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Built motors and detonation

Old 12-15-2009, 05:07 PM
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Lev,
I thought you were running the Chinese 2871 and not the Garrett.
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Old 12-15-2009, 05:23 PM
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I blew mine a year ago with Wiesco Pistons...I don't have pictures but all 4 pistons where messed up pretty bad.
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Old 12-15-2009, 05:25 PM
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Originally Posted by sixshooter View Post
Lev,
I thought you were running the Chinese 2871 and not the Garrett.
true
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Old 12-15-2009, 06:07 PM
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Originally Posted by levnubhin View Post
All good info guys, keep it going. I think this is an important thread so that people with less knowledge don't think built motors a bullet proof. I'm running 22 psi right now (want to run 25) with a devils own WI kit. I'm using the #7 nozzle set to come on at 10 psi. I've been using Heat which is like 97% meth. I'm going to run an led to the pump so that I know it turns on when I hit 10 psi, other than that what other fail safe could I put in?
+1 on the important thread! can a mod please save it?

you could do the whole per cylinder EGT thing.............

to the guys that have had failures in their built motors, what cylinder did it take place in?
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Old 12-15-2009, 06:55 PM
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Originally Posted by Savington View Post
Has anyone ever measured line pressure? Is the spike when a nozzle clogs big enough to trigger a failsafe?
I think you are on to something. What about using a low fuel preasure gauge to monitor the WI. I would have to think that the pump that supplies the water would be adequete enough to maintain preasure, whether a nozzle is clogged or not, but maybe not.

It would be a simple profect. I could see how you could purposely clog an injector and see what, if any, preasure spike you have. If it does not monitor spikes very well, at the very least, you know if the system is preasurized.

That leads to another interesting question, perhaps for another thread, but what keeps the WI injecting the right amount of water from short boost durations to long boost durations? Do the systems have a regulator that keeps the preasure from spiking to high, and maintains adequete preasure during long periods at WOT?
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Old 12-15-2009, 07:04 PM
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Originally Posted by Ben View Post
This.

You're not running a little turbo that hard, are you?

Do you have easy access to E85?
nope, 11.5psi. No desire to run E85. I run 5* back from MBT on the track.
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Old 12-15-2009, 07:05 PM
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I
Originally Posted by JasonC SBB View Post
According to Rebello, the way to avoid that is to do 3 quick dyno pulls 3x in a row. That will get the internals good and hot, simulating a long WOT run. Ideally the 2nd pull is a bit stronger than the first, and the 3rd is no weaker than the 2nd, or something like that. I don't know how to keep the intercooler exit temps the same though...
I loaded up the motor on steady state at 4k rpm for 20seconds, then ran up to redline to listen for det.
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Old 12-15-2009, 07:08 PM
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Originally Posted by hustler View Post
nope, 11.5psi. No desire to run E85. I run 5* back from MBT on the track.
That was for Phil-atio, not you.

I have no desire to run E85 either (for political reasons), but its benefits in FI engines is undeniable.
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Old 12-15-2009, 07:21 PM
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I'm interested to see more photos of forged failures and possible reasoning behind those failures.
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Originally Posted by codrus View Post
Basically I've come over to the camp of "If something is a reliability problem on the track, just ask Andrew and do what he says".
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Old 12-15-2009, 11:15 PM
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Originally Posted by hustler View Post
I loaded up the motor on steady state at 4k rpm for 20seconds, then ran up to redline to listen for det.
Is this the best strategy for simulating a track run in the dyno room? If not, let's talk about what is.

Like Sav, I can't justify running E85 on the track, but for competitive reasons I WILL be running it for autocross, and I intend to tune to mbt everywhere, especially in the boost building cells while running E85, and I will run my 2560R at as high a boost level as I can get without it breathing fire.

I can run E85 on the street, as it's accessible. For the track, though, I will be stuck with gas, and probably should build a tune like hustlefucker did, 5* retarded from mbt, slightly rich ve, abuse it in the dyno room listening for det on street gas, then just fill up with 100 octane at the track. Safe strategy?
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Old 12-16-2009, 12:08 AM
  #51  
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Originally Posted by Savington View Post
Has anyone ever measured line pressure? Is the spike when a nozzle clogs big enough to trigger a failsafe?
I have. With a 5 GPH nozzle, my pump produces the same pressure (about 140 PSI at its current setpoint) regardless of whether the nozzle is flowing or not.

The pumps we're using (Shurflo and similar) were originally designed for agricultural and industrial use, operating at several gallons per minute. Put a nozzle rated at a couple of gallons per hour on one, and they can't even tell its there.
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Old 12-16-2009, 02:13 AM
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Originally Posted by JasonC SBB View Post
Was the piston eaten on the exhaust side?
HOw did the exhaust valve corresponding to that point in the piston look?

What happened there is that detonation eroded/melted the piston top, like it ate it. Too much advance can cause that type of detonation. Some motors that detonate slightly will do that, though usually they'll eat the head gasket first, like BMW motors.
Sav?
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Old 12-16-2009, 02:24 AM
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19 degrees advance at 21psi. Not all that outrageous IMO for an 8.7:1 compression motor using 100 octane fuel and water injection. Like I said, nobody heard any detonation.

Valves aren't great, but nowhere near what the piston looks like:
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Originally Posted by codrus View Post
Basically I've come over to the camp of "If something is a reliability problem on the track, just ask Andrew and do what he says".
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Old 12-18-2009, 02:49 AM
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Detonated low comp supertechs. Melted pistons were likely caused by bandaid engine management and lack of tuning.
Attached Thumbnails Built motors and detonation-piston-5-.jpg   Built motors and detonation-piston-1-.jpg  
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Old 12-18-2009, 02:58 AM
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I don't have track plans but this thread makes me want to stay far away from MBT, use WI only as a det preventer, buy an AIT sensor for my PLX system, flowtest my injectors etc etc...


Thank you thread for taking 40+ whp of fun out of my life.

Last edited by Faeflora; 12-18-2009 at 01:13 PM.
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Old 12-18-2009, 12:26 PM
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Sav, the melted hole in your piston is near the INTAKE valves? Does the head near the hole have some sharp edge or pointy bit that may be a hotspot that starts detonation? Did all your cylinders show some detonation or was it only in the one cylinder with the low flowing injector?

Can you inspect the head gasket metal material near the melted hole? Look for melty metal.

Oftentimes the detonation happens near the exhaust valves because that is hottest spot in the head.

According to Rebello, there is a type of detonation that is not loud, but progressively eats the head gasket and/or the pistons. Common in BMW's.

Or it ping'd only on the track and not on the dyno.

It seems to me that at your power levels, for the track, one would need to pay attention to per-cylinder AFRs and timing. If the airflow distribution to the cylinders is uneven, one cylinder would go lean. Which cylinder holed its piston again?
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Old 12-18-2009, 12:52 PM
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Originally Posted by faeflora View Post
Detonated low comp supertechs. Melted pistons were likely caused by bandaid engine management and lack of tuning.
That scares the **** out of me. How much spark advance at max torque? How long and how much detonation did that take? After 8-hours of track time, detonation would have killed this motor if any detonation were occurring, right?
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Old 12-18-2009, 01:05 PM
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Can you see really light detonation like that on the turbine?
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Old 12-18-2009, 01:26 PM
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Originally Posted by hustler View Post
That scares the **** out of me. How much spark advance at max torque? How long and how much detonation did that take? After 8-hours of track time, detonation would have killed this motor if any detonation were occurring, right?
The motor these pistons were in was built, operated, and tuned by a moron. I don't think you can get useful data out of that other than "don't waste money on a built motor if you're a moron".

That's why I didn't build my own motor and will have someone else doing the tuning- failsafe just in case I'm a moron and I don't know it.

You know, I wonder how OEMs go about tuning for high boost. If I look at high performance factory turbo motors, OEMs seem to tune wayyyyy away from the bleeding edge of performance. They don't run as much boost, don't use WI as a power adder with meth or timing etc. That's why the turbo performance aftermarket exists- since OEMs leave a lot on the table. I assume that OEMs do not want their customers busting rods and shattering pistons and that's why they play it safe. My guess is that OEMs run pretty far away from MBT and have extremely conservative closed loop trim maps. Do we honestly expect that our built motors will last 100K+ miles with so much more incurred risk? If we **** up and put 87 octane into our motors, probably half the built motors here will sustain significant damage. If I put 87 octane into a factory turbo engine it would probably run like **** but I'm guessing it wouldn't detonate and break. I used to think hustler was a ***** for tuning on 91, running minimal boost (for his motor), and backing off timing but when you look at the thousands of $ of outlay for that built engine, those decisions seem very sensible.
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Old 12-18-2009, 01:42 PM
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That piston pic i think it was savs piston wasnt destroyed by detonation im 90+% sure that was caused by either an extreme lean condition or an extended lean condition, Possibly doing a long pull at a slightly lean state. do you have a wb? what were your air fuels? i would be surprised if you were seeing below 12.5. You should give your injector o-rings and fuel filter a look. if you dont come up with anything from there what did that to the wiesco pistons in my dsm was the o-ring thing that goes from the pump to the line in the tank cracked and it was bypassing fuel back into the tank.
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