High RPM??

[local 11 spark]

Had my new boat out yesterday, for one short run I gassed it to top end speed, and the tach was reading 4500 rpm. Is it safe for the engine to go that hard or harder?? I've got 11 hours on it...

[zegm]

With 11 hours on it I don't think you hurt it but I wouldn't keep the RPM's up there long.

[local 11 spark]

But, as I get more hours on the engine, is that high of RPM's normal??

[Buttafewcoe]

WOT (wide open throttle) should have revs in the 4800 range.
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Short answer.....yeah, you're good.
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B

[zegm]

For the old Chevy 350 (5.7L) block yeah that is approaching the upper limit.

[MasterMind3002]

Butta's right..............4800 is normal for WOT.

These engines are extremely tough, but its not recommended to run them WOT for any extended period of time.

If your under a load, footing for instance, I never worry about it cause the rpms never reach the max due to the ski load.

[zegm]

I have to laugh a little bit here for the old 350 chevy block that can be called "high" rpms, for a BMW 4.4 Liter V-8 block she is just starting to get exciting at this rpm!

[MasterMind3002]

Actually zeg, I've been told that the Indmar engine is built from the Corvette platform and is actually a high rpm block. Indmar beefs the engine up, lowers the compression and programs the computer for lower rpms to increase durability.

While you won't find it in the manual, I have some friends in the know that claim that the 325 Indmar can run all day at max rpm.

Although, I don't recommend trying it........

[zegm]

Actually it is the old small block Chevy engine. The 6.0 Liter is the new Chevy block with the Aluminum heads and the roller lifters which is the same block that is used in the Vette (1996ish) and all SUV's and trucks since 1999 at which time the old 350 was killed off production GM vehicles! This block is 4.8L, 5.3L and 6.0L versions based on bore and stroke.
It is a new design but still old technology. It does not have overhead cams or 4 valve cylinder heads. As a boat engine it is perfect because it makes great low end torque, as a high performance high tech engine it ranks low on the scale. Even the new Ford V-8 which has been out close to 20 years has overhead cams and if you get the cobra you get twin cams and 4 valve cylinder heads. It boils down to cost and it is cheap to make an engine with pushrods (100 year old technology) than it is to make one with overhead cams and especially twin cams and 4 valve heads. You could get a Vette in the late 80's and early 90's with this feature (the engine was made by Mercury for GM) but no one bought it and it was discountinued. My 1997 BMW 4.4 Liter V-8 (268cubic in) makes 292Hp (rear wheel which is another issue add about another 15 to 20% for at least 335hp at the crank) and 325ftlbs of torque (variable twin cam 4 valve heads) while the small block 5.7 Liter which we all know as the small block chevy 350 makes 325hp. Anytime you make more than 1 hp per cubic inch you are doing very good! Don't get me wrong I have owned and own several Chevy trucks and I love them, but I also own a 100% aluminum BMW engine in my 540i 6 speed and I really love this one! But we don't need that in a boat and I don't want to pay for it either!

[bobwells]

Small block chevy's are famous for turning some high rpm's , Factory motors probally still put red-line at 55-5800. They arent designed to stay at that range long without some serious engine building, how those nascar motors stay together at constant 85-9000 blows my mind, boy would I love to of gotten hold of one of those babies in my early days! I have been known to "pump" one up to about 7500 and side step the clutch wow what a rush ! I loved it. For our boating purposes lets stick with the reccomended 4800 WOT for short burst, I baby the heck outa mine, I very seldom run it over 3 grand.