Compression ratio of hybrid JZ engines.

[Enchanter]

Using the info above and assuming all the heads have the same combustion chamber size,(which looks very likely) I have calculated that using pistons from a 1jzge in my 2jzge I should come out with a CR of 11.8:1.
Ive also found that 2jzge and 1jzgte pistons are very close if not identical, anyone have a pic of a 1jzgte piston ?
+rep to anyone that can double check those calculations for me, Im not 100% sure on them.

If Iam right I need to find a 1jzge

[gianttomato]

Two 1JZGEs on ebay right now.
http://cgi.ebay.com.au/TOYOTA-1JZ-NO...QQcmdZViewItem
http://cgi.ebay.com.au/TOYOTA-1JZ-NO...QQcmdZViewItem

The one with the silver rocker cover might have a mid sump. I'll happily do a swap for a rear sump with cash incentive if it does.

[Enchanter]

Nice find gianttomato, i emailed him to see if he would part one out but he said no. Funds dont allow $1100 (incl freight) for a full engine atm.

For anyone interested I have found a far better way of calculating chamber volumes. Use modeling clay instead of kero, (not paydoh, its too elastic), no leaking past valves etc. Then simply measure the volume of the clay by immersing it in an accurate measuring jug/beaker with water up to say 80mls and measure the difference.

A 2jzge piston is 7.5cc using this method, I dont have a big enough (accurate enough in one go) beaker for the head yet but Im confident it will be spot on once I get something decent.

The standard 2jzge HG is measured to be 0.3mm in thickness so I have calculated it to be 1.8cc

Thanks 1jracing for the 1jzgte piston pic, it looks pretty much identical to the 2jzge piston, but I can't tell if there is a slight depression in the center like the 2jzge one or not. If there isnt a depression that would equal a slight CR increase for a 2jzge, which would make me happy, but Im itching to find out more on a 1jzge piston

[1jzracing]

the 1jzgte pistons are dead flat .... no dish at all only the valve cutouts

they are forged and will drop straight into a 2jzge from my measurments/ calculations as long as the gudgeon is the same size (most likely)

well done!

[JustCallMeOrlando]

they are forged

Since when are 1JZGTE pistons forged? Not even 2JZGTE pistons are forged. I'm confused

[Enchanter]

...this still gives the 1j CR of more like 8.7:1 ..... its getting closer if i kjeep it up ill get it down it to 8.5:1 yet ...

Have you had anymore luck with the CR ?
Its only about 2cc away from 8.5:1, whats everyones oppinions on heat expansion, would it be enough to cover the 2cc discrepancy ?

Im having trouble getting the 2jzge to add up as well.

It may be possible that the factory may have rounded the CR figure down to the nearest .5

[1jzracing]

Since when are 1JZGTE pistons forged? Not even 2JZGTE pistons are forged. I'm confused

well thats what ive been told and it seems to be the general consensis that 1j, 2j and 1g turbo engines all use forged pistons.... i may well be mistaken

anyone have any further info on this ????

ps if theyr not forged they are BL**DY strong!!!

[JustCallMeOrlando]

1G is definetly not forged. Methinks your info was mistaken, all things i've read/seen point to the 3 engines not having forged pistons, just a decent, fairly rugged design.

[ed]

i concur 321

[1JZ.747]

i concur also, not forged

[onboost]

A bit off topic....

2JZGE engine has 10 : 1 comp right .....

2JZGE engine uses a .3 mm gasket comparing to 1.0mm 2JZGTE right ....

now using a standard 1mm gasket and either of the 2jzgte or 1jzgte heads or even a 2jzge head you should end up with around 9:1 comp which to me is quite turbo friendly. This is something i ll be looking into as a back up motor..

[Nat]

I have a standard 2JZ-GTE head gasket here it is 1.3mm not 1mm. I ended up using a 1.8mm gasket on my 2JZ-GE build up.

The 2JZ-GTE uses different pistons as well which results in a lower CR compared to the -GE even if the same HG is used.

A bit off topic....

2JZGE engine has 10 : 1 comp right .....

2JZGE engine uses a .3 mm gasket comparing to 1.0mm 2JZGTE right ....

now using a standard 1mm gasket and either of the 2jzgte or 1jzgte heads or even a 2jzge head you should end up with around 9:1 comp which to me is quite turbo friendly. This is something i ll be looking into as a back up motor..

[Enchanter]

..The 2JZ-GTE uses different pistons as well which results in a lower CR compared to the -GE even if the same HG is used.

Agreed.
The head, pistons and gasket all have different cc's between the various engines. Plenty of people have successfully turboed standard 2jzge engines though, so putting a 1mm (or 1.3mm) on the 2jzge would probably be very safe.

[Talasas]

Just for my own sense of curiosity, what are the differences in crank, rod and piston between the GE and GTE engines?

[Norbie]

Crank and rods are the same, pistons are same construction but crown is different to acheive compression ratio differences.