3uzfe Pistons failure

[Lextreme II]

Believe it or not for the past two weeks there were two 3UZFE with supercharger blew the motor. They both were running Procharger C2 and ran about 6 psi. I am not sure if these two owners got the SC system from the same company, they both blew their motors.

From my personal experience the 3uzfe rods are weaker then 1uzfe and Lexus are known to have weak ring lands. I just couldnt believe it with only 6 psi it can do so much damage. Both systems were factory tunned before shipping.

Why did those pistons failed? Very interesting question nevertheless. I would expect at least 11 psi or so that 3uzfe can handle.

 

[Zuffen]

Any photos and we may be able to suggest a cause.

 

[jibby]

You maybe right and guess who told me those exact same words your pal Todd at Tm. He had told me the pistons and rods are weak on both those engines. Also said it is not wise to push them over 450hp with those pistons and rods because that is about all they can take. Does the Procharger C2 generate 450+ hp at 6 psi? Also, could fouled timing and improper fuel mixture have played a part in the engines blowing in combination with the C2 chargers? This is what I know, which probably isn't very much, but I am learning quickly with the help of this forum.

 

[Lextreme II]

No he was making 350 rwhp at 6 psi. I would discourage any 4.3 Liter owner from forced inductions unless pistons and rods are upgraded.

 

[Matt Skinner]

I'd guess it was running too lean. I dont know whether the standard ECU can cope with having all that extra air crammed into the engine, but even if it can I doubt the standard injectors can supply enough fuel...

 

[JBrady]

Personally I do not believe these engine failed from normal combustion at 6psi. I believe they either detonated or suffered pre-ignition. Cracked ring lands are typically detonation. I do not know what fuel system is being used but I caution anyone from using single point fuel enrichment on EFI manifolds. By this I mean using one or two auxillary injectors at the throttle body. The only correct way is to add the fuel at each port. This can be done with larger injectors/retune, 8 secondary injectors mounted at the ports or even increasing fuel pressure with boost to cause the stock injectors to flow more. Ignition timing is also suspect.

 

[Lextreme II]

John,

Where have you been? We miss you here. You are right on the nail. I just cant believe a company making these kits would have tuning problems...

 

[sc430blue]

Were these luxury motorworks kits? What happened, hole in piston, broken landing?

 

[rytherwr]

3uzfe/2uzfe rods/pistons are definitely shaky

Knowing what I now know from my experiences with TRD supercharger and nitrous on a 2uzfe, I can tell you the pistons and rods in either one of them are not up to the task of coping with very much cylinder pressure for a prolonged period and that is independent of wrong tuning, detonation etc. You can see what happens in the pics of my 03 2uzfe the Lex has on the FI registry. Trust me when I say be careful with hotrodding those two particular motors with stock pistons and rods.

Wayne

 

[stevechumo]

Due to the fact that the ring land is damaged, I believe it's because of detonation. It happened to me once and that made me dig deep into this problem. Lack of fuel and too much timing are mostly the cause for this. With 6 psi, I think it's ok for most stock pistons & rings, not to say they're Toyota stuffs. With proper tuning of fuel & timing, they can also handle up to 9 psi safely. I also heard that centrifugal superchargers can be over-revved and the boost can go past the desired psi from the pulley. The pulley is not like the wastegate (external wastegate preferrably) in a turbo system that can control the boost precisely.

 

[Lextreme II]

Wayne can tell you first hand. For some unknown reasons, Lexus pistons tend to crack the ring lands. My suggestion the very least get some 1uzfe rods or get H Beams with special pistons and boost all you want.

 

[Lextreme II]

Ok,

Here are the pictures.... 4 pistons cracked in multiple locations.....

 

[Toysrme]

Ugh oh, looks like the curse of the aluminum v6's (MZ's). I've seen that a dozen times atleast.
Good stock pistons, nice high temp coating on the face... But they crack the ring lands (or just blow a hole through the piston face) anytime they get remotely lean. With, or without pre-ignition.



I would say, barring this is some random thing - everybody with a boosted 3uz-fe, take one step towards running richer & make sur eyou have cool plugs installed!

 

[jgscott]

Seems like it was Detonation all the way to me. Had to be 1 of two things or both. FI can show good A/F at one RPM then go lean at a diffrent RPM band.

1. To lean on A/F.
2. Too much Timming for the stock ECU to deal with.

 

[stevechumo]

I believe that it was pre-ignition at a point where there's more pressure than the other areas. The pistons were pushing up while the detonation occured before Top Dead Center. :angryfire I don't know what fuel system was used in this setup but it's very unlikely that 6 psi can cause this much damage, unless some fuel components got malfunctioned and too much timing. Or it could be just from the hot sparkplugs. Even some early model Honda Civics can withstand 6 psi for years.

 

[Toysrme]

The TRD supercharger on the 1mz-fe v6's blow ringlands at the stock 4psi over time. You just need to be running a little lean & hot in the chambers IMO.

I'm not trying to say anything there but... Just food for thought.

 

[Lextreme II]

Speaking off lean... When I changed my radiator couple of days ago. I accidentally pulled the vacuum line out of the wastgate. I drive like 50 lbs right foot and hear pinging for couple seconds or so. The car boosted up and over 20 psi. (autometer gauge only show 20, but i think it when like 25-30 psi). I let the gas off very quick. However, the engine health seem to be fine. No change in anything at all. I quickly plug in the vac line.

 

[Toysrme]

The good thing about the copper plugs you put in there - they melt easily. if there were a big problem brewing, you'd be running with weak spark & minus a few cylinders already.


If it runs smoothe, you're fine. :smileysex

 

[stevechumo]

Speaking off lean... When I changed my radiator couple of days ago. I accidentally pulled the vacuum line out of the wastgate. I drive like 50 lbs right foot and hear pinging for couple seconds or so. The car boosted up and over 20 psi. (autometer gauge only show 20, but i think it when like 25-30 psi). I let the gas off very quick. However, the engine health seem to be fine. No change in anything at all. I quickly plug in the vac line.

Oopp! You felt good with the power, didn't you? :veryhappy Normally in that case for a few seconds when your engine was already prepared, it wouldn't damage. The worst is only some very minor dents on top of the pistons. I would check the compression to make sure of its condition because very minor damages will not give you any different feeling at all, but they could be there.

 

[Nick M]

Personally I do not believe these engine failed from normal combustion at 6psi. I believe they either detonated or suffered pre-ignition. Cracked ring lands are typically detonation. I do not know what fuel system is being used but I caution anyone from using single point fuel enrichment on EFI manifolds. By this I mean using one or two auxillary injectors at the throttle body. The only correct way is to add the fuel at each port. This can be done with larger injectors/retune, 8 secondary injectors mounted at the ports or even increasing fuel pressure with boost to cause the stock injectors to flow more. Ignition timing is also suspect.

Sounds correct to me.

Assuming a cast piston, with detonation, the engine will grenade.