Dumb question, Aluminum vs Stainless

[TPD211]

Question,<br /><br />Aluminum and a Stainless prop, both same diameter and pitch, which will turn the higher rpm's?<br /><br />I have a stainless 14 X 13 on my 88 Spl. It turns 5000 at wot. Will a aluminum 14 X 13 turn higher rpm's since it weighs less than the stainless?

 

[wvit100]

Re: Dumb question, Aluminum vs Stainless

I don't know what a Spl. is but 5000 rpm seems kind of high. What kind of motor is it?

 

[DJ]

Re: Dumb question, Aluminum vs Stainless

You might see a slight difference. The blade "flex" difference of the two is what will make for some variance.<br /><br />I would put an 11" on that '88'. Get the WOT rpm's up to around 5500. My family had an '88' on a 22' pontoon. The 11" was the right choice for that rig.<br /><br />That deckboat is a big load for an '88'.

 

[TPD211]

Re: Dumb question, Aluminum vs Stainless

Thanks DJ,<br /><br />I'm leaning towards the 11' pitch.<br />The boat only weighs 1800 lbs, this is a lot less than a comparable length fiberglass boat.<br />The 88 SPL runs great, top end is 28 mph at 5000 rpm's.<br />I agree, I do need to get it to 5500 rpm's.

 

[DJ]

Re: Dumb question, Aluminum vs Stainless

Triggerr,<br /><br />1800 pounds is no lightweight for an engine that size. The other thing is that boats like that tend to gather big loads-people/gear.<br /><br />I think the 11' will give you great performance. You may not lose any speed and your planing time will be much better.<br /><br />Good luck, let us know!

 

[Lark40]

Re: Dumb question, Aluminum vs Stainless

How can you expect correct answers when you do not indentify what type of engine you have?<br /><br />I have no idea what you are talking about (Spl.???) - an inboard, an i/o, or an outboard. 5500 rpm would blow anything but certain outboards. Now, what do you have?

 

[TPD211]

Re: Dumb question, Aluminum vs Stainless

The motor is a 1993 Evinrude 88 Special, as in 88 hp.<br />It is a crossflow model, optimum (sp?) rpm's are 5500 for this model. I thought most people knew what a SPL was......<br />

 

[Lark40]

Re: Dumb question, Aluminum vs Stainless

Thanks for the info. I was an Evinrude dealer, but that was long before 1993.<br /><br />My understanding is that stainless props rev higher at the same pitch. For example, 21" SS will rev close to 23" AL.<br /><br />Of course, if you have a 13" SS, you can try it, but I would guess that you may need an 11 or 12".

 

[DJ]

Re: Dumb question, Aluminum vs Stainless

Triggerr,<br /><br />I know exactly what an 88 SPL is. It is the economy version of the crossflow models. Most were sold wiithout oil injection and some without power tilt and trim. Both those items were frequently dealer ad ons. Many of these engines were packaged with boats, such as yours. Lowe was owned by OMC. I used to own a Lowe.<br /><br />The SPL's also were available in: 28, 48, 88, 112, 115.<br /><br />My point was is that a wide open throttle of 5000 is too slow for that engine and you are lugging it with that heavy load. Prop it down so it can breathe a little easier.<br /><br />BTW, stainless props typically rev SLOWER than aluminum. They (SS) hold their bite better because of less blade flex.

 

[TPD211]

Re: Dumb question, Aluminum vs Stainless

Thanks for the responses guys. I am looking to get a 14 X 11 aluminum pitch prop as soon as I can. I'm also considering real hard in having the current stainless prop repitched. Cost is about 50 bucks or so.<br />I was at Boat World in Orlando today and was going to get a Hustler prop, 13 1/4 X 15. The salesman talked me out of it, citing the poor quality of the castings of the props. He said alot of these props spin the hubs and the blades tend to shear off for no apparent reason.<br />Aluminum was 50 bucks and the hub system was 40 bucks. Almost worth the price to try it but after talking to the salesman, I decided to pass on it.

 

[phatmanmike]

Re: Dumb question, Aluminum vs Stainless

The SPL's also were available in: 28, 48, 88, 112, 115

and also 14hp, i have one, 1988