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

[timbosaurus]

I dont think toyota sell them anymore... and the price for those in the for sale section is bloody good. Good condition Toyota pistons will take a pretty hard beating. The only real reason to go aftermarket is if you want higher than 10:1 comp, you plan on running high boost, or you can't find good secondhand 9.7's.

An aftermarket set of pistons is going to be around the $800+post (US) or $1000 (local) at the moment... so you should decide if you think it's worth the $500+ difference for no real power gain. (unless you boost comp to 12:1 or something, but then you'll have other issues)

I know it sounds silly, but some people actually think that just putting in forgies will increase their power. If the comp is the same, power will be the same. Technically forgies could even be heavier! Even if you do get higher comp and/or forged pistons to facilitate a big power engine, you'll have to spend even more money on either cams, turbo, bottom end to handle the higher pressures/revs, carb or EFI tuning, studs, etc to use their potential.

So if you want a moderate rebuild, just use the toyota gear... a nicely rebuild 9.7 would certainly turn 100hp at the wheels, and all the parts needed to rebuild it (including secondhand pistons, machining, full gasket set, head reco) should be under $1000.

If you want to go the next step and build a high power NA or turbo engine, expect no change from $5k unless you spend years hoarding parts. New cams, valves, springs, and pistons add up, plus all the extra machining and tolerancing, bigger fuel system, the supercarbs you'd use or EFI, injectors, the balancing etc. Then you'd be looking at UP TO 150hp at the wheels N/A or UP TO 200hp turbo. More than that take time, experience with the engine, trial and error, and did I say time??

Cheers,
Timbo

[Baconer]

Only reason i was after new ones is for the same reason you stated, a good set will take a beating. I was only after new 9.7 pistons, not forgies or higher comp ones so that i knew the history of the pistons. If new ones are too hard to find though then i might have to go second hand afterall.

Ill give my mate a call tomorrow to see if he can source a new set from anywhere and go from there.

Thanks to all above for the help

[o_man_ra23]

I agree with all of what Timbo says on there. At a guess, my turbo engine will cost around $3k, but then you have a lot of ancilliary equipment needed to install it, and that will probably end up taking that other $2k and a bit more. And that was with buying a motor which already had oversized Toyota pistons, and having the turbo for free!! Helps that I can do just about all the work myself, and I have got a few good bargains along the way, but still outlines that getting power out of these motors isn't cheap. It is however, a lot easier from an engineering point of view.

[RAd28]

I have a spare 9.2:1 bottom end here, and i've been tossing up whether or not to rebuild it and raise the comp, then put a freshened head, with the cams i've just bought, or to take the 9.7:1 motor out of the car i've got, and do the same to it...

Biggest question there i guess is how much power difference will ~0.5:1 compression make? if i deck the block on the 9.7 motor to 10:1 or higher is it going to be worth the effort?

[o_man_ra23]

Decking the block and head on the 18R-Gs can be a pain, as you loosen the chain by a fair amount, which brings your tensioner to a stage where it can't keep up. You are far better increasing compression with pistons. Yes, .5:1 compression increase would be noticeable... it would have more torque the whole way through the revs, making the motor more driveable.

[RAd28]

If chain tension is really that much of a major issue, is there any reason why you couldn't weld a small block onto the back of the big slipper for the tensioner to push on? the chains doesn't get too close to itself through that part of the loop does it?

[o_man_ra23]

Couple of things:
welding to the back of the slipper will involve heating the crap out of the slipper material. I don't know what that material will do when heated like that (but the bonding material might not like it)
Radius of the slipper will be too large and may cause excessive wear at the edges leading to premature failure and possible chain damage

Plenty to think about before you go lopping metal off that can't be put back on.

[Steve M]

If you can't weld to the slipper, why not lengthen the tensioner?

I've had different tensioner pistons made up before. It can't be that hard to get a longer one made up. You might even be able to weld onto the end of it to build it up to length.

[RAd28]

yep... all good points... will keep thinking...

[Omegaman]

The thingee in the second pic is the idle up valve, the big hoses connect to the plenum and another one is t'eed into the aux. air valve supply (which comes from a big pipe underneath the throttle). The little hose connected to a eletric solenoid which switches vacuum to the thingee which then bypasses air to increase the idle. Not required if you dont have air conditioning.
Rudi

I've been searching for an answer to the connections of the big au=ir hoses on the 18rgeu EFI motor. This is what i've found so far. Above.
the hose that comes from the big pipe under the throttle connects at a tee section, where one side goes to the solenoid attached under the plenum on the runners.
Where does the third end go?
I've checked rivers mamoth thread for pics, none. Anyone have a diagram or can tell me.

p.s river, i know your busy, any further diagrams of the geu motor, as your 18rc/gu's etc.

[BlueMeanie]

Omegaman, have you got this pdf?
http://users.on.net/~csharman/docs/18rgeu.pdf

Cheers, Jason.

[machschnell]

Here's some info for the 18R-GEU guys wondering what all the ports are on your intake manifold.






In the pictures above: sorry cant find piccies but hope this helps
1/ This is the main PCV port, as seen in this pic, it connects to the cam cover PCV outlet. The port on the manifold actually routes to in front of the throttle, not directly into the plenum.

2/ This is the input for the idle up valve - see http://www.18rg.com.au/tech/18rgeu-diagram.jpg - the other side of the idle up valve connects to the port underneath the throttle body.

3/ Brake booster vacuum line

4/ 3-pronged vacuum line outlet, for fuel pressure regulator and boost gauge. The other is blocked.

5/ Single vacuum line outlet, for my ECU. In this location used to be the air-con idle up valve - a VSV controlled diaphram that increases idle when your air-con compressor kicks on.

6/ Crank case breather outlet on the block. I've got this running to an oil catch can, partially visible under the intake pipe.

7/ The other side of the catch can runs to the intake pipe, pre-throttle

8/ These two vacuum port outlets on the throttle body, one goes to the vacuum advance on your dissy (i dont have this, cos my computer controls ignition advance), and the other goes to your charcoal canister.

Note the two outlets above the throttle body that arent connected. These circulate coolant around the throttle for emissions purposes, and also impede power output - disconnect them.

It's also worth noting that I have removed and blanked off the cold start injector. I never visit sub-zero temperatures, so i see no need to keep it.

[Omegaman]

Omegaman, have you got this pdf?
http://users.on.net/~csharman/docs/18rgeu.pdf

Cheers, Jason.

Yes i do have this PDF.
As in my pic, the red lines represent my hoses, which has a T section (blue dot) and a third hose going no where.
I might just get rid of the T, and place it how the dig shows it.

Mach...... Thanks for that info.

[o_man_ra23]

Your T section may go to your lower crankcase ventillator (which isn't found on some 18R-GUEs like the one I have). So it may be worth checking to see if it fits that.

[Omegaman]

the crankcase ventillator?

Would or should that be a plate on the block, with the connection coming out for a hose.?

Because I never had one. This is a mystery to me, as it was connected somewhere previously..