High-comp 2JZ turbo?

[Norbie]

So my 2JZ-GTE is getting more and more rattly as it ages, I don't know for sure what's causing it but it sounds like big ends. A rebuild is expensive, but on the other hand low-km 2JZ-GE's can be had for $500 if you shop around.

So what do people think about a hybrid 2JZ, ie NA block with TT cylinder head? I'm thinking with a thicker head gasket I can get the compression down to 9.0:1 which is quite reasonable, and I'll probably get the cylinder head rebuilt with a quick clean up of the ports. It's a cheap way to get a fresh 2JZ - in theory?

Discuss.

[takai]

No oil squirters though, which is a bit of a bummer. And strange squish areas on the pistons.

Maybe a GE bottom end with GTE pistons?

[BeRad]

Replace the big ends?, it can be done easily enough and is inexpensive really, but then it might not be big ends and a total waste of time.

[The Witzl]

Comon now Norbie - rebuilding an engine is really not that difficult, nor expensive. The major cost will be your head service - thanks to 24 valves to service and lap.

The bottom end rebuild on my 18RG cost me a massive $375 including rings and bearings - i saved a bit of money by asking him to machine all parts and supply the correct bearings so that all i had to do was assemble the engine.

So long as you can get bearings and rings easily enough - i couldnt see a bottom end rebuild costing you over $600 (chrome rings = $ouch)

[Norbie]

Oil squirters aren't a major concern. GTE pistons in a GE block would be ideal but chances are mine are worn out, and buying new ones would defeat the purpose (ie cheapness).

I suppose I really need to do some investigation and find out why my engine is rattling - it could just be a shagged keyway in the harmonic balancer (a common problem on JZ's), but even so I kinda like the idea of a high-comp 2JZ. Better off-boost response, quicker spool, these things will be important when the new turbo goes on! There's also the fact I need to pull the head off anyway so it's not much extra work to swap the block.

[Hen]

A line from Ed regarding mods that he regretted (thought it may have originally come from you Norbie):

regrets: any mod that i thought 'hmm, i *should* do it this way' and proceeded to do it a quicker, easier way..

From post #14 in this thread

Work out what's wrong and fix it properly. I suspect that by the time you get a GE bottom end on and working well you'd have wished you'd just rebuilt your current engine.

Hen

Edit - A hi-comp 2JZ turbo may itself be a good idea, but I doubt it is a good solution in your current situation.

[EldarO]

if you decide to go GE way, www.supraforums.com has alot of info on what people are doing in their NA-T A80's.

Elmo.

[CLG]

I think you'll find the differences in compression in JZ motors is actually in the heads anyway, so applying a TT head to an NA short motor, will give you the same turbo mill's compression?! Heads (and combustion chambers too from memory) are different between the two motors.

[gianttomato]

NA motor + TT pistons + GT40 + NOS = 12.04 @155.

Or something like that.

[The Witzl]

i;m sorry - what did you just say GT?

I was busy with teh boobies.

[The Real Roadrunner]

ask roccos performance.
9 sec passes from memory on stock 2jzge long motors.

[mux]

I'm with the real roadrunner...

I mean why ask people that haven't done it. you should direct your question to someone that's done it.

Ask GT8 or roccos or racecraft.

My brother and I have done a 18RG Turbo with Jag pistons which = (approx) 11:1 static compression + 6psi with only a haltech F9 and locked dizzy and that was awesome. come 2psi in 3rd it would start smoking them up. Surely the squish area on NA 2j to 2jt aren't going to be that different, especially if it's for daily driving (Opposed to out an out racing).... $500 it's worth the risk.

[1JZ-Rolla]

I'm a big fan, this would definately be my avenue to take if I was allowed larger capacity in my car, mountains of torque from low in the revs. Sure, you may not be able to cram 20psi into it (roccos run methanol remember, much better knock resistance than pump fuel), but 10-15 psi and a good tune would have to still turn some good numbers and feel like a massive capacity engine!

[JustenGT8]

How cheap are n/a JZ's Norbie...cheap as chips that's how cheap

Biggest issue for you with be ECU. Very different VE's between n/a engine and TT so timing and fuel tables will be out....how much out i don't know but could be out enough to go BANG.

With progammable ECU i'd say go with the n/a engine. You know it's the same strength and would make for a much nicer street engine.

[Norbie]

Peter Costello: heads are different but pistons are different too, it's the shape of the piston which changes the CR. I vaguely recall someone CC'd the combustion chambers a while back and they were nearly the same between GE and GTE?

Justen: there's no way I'd try this with a stock ECU, I have a Haltech E6K sitting in the garage so that will be running the show. If I go ahead with this I will install the HKS 272 cams and GT35R turbo at the same time so programmable ECU is a given!

With those cams I'm thinking more compression would be especially beneficial, but the question is how much? Leave it at the stock 10:1 or try to lower it a bit with a thicker head gasket? Keep in mind I'm shooting for 700hp at the flywheel (or as close as I can get) so I need to run a fair amount of boost.