18rg pistons in a 2tg?

[Noof]

Anyone know if this works??
I have a heap of questions if it does.

Firstly I have the 18rg pistons which are similar to the 2tg ones I think (reassembled the 18rg to get rid of it but still have it)
Stats
2tg original piston size 85 mm bore is currently 86 but damaged (see below)
Pin Diameter x Length 22 x 60mm
Pin Height 39mm

3t pistons 85 mm
Pin Diameter x Length 22 x 60mm
Pin Height 35mm


18rg (the ones I have) pistons are 88.5 mm? I think??
Pin Diameter x Length 22 X 64mm ?
Pin Height 39.75mm ?
Correct?

Which rods?

which crank? can I still use the 3t crank or is the pin height make the piston too high?
There is less than 1 mm difference between the pin height of the 18rg and 2tg pistons?
so my first guess was 18rg pistons with 2tg rods and crank?

Boring to 88.5 should be no worries for the block and it may be necessary with my block as it is already at 86 and has some pits in #2 wall which possibly will prevent me using 86.5 mm pistons which are the largest I can get easily?

How about the valve reliefs? They look the same on the 18rg piston as the 2tg? so they should be ok right?

I also have a 3T block in good nick but would rather use the 2tg one. I wanted to stroke (3t crank) but the damage to the block has made me rethink?

Any guidance would be appreciated.
Thanks
Nathan

[Celica RA45]

use 2t rods with the 18rg pistons will put it out to 1750cc with the 2tg crank

[hks7mgt]

Noof - what are you trying to achieve mate? Are you trying to build an engine with second hand parts on the cheap. Last i heard, 2T or even 3T forged pistons (oversized or what ever) were about the grand mark.

[Noof]

I am trying to build an engine without going overboard. I can get cast pistons for the 3T which are 60 thou oversize (86.5ish) for about 400 (including flycutting) and by the time I use oversize rings i can probably bore out to 87mm ish which might get around my damage but it might not too ....... I have a set of 88.5 mm 18rg pistons so why not use them if it can be done!
I am just scared that the damage is greater than I am going to bore out if I use the 86.5 mm pistons?

[hks7mgt]

this is a little out of my league, but i'd consult an engine builder.

looking at the specs of the Kameari piston kits you can buy, the 18RG pistons you have appear to be the same spec as their 2lt pistons;

2TG 2000cc Piston

Manufacturing Method Forged
Type High Comp
Bore 88.5, 89
Pin Diameter x Length 22 x 60mm
Pin Height 35mm
Piston Ring Thickness 1.5 x 1.5 x 2.8mm
Rod Type 2TG, 3TG Rods
Crankshaft 3TG, 3T, 13T

I recal ToySport mentioning using a funny piston in the 2TG's and the 18RG may have been that piston. Celica RA45 even suggested it. You might be on a winner here Noof

[Noof]

Cool,
Hopefully one of said engine builders might weight in here with an opinion?
I think it should be ok and kameari was where I got the above specs too.
Might take the 18rg apart again and see what pistons I have.
What is the best way of cleaning them up. soft wire wheel?
I have an ultrasonic bath here so..... I could chemically clean them?
but with what?

[71TA22]

I'm not a profesional engine builder but can confirm that 18RG pistons work in a 2TG with the 2TG crank and rods.

[S. Lowlux]

Hey, Noof, that leaves a lot of left over 18 RG.
May I please purchase the RG oil pump from you, that is if it is the correct pump, the one with the spacer.
Owen

[Noof]

Ok cool so we all think that this could work?
Nice.
Will check if the pistons are the ones I think they are and then may post some more.

I am guessing that there is no way to stroke this engine? Logically if the 18rg pistons are close enough to the 2tg ones then the 3t crank is not going to work.

No other combinations work? May have a look at the maths of it all later..........


Owen, drop me a PM with an offer and I will take a photo checking if the pump is the one you want. I would think that it is as I think that this engine is an original 18rg not a mock up with an 18r block.

[Noof]

Ok pistons are the 88.5s and they look remarkably like the 2tg ones..... Great

Any of the experienced engine builders out there want to give me just that little more confidence that this will work ok? There is a slight difference in pin height? Do I need to get a thicker head gasket?

Cheers
Nathan

[hks7mgt]

i'm interested to. Come on, someone out there must know the answer

[Noof]

Surely someone knows something about this build?
Do I need a 1 mm head gasket to cover the difference in pin height of the pistons?
Anyone?

[Celica RA45]

for 1 you will need a big bore head gasket and std will be fine its only 1mm amd from memory they are about 1.8mm thick any way

[Noof]

Cool. Now does anyone else have an opinion on whether this will work?
Anyone?
Has anyone built something similar?

[w810sc]

As long as you have a head gasket with the right bore size it will work. If the piston sticks out the block too much just mill it down or get a thicker head gasket and re-calculate your compression - cc the head, cc the dome on the piston and calculate the cc of the head gasket bore size then plug these numbers in the formula you can find on the net. As for the valves, you can correct the angle of the valve reliefs by milling them down. Use clay dough / plasticine in the combustion chamber to find out if you need to do this.
If you already have the 18R-G pistons then just buy the bigger bore h/g and bore and hone the block as a quick fix.
If you prefer to spend a bit more I personally would go down the longer stroke route (3T crank) and bigger pistons to get the best of both worlds or buy a 2T-G that already built with the goods.