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Discussion Starter · #1 ·
ive been doing some research and ive been surfing on supra forums. ive read running tt pistons and tt oem hg on a na ge is bad? ppl said it would lower your compression to under 8:5:1 and would ruin your quench. some ppl even said if you run tt pistons you should run na hg. ive never heard of that and would think the na hg wouldnt hold even with headstuds? what are your guys take about running tt pistons and oem tt hg or na hg? are their any of you guys running tt pistons and oem tt hg? how long has it been holding up. also are there any guys running tt pistons on na hg? thanks
 

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tt pistons and tt hg = the good

it's standard protocol as far as i'm concerned, the only other option in my eye is a 1mm HKS or greddy - but you gotta pay twice the amount for them
 

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I've heard you actually end up being around 8.3/1 can't say for sure though.

Currently I've got JE 8.5/1 pistons and a GTE head gasket, everything's been running fine for 3000+ miles, but no boost yet so I'm getting around 16mpg city.
 

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You are correct about the Compression Ratio dropping. However it isn't "bad" people do it all the time and make great power. Lower compression also is safer for pump gas and boost as well.

However. Yes. You Are Correct. About everything... Including the Quench. But i suppose in the real world it really isn't that important.

The stock GTE head gasket is ~1.2-1.3mm
The stock GE head has a "recessed combustion chamber" while the GTE head does not. "The entire combustion chamber on the NA head is recessed about .025" *

so the combination you've mentioned using a thicker 2mm hg, would result in a CR less than 8.5, probably closer to 8.0:1 (that's just a guess)

Using a Stock TT HG + TT Pistons + TT Rods + GE head = a CR of 8.3:1 **

*
DaveH (NA-T guru on SupraForums)
**GE head w/ TT shortblock & HG = 8.3:1 compression?


And finally. Before you say I'm wrong.
TonyTheTiger agrees with me ;)... and so do Boost Logic:cool:
 

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I've heard you actually end up being around 8.3/1 can't say for sure though.

Currently I've got JE 8.5/1 pistons and a GTE head gasket, everything's been running fine for 3000+ miles, but no boost yet so I'm getting around 16mpg city.
if your pistons are JE 8.5:1 for the 2JZGE then you have 8.5:1.
If they're for the GTE then you have 8.3:1

And its OKAY to do. Lots and lots of people do it.
 

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sorry to thread jack, but a local guy is selling a 2jzge with tt pistons/rods brand new never driven.however the hg was left stock. he said tops of the pistons were CNC machined a little to lower compression more so the stock hg could be used. This was all done by a prof. engine builder.should i be concerned about the na hg still or just have a tt hg installed to be safe?
 

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You are correct about the Compression Ratio dropping. However it isn't "bad" people do it all the time and make great power. Lower compression also is safer for pump gas and boost as well.

However. Yes. You Are Correct. About everything... Including the Quench. But i suppose in the real world it really isn't that important.

The stock GTE head gasket is ~1.2-1.3mm
The stock GE head has a "recessed combustion chamber" while the GTE head does not. "The entire combustion chamber on the NA head is recessed about .025" *

so the combination you've mentioned using a thicker 2mm hg, would result in a CR less than 8.5, probably closer to 8.0:1 (that's just a guess)

Using a Stock TT HG + TT Pistons + TT Rods + GE head = a CR of 8.3:1 **

*
DaveH (NA-T guru on SupraForums)
**GE head w/ TT shortblock & HG = 8.3:1 compression?


And finally. Before you say I'm wrong.
TonyTheTiger agrees with me ;)... and so do Boost Logic:cool:
YOU ARE WRONG!

1) The stock GTE head gasket compressed thickness is = 1.35 mm
2) for TT pistons and 2mm hg CR = 8.37:1

I don't known what mean "recessed combustion chamber" term, but you can calc CR youself using real numbers from:
1) http://my.is/forums/attachments/f114/25736d1264219464-ge-build-question-01lexusis300-1.pdf
2) http://my.is/forums/attachments/f114/25757d1264432906-ge-build-question-toyotasupraturbo.pdf

My results here


Please find any mistakes?
 

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Discussion Starter · #11 ·
It's believed the GE head flows better so I don't think anyone would have done that
here are 2 quotes from supraforums.


(quote 1
If the head is cut should the gasket thickness increase by the amount that is removed from the head over the .2mm of the stock NA gasket?

If you cut 1mm from the cylinder head, would that require use of the TT gasket(1.2mm) to maintain the correct quench/squish?


My head has been cut around .75 of a MM and I am using a TT gasket with TT pistons/shortblock. So in theory this brings my CR up to around 8.6-8.7 and the quench/squish a good bit closer to what it should be... quote)

(quote 2
In fact,I am thinking of milling my head so the combustion chamber is similar to a TT and use a TT gasket. The reason for this, is if I ever need to resurface my CR's won't change as much as if it was recessed like it is.

Although, not milling it will allow the head to live longer since there will be more material there for future removal quote)

thats why i asked the question..
 

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I've milled my GE head by 0.025" just so it removes the step between the gasket and the bowl of the combustion chamber.. It was merely to achieve something similar to the GTE's pentroof style chamber.

Besides that, unless you are shooting for huge amounts of power (800+ WHP) and always restricted by the fuel you are using, I won't worry too much about issues with quench or whatnot. As long as the compression ratio is still in the 8's, there is negligable difference as far as compression goes, and I would recommend the TT headgasket over the GE gasket anyway. The GE gasket is pretty thin and weak actually, and it not as forgiving as the TT headgasket.
 

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Here is my setup:
IS300 GE VVT-i Head,
IS300 GE Block,
3.4L GTE Stroker kit (pistons, rods, crank),
OEM TT HG.

Makes ~1300RWHP @ 39 PSI boost Turbo Only and over 1600with N20.

Nuff said.

TT internals + TT HG = GOOD! FOR THE GE LONG BLOCK, THIS WAS ESTABLISHED YEARS AGO!
TRUUF.
 

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Here is my setup:
IS300 GE VVT-i Head,
IS300 GE Block,
3.4L GTE Stroker kit (pistons, rods, crank),
OEM TT HG.

Makes ~1300RWHP @ 39 PSI boost Turbo Only and over 1600with N20.

Nuff said.

TT internals + TT HG = GOOD! FOR THE GE LONG BLOCK, THIS WAS ESTABLISHED YEARS AGO!
Well that's all you need to know right there! :p
 
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