12:1 pistons in 2tg

[geraldf]

hi new to the fourm, have a few question about 2tg, sorry if they have been asked already
but wat kind of mods have to be done to a 2tg engine if you run 12:1 comp pistons
has anyone done it already?

[ToyTA22]

Hi and welcome to forum. Why do you want such high compression? You will have trouble, even with 98 octane petrol, with detonation. Which means unless you are setting up engine for pure competition use, which will need cams with massive overlap and duration, to require that compression, would be terrible to drive on the road.
I have not built my 2tg as yet, due to now being unemployed and otherthings happening at moment, but have 10.5:1 wiseco 3tc pistons which I will be using with a 3tgte crank and Eagle forged conrods which I already have. Head is a 2tgeu 88260 and will have mild porting, shape is more important than size for this engine. Camshafts, cant remember grind specs but are about 290 duration 10mm lift.

[JustenGT8]

Did one back in the late 80's with set of TRD pistons, big TRD cams and all the other required fruit. One of the best sounding engines I've ever heard and the throttle response was like a bike engine. We ran it on Avgas, which was easily available from Canberra airport back in those days.

These days you would run E85 and it would be fine. But, not a trivial build to undertake and as mentioned, not really worth it unless you run ams and all the other gear to survive 8000+rpm. Looking at around $5-8000, depending which bits you can do yourself?

[geraldf]

Thanks for the reply's guy, the reason in usiing 12:1 is that i got a set really cheap, i guess that's why they were so cheap
Im gonna have to rethink things as i cant afford to spent big money on the rebuild.
Well if anyone has any other advice feel free to add to the coversation
Could i use the pistons with a thicker head gasket?

[JustenGT8]

Apart from the fact you won't find a gasket thick enough to make any difference, it's a flawed plan that compromises the whole engine.

You can build a more standard engine around the pistons. Just be very clear you will need the E85 to avoid det and there's a lot of wasted potential sitting there.

I think you are better off just selling the pistons though, sorry.

[geraldf]

I think your right, my intension was just to build a 2tg out of a 2tb engine, nothing as extream as a race engine just something that sounded nice and drove well. I paid 150 euro for them, if anyone knows anyone looking for a set let me know, they are standard bore

[MorGo]

High comp pistons in small displacement hemi engine.. Not a good idea.Why? To acheive the compression the piston dome must be massive! Due that the cahmber comes more like the orange peel than "half hemisphere".Chamber surface area vs. volume gets very poor,the dome is effectively disturbing the burning and destroying any charge motion there might be.
Hemi head with flat top pistons is way better but still quite poor on charge motion (notice what was done to 3T-GTE ports..) and of course needs to be boosted to make power (due the low compression by flat top pistons)

[geraldf]

@MorGo that's getting a bit technical for me but i think i get wat your saying, high comp pistons are pushing the combustion either side of the big domes and not directly down as they would with lower comp pistons
A good point and yet another reason not to go with such a high comp piston
Some great advice and i thank everyone for they're input
Is there any engine that these would work in or would be worth putting in?

[JustenGT8]

They run fine...awesome in fact, in a race engine built to rev and with the right fuel. TRD didn't make pistons at this comp ratio purely for fun

[king-szeitszam]

Is there any engine that these would work in or would be worth putting in?

I'm pretty sure the only people that will go for these are 2TG owners looking to build a competitive or recreational track/rally vehicle.
It's becoming less and less practical these days to run highly strung engines in daily drivers.

You can try posting them for sale on here, someone might snap them up for their collection.


Use funds to build a hybrid- 3T crank in the 2T block with a 2TG head (not 88262 variant). Bore the cylinders, get some O/S pistons and twin carbies with nice big jets and you'll have a 2.0l torque monster.

[geraldf]

@JustenGT8
yeah i would like to be able to do a race build but im on a budget and want it as a daily/weekned driver
@king-szeitszam
i have been looking at some similar builds posted here, i think this is the way to go im going to look into doing this
thanks for the advice

[MorGo]

Yeah,sell them to someone Historic rally/race competitor who need to be 1600 cc.

[geraldf]

yeah, if anyone knows anyone looking for a set of these let me know, i'll put them up on for sale with pics over the weknd if anyone want to have a look

[Toycrash]

yuuup!
pm me for know more details about them

[geraldf]

pistons are 86mm supertech 12:1 comp willing to swap for 3t crankshaft or set of similar pistons with lower comp, 10:1