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rbarna
06-09-2009, 01:36 PM
Ok, so here's what I know:

Quicksilver 48 19P
350 SB possibly not stock cam
4300rpm
trim medium
53mph

Where should I go from here on props?

I think I could have trimmed up a bit more but it felt like it was loosing grip.

Thanks!

-Ross

rbarna
06-09-2009, 01:47 PM
It's a 1.47 drive ratio
I think my RPM gauge is wrong.

BUIZILLA
06-09-2009, 02:08 PM
4300 rpm on mine was with a 25" prop

best was a 22 turbo at 4700

rbarna
06-09-2009, 02:13 PM
So I'm either:

1) Not producing enough power/RPM from the engine
2) Not trimming properly
3) Have some junk stuck to the bottom of the boat

Right?

BUIZILLA
06-09-2009, 02:15 PM
:yes:

SilverBack
06-09-2009, 02:20 PM
You must be off on your gear ratio. 4300 with a 1.47 ratio and a 19 p prop would go 53 with no slip at all. You must be getting more rpms or less mph or have a different gear ratio.

rbarna
06-09-2009, 02:33 PM
How can I determine if the RPM gauge is wacky? Try another one?

Could it be wiring?

SilverBack
06-09-2009, 02:43 PM
Let me start by saying that there are people here that know a lot more about it than I do. With that being said...I would check the speed with a GPS speedometer or hand held GPS. Then if you are correct about your speed I would say the next most likely thing would be that you have a higher gear ratio than you think that you have. If you have a higher gear ratio you may need to try a lower pitch prop or change your gear ratio.

VetteLT193
06-09-2009, 02:43 PM
Make sure your drive is 1.47 ratio. sounds 1:32 to me

rbarna
06-09-2009, 02:44 PM
I have GPS speed and confirmed 1.47 drive ratio.

SilverBack
06-09-2009, 02:54 PM
How did you confirm your gear ratio? It does not add up with a 19 pitch prop. All props have slip and I would say with this setup you would at least be around 15 percent. I think that I would double check. One time a paid a shop to check the gear ratio in a drive and go through it and check it out and they still got it wrong. I did thousands of dollars to "fix" my engine when I had the wrong gear ratio the whole time.

VetteLT193
06-09-2009, 03:00 PM
I have GPS speed and confirmed 1.47 drive ratio.

Can't really say what's up then. I blew my last drive at over 5000 spinning a 23". I do have a cam, exhaust, demon carb, ignition, blah blah blah.

With the new drive with a nose cone and 5 guys, cooler, and 3/4 tank of gas I got it up to 4800 this past weekend. Didn't have GPS to tell you the speed though.

How did you confirm the drive ratio? Our boats were so old you never can tell what was changed... even internally. ***edit*** posted at the same time as silver..

rbarna
06-09-2009, 03:31 PM
It's a brand new drive and my mechanic took a picture of the drive ratio stamped onto the drive by merc.

The mechanic said my RPM gauge must be wrong. It's original and not in good shape at all. he said he would hook up a snap-on.

rbarna
06-09-2009, 03:55 PM
Looks like I should be turning more like 4800rpm. I'll hook up a new gauge and check.

Looks like if I move to a 22 or 23 I'll go in the low 60's.

BUIZILLA
06-09-2009, 04:21 PM
it will run 58-59 GPS with a 22 Turbo or 23 Mirage if it's a 260-270

minxclassic20
06-12-2009, 01:40 PM
Im running a stock motor in mine with 23 quicksilver cut to a clever, on GPS with just me in the boat is 60.2 at 4700RPM, and its 1.47

CHACHI
06-12-2009, 01:47 PM
Ross, had an '87 Minx with a 350 MAG, 270 HP.

Would run 62 and change with a 23 cleaver.

Tried an Alpha SS with the same prop and absolutly no difference.

Ken

VetteLT193
06-12-2009, 01:52 PM
let me know if the gauge is wrong. My original worked when I pulled it, you can have it if you need it.

MOP
06-12-2009, 01:53 PM
Looks like I should be turning more like 4800rpm. I'll hook up a new gauge and check.

Looks like if I move to a 22 or 23 I'll go in the low 60's.

With a 19 the engine should be screaming in the low 5's putting some hurt on the Alpha. I have a hunch you have other issues. If the 19 came with the boat the prior owner put it on for a reason, opinion before you start dumping $$$ do the cheap stuff a compression check, verify gear ratio and go over engine tuning specs. And yes check the bottom, every Minx I ran with ran @ 60+or-. Always do the basics before you dump the bucks, it is very easy to get carried away up here!

Phil

Donzi Racer
06-12-2009, 05:42 PM
Ross, how is the botom of the boat? How long in the water since it has been cleaned? That can really slow one down. The prop is definitely too small for that boat and engine. At least a 21 to 23 pitch. If I remember the motor is a Big Daddy 325 hp 350 cu in motor. I was thinking that should push that boat at least to 65 mph. With our minx we were getting 62 to 63 mph with the stock 270 hp engine, that was not GPS. Seems like you have some room for improvement. Bigger prop could also let you trim it a little more to get some more speed. Where is Grizz on this. What prop does he need Randy? Tom

VetteLT193
06-13-2009, 08:44 AM
The other thing is, when you buy a boat with a prop on it you probably don't know what is on it. regardless of what the prop says. It could have been re-worked a time or two at a prop shop, etc. so it could be a 19 with a big cup job + added pitch... it might be just a junky prop all together.

The boats came stock with a 23" cleaver so it should spin that, and might be a good base line if you eBay one. they are pretty cheap and wouldn't make a bad spare in the long term. Or just come to the next event and get with grizz to prop test.

DC18
06-14-2009, 10:40 PM
The other thing is, when you buy a boat with a prop on it you probably don't know what is on it. regardless of what the prop says. It could have been re-worked a time or two at a prop shop, etc. so it could be a 19 with a big cup job + added pitch... it might be just a junky prop all together.

The boats came stock with a 23" cleaver so it should spin that, and might be a good base line if you eBay one. they are pretty cheap and wouldn't make a bad spare in the long term. Or just come to the next event and get with grizz to prop test.

I have a Merc Cleaver, 14-1/4 X 23P that is labbed. I beleive it is too small for my boat. If you decide you want it, let me know.

rbarna
06-15-2009, 02:42 PM
What price is "cheap" for a 23P Cleaver?

rbarna
06-15-2009, 09:10 PM
would this be a good option for a Turbo?
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220215307604

VetteLT193
06-15-2009, 09:18 PM
Is it possible to drag the boat to an event? We would all like to meet you... the prop you have will work until you get to one and BigGrizzly will hook you up with the only prop you need.

As he told me, you only need ONE prop. Don't screw with buying and buying and buying if you can just buy one.

He'll let you test them out, then buy the ONE prop you need.

And, it's worth going to an event regardless. :wink:

rbarna
06-15-2009, 10:53 PM
where/when is the next event near NYC?

VetteLT193
06-16-2009, 06:44 AM
where/when is the next event near NYC?

The dustoff is probably the 'close' one, which just happened and isn't exactly close to NYC either.

Someone else in the North East will know more than me... hopefully chime in.

BigGrizzly
06-16-2009, 03:03 PM
That boat ande engine combo will not go low to mid 60's. Buiz is close Georg Carter has figures on his old minx.

rbarna
06-16-2009, 07:05 PM
Mr. Grizzly: by not go mid/low 60's you mean it will go slower?

gcarter
06-16-2009, 07:39 PM
Ross, it needs a few more ponies to go a consistant 65. Mine did about 65 a few times on cool days. On warm days it would do about 62 +/- pretty consistantly. I tried a number of props in the 22-24" range. Even a couple of Turbos.
My all around favorite on my boat was a Hydro Q-4 22" X 15". It was very stable and never blew out.
I bought it on eBay for $250.00.

rbarna
06-16-2009, 10:49 PM
Just got a Turbo 23 on ebay for $160... I'll hook up a proper RPM gauge and see what we get!

MOP
06-17-2009, 12:52 AM
Turbo is a decent prop good all around performance, hope a new tach makes more sense of the speed/RPM thing. If you get time to come out on the island I have a 4 blade 22 Turbo you can try, have to see what the 23 does first. George you forgot to mention how freaky the Minx was with the cleaver! Phil

MOP
06-17-2009, 12:56 AM
Just thought of something, look behind the tach see if it has a cylinder setting IE: 4,6,8!

mattyboy
06-17-2009, 07:37 AM
you just missed the dustoff it would have been a great chance to try a ton of props between runs it looked like the pits at an offshore race.

the next event in the NE is winnie the last weekend in july check the event section for details

the stamp doesn't mean much if someone opened her up your numbers are dead on for a 1.3 drive at 10 percent slip

possible causes figuring 10 percent slip average

the prop is mis marked and is a 20-21 ish prop with 10 percent slip and a 1.4 ratio

the tach is off by 200 or so rpm at 10 percent slip 19 pitch 1.4 ratio your at tad over 4500 rpm not 4300

the difference in one gear ratio drop is almost the same as changing an inch of pitch roughly around 200 rpm difference

bottom paint??

BigGrizzly
06-17-2009, 08:16 AM
Yes I doubt that combination will go above 60. Georges engine was not stock. Scott Pearson's 18 with a raised X got 61 I believe, with a Mirage Plus, first time the Turbo was ever beaten, Of course it was 21 Turbo against 23 M+.

rbarna
06-17-2009, 08:53 AM
The drive was BRAND new and was ordered from Mercury as 1.47

Bad RPM gauge. Hope to fix it today.

kcatucci
06-17-2009, 10:46 AM
I got my Minx brand new in 1986. Before I changed the motor it was 62+/- every time.

MOP
06-17-2009, 09:36 PM
Having run cleavers on several of my boats I can not for the life of me understand why the Minx came with one stock! A cleaver is a stern lifting prop the exact opposite of what our deep V's need, plus it can do some pretty scary stuff at speed trimming. George and I both have scared the krap out of passengers when running our cleavers, they can give you a wicked azz end twitch that will throw your passengers to one side. I had this self same discussion a couple of seasons back with one my kids friends, he said your nuts. So a quick prop change on the 22 and off we went, I made him sit in the back with Michael next to me. At about 4,000 I ran the trim through a couple of up/down cycles, the kid near kraped himself getting slid across the back seat point made! I got rid of mine cheap to a guy that ran twins, they need the azz lift and work fine in pairs. My 22 is 1/2 MPH faster with a round ear bow lifting prop, I just can not understand people running cleavers on these single engine hulls that definitely need bow lift.

BigGrizzly
06-18-2009, 09:10 AM
MOP, you know the drill. The best prop is the new one they just purchased. Your problem is like mine we are old and have been there and don that. Darn new kids. Truth is that some clever are good and a tad different. BUIZ had an old limited production clever on his 18 that was really a good one. I haven't seen one in years until his.

MOP
06-18-2009, 12:05 PM
Randy it did have one good trait the boat did not porpoise as it lifted the stern, but maneuvering in reverse sucked and the azz end twitch was spooky. I had two different Merc cleavers on the 22, a 21 I got from Truesdale when I was running the 300 and a 23 for the 383 I picked up from a friend. The did look a little different but I have no recall on the numbers, both SUCKED compared to my 4B Turbo Ultima. And again thank you very much for steering me toward the Turbo it great in all respects!

Phil

BigGrizzly
06-19-2009, 07:59 AM
MOP, the problem with the numbers is Merc had a couple of configurations with the same numbers. Really weird, they even look different. When I saw BUIZ I about crapped I had not seen one in years. Yesterday I heard of another one that popped up out of nowhere. All seem to be 23 and 21 pitch. As for helping you, again it is the application you would have found it eventually, you always do.