My turbo Yamaha jet ski... need help
08-20-2016, 09:06 PM
#1
My turbo Yamaha jet ski... need help Well l'm having a little problem here and I cannot figure it out. I've built several turbo setups and this one has me stumped, so I was hoping you guys could help!
The setup:
2013 Yamaha FZS
1.8L Four cyl, 4 stroke
8900 rev limit
Borg Warner EFR 6758 turbo
14"x12"x4" CXRacing A2W IC
570cc Injectors
So the hot side is completely water jacketed, minus the turbine housing itself. The turbo is internally gated, T25 flange. The whole setup is a bit hard to get to considering it's down in the hull, so this complicates things a touch. The engine cooling system is untouched and the turbo system and intercooler has its own water supply at about 80psi.
So the maiden voyage, one wastegate pressure (15lbs), was hugely successful. I had no leaks, nothing. The ski boosted instantly and pulled hard and ran about 84mph on GPS. I was very happy. AFRs were in the high 11s and it was running about 8500rpm. I'm also running water injection, 1GPH injected directly into the compressor inlet.
So over the next couple days, I played around with the hull setup to dial things in. Ski was running great. I put about 2-3 hours on it and all was perfect. Then I'm out tooling around and mid pull, I feel a loss of power. I let off and drive carefully back to shore. I check everything out and nothing looks out of place. I do a compression check and check the plugs, all is perfect. I put a new set of plugs in just for the hell of it and dropped it back in the water and it would only boost 11lbs. And the turbo was also getting MUCH hotter than it was previously. This lead me down the path of a boost leak. I didn't touch the ski for a couple weeks as I had to go out of town. Over the next few days after getting home, I've played with everything. I boost leak tested and cannot find any leaks. I've adjusted the wastegate and I can get the boost back up to 15lbs, but the boost comes in so lazy now and even though boost is back up to 15lbs, I'm down almost 10mph and 600rpm. The ski just isn't making power. I feel like it's heat related and the turbo is just pumping out massive amounts of heat. I cannot even touch the silicone outlet of the turbo, that's how hot shes getting. For the first 2-3 hours, it got hot but not like this.
So I'm stumped. It's acting like a boost leak, but I can't find anything. Does anyone have any ideas on what I could be missing?
Thanks!
Adam
The setup:
2013 Yamaha FZS
1.8L Four cyl, 4 stroke
8900 rev limit
Borg Warner EFR 6758 turbo
14"x12"x4" CXRacing A2W IC
570cc Injectors
So the hot side is completely water jacketed, minus the turbine housing itself. The turbo is internally gated, T25 flange. The whole setup is a bit hard to get to considering it's down in the hull, so this complicates things a touch. The engine cooling system is untouched and the turbo system and intercooler has its own water supply at about 80psi.
So the maiden voyage, one wastegate pressure (15lbs), was hugely successful. I had no leaks, nothing. The ski boosted instantly and pulled hard and ran about 84mph on GPS. I was very happy. AFRs were in the high 11s and it was running about 8500rpm. I'm also running water injection, 1GPH injected directly into the compressor inlet.
So over the next couple days, I played around with the hull setup to dial things in. Ski was running great. I put about 2-3 hours on it and all was perfect. Then I'm out tooling around and mid pull, I feel a loss of power. I let off and drive carefully back to shore. I check everything out and nothing looks out of place. I do a compression check and check the plugs, all is perfect. I put a new set of plugs in just for the hell of it and dropped it back in the water and it would only boost 11lbs. And the turbo was also getting MUCH hotter than it was previously. This lead me down the path of a boost leak. I didn't touch the ski for a couple weeks as I had to go out of town. Over the next few days after getting home, I've played with everything. I boost leak tested and cannot find any leaks. I've adjusted the wastegate and I can get the boost back up to 15lbs, but the boost comes in so lazy now and even though boost is back up to 15lbs, I'm down almost 10mph and 600rpm. The ski just isn't making power. I feel like it's heat related and the turbo is just pumping out massive amounts of heat. I cannot even touch the silicone outlet of the turbo, that's how hot shes getting. For the first 2-3 hours, it got hot but not like this.
So I'm stumped. It's acting like a boost leak, but I can't find anything. Does anyone have any ideas on what I could be missing?
Thanks!
Adam
08-20-2016, 10:37 PM
#3
I did have one thought that I will check tomorrow. There is a rubber damper that goes between the tb and the intake. Some people claim they can tear. If that were torn, I don't think it would show up as a boost leak because the tb would be closed. But it would show up when I'm actually riding. So I'll look into that tomorrow.
08-21-2016, 08:37 AM
#5
I boost leak checked to 20lbs, no leaks. I'm working on it right now. That damper looks OK but I'm going to replace it with an aluminum piece just to rule it out. I also yanked the ic and just pressure tested the water side to 100psi and it is good. I did find some water inside it, so it must be residual from the water injection. I wonder if it's just the water injection causing the problem. I'm spraying so little and spraying it pre compressor that I really didn't expect to find any in the pipes or ic.
08-21-2016, 08:57 AM
#6
Some pics of the damper. It's pretty flimsy, I can see how it breaks. But mine appears to be OK. I'm wondering if it's flexing under boost and leaking? I'll replace it while it's out.
Anyways, I'm still not convinced this is my leak. The water in the IC wouldn't explain the slow spool and the high heat coming from the compressor. I'm still stumped...
I could pull the turbo and check the exhaust side for anything obvious, but it's a ton of work and I can't see how anything would be going on there. The exhaust is 2.5" off the turbo then goes to 4" to the exhaust outlet. The turbo shaft assembly spins freely, no play, etc. Feels good. This is a weird one.
Anyways, I'm still not convinced this is my leak. The water in the IC wouldn't explain the slow spool and the high heat coming from the compressor. I'm still stumped...
I could pull the turbo and check the exhaust side for anything obvious, but it's a ton of work and I can't see how anything would be going on there. The exhaust is 2.5" off the turbo then goes to 4" to the exhaust outlet. The turbo shaft assembly spins freely, no play, etc. Feels good. This is a weird one.
08-21-2016, 09:00 AM
#7
Another thought... you can see water on the third pic on the aluminum. If that damper were sealing, there wouldn't be any water there. Hmm. That also means that water is making it all the way through the IC and piping to the Tb. Or it's at least condensing there. I guess I'll get the aluminum damper in and dry all the pipes and IC out, leave the water injection off, and go from there. I did run the water injection in the exact same fashion with my centrifugal blower before the turbo and never had an issue.
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08-22-2016, 07:25 AM
#11
I will check it out tonight. I'll have to think of a creative way to pressure check the hot side.
Just curious, wouldn't a hot side leak pre turbo just act like a cracked open wastegate? Once the drive pressure that's needed is reached, I don't see how it would effect the performance of the turbo. I can see how it would cause slow response, but not top end power loss. Not arguing here, just curious. Thanks for the help!
Just curious, wouldn't a hot side leak pre turbo just act like a cracked open wastegate? Once the drive pressure that's needed is reached, I don't see how it would effect the performance of the turbo. I can see how it would cause slow response, but not top end power loss. Not arguing here, just curious. Thanks for the help!
08-22-2016, 11:19 AM
#12
pressure and temp before and after IC?
08-27-2016, 05:50 PM
#14
08-27-2016, 08:32 PM
#15
Well, you nailed it. I finally pulled everything apart since you cannot see anything. The gasket between the turbine housing and the uppipe was blown out along one edge. I cleaned everything up really good and used no gasket and copper RTV and it's good as new! Ski is making more power than ever. Hopefully we will get some calm water and I can do some WOT tuning. I think she should do 87-88mph once dialed in.
08-27-2016, 11:07 PM
#16
Well, you nailed it. I finally pulled everything apart since you cannot see anything. The gasket between the turbine housing and the uppipe was blown out along one edge. I cleaned everything up really good and used no gasket and copper RTV and it's good as new! Ski is making more power than ever. Hopefully we will get some calm water and I can do some WOT tuning. I think she should do 87-88mph once dialed in.
08-30-2016, 10:32 AM
#17
Well, you nailed it. I finally pulled everything apart since you cannot see anything. The gasket between the turbine housing and the uppipe was blown out along one edge. I cleaned everything up really good and used no gasket and copper RTV and it's good as new! Ski is making more power than ever. Hopefully we will get some calm water and I can do some WOT tuning. I think she should do 87-88mph once dialed in.
08-30-2016, 11:06 AM
#19
+1. I've gone high 60's and at that speed you are straight buggying. High 80's is getting into the nah, no thanks territory. Thing is, these things feel so godam stable. Make you really want to push it. 15 years ago I was going 60 but it was a ******* work out. At least on the Hudson River. 60 on a modern ski is melow.
08-30-2016, 11:48 AM
#20
I will check it out tonight. I'll have to think of a creative way to pressure check the hot side.
Just curious, wouldn't a hot side leak pre turbo just act like a cracked open wastegate? Once the drive pressure that's needed is reached, I don't see how it would effect the performance of the turbo. I can see how it would cause slow response, but not top end power loss. Not arguing here, just curious. Thanks for the help!
Just curious, wouldn't a hot side leak pre turbo just act like a cracked open wastegate? Once the drive pressure that's needed is reached, I don't see how it would effect the performance of the turbo. I can see how it would cause slow response, but not top end power loss. Not arguing here, just curious. Thanks for the help!
