Bean

iTrader: (1)

not sure if you wanna splurge on a $300 headgasket to lower the compression?

THIS article
http://www.supraforums.com/showthrea...threadid=97349

from a very reputable person, states the measurements of headgaskets...

the stock GE motor gasket is .3mm... as most of you know you need a 1.8 to 2.0mm headgasket to achieve 8.3-8.5:1 CR...

the stock GTE gasket is 1.6mm... this achieves 8.875:1 CR from a cheaper $130 gasket... for those of you not running high boost levels (ie. less than 21psi or so), the TT headgasket would actually be superior...

Gixer 1000

Thx alot for the info bean

motorheaddown

Bean,

While I appreciate the complement, please keep in mind the numbers I posted on SF are just that... numbers. I plan on measuring the change in compression by measuring the change in squish band thickness after the head is re-installed with a thicker hg. Until then, what I posted is just the *theoretical* change in compression ratio. In fact, it would be nice if someone confirmed my calculations just to be sure. (It's good science that way.)

Thanks,
-scott

awj

I'm not convinced it is necessary to drop the compression. That book mentions many other ways to avoid detonation. After experiencing first hand, (though not extensively) with proper set-up, possibly 20 pounds could be run before compression becomes an issue. But I am speculating and wont be able to prove anything for a while (so try it at risk). Of course, ambient temperature must be accounted for:

94 octane, 50F - 17psi, 10:1 - no detonation (2/1/03)

side mount, 2 550 aux, T04, tt pump, stock rail and injectors

motorheaddown

Certainly, practice wins over theory. However, you can't argue with Toyota engineers who designed the GTE motor to run at 8.5:1 c/r on maybe 1bar of boost. To run a GE motor at 10:1 at over 1bar seems like you're asking for trouble.

I know ComputerWiz ran 10:1 compression on his 60-1, .58 A/R, but I think he eventually blew a hg. If so, he probably should have listened to his tuner and the Toyota engineers.

-scott

Bean

iTrader: (1)

i think compwiz had a T04E-60, not a 60-1... sc300t has a 60-1 and he hasn't blown his yet...

i plan on testing this out...

but there are also other methods of cooling the intake charge besides an intercooler; and those same methods would also help with detonation control too

wayne

iTrader: (27)

the stock GTE gasket is 1.6mm... this achieves 8.875:1 CR from a cheaper $130 gasket... for those of you not running high boost levels (ie. less than 21psi or so), the TT headgasket would actually be superior...


I went this route and I have had no problems so far. Then again I'm only running 15psi right know. Hopefully after another trip to the dyno I'll be able to crank up the boost a little more.

Bean

iTrader: (1)

thanks for the info wayne... i'll prolly be hitting that route myself...

Dew23

iTrader: (1)

What octane gas are you running, the other trick is to use two tt
headgaskets which will drop your compression.

Gixer 1000

I own a 93 sc300 (5 spd) and have oil in my coolant. Im gonna take the head off myself, i just pray i can put it all back together right, and was wondering witch gaskets would swap.

I was going to get a gasket set from the dealer (240.00)
but im wondering if a tt gasket set would be better.
Correct me if im wrong, but the head gasket is the only one that will swap from the t.t. to the n/a. I figured all the other gaskets and seals for the tt would be different.

Im just trying to get the car to run good untill i go turbo in about a year, at witch point im going with low compression pistons, stronger rods, etc etc.

motorheaddown

FYI, the GTE and GE motors share the same rods, crank, and block. Stronger rods are not required IMO.

Also, does anyone *really* know if the TT pistons alone will reduce the compression? I'm not at all convinced that will happen. If you read the new car feature book posted on the mkiv.com web site, the only real difference between the GE and GTE pistons is oil cooling and the top ring. That's it.

Think about it. The heads are different, and the hg's are different sizes. That's probably enough to lower the compression to 8.5:1. Why go to the trouble of making a piston that lowers the compression even more?

Comments anyone?

-scott

Bean, apparently wayne has the answer you were looking for about running just the TT hg.

Gixer 1000

I was told these were NOT the same, that the tt motor had stronger internals ....

can someone confirm/deny this info ?

motorheaddown

I never post anything without direct knowledge or *great* references. You have mis-information.

Read the bottom of this page:

http://www.mkiv.com/specifications/ncf/ncf93/ncf080.jpg

The only real difference between the GE and GTE internals is the geometry of the head, oil cooling of the pistons, and timing on the exhaust cam. The GTE exhaust cam opens one degree sooner and closes one degree later. Believe it or not, that's it.

Regards,
-scott

Gixer 1000

Thanks alot scott.
If i had a nickel for everytime ive read or been told misinformation ...

I wish everyone followed your creed about posting!

Bean

iTrader: (1)

i think throwing in a TT headgasket and either the TT head or the TT pistons (or maybe a combo of all 3) would lower the compression to 8.5:1... there are ways of finding this out

does anyone happen to know the combustion chamber size of the GTE and GE head? are they the same? this has a lot to do with CR too

and how different are the pistons on the GTE motor vs the GE? i've also heard the GTE pistons were heat-treated too