Chaparral Sunesta 220, wrong prop?

[Stang_Guru]

First post here and would appreciate ANY help you guys can give as im still learning things as i go with this project :lol:

I am fairly well at doing my research into things before giving up, but ive hit a brick wall this time and will try to give all the details i can that may be helpful.

Started a project restoration last year. Bought a used and neglected 1994 Chaparral deckboat( former saltwater boat, now only freshwater lake boat). solid boat, needed some mechanical and cosmetic TLC, but overall, a nice project and what i needed. it had a Mercruiser 305 lx, and alpha one outdrive. after running it twice, realized it was failing, had it checked by my mechanic. cracked block. had a new Rapido Marine 5.7 longblock but into place. heres where im lost. max RPM 3800-4000. gps 33mph. did 38 with the cracked 305 :facepalm: i know there is more life in this engine, so is it the prop?

1994 Chaparral Sunesta 220
3400-3500lbs dry
Mercruiser 5.7 350ci lx
Mercruiser alpha one ( tags say its correct with 1.50r gearing).
New fuel pump, lines serviced.
carb rebuilt.
new ignition.
outdrive fully serviced, new impeller, fluids, and new gimbal bearing.
everything gone through and serviced.
Unknown prop brand. Its stainless steel stamped Turbo 14 1/4 x 17p

This boat is hard to get on plane, takes a few attempts with only me and the wife and less than 50lbs of gear, and half tank of fuel. Engine fires on first crank, smooth as silk running/idleing/revving, no missfires or sputters.
This boat will be used for cruising/fishing 80% of the time but do accasionally like to pull tubes and maybe skis in the future.

you guys have the best boating forums on the planet, would be great to be able to solve this.

 

[Levinz11]

Re: Chaparral Sunesta 220, wrong prop?

Original distributor? Is the timing advancing?

 

[Stang_Guru]

Re: Chaparral Sunesta 220, wrong prop?

Original distributor? Is the timing advancing?

new distributor, wires, plugs ect.

i have no way of testing the timing, and my mechanic is an hour and a half from me near the lake i go to.
fairly sure he checked all that when he installed it. 100% faith in his work

the engine runs smooth as butter, not one hiccup or hesitation. got up to about 33mph 4000-ish and just stayed there. after researching, it leads me to believe it may be the prop, but i cant find any info on what the factory prop size should be. the boat had a 305 when i got it, but after reading through some post, i may be wrong but it seems the 305 had different gearing than the 350, and the outdrive does say 1.50r, leading me to believe that the boat originally had a 350, and at some point it was replaced with the 305, and if thats the case, the original owner may have changed prop to compensate, so im not sure what i should have now.

 

[steelespike]

Re: Chaparral Sunesta 220, wrong prop?

If the tired 305 managed 38 mph with the 17" prop and a 1.50 outdrive I think the 350 would be off the chart.
I figure you need to make up about 800 rpm.You can't do it practically with a prop change.
You would need to drop to about 13" pitch I think that only leaves 2 props smaller.
A 13 is something you might find on a big cruiser or a big pontoon.
At 4800 rpm a 13" prop would produce about 35 mph.
If you could make 4800 with the 17" it would produce about 38.6

 

[Stang_Guru]

Re: Chaparral Sunesta 220, wrong prop?

If the tired 305 managed 38 mph with the 17" prop and a 1.50 outdrive I think the 350 would be off the chart.
I figure you need to make up about 800 rpm.You can't do it practically with a prop change.
You would need to drop to about 13" pitch I think that only leaves 2 props smaller.
A 13 is something you might find on a big cruiser or a big pontoon.
At 4800 rpm a 13" prop would produce about 35 mph.
If you could make 4800 with the 17" it would produce about 38.6

even at 38 that seems too slow. ive done TONS of research and all other identical boats ( year, drivetrain, model/trim) with my exact setup are seeing no less than 43-48mph. im starting to scratch a bald spot with this one :facepalm::lol:

 

[NHGuy]

Re: Chaparral Sunesta 220, wrong prop?

Do you know how to operate your trim? If you raise it as your speed comes up the hull lifts and allows more speed.

If you are already doing that and the motor is right, I'd weigh the boat and see how close it is to original. It might be waterlogged and too heavy.
I'd think a 17 pitch is probably right for your boat. Maybe a 19 if everything is perfect and you are running lightly loaded.

 

[airdvr1227]

Re: Chaparral Sunesta 220, wrong prop?

Remember you're talking 20 year old boat. If it's not a little bit waterlogged I'll eat my hat.

 

[Stang_Guru]

Re: Chaparral Sunesta 220, wrong prop?

Ive ran boats for years, also have a procraft fish and ski, so trim isn't the problem, although the waterlogging had came to mind. Im not even sure how i could even check for that.

 

[emilsr]

Re: Chaparral Sunesta 220, wrong prop?

If you're only able to turn a 17p prop at 4k rpm, my guess is not all the ponies are present and accounted for. Even a waterlogged boat (weigh it; that's the easiest way to check) should perform better with a 350 than with a 305.

Doesn't really sound like a prop problem to me. I'd get it back to the mechanic and have him check things again. Even the good ones make mistakes from time to time.

 

[Stang_Guru]

Re: Chaparral Sunesta 220, wrong prop?

I may have to. Something is definitely off. Even though it runs perfect i guess that doesn't mean everything. All the hardware was used from the 305 onto the new 350 as in the new engine came as the block/internals/fully assembled heads and he checked the valve adjustments. Then he used the 305 intake, carb (with rebuild), wiring harness, ps pump, pulleys, ect. New fuel pump, starter, and distributor. Does all that sound right or is there something i should be looking into?

 

[airdvr1227]

Re: Chaparral Sunesta 220, wrong prop?

Was it a marine engine? Haven't I read somewhere that the cams can be different?

 

[Stang_Guru]

Re: Chaparral Sunesta 220, wrong prop?

Was it a marine engine? Haven't I read somewhere that the cams can be different?

Yes, it was a new longblock from Rapido Marine.

 

[Maclin]

Re: Chaparral Sunesta 220, wrong prop?

The 305 gave a good baseline, and my opinion is the new engine should at the VERY least match the 305's numbers (and LEAP out of the hole) and that the new engine needs to be dialed in more.

Some potential factors:

• That is about the RPM that too-tight of valve lash shows up.
• Maybe he has the timing not at full advance spec for some kind of breakin period.
• Maybe the advance curve in the distributor is not right.
• Make sure the carb is getting full throttle when the throttle cable is at full, sometimes it is the simple things.

Regarding the prop, it really cannot be the suspect here. Let's say that the carb cannot really keep up now, like it is a 2bbl and really should be a 4bbl, the symptoms would be way different, more like the boat would LEAP out of the water then run out of rpm's and stay at the lower end of the operating range. Since yours is doggy from the start then then a prop change would only help the hole shot and you would not even get to 25mph I bet.

What should happen after an engine change like this is the prop ends up being too small and you overrev. Again with the boat leaping out of the water. A properly tuned 5.7 when compared to similarly tuned 5.0 has 50ft lb more torque potential available. In my opinion you need to go "find" them there missing pounds of feet

 

[Maclin]

Re: Chaparral Sunesta 220, wrong prop?

By the way, have you talked to the mechanic? I know I was pretty proud of "my" (automotive) engines when people brought them to me back in the day to replace, tune, etc. If they did not perform then I took it as a potential smudge on my reputation and always made sure I got a chance to rectify anything I missed or replace a bad part that had showed up.

 

[greiffster]

Re: Chaparral Sunesta 220, wrong prop?

Stang,

I know this post is about a month old. Maybe you've moved on, but I thought I'd chime in since i have the same boat, but a '96.

Just for reference, I have the 305. Mine will do about 32mph at 4000rpm, moderately loaded. It might see 38mph with just me pegged at 4400rpm. No way its ever seen 40. Its just a big heavy bastard and drags a lot of water. I cant say that i have ever had problems getting it planed, even with 11 on board.

-mike

 

[500dollar744ti]

Re: Chaparral Sunesta 220, wrong prop?

even at 38 that seems too slow. ive done TONS of research and all other identical boats ( year, drivetrain, model/trim) with my exact setup are seeing no less than 43-48mph. im starting to scratch a bald spot with this one :facepalm::lol:

Your boat is similar to mine, 22.5' Cobia with 350 Magnum (carb). Where in VA are you located?

Anyway, with a 17p on mine, the boat jumps out of the water and goes about 42mph, that's my spare prop. I have been running a 20p which is kind of hard to get up on plane loaded but with just two people it gets up on plane and does 51mph.

You should be running at least a 19p but your engine isn't making the power it should. It 'ought to be over-revving with a 17p on there and jumping up on plane easily.

What's your timing set to?

edit:// I just read you used the carb from the 305, that could be your problem, not enough fuel for the added displacement.

 

[greiffster]

Re: Chaparral Sunesta 220, wrong prop?

Stang,

I know this post is about a month old. Maybe you've moved on, but I thought I'd chime in since i have the same boat, but a '96.

Just for reference, I have the 305. Mine will do about 32mph at 4000rpm, moderately loaded. It might see 38mph with just me pegged at 4400rpm. No way its ever seen 40. Its just a big heavy bastard and drags a lot of water. I cant say that i have ever had problems getting it planed, even with 11 on board.

-mike

So I did some speed testing this weekend and can report the following: 40 mph @ 4400rpm with 5 on board, 1/2 tank of gas. Really had to tweak the trim to find the sweet spot to get it up to 40. Feeling like it may get to 45 mph, very lightly loaded. I guess its a bit faster than I thought.

 

[Stang_Guru]

Re: Chaparral Sunesta 220, wrong prop?

Your boat is similar to mine, 22.5' Cobia with 350 Magnum (carb). Where in VA are you located?

Anyway, with a 17p on mine, the boat jumps out of the water and goes about 42mph, that's my spare prop. I have been running a 20p which is kind of hard to get up on plane loaded but with just two people it gets up on plane and does 51mph.

You should be running at least a 19p but your engine isn't making the power it should. It 'ought to be over-revving with a 17p on there and jumping up on plane easily.

What's your timing set to?

edit:// I just read you used the carb from the 305, that could be your problem, not enough fuel for the added displacement.

After taking a few days to do some troubleshooting of my own, I found the issue being fuel/carb related, for sure. after short run I started getting heavy flooding, black smoke, and major backfiring. leaned it out a bit and it perked up and started jumping on plane MUCH faster, and with the throttle at full, but still only 3800-4000rpms, no backfiring, but now the lower midrange would flood and backfire. a little more tuning and it was back to heavy flooding and backfiring, and rough idle, surging very badly.

been working step by step with the mechaninc and realized we had a previous miscommunication and the carb HAD NOT been rebuilt when put on the new engine. he is doing that now. I had read up on the parts swaps before we took on the project and thought the 305 carb could be used on the 350, was I wrong? can it just be rejetted for extra fuel need?

 

[Stang_Guru]

Re: Chaparral Sunesta 220, wrong prop?

So I did some speed testing this weekend and can report the following: 40 mph @ 4400rpm with 5 on board, 1/2 tank of gas. Really had to tweak the trim to find the sweet spot to get it up to 40. Feeling like it may get to 45 mph, very lightly loaded. I guess its a bit faster than I thought.

I'd like to borrow that 4400rpm from you :laugh:

Even playing with the trim I can only best 34mph/@4000 with 2 people and 1/2 tank, and that's makes the bow start to get very bouncy and have to back out a bit to smooth it up. good to hear yours gets up and scoots, I hope to be doing the same soon.

 

[pylotttt]

I realize this is a very old post, but an update with the fix would have been nice.