would you consider going 3323 if the stock was 2212 and you don't do a very light hone? Or do you risk it being too tight? 0.0005" isn't all that much....
I appreciate the input and help guys.

[sunray]

Well then would you consider going 3323 if the stock was 2212 and you don't do a very light hone? Or do you risk it being too tight? 0.0005" isn't all that much....
I appreciate the input and help guys.

If you are hell bent on not boring it out then I would suggest doing a doing a quick hone, re-ring and stick the original pistons back in. Its not worth the cost of new pistons in an un-refinished bore. You'd be wasting your money.

[rob rayne]

if ur putting gze pistons in a 20v block are u using the 20v rods? silver top or black top?

[Rastaracer]

After you hone the block, accurately measure the bore, find out what the oil clearance should be, then go from there. Jeff

Actually, you should get your pistons first and take them to the machine shop so they can bore and/or hone your block to fit the pistons.

[Special K]

general question but how does one pick what oil clearance to run?

[mxr]

I know for me I apways save a lot of money by doing my own measurements and assembly. I tell the machine shop what I want, I never let them tell me what I need. Good measuring tools like micrometers and a good dial bore gauge have reaped many rewards in engine building for me.

I have looked at bore gauges and they seem to be from 70-250 dollars. What is the accuracy of yours?

if ur putting gze pistons in a 20v block are u using the 20v rods? silver top or black top?

Its a silvertop. I wouldn't put any boost on blacktop rods.

Actually, you should get your pistons first and take them to the machine shop so they can bore and/or hone your block to fit the pistons.

This is what may very well happen. Depending on the quotes I get, I may just get the motor bored for the o/s pistons.

[mxr]

Would anyone know who may have access to the 8.9:1 4agze pistons? Otherwise I don't really have a choice but to run the mark 1-3 8.9-1 pistons.

[GTSSportCoupe]

GTSSportCoupe, that information doesn't tell you anything.

Jeff

I was providing part #s for reference only, not trying to answer his question. He might be safest to bore out 0.5mm and go with the 0.5mm oversize pistons and rings. In that case, the numbers I provided would be helpful.

[sunray]

To answer your question about bore gauges, a god dial bore gauge can have different sensitivity deleding on what dial indicator you mount. Mine came with one acurrate to 5 ten thousandths but when working with Ford 4.6l and 5.4l engines I have to put one that goes to 1 ten thousandth to clearance those. The half a thou one is fine for toyotas though.

[mxr]

I was providing part #s for reference only, not trying to answer his question. He might be safest to bore out 0.5mm and go with the 0.5mm oversize pistons and rings. In that case, the numbers I provided would be helpful.

Except Toyota says that the 0.5mm o/s don't exist and the pn is bad....