Project Thread Supercharged 1UZ Bangkok Drag Truck

[XR8tt]

The only failures I have ever seen on these (std) engines are rods and sleeves everything else seems to hold out.

I hope your right.. A big S400 turbo is about to test strength...

 

[JBrady]

Yes, yes, and yes. I have talked to the dyno operator and he says this is "delivered torque" . . . . without corrections. I do not know why he used this particular method. I sent him an e-mail for more info. There is NO WAY this motor made 955 ft. lbs. of torque w/o NOS. There is a computation for converting this number to more familiar torque figures. I am waiting for my friend to send them to me. The HP figure from the run seems low! The dyno showed 280hp (at 5.5 psi) . . . running 72% duty on 565 injectors at a perfect AFR. Hell . . . the standard motor makes nearly that!

I have seen this before. What MOST do not think about is that rear wheel torque (as delivered) INCLUDES the gearing multiplication. So a 3-1 final drive would triple the DELIVERED torque. Most dynos correct the reading back to engine RPM to get a CALCULATED engine torque less drivetrain losses. Some dynos do not make this calculation and simply read out the ACTUAL or "delivered" torque.

If your engine made 280rwhp at 5500rpm that = 267tq (calculated)
Your actual 955rwtq / 267tq calculated should equal your dyno test total gear multiplication which calculates to 3.57 to 1.

Sorry to hear about the breakage. Probably a rod bolt.

 

[HarperRacingBangkok]

The broken rod.

The broken rod here;
http://drjeffbangkok.squarespace.com/journal/2010/10/26/oops.html

 

[M3TURBO]

broken rod/piston

Looks like the piston overheated at the top, expanded, tried to sieze and was then pulled apart, the rod broke as a result.

 

[JustenGT8]

Pop the wrist pin out.....good money you'll find the bearing has spun and closed off the oil feed

 

[XR8tt]

Need to see more.. The crank could have done alot of damage "after" the piston / crank separated...It's been hanging in there for a little going by inlet valve marks on piston... Was there any ignition retard when N20 was applied ???

 

[HarperRacingBangkok]

Yes, -5 at the NOS hit (40hp). The rod hit the block and cracked it through to the water passage. One valve bent. The head "looks" good, but will be examined more closely. The list of who or what caused the broken rod is getting longer, but keep them coming. I am already negotiating on a 2UZ and 1UZ. Does Lextreme have the steel rods and forged pistons in stock for immediate shipping?

 

[HarperRacingBangkok]

This is what the broken rod looks like:
The bottom of the piston is also broken. Hmmmmm . . . what happened?

 

[cribbj]

Justen makes a very good point. If you spun the bush in the top end of the rod, and blocked the oil hole, the rod would have been toast shortly after. And if it wasn't able to rock back & forth with the crank rotation, the bottom of the piston would have broken soon after, much as your photo shows.

Another good reason, IMO, to have piston squirters. I know your drag racing brethren think squirters are for sissies and are a waste of good oil pressure, but when you have things like this happen, you have to wonder if a bit more oil up there wouldn't have been a good thing, especially since squirters are cheap and pretty easy to install if you're already in the bottom end doing other things.

 

[XR8tt]

The pin doesn't have any bearing to spin..
The crank side is an area to look at..
I would say the crank has done this damage after the rod let go..
There is some skirt missing from piston and around under gudgeon pin..
If pin area seized ?? It doesn't show any signs of heat on piston or rod / pin area..
The pic shows one part where rod has broken.. It has snapped closer to big end as well..
What I have seen on some std rods on similar engines the rod bends with power / detonation [maybe] and the next rotation take the piston / rod out about this area as a bent rod is shorter pulling the piston down into crank counterweights..
If you look the piston has been shattered just under pin..
Naturally the piston is going to come down under combustion stroke till the spark plug is damaged.. Need more pics of crank, journal, other side of rod...
Something was wrong as power wasn't increasing ??
Either tune was wrong or there was a miss with engine ?? "Before" rod broke..
Was there any fuel enrichment when N20 was activated ???
Any timing retard ?? On forced induction engines N20 power levels are rated about double when it comes to tune compared to N/A...
Have the plugs been read and any logging to check on ECU ??

 

[cribbj]

Sorry Graeme, definitely looks bushed to me

 

[XR8tt]

Yes full floating pin.. But I doubt it would lock up being a FULL floating pin as they move in the pistons as well..
A spun bearing usually relates to big end issues..

 

[HarperRacingBangkok]

Thanks for all the thoughtful replies. I appreciate everyone's time and interest. We made one good pull with the NOS to 6500rpm without mishap and got data. It broke on the second pull at around 4500rpm. Well, I hate to say it, but we were taking the O2 readings off the other bank at the time of the mishap, of course. But that bank was good: excellent AFR with the small (we saw 40hp on the dyno first pull - after the purge) NOS dosage. It is a dry system, so, yes, fuel was added (on the AEM there is an independent NOS map) and, yes, timing was taken out. That data is no help because the action took place on the other bank. We were going to have checked the other bank next but . . . . Yes, of course, one can use two O2 probes, but . . . . . who does (there is a lesson to Lextreme readers here)? All the spark plugs looked great on both banks, including the hole with the broken rod. Hung/clogged injector comes to mind - sudden clog, then clearing of gunk causing a sudden imbalance, perhaps - I will have them flowed now (after the horse got out!). There is no sign of overheating on the piston, wall, or rings. I haven't taken the pin out yet to inspect. The bottom end was not touched/taken apart - it is all standard. Something may well have been different enough on that one cylinder to cause that rod to break . . . or, it was a bad rod . Remember, only 280hp. I agree, the piston broke up when it contacted the flailing rod and/or the crankshaft counterweights The rod break looks like a stress fracture letting go . . . . It is hard to know what happened with a high degree of certainty without an actual scientific investigation. But, I will check out all of the possibilities offered by contributors to this forum before I start it again - just in case. I guess I will x-ray all of my parts from now on. I am negotiating for a 2UZ bottom end and another 1UZ right now. If it is the 2UZ I will go '30 over with steel rods and forged pistons. Oh well. More to come. So, does Lextreme have 2UZ rods and pistons ready to ship? I want to go racing!

 

[JustenGT8]

Yes full floating pin.. But I doubt it would lock up being a FULL floating pin as they move in the pistons as well..
A spun bearing usually relates to big end issues..

2 others who broke rods found this to be the cause....good enough reason to check for mine?

 

[XR8tt]

2 others who broke rods found this to be the cause....good enough reason to check for mine?

Who diagnosed this to be the problem ??
You're saying power has nothing to do with it ???
An engine has countless miles on it and has no issues with pin ..
Years latter..
Double the power and it has nothing to do with power or tune ???

 

[JustenGT8]

One was on here so search for the post. Mild det was the likely cause...increased cyl pressure and the wrist pin grabs and spins the bush....only a matter of time after that?

Sounds plausible to me so just throwing it out there.

 

[XR8tt]

Yep detonation will kill these rods easy..
These pins float in both rod and piston...
With circlips on the side of each pin holding them in place..

 

[JustenGT8]

Full floating doesn't matter...oil film fails, wrist pin spins bush bearing?....the spun bush bearing has happened, they were thorough enough to post photos.

One who had this happen was an aussie guy with the engine in a Commodore and the other was in Europe from memory?

 

[HarperRacingBangkok]

Believe it or not, I found a set of new Lextreme forged steel rods here in Bangkok . . . and bought them. I also procured a nice 1UZ short block. The question is: Do I order forged pistons or not, at this stage? Standard pistons OK to 400hp? With 50hp shot of NOS, only 5-7 pounds of boost, and race gas? My heads are still good, but I have to replace the two bent valves.

 

[XR8tt]

I would definitely get some forged pistons..
I have http://www.cp-carrillo.com/ in my performance engines..
They can take the abuse of forced induction engines, have a GOOD ring package also..
I have some spare valves if you want ??? I take it they are inlet ???