I'm new to Land Cruisers, and have a 1992 LJ77 with the 2L-T motor. I think the 2L is listed at 22:1 compression, and the 2L-T at 20:1. How is the difference produced? Different head? thicker gasket? different pistons? Steve, Curious in Paraguay
2L and 2L-T compression?
- Thread starter stevehaines
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Start at post number 54 on this link, Read Behmoth60's post on the diesel theory. Good read.
https://forum.ih8mud.com/showthread.php?t=54296&page=2&highlight=compression
https://forum.ih8mud.com/showthread.php?t=54296&page=2&highlight=compression
Unfortunately my 2L+T has not blown up yet, but when it does and I tear it apart I will sure look into the pistons and combustion chambers to see where the difference comes. I can already bet on pistons though, because AFAIK the head parts are interchangeable (same cc inserts), and the rods (thus different pistons as well) are about the only thing that was upgraded when they factory T'ed the 2L.
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I enjoyed the explanation of the reason for the change in C.R. What I would like to know is, "How (rather than Why) did Toyota lower the C.R. on the 2L-T?" Where the question is leading me is, "Can I use a 3L (stronger and safer) head on my 2L-T motor, and thus produce a " semi-3L-T" ?? Steve in Paraguay
I may have read somewhere that the turbo cams had a bit higher lift, maybe piston clearance is higher with the lower CR ?
I think the 2LT-II updated head and 3L head could be essentially the same, anyway I wouldn't touch it before it blows
I think the 2LT-II updated head and 3L head could be essentially the same, anyway I wouldn't touch it before it blows
The reason for lower compression ratio in all engines (not just diesels) is to keep cylinder pressures lower.
for example,
2L 22 to 1 compression ratio (cr)
22 to 1 cr w/7 psi of boost 24.25 to 1 cr
w/9 psi of boost 26.39 to 1 cr
2L-T 20 to 1 w/7psi of boost = 22.04 to 1 cr
w/9psi of boost = 24 to 1
these are figures using a turbo compresion calcutaltor using 75% VE
Toyota like all manufactuers lowers the compression on turbo engines to keep the cylinder pressures at a safer level. Turbo boost increases the compression ratio when it forces more air in the cylinders. Diesels are more forgiving than gassers when it comes to turbo pressures due to the wider fuel/air ratio that they will run at. If you take a high compression gasser, add a turbo to it and run high boost (over 9 psi) it will most likely detonate due to the higher compression ratio. You would have to run racing gas just to drive it. With diesels you can add more fuel when running higher boost pressures and it will make more power w/no detonation.
In theory a non turbo diesel with make more power by adding a turbo due to the increased compression over a turbo engine. The advantage of a turbo engine is that it should be able to handle a higher boost than the non turbo before it grenades parts.
With camshafts; a non turbo engine needs a higher lift, duration,and valve overlap cam to make more power. A turbo engine needs a milder cam (with a shorter duration and less overlap) to maintain boost pressure. With a high duration and valve overlap you would loose most of the boost when both intake and exhaust valves are open at the same time. Pressure goes right out the exhaust. There are a lot of factors that effect engine performance but these are some of the basic items.
for example,
2L 22 to 1 compression ratio (cr)
22 to 1 cr w/7 psi of boost 24.25 to 1 cr
w/9 psi of boost 26.39 to 1 cr
2L-T 20 to 1 w/7psi of boost = 22.04 to 1 cr
w/9psi of boost = 24 to 1
these are figures using a turbo compresion calcutaltor using 75% VE
Toyota like all manufactuers lowers the compression on turbo engines to keep the cylinder pressures at a safer level. Turbo boost increases the compression ratio when it forces more air in the cylinders. Diesels are more forgiving than gassers when it comes to turbo pressures due to the wider fuel/air ratio that they will run at. If you take a high compression gasser, add a turbo to it and run high boost (over 9 psi) it will most likely detonate due to the higher compression ratio. You would have to run racing gas just to drive it. With diesels you can add more fuel when running higher boost pressures and it will make more power w/no detonation.
In theory a non turbo diesel with make more power by adding a turbo due to the increased compression over a turbo engine. The advantage of a turbo engine is that it should be able to handle a higher boost than the non turbo before it grenades parts.
With camshafts; a non turbo engine needs a higher lift, duration,and valve overlap cam to make more power. A turbo engine needs a milder cam (with a shorter duration and less overlap) to maintain boost pressure. With a high duration and valve overlap you would loose most of the boost when both intake and exhaust valves are open at the same time. Pressure goes right out the exhaust. There are a lot of factors that effect engine performance but these are some of the basic items.
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brownbear said:
That's the direction I'm interested in. But of course, not as long as the motor is running fine. Just a thought for the future, if mine does crack the head. I usually run about 85 kph on the paved road, up to 100 kph occasionally to pass. I'd love the details of what 2rivers did on the swap. Steve in Paraguay
This thread was just below your thread.... read 2rivers post.
https://forum.ih8mud.com/showthread.php?t=100284
https://forum.ih8mud.com/showthread.php?t=100284
I really wish I had the 3L head and the "upgraded" - post 93 2LT (no rockers) head side by side at the time to take some measurements. 
Would have been good to note for the archives since Toyota is silent on this. If anyone is in similar situtaion PLEASE???
As for details of the swap, its pretty straightforward, just a lot teardown and patience setting up the cam with the appropriate shims (and waiting for said shims on backorder). Robin on this board also has first hand wrenching experience. I have a sheet from Allhead which has all the specs/torques etc needed for the 3L swap. I want to post it up here, but I will ask them first to get permission.
JOhnny
PS BRownbear - we did the Telkwa Pass run on Sunday.. good times! I understand you might be busy these days though. Congrats! There will be a next time for sure, we figure annual run.
Would have been good to note for the archives since Toyota is silent on this. If anyone is in similar situtaion PLEASE???As for details of the swap, its pretty straightforward, just a lot teardown and patience setting up the cam with the appropriate shims (and waiting for said shims on backorder). Robin on this board also has first hand wrenching experience. I have a sheet from Allhead which has all the specs/torques etc needed for the 3L swap. I want to post it up here, but I will ask them first to get permission.
JOhnny
PS BRownbear - we did the Telkwa Pass run on Sunday.. good times! I understand you might be busy these days though. Congrats!
There will be a next time for sure, we figure annual run.
2rivers said:PS BRownbear - we did the Telkwa Pass run on Sunday.. good times! I understand you might be busy these days though. Congrats!
Thanks!
Yah I would liked to do that run. We will for sure soon. I got a good month to go on getting my truck fixed up. I don't want to miss another summer of wheeling...