18r piston question

[quikestsilva]

gday, have a questiuon bout 18r pistons, are 18r and 18rg pistons the same? i understand that the G in toyota language is for twincam, but was unsure if they have different compression ratio's, i have a 2tg which is running 18r or 18rg pistons, i need a piston, they are 88.5mm and was told that they are the 9:7:1 compression ratio but the bloke who said didnt seem to keen so i thought i wasnt gunna trust his judgement, i can get picks up of the piston if really needed, im down in tassie and am wondering where is the best place to try n track a piston down was thinking gorringes? all that is stamped in the piston is ART on one side which seems to be on all of them and the letter 4 on the other side, nothing wrote on the top, how can i tell wat compression ratio they are for and wats my chances of getin one? hope i make sense, any help is appreciated, cheers kyle

[o_man_ra23]

To start with, your gramma and punctuation is a little lacking, the facke that your whole post was one sentence and had no capitalisation whatsoever did make it hard. Secondly, how did you cram 18R pistons into a 2TG?? Yes there most certainly is a difference between the 18R and 18RG pistons, and there are 3 types of 18RG pistons to make things more confusing. Posting a pic of your piston will be most beneficial. If they are indeed 9.7 pistons, then they are 18RG domed pistons. Any of the RG pistons are hard to find, and usually sell for $600 a set or more, unless you can get a good second hand item. You will also need to measure and check for an overbore size.

Another thing to consider is that if you have 18R pistons in a 2TG, then the compression ratio will be much greater than what the piston will be stamped with. A factor to consider when tuning.

Cheers, Owen

[quikestsilva]

i got a chance to take some photos of the piston, they are as below. Written on one side is the number 4, on the other side it has ART and on the inside it has 88252 if that helps

[Screamn_Sleeka]

I can tell you what you have, and thats 18R-C rods with R-G pistons which are 9.2:1 compression.

But ive got no idea what you are asking.

[quikestsilva]

im askin where can i get a piston from

[Screamn_Sleeka]

Pull it out of a 18R-G would be logical.
Dont use it if it says 88210 or 88270 cause it wont be the same compression ration, 9.7 and 8.7 respectively.

Cant really buy them new.

[quikestsilva]

k thanx 4 that m8, do u no where i could get a block from by any chance? cheers

[crowncustom]

Pull it out of a 18R-G would be logical.
Dont use it if it says 88210 or 88270 cause it wont be the same compression ration, 9.7 and 8.7 respectively.

Cant really buy them new.

Look on the underside of the piston to see what part number as stated is stamped there and we may be able to determine what you have.
But here in Tassie mate looking for RG stuff is like trying to find a needle in a haystack.
Cheers Brett.

[o_man_ra23]

Pull it out of a 18R-G would be logical.
Dont use it if it says 88210 or 88270 cause it wont be the same compression ration, 9.7 and 8.7 respectively.

Cant really buy them new.

88230 is also 9.7, you need 88250 or 88253 pistons. The pistons may also need some machining to fit your application, depending on what your current setup had done to it.

Cheers, Owen

[Steve M]

Screamn_Sleeka

I think you'll find that the 88252 pistons are actually 9.7:1 pistons, and were also available in 0.5mm OS too.

88210, 88233 and 88252 pistons are the ones that I am 100% sure about being 9.7:1 compression ratio. 88251 was 8.7:1, 88270 was 8.3:1.
I've seen some 9.2:1s before and from memory they were 88232, but they had 9.2 cast into their crown.

If that piston/rod combo came out of a 2TG, I have my doubts about it being an 18R rod, but it is definately not an 18RG rod.

quikestsilva, If you want a single piston, they can be made by JP engineering in Adelaide. Last time I checked (a few years ago, now) the price was $150 + GST per piston if you send over a sample. I am not sure if they were able to do 88.5mm bore as it is an odd size. They might be able to do it. I know they've done 92mm 18Rg pistons before, but that won't be much good in a 2TG.

[quikestsilva]

Well ive had no luck finding a 18RG piston, i have a 3tc which came out of my t18 and i am looking at doin the 2tg head with the 3tc block, i no im stupid for not going this way in the first place but i was unsure on what to do with the cam in the 3t block and have since read more about turning the cam around.

In the 2T block i checked the pistons and bore so i could get a set of rings, big ends/mains bearings etc, all was good until my young bloke had decided to play with the piston and left it in the middle of the shed floor in which i didn't see and ran over the piston in my car, would the big ends/mains bearings from the 2T fit into the 3T? i am unsure as i no the conrods are different sizes and im guessing the cranks are as well? correct me if i am wrong.

Im trying to do it the cheapest way i can as well, so thats why i am asking if the bearings will fit the 3t so i dont have to buy other ones, how much would i be looking at for someone to turn the cam around if i can't do it myself?

[o_man_ra23]

The cam should be replaced with the 2TG's auxilliary shaft. The bearings can either be turned around (pay a machine shop, and buy new cam bearings(thats what the aux shaft bearings for 2TG will be listed as) while you are at it), or you should be able to get the blanking inserts from your 2TG block and put them in (pretty sure they had blanking inserts, I know the 3TGTEUs did). Go to local parts supplier and get them to pull out the bearing book, and look up the part numbers for 2T and 3T big end bearings, and see if they are the same, pretty sure they are.

Cheers, Owen