For the love of a tractor engine: The life and times of the 18R-G

[o_man_ra23]

I have listed the part number for either housing in this thread. But if you give a side on shot of the whole thermostat housing, I can tell you which one it actually is as not all 88270 heads were destined for EFI. Also the thermostat lower housing may have been replaced at some stage.

[Steve M]

I think you've got a mix-n-match engine there.

I reckon the block is from an early model and you might have some after market pistons (~10.5:1 CR) in it too. The timing case is a late model item.

[o_man_ra23]

Agreed, those pistons are wild. A lot wilder than the 9.7's I had, and don't even look remotely like my 8.3's

[Javal]

Agreed, those pistons are wild. A lot wilder than the 9.7's I had, and don't even look remotely like my 8.3's

Agreed, those rises look pretty darn sizable. Also that corona is HOT. I have a thing for the RT3x > RT7x coupes.

On topic, my pistons should arrive in a few weeks, then maybe i will have recuperated enough money after touring to get my bottom end together

[roadkill]

Hi,

Pretty sure that thermo housing is the efi one. I thought they were the only one with the cast sensor in the front.

bEn

[o_man_ra23]

Mine doesn't have a cast sensor at the front, it has the bypass at the front.

[Steve M]

If the EFI water outlet was to be put onto that thermostat housing, the radiator hose would have to go through the tappet cover.
The outlet mounting holes are on the wrong offset for that to be the EFI thermostat housing.

[roadkill]

Hi,

will have to check mine when i get home, there might be different castings for them too perhaps?

bEn

[o_man_ra23]

Going back through, my non-EFI castings looked like that, my EFI casting looks completely different.

[mark corona II]

I think you've got a mix-n-match engine there.

I reckon the block is from an early model and you might have some after market pistons (~10.5:1 CR) in it too. The timing case is a late model item.

The pistons are marked "art" on the skirt, and hks on the dome. I assume they are hks pistons. in a nutshell, I want to build a n/a motor with 150 horse. can, or should I re-use these pistons in my build. so far everything looks ok. 270 cams?, with high compression pistons? that doesn't make sense, a very thick head gasket came off. what compression ratio can i safely use with 98 octane, (us) fuel. this will not be a daily driver. I would like to avoid buying another piston kit, they are 1000 bucks and these seem to be in fine shape.

[JustenGT8]

The pistons are marked "art" on the skirt, and hks on the dome. I assume they are hks pistons. in a nutshell, I want to build a n/a motor with 150 horse. can, or should I re-use these pistons in my build. so far everything looks ok. 270 cams?, with high compression pistons? that doesn't make sense, a very thick head gasket came off. what compression ratio can i safely use with 98 octane, (us) fuel. this will not be a daily driver. I would like to avoid buying another piston kit, they are 1000 bucks and these seem to be in fine shape.

You won't know if you can reuse the pistons until you get the block checked and decide whether it needs a rebore....18R blocks seem to go out of round so often need a bore. If so then you'll need oversize pistons...if not then you are sweet.

Nothing strange about high comp pistons and 270 deg cams....that's a pretty decent cam size for the street. Lift specs is what you need to check but a dummy assembly to check clearances is what will be needed to be sure.

150hp from n/a isn't hard at all. I had a 200hp n/a as my daily driver with 45mm webers, 282/290 cams, approx 10:1 comp and 2TG elec dissy.

[river]

Hi,

The initial 18R-G pulled 145hp, so 150 should not be an issue.

seeyuz
river

[o_man_ra23]

Actually it isn't the bore that will determine if you can reuse the pistons, but rather the pistons themselves. If they are not worn heavily, then even the worst of bores can be sleeved at a fraction of the $1000 cost of new pistons.

If you are referring to RON98 fuel, then this is what I will be running my 18R-GTE on, and it is what I run my DR-Z400E on. Even my YZF600R which had over 200hp per litre capacity was running happily on RON96 fuel with a valve bounce rev limit of 14000rpm. So really you should be able to happily accomodate 75hp per litre.

ART was the original manufacturer for Toyota. I am actually going to throw out a wildcard and say that your pistons may have been made by ART to HKS specifications. Good pistons to have. Plasticine is what you want to use on a dummy fit to check clearance.

[mark corona II]

Actually it isn't the bore that will determine if you can reuse the pistons, but rather the pistons themselves. If they are not worn heavily, then even the worst of bores can be sleeved at a fraction of the $1000 cost of new pistons.

If you are referring to RON98 fuel, then this is what I will be running my 18R-GTE on, and it is what I run my DR-Z400E on. Even my YZF600R which had over 200hp per litre capacity was running happily on RON96 fuel with a valve bounce rev limit of 14000rpm. So really you should be able to happily accomodate 75hp per litre.

ART was the original manufacturer for Toyota. I am actually going to throw out a wildcard and say that your pistons may have been made by ART to HKS specifications. Good pistons to have. Plasticine is what you want to use on a dummy fit to check clearance.

Is it ok to ask a million questions?. (i've read the entire post)
the "art" is more prominent, and on the outside of the piston. the hks is very tiny. I should also say the p/o was running these pistons with the stock "270" series cams. please tell me the possible engine set-ups with high compression and stock cams. I've heard this is a no no. is it possible that these cams have been reground to different specs? how do I check? I have some "haters" telling me not to run hks pistons. unreliable piston lands. the pistons look great. no visible scoring, the block looks to be re-sleeved recently, visible hatch marks and the like.
When I take my block to the machinist, is there anything 18rg specific to check or machine?. what not to do?.

[JustenGT8]

Actually it isn't the bore that will determine if you can reuse the pistons, but rather the pistons themselves. If they are not worn heavily, then even the worst of bores can be sleeved at a fraction of the $1000 cost of new pistons.

Hmm, you must have a good source for sleeves and a friendly machinist as i couldn't get a block sleeved for anything like a 'fraction' ?? Using quality sleeves like darton would soak up $500+ with at least the same in machining. Pistons on the other hand come up at all sorts of prices (my new 2.2 litre only cost me $200 the set). Either way, a fresher block would be a better option than sleeves for an 18RG.



1st step is checking the bore no matter what so once you know what you are dealing with the decision can be made on the next step. Your block sounds to be in good nick if you can see the crosshatching....BTW it doesn't look sleeved to me?

The pistons sound pretty special?

High comp pistons with the stock cams isn't a problem, just a bit of a waste as you won't see much in the way of gains. It'll sound horn though with that hi comp cackle on overrun. I'd suggest you get some cams as well though to make the most of the package. Some mild 272's will really wake it up without costing you bottom end torque/response.

If you don't have the gear to measure everything up, get the lot to a reputable machinist and he'll have the best idea of where to go next.