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

[Steve M]

Also 18R-C pistons fit in the 18R-G with no problems at all plus 18R-C conrods work as well plus they are lighter than RG ones but make sure u use the 4 18R-C ones,not like I did and busted a piston and bent a rod plus from my own experiences with RG'S I reckon with using flat top 18R-C pistons the engine revs alot smoother than RG pistons,and it also revs harder and not as harsh as RG pistons.
Cheers Brett.

Hmm, I don't really like that idea.
point 1: major compression ratio drop from upto 9.7:1 down to about 7:1. (turbo?)
point 2: the valve reliefs in 18RG(E)(U) pistons are actually taken below the level of the block's deck. 18RC flat tops do not have this relief. If someone used a head that had been surfaced, those hard to find valves would be getting very close to the pistons.

I don't see how using mixing and matching 18RG and 18RC pistons would result in a busted piston and a bent rod. A serious imbalance I would expect, but those results I would not.
I know 18RC pistons have been used with 18RG heads, most times I've heard of this it has been to drop compression for forced induction, but most times I have heard of this the pistons have been modifies to suit the different valve positions.

Thiat post surprised me and now my brain is spinning, it goes against all of my thoughts and expectations but hey, each to their own. I for one will never be using 18RC pistons in any of my 18RG engines.

[tricky]

I'm with steve on this one. The cause of the busted piston could well be independent of the parts mismatch unless the incident occured at stratospheric RPM, but that seems unlikely considering that the engine was smooth. Also, the compression would be less than desirable for NA applications. The piston is not only lower, the 18RG combustion chambers differ from the RC ones, so there is a significantly greater combustion volume. This leads to lower efficiency, less economy and poorer response.

leroy, FWIW, I have a funny feeling that my engine started life as an 18R-C. I say this because it is a diverse mish-mash of mis-matched parts (lol). My block has the dipstick on the correct side and the oil filter mounting block is correct, but other than that, almost every part of the engine is from a different model... 18RC dizzy (now 88270), 18RC/88270 rods, 88210 head, 88270 cams, 88270 aux shaft, 9.7 pistons, 88251 timing cover, no block breather... Ya get my drift. Basically, I'd only convert an 18RC to RG spec using 18RC parts if I needed one in a hurry and I was short a few parts. Otherwise, I'd spend the time to source proper bits.

[Mr DOHC]

also, the rods may be lighter {not sure} but they are weaker

[RA23]

Thanks for that Steve.

3. I suppose so, but that would mean that the air coming from the block breather would blow up from the bottom of the catch can and put all the oil straight up into the out hole, thus defeating the purpose of the catch can.

Yeah, of course. didn't think of that. I was just wondering where that breather is originally linked to. I'll look that one up in the manual.

[scootaphill]

an 18RC Block has the numbers stamped "normally"
an 18RG Block has the numbers stamped "UPSIDE DOWN"

just a quick way to pick the difference in blocks

cheers

[ra_28]

Hmm, I don't really like that idea.
point 1: major compression ratio drop from upto 9.7:1 down to about 7:1. (turbo?)
point 2: the valve reliefs in 18RG(E)(U) pistons are actually taken below the level of the block's deck. 18RC flat tops do not have this relief. If someone used a head that had been surfaced, those hard to find valves would be getting very close to the pistons.

I don't see how using mixing and matching 18RG and 18RC pistons would result in a busted piston and a bent rod. A serious imbalance I would expect, but those results I would not.
I know 18RC pistons have been used with 18RG heads, most times I've heard of this it has been to drop compression for forced induction, but most times I have heard of this the pistons have been modifies to suit the different valve positions.

Thiat post surprised me and now my brain is spinning, it goes against all of my thoughts and expectations but hey, each to their own. I for one will never be using 18RC pistons in any of my 18RG engines.

The 18rc pistons do not have to be modified for the 18rg valve tust me i used a set hypoid 18rc pistons in my first turbo 18rg motor and they have no clearance problems only when i broke a timing chain the valves hit the pistons.

[jeffro ra28]

after a head and block surface grind you may loose .040". Will they still clear?

[scootaphill]

Does anyone know the
a: M.O.P (Maximum opening point) b: "Lobe centres" or c: "Phase" All the same thing

OF

1. STD 18RG
2. STD 18RGR
3. STD 18RGEU

any ideas on what lobe centres you would run on 272/288 or even 304 cams?

food for thought

[The Witzl]

Phill,

I dont have any tools to measure this, but i certainly do have a spare set or two of 18RG cams - 88250 set and 88251 set.
I'll be fudged if i know what the differences are, but i'll certainly try to borrow a cam dial or something to measure them.


Comparing the 18RC and 18RG rods - i would certainly not be using 18rc rods myself. They just look so pissy and weak compared to the 18RG ones. I'll get some side on comparisons to go with the comparison pics earlier in this thread.
I'm with Steve on the 18RC piston usage too...




Now here are some more reference pics

Here is a direct comparison of the EFI thermostat housing and the carby one. The EFI one is on the right....




This is my engine at the moment, part the way through putting on the EFI manifold....

[scootaphill]

looking good Karl...are you going to use the original fuel pump as a lift pump to a swirl pot then high pressure from there to rail?
if you dont already have the fuel line that screws into the rail, i would be looking for it now... its a pain in the ass to get to with the plenum and throttle body in place...
as for the MOP, Phase ect im just trying to get more out of her b4 i sell her back to simon so i can put the price up "evil laughing is over coming me"
cheers

[Norbie]

Speaking of fuel pumps, I need to upgrade my fuel system for the forthcoming uber-RG. My current setup is a VL high-pressure pump feeding directly from the tank and into the stock fuel line, which worked OK in the past but it doesn't offer protection against surge and probably won't flow enough for the new engine when I crank up the boost.

Anyway, I have a friend who works with stainless steel every day and he's offered to make me a stainless surge tank. My idea is to try mounting an internal Walbro fuel pump inside the surge tank, with the pump hanging off a bracket from the top of the tank, much the same as pumps are mounted in OEM fuel tanks. Then all I have to do is replace the VL pump with a low-pressure lift pump and I'll have a nice neat high-capacity surge-resistant fuel system.

Anyway, if my internal-pump surge tank idea works out OK I might get a few of them fabricated. Would anyone else be interested in such a device? *looks at Karl*

[The Witzl]

i'd be interested - IF i had a boot tank and not an under-floor drop tank!

I have an RA28 you idiot!!


I'm actually working on some ideas and designs for internally mounting and baffling my spare RA28 floor tank... Either that or just go all out and make a custom drop tank!

<duffman>

OH YEAH!

</duffman>




Currently my fuel system incorporates a nice external lift pump, VL bosch pump, and surge tank (not povo-spec like my AE71)..... see the pics below for the new system:

[TurboRA28]

Yeah i'd love to get rid of the tank/pump from the boot area in the 28.. Damn lack of space for surge tanks.

[The Witzl]

joel - i think some measuring, designing and test-fitting of some custom drop tanks is the go mate

[scootaphill]

Q. 1 Does the swirl pot need to be that big?
Q. 2 Is there a formula for working it out?
Q. 3 If it doesnt couldnt you make a trick smaller one to fit in engine bay?

this would help solve the "room in the boot" issue and you'd have less high pressure fuel line to worry about.

[The Witzl]

phil,

that is just a plain old surge tank buddy, and there is mainly just speculation and heresay on what volume it should be - yes you could have a smaller one, but i would rather just have a good intank pump

[SRacin]

volume you can make some educated guesses about based on injector duty cycle, fuel pump flow rate, if the return goes back to the tank or not, and what your estimate longest right /left hander your ever going to go around etc etc..or 1.4 mile or whatever your into.

[The Witzl]

WOW!!! I just scored from ebay a freaken awesome TRD and performance book for Toyotas.... including HEAPS of TRD part numbers and bits for 18RG engines

I'll be posting numbers soon

[Damo82]

Bloody brilliant Karl, I'm in the middle a rebuild so they might come in handy

[Mr DOHC]

ebay aus karl????