kidturbo

That recall was after shaft broke. ECM stops firing injectors at 5800rpm on the bench. I've yet to find a way around that hard limit. I built these to spin 6000R, and they've been to the limit couple times before. On the dyno the torque curve falls off around 4200R.

kidturbo

Ok surface drive guru's, need some input on drive height based off the video I've been able to gather. Tomorrow they both come off, and thinking we moved them down another hole, 3/4".. My best data is comparing the 17"x34P 4 blades to the 18"x34P 4 blades. The 17's I can easily shift at 20mph and then need to back off throttle just to get hooked. Both the 18x32 and 18x34 require reaching 40mph before shifting because they are hooked up much better.. Dropping them one more hole would likely allow us to run the more common 17" props. As where the only other big pitch used 18's I've found avaialbe, are the 40 pitch 6-blades Tyson was running on the Skater..

Red line in video is the relative prop-shaft position at full down trim. I left the sound on to help identify transmission gear and boat speed. Max of 60mph. First half is video from last Friday with camera directly in front of Port drive. Second half is from the camera mounted on water pickups, in fresh water.

Please let me know what ya think..

payuppsucker

It looks like that driveshaft has been partially cracked prior to this failure or maybe it’s just the lighting in the pic.

kidturbo

I would certainly agree with that statement.. By amount of rust, likely cracked on Tuesday in the choppy waters video above. We sprayed down bilge after that run...

Keith Atlanta

Payupsucker: It looks like that driveshaft has been partially cracked prior to this failure
Dr Kid Turbo: Do you concur
Payupsucker: Yes, I concur
Dr Kid Turbo: Yes, I concur

kidturbo

LOL...
I'm bringing in two specialist tomorrow, just to be certain it was there. That is if they also concur..

My money is on it was likely a defective piece to begin with. With only 20hrs on the meter, I'd hate to think those two little 6L diesels could ravage the best everyone else in this industry has came up with, so easily quickly.. We haven't even pegged the throttles yet...

payuppsucker

I wasn't talking about the rust but rather the appearance or the fracture. In my experience when a moving part partially cracks but doesn't fail completely there will be some hammering adjacent to the crack. The shiny area on the outer edge would be consistent with hammering (if I'm seeing what I think I see).
The grain also appears to be two different shades which you usually see when the failures occurs separate from each other.

payuppsucker

I have three different opinions on this...........

My selfish side: leave the drives where they are because I'd be really interested in the 17 inch props if you end up not using them.

My unselfish side: Since you have three sets of props there's no way I wouldn't try dropping the drives one hole and trying the 17s down there.

My unbiased side: I think you're going to end up running 18s regardless due to weight and hull design. Heavy straight bottoms like big diameter

kidturbo

Well being we currently own "zero" sets of props tested, I'm kinda leaning towards the size easiest to find..
The 18's do certainly hook up better, but are harder to spool up without air tubes. The 17's are certainly easier on the engines at current height, but just feel like bald tires on ice...

suncoastexotics

that was funny....didnt expect to hear someone in the middle of Sarasota bay come up to us and say "Hey, is that the Duramax boat"? LOL