http://www.spracingforum.com/forums/...whp-and-677wtq

While looking for a turbo for street driving I saw this build thread ^^^^ and fell in love with the results. I want to recreate this build

I currentally have a TT head gasket on wish list for my 2jzge that currentally has a 2.4mm(bad idea) its a toss up between the OEM 1.3mm and cometic 1.6mm HG

 

Is the 2.4 a bad idea? Is that with or with out the gte head!

 

I put a 2.4mm or maybe it was 2.5mm cometic HG on my non vvti stock 2jzGE long block. and from what i have been told and read about is that this was a bad choice.

some food for thought too,


https://www.clublexus.com/forums/per...usestions.html

http://www.supramania.com/forums/sho...light=2jz+6262

http://www.supramania.com/forums/sho...nto-MK3/page34

http://www.supramania.com/forums/sho...-2jzge-T-build

 

I'm about to get my head rebuilt and surfaced for na-t so this an interesting thing.. So Cometic is a nono? Causing oil seep?

 

you will need a quick spool valve to get those kind of results on the low end, but the top end you can get without one. no need to reinvent the best headgasket, just get an oem TT one. if you need more power than that you need a low compression piston setup, or just use ethanol and go high compression.
The need for super thick headgaskets has come and gone already.

 

Bringing this back to ask specifically about the Cometic 2.4mm head gasket. Does anyone know what the compression ratio change is when using it on a non-vvti 2JZ-GE (10.0:1 stock)?

I'm trying to figure out if it will get me close to a stock TT's 8.5:1 using a 2JZGTE head. This would be on a car that probably won't see more than 15-16psi. Possibly 18psi down the road but that's it.

Edit: I'll add-- the fuel management is going to be done with a completely stock OBD1 2JZGTE USDM ECU and all the associated electronics and a set of stock USDM turbos. Nothing new and nothing exotic like an AEM V2, and dyno time.

 

Doing some math I'm getting roughly the following:

2JZ-GE block and pistons w/ Cometic 2.4mm head gasket -- 8.05:1 compression

2JZ-GE block and pistons w/ Cometic 1.8mm head gasket -- 8.85:1 compression

The 2JZ-GE OEM gasket is 0.45mm

Do these figures sound correct? Also, what difference do I need to account for if I'm using a 2JZ-GTE head?

 

Kahn you can run 18 psi on the TT gasket and ge head all day long. much thicker and you are loosing spool and power.
2jzgte head makes a difference, as there is no recess in the chamber on the GTE head like the GE head has so you will need a thicker gasket like a gte gasket with the gte head and the compression would be higher than if you were using the GE head.

 

If you are staying on pump gas and under 20psi you will be fine with a TT gasket no problem. I'd even venture to say as long as you had a killer tune you could even use a stock gasket at 10.1 compression if you stayed under 16psi.

 

Thanks guys. I'm happy to learn the engine can take a lot on 9.x:1 as it is. I know engine tuning technology has come a long way in recent years. What I'm looking into the 1.8mm and 2.4mm gaskets for is primarily emissions compliance and the fact that I will be using a stock OBD1 USDM 2JZGTE 6-speed ECU and a USDM GTE head. No modern tuning other than maybe some basic BPU stuff.

Therein lies why I'm looking to keep the compression ratio closer to a stock 2JZGTE's 8.5:1

And no, my boost won't be going over 18 psi since I will be using the stock twin turbos.

I'm looking into the gasket route or possibly getting TT pistons installed. My block is at 223k currently and will be higher when it's go time.

 

the gte head has a smaller volume so running a gte head will raise the compression some I think, will have to look at the numbers again, you may need even a thicker gasket. your squish will also be less optimal the thicker the gasket is to keep in mind. 8.5 is a super safe compression ratio, but it has to be gotten to in the right way. a super thick gasket is generally not the right way anymore. I think the stock gte one is too thick these days even.