VIP Vixen 5.7 Prop?

[tompi69]

Hello there,

I'm new to this forum and want o ask some questions to the helpfull ones who want to give me some advice. Boating is relatively new but engines and tuning has been my activity for years in car racing. I just bought a 98 vip vixen with a 5.7 liter mercruiser and alpha one sterndrive with solar 14.5 19 pitch aluminum prop. As I always want to maximalise my stuff I began searching for the technique behind my and boats in general. Everybody always talks about WOT rpm's and how to calculate your prop. My vip does almost 5000rpm's but the last 500 he does also really fast as a car who is in first gear and has almost no resistance. What I want to know is if a mercury 5.7 goes to he maximum rpm without letting him work how much does he achieve. I got the feeling that he stops at approximate 5000 rpm because the engine is mechaniccally just not able to go higher. If this is the case The 5000 is not a good reference to choose my new prop on.
On the alpha One sterndrive is also marked 1.52R (is this a possible gearing).
I only find 1.47 or 1.62 as normal gearing not 1.52. Is this also possible?

thanks already

Little belgian

 

[steelespike]

Re: VIP Vixen 5.7 Prop?

Can't help you much with details but your motors max rpm range should be on a label on the motor.I'm guessing the max rated rpm is about 4,600.Usually there is no need to get too complicated when figuring performance and prop selection.Usually if you have the present prop size,maximum rpm and speed
you should have a good idea if it is performing as expected.If the performance is not up to par then further investigation is in order.

 

[Bondo]

Re: VIP Vixen 5.7 Prop?

Ayuh,...

I'd try a 21" prop to see if you can get the WOT rpms down to 4800 or so...

If you have the T-Bolt V igntion,.. Yes, it has a rev limiter...

 

[tompi69]

Re: VIP Vixen 5.7 Prop?

Thanks guys,

I didn't look very well and the 5 was a 6 so I have a 1.62 alpha one sterndrive. This explaines the wrong mounted prop. The previous owner did't use the new prop and surely asked the standard one for a normal 5.7 mercruiser with alpha one sterndrive (not knowing than he had other gearing).
My biggest problem is that I live in such a small stupid country that I don't have the oportunity to try some props out and the prices are so rediculicely high that I'm not planning to buy 2 just to have one who's perfect.
I was thinking about a michigan wheel REVOLUTION 4 but don't know if I should take a 19" or 21". Whatever if I buy the two in the states it's still 25% cheaper than one of those overhere.
Does anyone have some experience with this prop? or other suggestions?

 

[steelespike]

Re: VIP Vixen 5.7 Prop?

If I was stuck and had to go with one prop not likely to be able to replace
I would go with the 19.If you end up under propped you can still use it just stay within rpm range.If you do the 21 and end up over propped you really shouldn't use it.You might have the tach checked to be sure it is accurate.
It should no doubt improve overall perfromance just by going to stainless.
Generally a 4 blade prop is selected to improve low end performance.It is usually considered the 4 blade will reduce max rpm and speed though the change to stainless my temper that.
Usually you wouldn't change both the material and blade number.In my mind its better to try a 3 blade stainless and then determine if a 4 blade is required.

 

[tompi69]

Re: VIP Vixen 5.7 Prop?

Yeah I agree that I want to change too much parametres at the same time.... I should know better!!!
I will buy a stainless 3 blade prop with 21 pitch and see what I have. Anyone a suggestion which brand and type of 3 blade prop? Ballistic, stiletto, laserII??? It's such a difficult matter and mathematical almost impossible to calculate, Just too many parameters! There are far more components on racing cars and still it's easier to predict that boats and their props.


BUT........ IN MECHANICS :FOR EVERY PROBLEM THERE IS A SOLUTION ..........as long as we are healthy!!!

 

[steelespike]

Re: VIP Vixen 5.7 Prop?

You might consider something like the Hustler props.Aluminum that deliver close to stainless performance for the aluminum price.
You might be able to buy 2 for the same investment as one stainless.