The 18R-GTE reference manual ...

[JustenGT8]

That just reminded me of another turbo 18RG a mate built here in Canberra. He used Jag pistons which were 92mm from memory and gave a comp ratio of around 12:1. I have to say it was a very impressive performer. Handled 6psi no probs and was a total torque monster. Spooled up a CT26 like you wouldn't believe. Never fully developed it as needed much bigger injectors and ran out of bucks...not sure where it ended up.

This little experiment was inspired by some Porsche racers that run 13:1 comp ratio and up around 15psi of boost. Goes to show that with the right gear hi comp ratio turbos are very feasible and make for great performers. If the UZ ever gets a set of forgies i'll be very tempted to stick with the stock 10:1 and wouldn't ever go lower than 9:1

[Steve M]

So I take it that the bore spacings are different between 18R and 22R, yes?
I haven't really looked for a crank yet, the only wrecker I checked didn't have one.

That oil pump looks a bit different to the standard 18RG items, what's happened there, Justen? Are you going for a front sump set up or is that how it came?

[JustenGT8]

Yup, the bore spacings in sthe big issue hence the offset grind.

The pump setup is a rear pickup as this engine was in a Hilux, i'll swap it all out for the RA install

[The Witzl]

Justen, it's not just the pickup that looks different there, its the body of the pump too. Tis interesting...

Here's one of my stock 18R-G oil pumps...
http://www.witzl.com/tech/18rg/18rg_love-012.jpg

Anyway... some pics of pistons in blocks.

# dark pic, but shows 9.7:1 piston in block
http://www.witzl.com/tech/18rg/97piston-crown.jpg

Here's another pic....

[Steve M]

Justen,
I'd love to get the details of the crank and rod grinding from you Justen if you have them as I plan to order pistons this week.
It would be good to know how much clearance I need inside the pistons for the small end of the rod to clear where the pin goes. Are you able to measure that.

Also, I wonder what volume that Hilux pump puts out.
18RG rotor height is 30mm, while cross sectional area is about 1.1cm^.
I like the idea of a bolt on tube pickup, it lends itsself to making a custom centred one better than the cast jobbies.

[JustenGT8]

I doubt the actual machined figures will be on the worksheet but i'll have a look.

Not sure what you are asking about small end clearance, there should be no issues with any of the proposed rod/piston combos?

[metcap]

offset grinds for all bores? same values?

[JustenGT8]

Got the machining sheet here and no dice i'm afraid. I would say yes that all are the same as the bore spacing difference is 1&2 and 3&4. No a big issue though as any machine shop could sort this issue in next to no time. The rods were also polished the whole bottom end balanced and then the rods and cranks shotpeened. The big ends also use ARP bolts

[Steve M]

Justen, my concern was that if the crank required the rods to set farther from the centre of the block (forwards and backwards) than normal, there would have to be enough clearance within the pistons to accommodate this change of position.
Your 22R pistons appear to accommodate this well, but it would be good to know what the gap width is.
One set of forgies we have has a smaller gap for the rod small end than the original pistons.
While it is nice when things just fit, it's even nicer to know that they will in advance.
Does that explain it better?

[JustenGT8]

Yup i see. The pic doesn't give you a good enough idea? I'll see if i can squeeze a vernier in there for an exact measurement

[JustenGT8]

Right'o, that is a bitch to get anything in there to measure but here's i could manage. The wrist pin width on the piston was 32mm. The gap from one edge of the piston to the edge of the rod was 4mm...couldn't get the other gap but obviously smaller, apporx 2mm?

Does that help?

[Steve M]

That's great. I thought it would be difficult to measure so that for going to the effort.

The measurement for the pistons looks stock (same as 18RG piston).
The rod must have had about 2-3mm (closer to 3) taken off its small end width to get those measurements. That shouldn't effect the bushing at all, which is always good.

I don't reckon I'll have any issues achieving similar measurements, so I guess it's time to go buy a crank, order pistons and pick up another block, one with the dipstick in the right place.

[JustenGT8]

The boss should be there for the dipstick in the casting, just have to drill it out?

[Steve M]

Yeah, I know. The only issue there is that the dip stick mounting heights on 18RG-s and 18R-Cs are different. I would have to knock up something to match the correct height.
I'll most likely do that anyway as we've found that by ading 10mm to the oil height in the sump and using a thicker oil (some shell synthetic thing) we've eliminated the right hand turn oil surge problem. No drop in pressure at all!

Plus, I know where a genuine 18RGEU block is. It is a later casting than my current block, so I'll see what the differences are and which looks stronger. I remember Celica_RA45 mentioning that he had some block warping problems at about 360hp. That's pretty close to the majical 200RWKW mark (30% drivetrain loss).

[JustenGT8]

I can't see an 18RG block ever having warping problems? They are truck size gear and super solid. Main cap issues perhaps but again it's revs that does this not boost so if you keep the revs sensible you should have no issues. 200rwkw is closer to 310hp and you'll have no issues at that hp.

There are a heap of 600hp+ 18RG kicking around Scandanavian lands where they love these things and apart fromARP bolts they are stock (but well built) crank and blocks.