upgraded 4.3 Prop suggestion

[dsmmace]

I have a 98 Bayliner Capri 1850 with the APS hull and a upgraded 4.3L. I would estimate the engine should easily make 250hp. I have the alpha one 1.81 drive ratio and nauticus trim tabs.

Previous to the upgrades the stock 2bll 4.3L boat would run 47mph (gps) @ 4800 rpm on a $100 21 pitch aluminum prop.

I have had lots of issues with getting the new motor running optimally, but now I would like some suggestion on a good 'starter' prop to test the new motor on and make adjustments/changes from there.

 

[Bondo]

Re: upgraded 4.3 Prop suggestion

Ayuh,.... Try the Biggest prop you can find,...
Running a 4.3l on an outdrive geared for a 4 cylinder is goin' to be a Problem in itself...
You might not find a prop Big enough...

 

[dsmmace]

Re: upgraded 4.3 Prop suggestion

Should I try a 23 pitch 3 blade to start?

 

[45Auto]

Re: upgraded 4.3 Prop suggestion

Did you change outdrives when you re-did the motor or did it have the 2.0 outdrive on the original motor?

I would borrow the biggest prop you could find to get a baseline WOT reading.

 

[dsmmace]

Re: upgraded 4.3 Prop suggestion

I believe it came with the 1.98 drive but changed up when the leg was changed.

The drive serial number was 0L047164. Can you tell ratios via the serial number?

 

[jkust]

Re: upgraded 4.3 Prop suggestion

I have a 98 Bayliner Capri 1850 with the APS hull and a upgraded 4.3L. I would estimate the engine should easily make 250hp. I have the alpha one 2.0 drive ratio and nauticus trim tabs.

Previous to the upgrades the stock 2bll 4.3L boat would run 47mph (gps) @ 4800 rpm on a $100 21 pitch aluminum prop.

I have had lots of issues with getting the new motor running optimally, but now I would like some suggestion on a good 'starter' prop to test the new motor on and make adjustments/changes from there.

I'm not quite getting all of this. Did you change the 2bbl to a 4bbl? What exactly was done to make the 4.3 'upgraded'?

 

[dsmmace]

Re: upgraded 4.3 Prop suggestion

Compression is almost 10:1, a Custom Comp cam was installed, balance shaft was removed and the engine was balanced and blueprinted. The heads had a small amount of flow work on the vortec heads. Edelbrock Performer intake manifold and Edelbrock 1409 carb and the typical suggested 1485? jet kit, but I changed the secondary jets up to the 0.095 so far, but that was before I realized the throttle cable wasn't installed and adjusted properly by the boat mechanic.

I have had too many variables over the last two years...

 

[180shabah]

Re: upgraded 4.3 Prop suggestion

Unless it was sold or high altitude, it should have come with a 1.8x or possibly even the 1.6x ratio in the drive.

What is stamped in the housing?
Has it ever been changed?

 

[180shabah]

Re: upgraded 4.3 Prop suggestion

Compression is almost 10:1

what's your fuel bill gonna be, runnin premium?

a Custom Comp cam was installed

specs? any thought given to resonance/reversion?

balance shaft was removed

WHY? only gonna net you a couple hp at the very top end

and the engine was balanced and blueprinted...

again I ask why spend the money for an engine that will be spinning less than 5k?

250hp estimate - is that crank or prop?

 

[Slip Away]

Re: upgraded 4.3 Prop suggestion

I too wonder why spend the money for so little gain.

 

[dsmmace]

Re: upgraded 4.3 Prop suggestion

what's your fuel bill gonna be, runnin premium?

I do for ethanol content anyways.

specs? any thought given to resonance/reversion?

Absolutely, I don't have the specs or number, I relied on my engine builder for that

WHY? only gonna net you a couple hp at the very top end

More cam choices are available without a balance shaft

again I ask why spend the money for an engine that will be spinning less than 5k?

My good friend is a very good and knowledgable engine builder, I don't pay much for his labor time. Plus the 4.3L crank isn't the stongest and I also removed the Balance Shaft. This is how I prefer to do things and it helps me sleep better at night.

250hp estimate - is that crank or prop?

It's an guesstimate, we didn't bother dynoing it. Comp Cams engine dyno software says just under 300 hp, but I look at that with skepticism.

 

[Randybeall]

Re: upgraded 4.3 Prop suggestion

Find a 25pitch prop and go make some test runs. Go carefully don't over rev the engine, but you likely have thought of that. I hope the cam is a torque producing grind because hi rpm horsepower is not what makes the best fun boat.

 

[dsmmace]

Re: upgraded 4.3 Prop suggestion

I will go home and check the receipt for the drive to check the ratio. I am hoping I get home and it is a 1.84 ratio. I am not the original owner of the boat so I don't know ratio. I am one of those kind of guys that keeps the original window stickers for major purchase items.

No I will not take it over 5000rpm and yes it is a torquey cam. Sorry I don't have the specs, but this is what my engine builder suggested and we also had reversion in mind.

 

[Bondo]

Re: upgraded 4.3 Prop suggestion

Ayuh,.... With such a little boat, you're gonna Need the 1.65:1 gears...
1.84:1s might still be too low...

 

[180shabah]

Re: upgraded 4.3 Prop suggestion

I do for ethanol content anyways.

??? Are you implying no ethanol in premium???

Absolutely, I don't have the specs or number, I relied on my engine builder for that

good to hear

More cam choices are available without a balance shaft

Cheaper too...

My good friend is a very good and knowledgable engine builder, I don't pay much for his labor time. Plus the 4.3L crank isn't the stongest and I also removed the Balance Shaft. This is how I prefer to do things and it helps me sleep better at night.

Fair enough

With such a little boat, you're gonna Need the 1.65:1 gears...
1.84:1s might still be too low...

Agreed

 

[dsmmace]

Re: upgraded 4.3 Prop suggestion

In Canada most regular and midgrade fuel contain up to 10% ethanol. Most Premium fuels do not have ethanol and even list a sticker on the pump stating so.

Pardon me for my mistake but I have a 1.81 drive ratio.

Someday I will tell you about my 98 Tahoe with a 383 stroker and supporting mods. I can't leave well enough alone.

 

[180shabah]

Re: upgraded 4.3 Prop suggestion

In Canada most regular and midgrade fuel contain up to 10% ethanol. Most Premium fuels do not have ethanol and even list a sticker on the pump stating so.

Profile not filed in, didn't know we were dealing with Canada....

 

[Tail_Gunner]

Re: upgraded 4.3 Prop suggestion

Ayuh,.... With such a little boat, you're gonna Need the 1.65:1 gears...
1.84:1s might still be too low...

Bondo is dead on here..I have a modded 4.3 280 plus hp...I can turn a 23 right to 5000....thats with a 1.66 ratio...The hole shot is laughable...You gonna need some new gearing...1.5 kinda

http://forums.iboats.com/showthread.php?p=2192708#post2192708


I went with the 270...that 266 was very tempting...

 

[dsmmace]

Re: upgraded 4.3 Prop suggestion

Wow. I didn't think it would be that bad. What speeds?

I was wrong on my cam back then, I tried to get the specs from my engine builder, but he has it filed away and he is too busy for me to bother him to look it up.

Now I definitely know my boat isn't running right. Last time out I couldn't turn over 4500 rpm and go over 40mph with $100 reman 23 pitch. The motor was out over the winter having the fiberglass repaired on the bottom of the boat. I discovered two nights ago that the throttle cable was totally out of wack, not letting the choke close and I'm sure not letting me get full throttle. Before the motor was taken out this winter I had tons more power and could turn a damaged 21pitch over 5000 rpm with throttle left, leaving me guessing.

Process of eliminating and a couple more years and I might get this tub running right yet.

I think I will trade in my repaired 21 pitch and pick up something more.

 

[Roadrage]

Re: upgraded 4.3 Prop suggestion

dsmmace Where did you get the engine work done in toon town ???
I am curious to what $$$ your upgrades Cost as to Increase in perf ...
I would also like to increase the hp of my v6.
If a simple intake,carb & cam can give me satisfaction . without increasing the CR . Only have 200hrs on boat . but wish i had had v8 from the start.
My lil v6 like the fuel as much as a v8 i think?????
I was thinking a v8 swap & sell off my v6 to my buddy & try & lessen the blow $$
Cant see me selling boat . I like it too much ...