1jz 1.5jz
#1
1jz 1.5jz
i read all i can about the 1jz and the 1.5jz, but i need to undestand something.
common sence will tell me that you need to do some changes to the engine management if you add an additional .5L to an engine (correct me if i'm wrong).
what do the guys running the 1.5 do, just add more fuel pressure or something.
and i heard that 7500rpm on a 1jz is actually 6500rpm or something on a 2jz, will the addition of 3L bottom end change the rpm cluster?
these are just some of the things that i'm curious of
common sence will tell me that you need to do some changes to the engine management if you add an additional .5L to an engine (correct me if i'm wrong).
what do the guys running the 1.5 do, just add more fuel pressure or something.
and i heard that 7500rpm on a 1jz is actually 6500rpm or something on a 2jz, will the addition of 3L bottom end change the rpm cluster?
these are just some of the things that i'm curious of
#2
I do not think you will find many people who have done the 1.5jz conversion in the States. Your best bet is to ask the questions over on the Australian Soarer forums as quite a few of them have actually done it over there.
http://www.lexus.australia.as/entry.htm
http://www.lexus.australia.as/entry.htm
#3
Originally Posted by sc3boost
i read all i can about the 1jz and the 1.5jz, but i need to undestand something.
common sence will tell me that you need to do some changes to the engine management if you add an additional .5L to an engine (correct me if i'm wrong).
what do the guys running the 1.5 do, just add more fuel pressure or something.
and i heard that 7500rpm on a 1jz is actually 6500rpm or something on a 2jz, will the addition of 3L bottom end change the rpm cluster?
these are just some of the things that i'm curious of
common sence will tell me that you need to do some changes to the engine management if you add an additional .5L to an engine (correct me if i'm wrong).
what do the guys running the 1.5 do, just add more fuel pressure or something.
and i heard that 7500rpm on a 1jz is actually 6500rpm or something on a 2jz, will the addition of 3L bottom end change the rpm cluster?
these are just some of the things that i'm curious of
#6
But, no.. you do not need to compensate for the extra .5 liters. The stock 1j computer will work fine. Are you aware of whats needed to do the conversion? It's not as much as people think
i'm in the process of finding a soarer clip to do the swap, and then i'll just take my time and build up my current 2jzge bottom end, i'm in no hurry.
and is the person with the 1.5 on this forum???
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#9
Originally Posted by sc3boost
i'm thinkig that you just need a new head gasket, once you know the proper squish of the new bottom end and the current 1j head.
No.
They run the same compression ratio.
They have the same pistons.
They have the same rods.
Find the logical conclusion
You'll need the 2jz timing belt (cam gears are interchangeable on both motors)
I think you don't understand what an ECU does.
It calculates how much fuel you need for a given amount of air. The air volume changes yes, but the ECU can still measure that volume of air and still inject enough fuel. You'd still be using whatever air-sensor that the car was already using (whether it being a stock 1jz map sensor, or something else like an aftermarket 3bar or a MAF sensor)... so the measurement SCALE will not change... it will be reading more air, but the ECU will already know what to do with it...
It also adjusts timing, which won't change.
Understand?
Things like displacement don't have to be custom tuned... things like cam changes, head ports, injector changes, etc DO
#11
Originally Posted by SinisterSC
Yeah who in MD? I'd like to meet em and see the car.
#13
Originally Posted by Bean
No.
They run the same compression ratio.
They have the same pistons.
They have the same rods.
Find the logical conclusion
You'll need the 2jz timing belt (cam gears are interchangeable on both motors)
I think you don't understand what an ECU does.
It calculates how much fuel you need for a given amount of air. The air volume changes yes, but the ECU can still measure that volume of air and still inject enough fuel. You'd still be using whatever air-sensor that the car was already using (whether it being a stock 1jz map sensor, or something else like an aftermarket 3bar or a MAF sensor)... so the measurement SCALE will not change... it will be reading more air, but the ECU will already know what to do with it...
It also adjusts timing, which won't change.
Understand?
Things like displacement don't have to be custom tuned... things like cam changes, head ports, injector changes, etc DO
They run the same compression ratio.
They have the same pistons.
They have the same rods.
Find the logical conclusion
You'll need the 2jz timing belt (cam gears are interchangeable on both motors)
I think you don't understand what an ECU does.
It calculates how much fuel you need for a given amount of air. The air volume changes yes, but the ECU can still measure that volume of air and still inject enough fuel. You'd still be using whatever air-sensor that the car was already using (whether it being a stock 1jz map sensor, or something else like an aftermarket 3bar or a MAF sensor)... so the measurement SCALE will not change... it will be reading more air, but the ECU will already know what to do with it...
It also adjusts timing, which won't change.
Understand?
Things like displacement don't have to be custom tuned... things like cam changes, head ports, injector changes, etc DO
The new engine will be a 3 litre rather than 2.5. I'll need to cut back the fuel to allow for the 800s. I'm currently thinking that an overall fuel reduction of 45% (as a starting point) will allow for the move from 440s to 800s.
However, I will be keeping the original ECU from the 1jz (which was set up for a 2.5 engine) and your post has made me wonder if my thoughts on fuelling are correct. Can you comment please?
#14
Originally Posted by SimonR
I'm in the process of converting to a 1.5jz and am installing 800cc injectors at the same time. The Emanage is currently set to cut back fuel by approx 16% after a previous upgrade from 380s to 440s on the 1jz engine.
The new engine will be a 3 litre rather than 2.5. I'll need to cut back the fuel to allow for the 800s. I'm currently thinking that an overall fuel reduction of 45% (as a starting point) will allow for the move from 440s to 800s.
However, I will be keeping the original ECU from the 1jz (which was set up for a 2.5 engine) and your post has made me wonder if my thoughts on fuelling are correct. Can you comment please?
The new engine will be a 3 litre rather than 2.5. I'll need to cut back the fuel to allow for the 800s. I'm currently thinking that an overall fuel reduction of 45% (as a starting point) will allow for the move from 440s to 800s.
However, I will be keeping the original ECU from the 1jz (which was set up for a 2.5 engine) and your post has made me wonder if my thoughts on fuelling are correct. Can you comment please?
As far as your setup, I don't know how well the stock ECU is going to be able to control such a LARGE jump in injector size (from 330 to 800). Your idle/startup is probably going to suck.
#15
Yes, that's the point. With a 3 litre engine and 800 injectors, will I be:
1/ Cutting back the fueling by 45% (approx) on the basis that I have 3 litres which would normally use 440 injectors (in the 2jz) or;
2/ Cutting back the fueling by 52.5% (approx) on the basis that I am still running the 1jz ECU and that it will automatically cater for the additional airflow (as I understand Bean to be suggesting).
The latter would be a problem as I believe that the Emanage can only cut fuel by a maximum of 50%.
1/ Cutting back the fueling by 45% (approx) on the basis that I have 3 litres which would normally use 440 injectors (in the 2jz) or;
2/ Cutting back the fueling by 52.5% (approx) on the basis that I am still running the 1jz ECU and that it will automatically cater for the additional airflow (as I understand Bean to be suggesting).
The latter would be a problem as I believe that the Emanage can only cut fuel by a maximum of 50%.