prop question, do rpm matter?

[gofastsandman]

Ok I need to come on in to the confessional. I am now running an SST I 15x16. `96 rude 150 compression 87-92 cold. Butterflies were closed. Yeah, I now know better. Engine runs nicely. Normal load and bimini up I only turn 5000-5100.

AV plate is @ 1 1/2 " above hull.

BRP tech support says my motor makes full power @ 5000 and that you are only putting more stress on the motor spinning it higher for no gain. They said it`s not a merc or a yami and was not meant to rev that high. This goes against everything I have learned and been taught. I have not timed the motor nor have I ever done a link n sync.

BRP said when they train their factory techs they tell them to prop motors at the mid point of the range. For me that is 5000.

I can hold plane @ 11 now , down from 17 mph so that is nice. I premix and run rec 90.

Confused,
GFS

[eggsuckindog]

Sandy as I said that is fine on a Rude, Mercs need 5400 minimum which is about all I can get now with that Stiletto I have, I wish I could swap it for a 17 because I like the prop alot. Correction, Rude Loopers need more RPM than the 90'V motors.

I was at the shop today picking mine up and they had a 17 Mirage and a 17 PowerTech, then the son pops up and said he had tried both of them and niether would trim his boat nearly as well as his - Stiletto - dad turns to me and says " maybe you need to stick with what you got"

If bumping around for props, this thing made a world of difference on mine, keep in mind they are aggressive and you will lose RPM against most other props, almost 300 for me but they work damn good on SeaCrafts. I got mine used for 150 so they are out there

[eggsuckindog]

Confused here when you say "smaller prop" the smaller prop should give less cruise speed and more RPM at WOT and should plane quicker???

[pelican]

running the correct pitch prop will allow your boat to plane quicker - think of it like this: you're driving a stick shift vehicle - you attempt to start off in 3rd gear - what happens ? same thing occurs with a boat engine,with way too much prop pitch.too much pitch,the boat's a dog outta the hole - no lift

as far as rpm is concerned:
think of it like this,you're running the engine on the hose - you "rev" it - the rpm climbs quickly -right ? runs and screams on the hose - right ? no load on the engine.for max engine durability,you want that engine to hit it's max rpm,with the boat loaded,as it's noramlly ran...there's a reason an engine mfg puts this reccomended range on an engine - that's where they want it to run.

it's all about "load" ...