3T Pistons in 2T Block

[sneaky pete]

We race a KE70 (and building a new KE35) in a 1600 class. We can only get 2T pistons with 2mm cast iron top and 2nd rings which is no good for racing. We can however get 3T pistons with 1.5 chrome rings (much better) at an affordable price (importing parts is just out of our league). So my question is - can one machine the block down to accept the 3T pistons and retain 1600cc? Besides shortenining pushrods is there anything else we would have a problem with ? would the engine still perform ? are we missing anything?

Input from forum memebers would be appreciated.

[NME308]

Hmmm... I have my doubts you could machine the block down far enough safely to make the 3T pistons sit flush. There will be only a certain amount you can machine off before you will compromise water jackets etc.
The 8mm difference in stroke i.e. 70mm for 2T and 78mm for 3T makes me feel uneasy at the prospect!

I fully understand the concept of working with what easily (and affordably) comes to hand and fully sympathise with your problem. To throw out another idea - I wonder if there is any other motor sharing rod end sizes in 131.19mm (5.165in) length you may be able to source? An 8mm longer rod would allow you to use the available 3T pistons too. One of the subaru engines has this rod length but I have not time to find its exact journal and pin diameter at present...

Cheers,
Jason

[J-M kujala]

Late type 2T pistons got 1.5mm chrome rings, 9.0CR and they found from TA60 Carina.

4mm van be macined down, but then hot some pushrod issues and shorten headbolts etc. Guys have been done it overhere to use 3SGTE stock pistons in a 2T.

Not +8mm rod, just +4mm ;-) If use 8mm longer stroke, the piston comes 4mm higher and 4 mm lower..

I got those rods but they are not for stock type pistons with press type pins..

[NME308]

Not +8mm rod, just +4mm ;-) If use 8mm longer stroke, the piston comes 4mm higher and 4 mm lower..

Haha my bad I obviously typed that in waay too much of a hurry!
Unfortunatley the 127mm or 5.00 inch rod does not appear to be supported in anything common with correct journal and pin size that I can see... So much for that idea anyhow!


Cheers,
Jason

[J-M kujala]

Yeap, thats why i order custom ones ;-). Basicly needed to order 80 pieces (127mm) (group buy with friends) to beat the price to near stock lenght H-Profiles. I have a big list at rods etc but nothing near at that lenght. Or if found, journals are far away from correct. BMW M20 130mm rods have been used, but crank rod journals are needed to re-grind a little smaller... Not Possible in this case but in many case (more stroke)

[sneaky pete]

Thanks everyone. This is the only Toyota in a "sea" of Nissans & Fords (1600 stock class) and the Toyota is presently leading on points !!!!!!! (my son is the driver) so hence the pressure to keep it in front.
So if we are talking about 4mm surely 2mm off the block and 2mm off the head is no great shakes ? I really am worried about running 2mm cast iron rings - we run in 2nd and motor is just about to hit 6500 at the end of the straight (3.9 diff). If we can get decent pistons we can safely run a 4.1 diff we have got and keep those "mongrels" behind us !

[J-M kujala]

2mm off the block and 2 at head, thats death penalty to the engine, squish is to big and it will start knock pretty easily. Squish is good to be near 1.1- 0.9, with 2T pistons and tenth smaller with 3T pistons.

I prefer to get 9.0CR late type 2T pistons with 1.5mm rings, they are still available.

Usually 1.5mm version do not have wear / damages after high rpm use that often than 2.0mm version have. at personally never seen bad 1.5 mm piston what got ring /groove problems in N/A engine. 2.0 mm are usually worn out .

But i think they can hold that 6500 rpm easily when piston and ring are in good condition. And There is not too big lash between ring & groove. In a stock 2TG those pistons are revved up to 6500 rpm, without rev limiters.

[Rodger]

My suggestion is to buy a good quality set of pistons, such as a set of 2T Wiseco pistons and rings and they will last a lot longer and can be used over a few engine builds and run to 8000 endlessly. Buy a size that takes you as close as possible to 1600cc, I think 1mm O/S is it, need to do the calculations.

There would be no way you could take 4mm out of the top of the block and then shorten push rods and head bolts to bring the pistons flush. Taking 2mm off the head is possible. However by the time you have done all this you may have spent the cost of the Wiseco pistons and rings in the first place.

Regards

Rodger

[J-M kujala]

Problem is everything bigger than 0,25 oversize is to big, goes over 1600cc class cc limit

Usually in historic rally they prefer 0.2mm oversize, because with sear it goes Over 1600cc

And there is no Wiseco 2T pistons, otherwise than custom ones.

Supertech got some piston to 2T

[sneaky pete]

Thanks again for the support everyone. My son is so frustrated with this stuation - as mentioned he is leading, but only just. Someone spun him in one heat (it is close but not supposed to be bumping and pushing) and he lost points as a result (its tough racing!) We have saved up to build a new motor and now we cannot get the right stuff. Regulations allow oversizing according to manufacturers specs and I can get 60 thou (1.5mm) oversize pistons from agents at a very good price. Wiseco's are just way out of our reach with the exchange rate (oh man it pains me). As mentioned these pistons are unfortunately 2mm top and second ring with 4mm oil. All I can source here is cast iron in 2mm - cannot find 2mm chrome or moly anywhere. Now this is why I was asking about matching the 3T pistons cause we can get 3t WITH 1,5MM RINGS ISO THE 2MM ring 2t PISTONS. Because there is no limitations on how much the head can be skimmed we work it out to about 10.5:1 with about 12 deg advance - higher than that std fuel (95) just cannot do it.
Thanks again - all input much appreciated.

[J-M kujala]

are these out off budget ? last rows in the calatog are 2TC choises.

http://www.nolimitmotorsport.com/supertech/pistons.html

in ebay the price is now ~390 USD

if not then only good way is try to found oem 9.0CR original pistons with 1.5 mm rings..

0.75mm oversized aftermarket 1.5 1.5 4.0 pistons... http://www.ebay.com/itm/Toyota-2TC-1...3b637e&vxp=mtr (it was first hit at 2TC piston search from ebay)

[sneaky pete]

are these out off budget ? last rows in the calatog are 2TC choises.

http://www.nolimitmotorsport.com/supertech/pistons.html

in ebay the price is now ~390 USD

if not then only good way is try to found oem 9.0CR original pistons with 1.5 mm rings..

0.75mm oversized aftermarket 1.5 1.5 4.0 pistons... http://www.ebay.com/itm/Toyota-2TC-1...3b637e&vxp=mtr (it was first hit at 2TC piston search from ebay)

Hey man that is about what I earn in a month!
We thankfully get assistance by a special rate on the engineering and we do everything else ourselves.
Here is the old car and the new one:

[J-M kujala]

those cheaper ebay pistons are also out of budget ? those aftermarket pistons linked from ebay 65 Usd + Postages. not inside the budget.. i really understund if Supertech are out of budget, but any cheaper idea i cannot get than those 65 Usd pistond with 1.5mm rings / Grooves.

[sneaky pete]

those cheaper ebay pistons are also out of budget ? those aftermarket pistons linked from ebay 65 Usd + Postages. not inside the budget.. i really understund if Supertech are out of budget, but any cheaper idea i cannot get than those 65 Usd pistond with 1.5mm rings / Grooves.

Ah thanks a million JM. I just read the $390 quote and read nothing else - did not get what you were saying about the ebay pistons (stupid old .....!!!). I do not use ebay as much as I should (old school) thanks you taught me something. We will probably go with those Toto pistons at that price. What we will loose performance wise by .75mm o/s instead of the 1.5mm local pistons I am sure we can make up on "revability" and my nerves just could not take wondering when those cast iron pistons rings would let go. We are hoping to get enough money together for a big port head and this price will allow us that. Thanks again. Now we can at least get a good nights sleep!!!!! Any recommendations on how much bigger we should go on the cylinder bore to get a free revving motor ie 85.75mm + how much??mm - any comments anyone - obviously oil consumption and piston slap not an issue! We will gap the rings according to the bore. Any comments on gas porting? Is it worth it?

[J-M kujala]

0.75 mm against 1.5mm overbore you lose about 1.5% power. If nothing else not changing. Compression stays etc.

So at 150 hp engine its approx 2hp.

Usually those pistons are rated as a 0.75 overbore. So usually bore size is 85.75mm and piston is a little smaller. But like in original pistons, they are manufactured at quite big tolerance. So measure every piston. Toyota recommends 0.05-0.07mm clearance to bore. Its quite safe. Like mine wisecos expand more and work with 0.07mm clearance. SO my recommendation to engine what is going to get REVVED, use maybe 0.07mm clearance.

Big port head ? Why not port stock head ? Big port is not that good. With small DIY porting job can get easily better.