Which 1JZ?

[tazza_boyo]

Hi everyone,

I need some helpful advice here... I am looking to buy a 3rd generation supra which I will modify to compete in drag racing as well as autocross so not only should it have a very respectable 1/4 mile time, but it should also perform well in acceleration for autocross competitions. I am looking to modify the car around 600 - 800bhp.

Now then, I am not sure whether I should go for the 2.5 litre twin turbo or the 3 litre single turbo, and this is where I need you guys to point me in the right direction. Now i know the twin turbo will have better acceleration as standard compared to the 3litre single turbo, but when looking at power figures as I have mentioned above, then which is the best choice?

Having read a few forums a lot of the 1JZGTE guys end up going for single turbo conversion anyway, but this is my point, why convert to single turbo on a 2.5 litre when you can have a single tubro 3 litre?

As you can tell I am very confused, and thats why I'm looking to you guys to point me in the right direction.

I'm desperate to get myself a Mark III supra, but which one

[bgrieger]

The 1JZ was only a 2.5, and only had the twins for the MKIII supra. The 3L was either the 7M-GTE (which came with the car), or the 2JZ, which is borrowed from the MK IV supra and installed in the MKIII chassis. It was also only available as a twin turbo, though the 7M had a single.

Acceleration is driven by torque. The 1J has the lease, the 2J the most out of the box. Modified, it depends on what you want. In any case, the 2 3L motors are the better platforms to start with for high power modification. Of the 2, the 2J will require less upfront work to perform at these levels. The 7M will need less cash to acquire.

[tevolo]

I'd go with the 2jz. I think they're easier to come by too. Aristo's, SC300's and MKIV supra's have the 2jz engines.

Aristo - 2jzgte
MKIV Supra - 2jzgte
SC300 - 2jzge (non-turbo)

[Razo-E]

some 1JZ's came single turbo, but it's not a gigantic difference...

the 1JZ and 2JZ will have to be swapped in, while the 7MGTE is already installed..

the JZ's rev higher and are tend to be more durable in stock form (7M's are notorious for blown head gaskets and rod knock; usually resulting from the aforementioned BHG ), especially the 2JZ...

personally, I'd go for the 2JZ-GTE...

[TcmaBoy]

For autocross I would get a smaller car. For drag I would reccomend dropping in a 1UZ/3UZ. More displacement makes for better low end TQ for the hole shot. The Supra is a heavy car and you want low end grunt to get it rolling. The first 60 ft is where drag races are won and lost.

I did the 1JZ swap a few years back. I have had mixed feelings about it. A 2.5L does not produce a lot of low end power. It is ok if you run it with a small quick spooling turbo. The power band is placed just about right for driving, but it doesn't exactly get the car rolling from a stop. I think it would be great in something a bit lighter like a Celica. When I had an oppertunity a while back to trade my 1JZ straight up for a 1UZ I went for it, but the deal fell through. The extra displacement bumps up the bottom of the TQ band, and I think it is a better match for the car.