weights of drive oil vs speed of boat

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10-05-2006, 06:06 AM

#21

cobra marty

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Re: weights of drive oil vs speed of boat

Leave the box on and run my dyno and see.

10-05-2006, 07:39 AM

#22

KAAMA

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Re: weights of drive oil vs speed of boat

I did some changes this summer...-2" IMCO shorties, 5-bladed XP5 and switched drive lubes this year from the Redline Shockproof Heavy to the 75/90 Amsoil gear lube. Just thought I'd give the lighter gear lube a try and wanted to use Amsoil.

With all the changes this year the gear lube and the 5-blade 30" props were the last things I changed. When switching from some 5-bladed 28" props to some 5-bladed 30" props I expected to lose at least 200rpm---and was told that I could even lose up to 400rpm, but the engines stayed right at 5600rpm---so, I gained some speed as well. Slightly cooler temps may have contributed to it as well, but I think the lighter weight 75/90 drive lube had something to do with it. That Redline Shockproof Heavy is some really sticky stuff. Some guys I know jokingly refer to it as "grease".

Last edited by KAAMA; 10-05-2006 at 07:41 AM.

10-05-2006, 08:49 AM

#23

Wobble

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Re: weights of drive oil vs speed of boat

Quote:

Originally Posted by articfriends

Scott,how much did the climbing gear lube slow you dow? I ran the 69 gto I work on and race for a friend of mine last weekend and picked up a solid tenth over previous runs from lightening the rear brakes 25 lbs (he had humungous truck drum and backing plates on it). We run 75/140 in it and I want to try 75/90 this weekend if it doesn't rain but the owner is worried it will tear up the ring gear. If there is another tenth to be had then I'm going to do it. You know,I should just do it and not tell him

,if it beats the gears up after a few trips to the strip I'll just buy him some new gears,Smitty

We run M-1 75-90 in our dirt track UMP modifieds, putting around 750hp through 9" ford rear ends for up to 40 laps at a time. No gear or bearing failures yet.

10-05-2006, 09:42 AM

#24

articfriends

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Re: weights of drive oil vs speed of boat

Quote:

Originally Posted by cobra marty

A noise in your engine? Maybe that is where the speed went when you tried the ext. box. Great info. Good luck.

The ticking/clattering just started the other day a hour AFTER making the high speed runs as I was running the gas out of the motor going up and down the river so it wasn't slowing me down this season. It is something in the valve train,the motor has a tiny bit over 100 hours on it,50 of them this season,I'm just not going to try to fix it in the boat since I am freshening the motor this winter anyways and our season is over. With the 1 inch spacer out with the box on the boat still exhibited the the terrible handling effects the box created,I just drove thru them to make these high speed passes. The boat still only drove as fast or slightly slower than it did before the box so it didn't give me any speed. Boxes don't work on every v-hull and I have found out thru alot of testing and work my boat is one of them,Smitty