Glad the pistons made the short list! Now clean out that intake before you screw up the tops of those pistons with shrapnel!!
Twins with Twins, Anyone?
- Thread starter kidturbo
- Start date
Well now I'm back to chicken or egg questions.
Seems shaft is bent, not broken. Velocity stack is tweaked pretty good, and I couldn't budge it with a strap wrench couple months back.
Maybe she touched the wheel first, then things went south.. either way, they are both off and headed in fir a post mortem inspection. Cause one thing I've learned on this project, if one fails, the other is guaranteed to soon follow..
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Seems shaft is bent, not broken. Velocity stack is tweaked pretty good, and I couldn't budge it with a strap wrench couple months back.
Maybe she touched the wheel first, then things went south.. either way, they are both off and headed in fir a post mortem inspection. Cause one thing I've learned on this project, if one fails, the other is guaranteed to soon follow..
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Not to worry, charge cooler core took the bullets for ya.. I just honned the block with all the fine shavings for an hour to help seat the rings..
Gonna make ya up a logo that says;
!! VooDoo Tested And Approved !!
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Well I'm losing faith in Bullseye Power pretty quickly. Received the inspection report from one of their techs today which stated that the turbo ingested something, and that's what caused the compressor wheel to explode. Also stated that the bell / map ring was misaligned, and that was causing the wheel to touch the housing.. To which I replied with pictures of the inside of turbos taken a couple weeks back showing nothing touching, along with pics of the air filters. Which I'm guessing that nobody who runs that turbo uses one??
So Monday I am going to overnight that shrapnel filled air filter with a "Dunce Cap" sticker and chin strap on it for that tech to wear around, until someone escorts his unqualified body out the back door. I've heard some cop out statements over the years, but this one takes the cake. And last time I sent those in to be inspected, was because a map ring was touching on the other turbo. Since then, neither map rings has been moved, because I tried to adjust them last year, and both were seized at current setting. And when that other one was touching, you could hear it. Am sure I posted a pic of that issue somewhere on here a dozen pages back or so..
Owner is gonna call me Monday to re-evaluate the situation. But with less than 100hrs on these units, I just don't feel warm and fuzzy on reliability at lasting 1000hrs or more. Nor do I like relying on companies that won't own their failures. However the options for replacements are pretty slim. Open to suggestions.
So Monday I am going to overnight that shrapnel filled air filter with a "Dunce Cap" sticker and chin strap on it for that tech to wear around, until someone escorts his unqualified body out the back door. I've heard some cop out statements over the years, but this one takes the cake. And last time I sent those in to be inspected, was because a map ring was touching on the other turbo. Since then, neither map rings has been moved, because I tried to adjust them last year, and both were seized at current setting. And when that other one was touching, you could hear it. Am sure I posted a pic of that issue somewhere on here a dozen pages back or so..
Owner is gonna call me Monday to re-evaluate the situation. But with less than 100hrs on these units, I just don't feel warm and fuzzy on reliability at lasting 1000hrs or more. Nor do I like relying on companies that won't own their failures. However the options for replacements are pretty slim. Open to suggestions.
How about a Garrett unit? Like a G45-1500 (76x109 comp and a 89x82 turbine) and they’re water cooled.
That's certainly a good starting point size wise. The original Dmax boat sported a water cooled GT4094R, which while is known to be slightly over rated on it's power potential, suffered zero issues over the 300hrs I beat on it. The 550hp jet boat engine also sports that same Garrett unit today.
I do see the G45-1500 uses same ceramic roller bearing technology as the Bullseye units now. Which I think is plus in the reliability design. My only concern with the 4094 was shaft end play movement after couple hundred hours. Which I know they make a shim kit to correct, but it never touched the wheels. And since Bullseye didn't say a bearing failure was at fault, then our only other possible point of failure really just comes down to the compressor wheel letting go. The more I examine the carnage pics, the more that stands out to me.
There is no sign of impact to any fins at center, and it made no strange "contact" screams prior to the pop. That's easy to isolate because that engine was in free rev, while the other engine was lugging just seconds before it let go. About the only time you can hear each turbo clearly, is when getting up on plane. Low speed 15mph, no air noise rushing past your ears to muffle the engines. And I've heard some pissed off turbo compressors before.
The wife's MB once sucked a piece of rubber gasket into the compressor and sounded like a cat caught in the belt. Bent two blades backwards, lost 2-3lbs of of boost on the big end, but I never replaced it. That was over 6yrs ago, and car probably still running to day with that tweaked compressor wheel on it.. Not a CNC billet wheel, which won't bend before breaks. So while I see where the tech was going, he should be searching for signs of the crack that formed right prior to a blade exiting. Which I'll bet is on that one BIG piece that I haven't found in the bilge yet...
I feel like it would be pretty tough to even set up a shaft speed limiter in a case like yours where the props break free so quickly. Maybe I'm wrong. It would be great if you could! Good question for the Motec gurus
I wonder if one could machine pockets or recesses in the housing behind the compressor wheel to hold magnets to induce eddie currents in the compressor and slow it down. kind of self limiting. spinning slow would have little drag but the faster it spins the more the magnets and eddie currents would fight rotation. finding the right balance or magnetic strength so it would be negligible during normal use but provide enough braking force on over speed would be a pain though. something you'd likely have to test in a shop on a dyno where you could quickly swap out parts would probably be the only way to do it. but it would be maintenance free and nearly fail safe if done right
Heck, I haven't even set rev limiters on fueling yet. If I set that around 4800, might help keep the wheel speed down. But at this point we don't have a clue where it's spinning.
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I'm pretty sure he's using truck ECMs and not a Motec/Bosch type unit. On the aftermarket ECU's you can very very easily set shaft speed limiters and have them pull fuel to try and keep them below the allowable setpoint.
I know what he's using. But whether the Motec or Bosch MS can control shaft speed with fuel fast enough in these cases, I am not sure of.
Maybe an electronic gate, properly sized, would be fast enough?
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After a nice follow up call with the Bullseye, overspeed likely wasn't an issue. Nothing conclusive yet, but they feel it wasn't spinning more than 80k rpm or so under the part throttle free rev conditions. Also the wheel likely didn't let go because of the noted surge related stress. That will typically break a shaft, which didn't happen. Nor did the wheel crack where they would expected to see it let go, like when it ejects one out the inlet in couple chunks under fully loaded. Which leaves that threaded bell as our remaining suspect.
Turbos I would really love to try is a pair of these.. Regin feature would do great at limiting overspeed, while also recharging the batteries. Keep watching this technology, F1 been using it for years now.
Award-Winning E-Turbo Technology
The growing trends toward hybridization opens up possibilities to transfer electric boosting technology from racetrack to road. Garrett is pioneering
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Some updates on the turbos. Nothing conclusive for a cause of failure besides it went out of balance, and then ingested itself. After I brought it up, surge became the most likely cause. But no evidence presented to say one way or another.
Options / suggestions were upsize the turbine wheels to drive the compressor harder at lower RPM/Load. However that presents more unknowns on spooling, which with a few people onboard, and 1/4 tank of fuel, it could use a shot of spool juice just to get lit as things set. And we haven't even started big prop testing yet with full tank of fuel.
Changing the turbine wheels also meant changing the housings. Basically 2 new turbos again. And another shot in the dark at where it will be happy cruising during low speed and low loads. The current turbos perform great above 3200r and 30psi. However that also cruising at 70mph. Which until I get the windshield modified, is exact speed where the air starts flapping your eyelids like your running 120...
So plan for today is full rebuild of one turbo, then replace the [$900] ceramic bearing set in the second one. Open up the map grove to where she was running two years ago. Then put some gauges on intake and exhaust to go record some map data. If surge is the issue, we'll surly find it. If not, then Bullesye can go back to the compressor drawing board, and I'll swap to GTx units for the long haul. Figure these units lasted two years, bet they will last another month of prop testing. If surge is the issue down low, then be a good deal 2 fresh bad ass 476's come next month.
Options / suggestions were upsize the turbine wheels to drive the compressor harder at lower RPM/Load. However that presents more unknowns on spooling, which with a few people onboard, and 1/4 tank of fuel, it could use a shot of spool juice just to get lit as things set. And we haven't even started big prop testing yet with full tank of fuel.
Changing the turbine wheels also meant changing the housings. Basically 2 new turbos again. And another shot in the dark at where it will be happy cruising during low speed and low loads. The current turbos perform great above 3200r and 30psi. However that also cruising at 70mph. Which until I get the windshield modified, is exact speed where the air starts flapping your eyelids like your running 120...
So plan for today is full rebuild of one turbo, then replace the [$900] ceramic bearing set in the second one. Open up the map grove to where she was running two years ago. Then put some gauges on intake and exhaust to go record some map data. If surge is the issue, we'll surly find it. If not, then Bullesye can go back to the compressor drawing board, and I'll swap to GTx units for the long haul. Figure these units lasted two years, bet they will last another month of prop testing. If surge is the issue down low, then be a good deal 2 fresh bad ass 476's come next month.
I'm hoping you're able to get this licked! If GTX units are the savior that wouldn't be the worst thing.
At current $$$ per hours run time, those NLX units be approaching a cost of operation threshold which lead to changing out that last set of surface drives. Figured it up, counting the original NRE's, we are currently at 19k into turbos, with about 60hrs on each engines. That's $158.00 per hour of run time on the boat for the turbos. Don't think I can burn that in fuel, even at today's prices.. 30gallons per day is best I've managed to date.
What's actually kinda funny, Bullseye wasn't able to free up the threaded bell / map ring on the good turbo. Same one I had fixed last time cause it came loose and touched the wheel. So they knocked off a few dollars on a new replacement race cover. Even after I endeavored to explain to the owners, it's your flawed design not mine, so you really need to own it.. Now I get to hire a mobile welder to come remake two intake tubes.
However look for a video next week from me demonstrating how to free up seized 6" aluminum threaded parts with a gas oven and a little bottle of N2O.. Nos, it's just not for internal use anymore... If I can get that bell free, or at least out of there to replace with the new one, that would save rebuilding one intake at least.
Time to go out and bust A on things again. Have two weeks to get out on the water and test to make the 4th of July boat racing scene here. Skeeters are an issue in the evenings now..
Have 2 turbo back, along with the old compressor housings. Seems they only polish the pieces under the air filters now. But not the side you can actually see under a glass hatch.
No biggie, I have a guy locally who's good. Once done testing I'll pop the covers off, weld the bells in place, and then hit the big buffing wheels. If we keep em..
When I said the map ring was closed on both turbos, I wasn't kidding.
Compare the old cover map gap to the way I requested they set these to max opening.. 1/2 difference should shift those pressure curve a bit.. Hopefully back where things are happy again..
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No biggie, I have a guy locally who's good. Once done testing I'll pop the covers off, weld the bells in place, and then hit the big buffing wheels. If we keep em..
When I said the map ring was closed on both turbos, I wasn't kidding.
Compare the old cover map gap to the way I requested they set these to max opening.. 1/2 difference should shift those pressure curve a bit.. Hopefully back where things are happy again..
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Here ya go kids. More educational video, as promised.
Sorry, all the handy shop Nitrous bottles were empty.
Source: https://youtu.be/RWHkAJ-U9vc
Now, anyone wanta put wagers which came first, the chick or the egg?
I now know 100% certain how and why the other turbo to explode? Zero to do with surge..
Before I post the picture by picture breakdown, let just say issue we had over year ago with same turbo pictured above, might ring a BELL..
Sorry, all the handy shop Nitrous bottles were empty.
Now, anyone wanta put wagers which came first, the chick or the egg?
I now know 100% certain how and why the other turbo to explode? Zero to do with surge..
Before I post the picture by picture breakdown, let just say issue we had over year ago with same turbo pictured above, might ring a BELL..