aluminum prop comparison

[Scott06]

The Spitfire is Mercury's attempt at building a Rev 4 out of aluminum. So it doesn't surprise me the thicker aluminum 23 matches the 21 steel.

The blade shape , size , and rake are very different from a Revolution 4 so doubt it’s an attempt to copy. It just didn’t perform any different than a michigan vortex, which makes the published info on it look like BS

 

[cyclops222]

Price first. Quality last. New wave logic.

 

[MBAKER]

All this talk got me to thinking and I made a few runs the other day in current setup. Seems pretty typical to what I remember except top end speed is down and slip is up accordingly. Boat will stay on plane right at 2500 and between there and 4000 slip numbers seem ok above or below that and it goes up pretty fast. When the prop was new I feel like the speed was better at 4500 up something like 48 wide open but I don’t have any of that written down. Between about 2700 and 4000 it feels pretty good which is the lowest slip numbers right now.

22 2500
29 3000
33 3500
38 4000
40 4500
43 4800 (still has throttle left)

Overall still under propped which I already knew and I assume numbers would all improve going up slightly in pitch. Also wondering if this prop has changed over the past 6 year's and doesn’t hold water as well as I remember

 

[Stinnett21]

As previously said you need to go WOT to get an accurate baseline. Just do it momentarily enough to get a reading and back down. You won't blow your motor up if it's just for a moment.

 

[MBAKER]

As previously said you need to go WOT to get an accurate baseline. Just do it momentarily enough to get a reading and back down. You won't blow your motor up if it's just for a moment.

Not worried about it blowing up but it runs into the rev limiter. Can't get a true WOT read.

 

[Scott06]

Not worried about it blowing up but it runs into the rev limiter. Can't get a true WOT read.

if you have more slip quite possible you have some wear on the prop maybe some burn marks on it doesnt cost much to run a AL prop through a rebuilder. if one is not local try Prop MD in minnesota, I have done mine via mail order. Send it in after end of season

 

[jlh3rd]

Responding to your original post. You could get the same blade/diameter/pitch prop from different manufacturers and get different results. The reverse is true also. I have 3 different props from 2 manufacturers that all gave the same #'s.
propping can get expensive.
From all you've said, increase the pitch by 1" and keep everything else the same, including the manufacturer.

 

[Stinnett21]

Not worried about it blowing up but it runs into the rev limiter. Can't get a true WOT read.

The rev limiter is your WOT. Report your readings at the rev limiter.

 

[Scott06]

The rev limiter is your WOT. Report your readings at the rev limiter.

I think he still has throttle to go when he hits the limiter

limiter is normally 5100 or so maybe a touch higher for MPI

 

[MBAKER]

Correct I still have throttle left, at 48-4900, that’s just below where rev limiter kicks in. By feel and how much throttle is left it ‘feels’ like it might run 52-5300.. It’s not MPI, it’s a 5.7 carbureted.

I’m planning on trying a couple different props next chance I get. After talking with a couple others I’m Now just wondering if the prop could have fatigued and changed shape a little bit to where I’m not getting same top end and/or it’s slipping more on top than it used to. Not super worried since it still works well below 3500, just wasn’t expecting to over rev that much compared to what I remember. One of those props is the old 3 blade 19pitch that I have recorded numbers for so it should be a better comparison.

 

[Scott06]

Correct I still have throttle left, at 48-4900, that’s just below where rev limiter kicks in. By feel and how much throttle is left it ‘feels’ like it might run 52-5300.. It’s not MPI, it’s a 5.7 carbureted.

I’m planning on trying a couple different props next chance I get. After talking with a couple others I’m Now just wondering if the prop could have fatigued and changed shape a little bit to where I’m not getting same top end and/or it’s slipping more on top than it used to. Not super worried since it still works well below 3500, just wasn’t expecting to over rev that much compared to what I remember. One of those props is the old 3 blade 19pitch that I have recorded numbers for so it should be a better comparison.

Based on that feel I would go up 2" in pitch would probably get you there but you might loose holeshot and pulling ability some.

you could also have cup added to your current prop