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Location:
Cabooture QLD
Registered:
November 2002
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18R-GU specs
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Tue, 06 May 2003 14:20
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i need some help i need the specs of a stock 18R-GU engine i need things like bore , stroke , valve sizes , valve lift , any cam specs , any airflow rates
the engine is just a stock 18R-GU , with twin sidedraft solex carbs (well i don't have the carbs but thats what was on it) i'll post the head number as well sometime in case that makes a difference
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Location:
Mornington Peninsula
Registered:
September 2002
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Re: 18R-GU specs
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Tue, 06 May 2003 22:53
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I've got a manual at home for an 18R-G that might have that info in it. The U just stands for the polution controls used so the rest should be the same. I'll have a look tonight to see if I can find anything
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Location:
Canberra
Registered:
September 2002
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Location:
Cabooture QLD
Registered:
November 2002
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Re: 18R-GU specs
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Wed, 07 May 2003 02:50
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ok the Head on my 18R-GU is a Yamaha 11111-88250
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Location:
bris
Registered:
February 2003
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Re: 18R-GU specs
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Wed, 07 May 2003 02:53
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the u does stand for poolution gear, it means 'Japan Spec' pollution gear, please try and be a bit nicer about it too huh? instead of biting plps heads off... the U engine has a lot less power becuse it has less compression, to make it more economical
now...
Valves
overall length - intake - 106.8 mm
- exhasut - 105.1 mm
valve head contacting face angle - 45.5 degrees
valve stem diameter - intake - 8.465 to 8.475mm
- exhaust - 8.455 to 8.470mm
valve stem oil clearance I - 0.025 to 0.055mm
E - 0.03 to 0.06mm
limit - I - 0.08mm
E - 0.10mm
valve head thickness limit - I - 0.5mm
- E - 0.6mm
... this is just a sample, there plenty more if you tell me exactly what you want to know
as for the head, there fuckin tonnes, its not specified in the engine family code, WITZL posted a list of some of the different head types
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Location:
Canberra
Registered:
September 2002
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Location:
Rocky Mountains, Canada
Registered:
May 2002
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Re: 18R-GU specs
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Wed, 07 May 2003 04:05
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| toycelica77 wrote on Wed, 07 May 2003 12:23 |
... the U engine has a lot less power becuse it has less compression, to make it more economical
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Youll find the drop in compression had nothing to do with economy... it was done purely to reduce emissions.
Remeber the 18R-G's were performance engines, if you bought one, you didnt care so much about fuel economy.
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Location:
bris
Registered:
February 2003
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Re: 18R-GU specs
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Wed, 07 May 2003 04:41
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| M.W.P. wrote on Wed, 07 May 2003 14:05 |
| toycelica77 wrote on Wed, 07 May 2003 12:23 |
... the U engine has a lot less power becuse it has less compression, to make it more economical
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Youll find the drop in compression had nothing to do with economy... it was done purely to reduce emissions.
Remeber the 18R-G's were performance engines, if you bought one, you didnt care so much about fuel economy.
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this is what i meant, soz for the confusion...
and btw trent, you in the deep end, keep swimming 
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Location:
Canberra
Registered:
September 2002
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Re: 18R-GU specs
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Wed, 07 May 2003 04:53
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Location:
Brisbane
Registered:
May 2002
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Re: 18R-GU specs
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Wed, 07 May 2003 05:10
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| trent_kershaw wrote on Wed, 07 May 2003 13:58 |
oh, and the U stands for Yamaha head. It just happens to have pollution gear too
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Incorrect. The 18R-U doesn't have a Yamaha head, and neither does the 2T-U or the 4K-U! Conversely, the 3S-GTE and 2JZ-GTE have Yamaha heads but there's no U in the engine code.
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Location:
Canberra
Registered:
December 2002
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Re: 18R-GU specs
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Wed, 07 May 2003 05:22
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This might answer some questions:
BEFORE "-":
the letters indicate the engine family, for example in 18R-G
the engine family is R, in 2JZ-GTE the family is JZ.
The number(s) at the beginning is the number of the are for a certain
bottom end version (block, bore, stroke). The larger the number,
the newer the bottom end version. It may seem like the larger the
number, the larger the displacement but this is not always true.
AFTER "-":
G = twin cam (wide angle, 45 degrees or more between the intake and exhaust valves)
F = "economical" twin cam (narrow angle, around 22 degrees)
T = turbocharged
Z = supercharged
E = fuel injection
i = single point fuel injection
L = transverse mounted engine (seems to be an obsolete code)
B = twin carbs (only used on non-twin cam engines, obsolete code)
R = air injection
S = swirl intake ports (only a few made in mid '80s)
S = direct injection & swirl pot pistons (starting from '97/98)
U = emission package (Japan)
C = emission package (California)
LPG = LPG fuel
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: 18R-GU specs
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Wed, 07 May 2003 13:56
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Well well well.. what have we here... 18R-GU head information!! :)
Ok, here is the information i found about some of the variant 18R-G heads that were produced. I got this from the Yahoo Celica Group i think.
| Quote: |
> 88250:
> - 49657 single spring early rgu single dump ex ok head small studs on ex
> - 52978 same as above
> 88253:
> - 73086 double spring late rgu good head to start with large studs on ex
duel dump man
> - 62744 single late rgu still good head may be small stud ex should be
single dump
> - 81784 double spring late also
> - 87278 double spring late also
> 88270: these are ale efi heads all double springs alll good heads these
are the ones you use
> - 35140 biggest ports biggest valves no smog ports best casting
> - 08037
> - 49383 very late head newest ive seen
> ?:
> - 81225 same as above double late rgu if the head is a 11111-88253 not a
11111-88270
> 88253 88270s would be the heads of choice since these need very little
work from the factory these willl make lots of power with little porting
they will make a lot more power with a lot of porting the castings are a lot
thicker around the ports so there is a lot of room
the 88250s can be made good but the ex studs should be changed up to 10mm
ones for best sealing
all of these engines should have 8.5s to 1 but the efi 88270 heads they
should have 8.3 to 1
just be glad you dont have any of those 11111-88230 or 88210 heads they are
good paper weights
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Also a good point to note that ALL Toyota twincam heads were made by Yamaha. Its a common misconception that simply because Yamaha started embossing their twincam head on Toyota motors with "Yamaha" that all of a sudden Yamaha started making twincam heads. This is far from the truth. ALL Toyota twincam heads are of Yamaha design and make.
AS for the Motor's specifications, most of the specs from the "Green Book" as i like to call it are still applicable to the 88250 variant 18R-GU, the major difference between this model and the earlier ones is the pistons (went from 9.7:1 down to 8.7:1 compression ratio) and the valve sizes went up to 45/37mm in the 88250 head (not sure what they are stock in the earlier models, but i know its smaller) and the camshafts have a shorter duration to make up for the newly introducted emissions laws.... as was the reason for most of the modifications.
I have also heard that the 18R-GU came about in the introduction of unleaded fuel in Japan... but either way, the U still stands for Japanese variant emission control.
A couple of specs:
Cylinder Bore: 88.50-88.55mm wear limit: 0.2mm
Stroke: 80mm
88250 intake valve face size: 45mm
88250 exhaust valve face size: 37mm
cam specs...? i know the earlier cams had longer duration - visibly longer!
Air flow figures... no idea... except that from the green book the manifold vacuum at idle is: 380mm of Hg (mercury).. and i forget what that equates to in HPa or PSI
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Location:
Cabooture QLD
Registered:
November 2002
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Re: 18R-GU specs
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Wed, 07 May 2003 14:08
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thanks for all help everyone
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Location:
adelaide
Registered:
May 2002
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Re: 18R-GU specs
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Wed, 07 May 2003 14:25
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Hey do any or all or none of these specs apply to the 18R-GEU 11111-88270 Head motors?? Does anyone have the specs all in one document or on one web page? Also curious, if one was to perform a mild rebuild on an 18Rgeu but replaced the pistons with the older-higher comp. items, would this perform okay or would the cams be all out and stuff? ive got pretty much all standard efi gear.. but if this could be setup with the higher comp and bit of cam work would it get a very noticeable power gain?? or would you need to go all out in rebuilding it to semi-race spec with plenty of work on all aspects of the motor to really get a decent increase? because if so it would be way more cost effective to mildly rebuild it and wack some forced induction on like ive always thought..
Cheers,
_________________
BlackRA28
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: 18R-GU specs
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Thu, 08 May 2003 04:01
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well it really depends on where you want to take your 18R.
if you want forced induction, keep with the 8.3:1 pistons you have in the standard 18R-GEU, since they are plenty compression happy for a solid 7psi or so (im told)... and the rest of the work wil follow on from having the forced air bug....
if you dont want to ram air into your engine and simply let atmospheric pressure do that for you - then get yourself the 9.7:1 pistons (straight swap) and the early model camshafts (will have either 88210, 88211, 88230 or 88231 stamped on them) since they have the most aggressive profile. You certainly would notice these ghains.
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Location:
adelaide
Registered:
May 2002
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Re: 18R-GU specs
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Thu, 08 May 2003 10:15
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Thanks Witzl, very helpful advice, i agree.
Yes this is what ive thought, the two golden paths.. to make a nice forced induction motor or a nice NA motor.. Ive been pondering it for ages and probably will for a long time til i can decide, but pretty much because im still a bit of an ameteur in the field of modifying (only been in the game a year or two) itd be good to hear some opinions on the aspects of the two setups and what it would cost parts-wise for mild and hotter builds of na and forced.
what sort of power figures would you think the NA 9.7 early-cam balanced efi motor would get? as apposed to the standard 8.3 rebuild with mild 4-6psi turbo/blower stock ecu etc..? Im all for a non-turbo motor because it in the end less hassle, and cops cant see huge domed-pistons and lumpy cams when they open the bonnet ..
How much are a set of the 9.7 pistons and early cams worth roughly?
Is there anything to be wary of buying second hand pistons? because you never know, mite find some in US or interstate or something and they could be destroyed.. Can pistons be machined or forged etc if they have imperfections? cos i expect they are fairly rare..
Cheers,
__________________
BlackRA28
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: 18R-GU specs
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Fri, 09 May 2003 01:05
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the pistons CAN be bought new for around $600-700 a set. 2nd hand ones you would have to take on face value only.
Power you can expect from a late model head with early cams/pistons.... probably in the realms of 150-160 horsies.
Now with a mild forced induction (as queried) of around 4-7psi you can expect probably around 160+ horsies.
You can see where the forced inductin helps - it also increases torque a lot, which the N/A motor won't. Also the turbo would probably be easier to drive around town. Its all up to you my friend. I was going to go the N/A route, but when a full rebuild costs around $3000 i thought - NUTS TO THAT! So now im concentrating on EFI and either S/C or T/C?
P.S. i have only been doing this abour 1-2 years also mate!
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