94 chaparral 1930 ss with 4.3 prop help

[Lt1z350]

So boat is 19.3 long 2500 lbs by the reading I have done. 4.3 190 hp from what I can come up with as has 4bbl on it. It’s that lx thundervolt.
Just bought it and had a 19 pitch cheap Solaris prop 13.5 I believe I can get part number off it. Previous owner hit something and bent it up pretty bad. Edges were all cupped and ground down. On test before buying it we managed 45 mph by gps at 5000 rpm but if I hammered it the cavitation was bad so had to lift so wasn’t able to get a great feel for it.
I have a 17 foot bass boat so pulled off the 24 pitch 4 blade stiletto 13.5 I believe also and tried that out and not that great.
Poor hole shot took too long to plane 4500 rpm max 42 mph on gps. I could back it down to 4100 rpm and not lose but 2 mph like it was stalling out. Had a weird feeling on the boat. Runs out 65 mph plus on the bass boat 5800 rpm and has a good feel on the 950 lbs boat. But too much I assume on this heavy boat.
I’m reading you can go up on prop size also not just the pitch but I have no idea how this affects it.
I don’t mind spending more money on one if it’s going to be a good gain in hole shot and be efficient for top speed. I don’t want to get crazy but not against a good stainless steel 3 4 or 5 blade what ever gets recommended. I’d like to see closer to 50 mph if possible but don’t know if even a high end prop will get this boat there on this hp.
I have considered the later heads and better edelbrock intake for a 20 or so hp bump more so better bottom end.
But if the right prop can make it work I’m good leaving it alone for now as like to do an aluminum 5.3 ls carb swap if I reallly end up liking the rest of the boat in the next 2 or 3 years. So will be nice to leave as is for now and just get a little better performance from the right prop.
I just have no idea if a higher end prop is going to help enough as my baseline and test prop are so different and base line was bent and ground up so I’m sure not even biting the water as it should when ran 45 mph at 5000 rpm.
If I had to take a guess a 21 pitch seems like a happy middle ground but again I’d like to see someone give direction as know more about it.
Thanks

 

[Lt1z350]

This is the original prop part number that’s bent up

 

[Bondo]

Ayuh,... I'd start with a new 19" aluminum prop, 'n try it,.....
A 21" might give ya better top end,.... or not,..... you'll loose hole shot though,....

 

[briangcc]

Might help, might not....

My boat is very similar to yours, albeit newer. 4.3L MPI 180HP with Alpha 1 Gen II drive, 1.62 drive ratio. I swing a 4 blade 19P prop. I top out at 49mph (and change) on GPS.

19.4', 2600lbs+/- dry rigged weight per published specs...which I assume is what you're going off with your numbers.

 

[Lt1z350]

Ayuh,... I'd start with a new 19" aluminum prop, 'n try it,.....
A 21" might give ya better top end,.... or not,..... you'll loose hole shot though,....

It had that 19 on it and was at 5k which might be a little much? But again it’s tore up so now idea how much slip I was seeing. Aren’t some brands better then others on design? The prop I had was a whopping 87 bucks I looked it up so seems very cheap. So assume there is a better line of prop that people like?

 

[Lt1z350]

Might help, might not....

My boat is very similar to yours, albeit newer. 4.3L MPI 180HP with Alpha 1 Gen II drive, 1.62 drive ratio. I swing a 4 blade 19P prop. I top out at 49mph (and change) on GPS.

19.4', 2600lbs+/- dry rigged weight per published specs...which I assume is what you're going off with your numbers.

I’ll have to look up my ratio as it’s also alpha 1 I believe gen 2 I’ll pull the serial and double check it.
Had you ran a 3 blade prior? If so what results? Aluminum or stainless 4 blade on boat now?
I’m pretty sure I thought all of the mpi were 230 hp so that seems like a low spec for that setup. That’s an excellent intake design makes such good low end torque and good peak hp I wish I had it. I run a Holley stealth ram on my 92 formula firebird 383 and it’s very similar to that one so why I know it well. Lucky to have the best of the 4.3 setups.
I also assume with say towing tube and more people that prop probably becomes even more ideal as still comes out hard.
I had read the 4 blade cam give up top end was only concern but 49 if has good hole shot is really good. So you know the max rpm also?
Thanks for chiming in as this is a big decision as usually stuck with it or money lost.

 

[Lt1z350]

Well seems that my gen and year is using a 1.81/1.84 one or the other ratio gear drive so that’s gonna be off some and I’ll have to get a prop calculator. I was reading the 1.62 is from the v8 motors up to 2005. I bet with 230 hp mpi they gave that motor a little lower gear assuming that a 21 on my drive probably will be closer to your top end that’s if my weasy 180/190 can turn up that 21 ok. I need someone with a little more experience to chime in on all this with knowing the ratio difference.

 

[Lt1z350]

Prop Selector | Quicksilver Propellers | Mercury Marine

legacy.qsprops.com

Any of these sites worth a crap? I put in all the information and off the 1.81 drive ratio comes up with 8 3 and 4 blade props all at 21 pitch different sizes 13.88 to 14.25. It did recommend one 20 pitch the rest 21 though.

 

[briangcc]

I’ll have to look up my ratio as it’s also alpha 1 I believe gen 2 I’ll pull the serial and double check it.
Had you ran a 3 blade prior? If so what results? Aluminum or stainless 4 blade on boat now?
I’m pretty sure I thought all of the mpi were 230 hp so that seems like a low spec for that setup. That’s an excellent intake design makes such good low end torque and good peak hp I wish I had it. I run a Holley stealth ram on my 92 formula firebird 383 and it’s very similar to that one so why I know it well. Lucky to have the best of the 4.3 setups.
I also assume with say towing tube and more people that prop probably becomes even more ideal as still comes out hard.
I had read the 4 blade cam give up top end was only concern but 49 if has good hole shot is really good. So you know the max rpm also?
Thanks for chiming in as this is a big decision as usually stuck with it or money lost.

To answer your question, it came from the marina this way pre-rigged. I personally like it as it holds turns like there's no tomorrow. It's a 4 blade Aluminum. I'm in middle of my WOT RPM range going off memory - not hitting a rev limiter or anything. Could I gain maybe 1-2 mph if I switched to SS 3 blade? Maybe....but my pocket book won't like me once I tag a rock pile.

Mine is a 180HP MPI. My model year it was either 180 or 220HP in the 4.3L, non-cat, Merc power.

**Won't tell ya I have a 78 TA, w/1970 4 bolt 455 bored 60 over, sitting in my garage. Y88 gold spec edition almost fully optioned.

 

[Lt1z350]

To answer your question, it came from the marina this way pre-rigged. I personally like it as it holds turns like there's no tomorrow. It's a 4 blade Aluminum. I'm in middle of my WOT RPM range going off memory - not hitting a rev limiter or anything. Could I gain maybe 1-2 mph if I switched to SS 3 blade? Maybe....but my pocket book won't like me once I tag a rock pile.

Mine is a 180HP MPI. My model year it was either 180 or 220HP in the 4.3L, non-cat, Merc power.

**Won't tell ya I have a 78 TA, w/1970 4 bolt 455 bored 60 over, sitting in my garage. Y88 gold spec edition almost fully optioned.

So seeing quicksilver has the spit fire 4 blade aluminum and nemesis also aluminum. Their are cheaper props as these are only 200 bucks with the hub. Not sure which will give better performance. Does yours have any stamp on it or part number?
And very cool about the t/a I almost got a 1976 455 ram air 4 speed car in high school

 

[briangcc]

I can check when I get home to see if there's a part number on the prop.

 

[Lt1z350]

I can check when I get home to see if there's a part number on the prop.

Great thank you.
Just checked my lower oil and has some water in it. Not a lot but enough. Took apart water pump and blew out the lower gasket. Glad I’m going over everything on this boat. Hopefully he didn’t run it too long as the oil was newer and clean. Feel like knew had water and put oil in it. Water pump kit and new oil and keep an eye on it I guess.

 

[briangcc]

Side of prop: 834852A45 18P
Hub: J 14.5 x 18P

Looks like it's out of stock on iboats. Might find it elsewhere??

So it's an 18P 4 Blade....must of mis read it when I bought the boat. Ohh well. I know the GPS numbers are right as I run tests each year to confirm no dip in performance.

Another option...just repair what you have as you should see a performance improvement once its back to spec. Cost me $50 at a reputable prop shop eons ago to have one repaired.

 

[Lt1z350]

Side of prop: 834852A45 18P
Hub: J 14.5 x 18P

Looks like it's out of stock on iboats. Might find it elsewhere??

So it's an 18P 4 Blade....must of mis read it when I bought the boat. Ohh well. I know the GPS numbers are right as I run tests each year to confirm no dip in performance.

Another option...just repair what you have as you should see a performance improvement once its back to spec. Cost me $50 at a reputable prop shop eons ago to have one repaired.

So that’s a little bigger diameter but pitch down from what I ordered to try.
Hustler 14 inch 19p I liked it’s not cast aluminum but pressure molded and they use two different style blades on same prop and it’s a vented hub for hole shot. I read good reviews on most people that tried them and big thing was no mph loss from same 3 blade of same diameter and pitch. It was 100 bucks and has returns so nothing lost but some shipping if don’t like it.
Two blades for top end and two for hole shot seems pretty interesting so at that price figured why not.
I’ll test it out and post back. Also I cleaned up the 14 19 3 blade I have here straightened it and evened up all 3 blades so can try that again vrs the 4 blade.
I’m a little worried my 1.84 (on side of case found that ) ratio might need a 21 pitch but we will see.

 

[briangcc]

Usually....adding a blade means dropping 1" pitch but that varies across boats/motors/drives. You might hit right where you want to be with the extra 1" pitch and blade. Only way to know for sure is to give it a whirl.

 

[harringtondav]

Your '94 4.3 LX is 180 hp. Late '96 and on had Vortex heads and 190 hp. 14"-14.25" props are normal for your drive.
Prop selection has trade offs. You want enough pitch to keep your WOT rpm under 4800 on your engine/drive. Your speed at WOT will be what it is. Pricey props may gain you a few mph at the same pitch.
Pitching up may give you more WOT speed, but you also may loose ground.
High pitch and speed often come at the cost of slow hole shots/planing.
From my experience with a past 16'9" 2300# dry Larson with the same power package, I think you're at the power limit for your boat. 14" x 21P gave me good hole shot at the expense of 5000 rpm WOT. 23P held me @ 4800 rpm and higher top end, but worked the engine harder as indicated by the temp gage. Vortec heads and related carb re-jetting may give you another 10 hp.

BTW, don't diss Solas props. My new 19'6", 2900# dry 250 hp VP drive boat came with a VP 14 x 21P 3 blade VP alum prop. I replaced it with a 3 blade Solas SS 22P prop. My top speed/slip improved from 50mph/17% slip to 55mph/9% slip. Forum members recommended a top end Merc prop. I reckon I've got all the speed I'll get with my power/boat weight.

 

[Lt1z350]

Your '94 4.3 LX is 180 hp. Late '96 and on had Vortex heads and 190 hp. 14"-14.25" props are normal for your drive.
Prop selection has trade offs. You want enough pitch to keep your WOT rpm under 4800 on your engine/drive. Your speed at WOT will be what it is. Pricey props may gain you a few mph at the same pitch.
Pitching up may give you more WOT speed, but you also may loose ground.
High pitch and speed often come at the cost of slow hole shots/planing.
From my experience with a past 16'9" 2300# dry Larson with the same power package, I think you're at the power limit for your boat. 14" x 21P gave me good hole shot at the expense of 5000 rpm WOT. 23P held me @ 4800 rpm and higher top end, but worked the engine harder as indicated by the temp gage. Vortec heads and related carb re-jetting may give you another 10 hp.

BTW, don't diss Solas props. My new 19'6", 2900# dry 250 hp VP drive boat came with a VP 14 x 21P 3 blade VP alum prop. I replaced it with a 3 blade Solas SS 22P prop. My top speed/slip improved from 50mph/17% slip to 55mph/9% slip. Forum members recommended a top end Merc prop. I reckon I've got all the speed I'll get with my power/boat weight.

Thanks for the input so my boat a little bigger heavier the 14 19p is probably gonna be ok. Comes in tomorrow so will test it out this weekend and will post results as I hate reading a post and not seeing an answer and it goes dead. So many times I find what I’m looking for then get to the end and no final answer and I’m like noooo!!!! So I’m not going to do that to someone.
I only talked bad on this solas as it’s a low level aluminum the lowest line from what I found off the part number. I’m sure the stainless steel are much better.
I’m considering the better heads ( I build small block chevys and know them well). Port match to the better edelbrock intake clean up the bowls all that port work is good for 25 hp minimum. I don’t know how much an edelbrock intake helps I cannot find anyone that did it and said I saw x gains from it. I have 1.6 rockers from a v8 that will also work. Maybe do a better carb. All that if can squeeze 250 hp from it and gain a good 80 lbs tq o probably can go up to a 21 maybe see 55 from it depending on what I see from this prop.
I built a few 4.3 a-10 trucks back in the early 2000s with fbo a truck could gain 10 mph in the 1/4 mile but those were the cpi motors so also had a tune.

I ordered new plugs cap rotor and a perteonix 45,000 volt coil. With that I can take the .035 gap out to .045 and gain some mid range torque help come out of the hole. Little tricks from v8s should apply here also.
I’m going to post a thread on what little things can see gains or not just to help others along the way. Eventually I’d like this boat enough I’ll 5.3 ls swap it as these good running 4.3 motors can bring some only still to someone wanting to stay with it.

I’ll post back when back on water with prop and report results.
Thanks

 

[Scott06]

Well seems that my gen and year is using a 1.81/1.84 one or the other ratio gear drive so that’s gonna be off some and I’ll have to get a prop calculator. I was reading the 1.62 is from the v8 motors up to 2005. I bet with 230 hp mpi they gave that motor a little lower gear assuming that a 21 on my drive probably will be closer to your top end that’s if my weasy 180/190 can turn up that 21 ok. I need someone with a little more experience to chime in on all this with knowing the ratio difference.

Thats correct on my boat the carbed 4.3 came with a 1.81 drive, the mpi 4.3 which is 220 hp came with 1.62 drive as did the 5.0/220 hp carb and 5.0 mpi/ 260 hp.

the drive ratio diff between a 1.81 and 1.62 is similar to about 2” in prop pitch . I repowered my boat from a 4.3 to a 5.0 with a edlebrock 4 bbl and intake, kept the 1.81 drive just proped up from a 19” to 21” pitch prop.

 

[Scott06]

Thanks for the input so my boat a little bigger heavier the 14 19p is probably gonna be ok. Comes in tomorrow so will test it out this weekend and will post results as I hate reading a post and not seeing an answer and it goes dead. So many times I find what I’m looking for then get to the end and no final answer and I’m like noooo!!!! So I’m not going to do that to someone.
I only talked bad on this solas as it’s a low level aluminum the lowest line from what I found off the part number. I’m sure the stainless steel are much better.
I’m considering the better heads ( I build small block chevys and know them well). Port match to the better edelbrock intake clean up the bowls all that port work is good for 25 hp minimum. I don’t know how much an edelbrock intake helps I cannot find anyone that did it and said I saw x gains from it. I have 1.6 rockers from a v8 that will also work. Maybe do a better carb. All that if can squeeze 250 hp from it and gain a good 80 lbs tq o probably can go up to a 21 maybe see 55 from it depending on what I see from this prop.
I built a few 4.3 a-10 trucks back in the early 2000s with fbo a truck could gain 10 mph in the 1/4 mile but those were the cpi motors so also had a tune.

I ordered new plugs cap rotor and a perteonix 45,000 volt coil. With that I can take the .035 gap out to .045 and gain some mid range torque help come out of the hole. Little tricks from v8s should apply here also.
I’m going to post a thread on what little things can see gains or not just to help others along the way. Eventually I’d like this boat enough I’ll 5.3 ls swap it as these good running 4.3 motors can bring some only still to someone wanting to stay with it.

I’ll post back when back on water with prop and report results.
Thanks

A 4 bbl and intake on the 4.3 should get you close to the 220 hp of the mpi. The 4 bbl 4.3 alfa reman engines merc sells are rated at 225 hp

 

[Scott06]

I also assume with say towing tube and more people that prop probably becomes even more ideal as still comes out hard.
I had read the 4 blade cam give up top end was only concern but 49 if has good hole shot is really good. So you know the max rpm also?
Thanks for chiming in as this is a big decision as usually stuck with it or money lost.

Yes 4 blade will generally give up top speed but provide better holeshot, sternlift, and lower planning speeds. if you do loaded water sports like me its the way to go.