1986 Scarab III, 550hp 502's, TRS Drives

Question 1 is prop related. I had labbed 23p mirage plus' and ran 62 on gps at 5000 rpm. I knew I had a lot of throttle left, ended up finding a local guy to borrow a set of labbed 26p bravo 1's. 5000rpm ran 58 mph. Similar water/fuel level conditions. This just doesn't seem right.

Question 2 is tranny related I think. I keep overrevving the port motor when approaching full speed. As I'm climbing up around 4500 rpm it will over rev. Originally when I was running the 23's I thought I was just blowing out the prop or something but it did it with the 26's too. Could the clutch be slipping or something?

Any insight is appreciated.
Kris

My Black Thunder will run about 72 at 5000 with stock 26 Bravo 1's. Maybe try a set of stock ones. If he had the cup removed, that would mean a lot more slip on a heavy boat. As far as the trans, what does the trans fluid look and smell like? It should be clean and not smell burnt.

Yeah thats a thought. All he said is when he had them labbed he said he wanted to pick up 400 rpm, so I'm not sure what they did.

Nothing fishy with the tranny fluid. Did a full flush and refill at the beginning of the year when the motors were out.

Are you sure the engine is revving up and it's not just the tach. I had an issue like that before. At 4500-5000 one tach would suddenly swing up to like 6000. At that speed the engine and wind noise made it impossible to tell if it was actually overrevving. It turned out to be a loose ground wire on the engine. It seems that if the trans is slipping that bad, it would burn up the fluid.

Yeah thats one thing I'm sure of. I'm not running any kind of mufflers on my exhaust and you can definitly hear it and feel it. We are going to run it again tonight, I'll do a double check on the tranny fluid but everything seemed ok last night. I think it is burning some though because I had to top them off recently but I figured that was pretty normal. But like I said there was no odor and it wasn't noticably murky or anything.

It's not normal for the trans fluid level to drop. They should always stay at the same level. It is possible the clutchs are slipping in the one.

there is one thing you can try, may finish it off though, try to put it on plane easy on just the one engine with the ?? trans, the extra load will tell you pretty quick if the clutches are giving up..Rob

maybe I'll wait till the end of the year to try that one...