How fast does your 4.3L V6 push your boat?

[smitty1258]

Re: How fast does your 4.3L V6 push your boat?

ok, after reading all this I think there is something wrong with my boat!

180hp 4.3l LX

I can hit 40mph only on the calmest day with only myself and half a tank or less running around 4300 rpm.

With 2-3 ppl onboard with gear I can get 36-38mph about 4300 rpm.

21p prop, not sure on the ratio how do I find that out?

And how fast should I be able to get to?

 

[oops!]

Re: How fast does your 4.3L V6 push your boat?

'69 Searay with a Cobra I/O, 21P prop - 34 knots.
I tried a 19P prop Monday (because it was free and I wanted to see what would happen) - lost 3 knots at 3000rpm.
But the hole shot was better and she planed off quicker.

that ray looks like an srv 190.....thats exactally what the boat in the hull ext thread is/was.......fantastic boat !

it came stock with an inline 6

 

[642mx]

Re: How fast does your 4.3L V6 push your boat?

ok, after reading all this I think there is something wrong with my boat!

180hp 4.3l LX

I can hit 40mph only on the calmest day with only myself and half a tank or less running around 4300 rpm.

With 2-3 ppl onboard with gear I can get 36-38mph about 4300 rpm.

21p prop, not sure on the ratio how do I find that out?

And how fast should I be able to get to?

It should go faster than that, but before you shell out $600 on a quality prop, be sure your speeds have been verified with a GPS.

Any 4.3 powered 18-20 foot boat should run 45 mph or more. The gear ratio is stamped on the out-drive, but at this point, it really doesn't matter.

Your engine is maxing out at 4300 rpm, which means it has too much pitch. The target WOT rpm for a 4.3 is 4800. The 21 pitch is bogging it down, so if you went to a 19 pitch, it should be able to spin it harder and hopefully gain some top end along with a better hole shot. Its a good idea to try a prop before you buy a prop, find someone with a 19p and see if they will let you borrow it.

 

[wca_tim]

Re: How fast does your 4.3L V6 push your boat?

before changing props I might make sure the engine is in good tune, etc... and maybe check for water in foam, etc... that is if you have a fairly light boat...

It should go faster than that, but before you shell out $600 on a quality prop, be sure your speeds have been verified with a GPS.

Any 4.3 powered 18-20 foot boat should run 45 mph or more. The gear ratio is stamped on the out-drive, but at this point, it really doesn't matter.

Your engine is maxing out at 4300 rpm, which means it has too much pitch. The target WOT rpm for a 4.3 is 4800. The 21 pitch is bogging it down, so if you went to a 19 pitch, it should be able to spin it harder and hopefully gain some top end along with a better hole shot. Its a good idea to try a prop before you buy a prop, find someone with a 19p and see if they will let you borrow it.

 

[jkust]

Re: How fast does your 4.3L V6 push your boat?

These responses are very informative. Now I wonder why my 2003 mercruiser only has 190 hp when I see some of the other older carb engines are pushing over 200hp. If it is just a 4BBL carb that is the difference, I wonder why my engine doesn't have one. It seems like that should be a standard considering just having a carb is to me such an outdated concept. It has been 20 years since I have had another carbed vehicle, I can't even recall the ways to squeeze more HP out.

Then I wonder why my Chap is so darn heavy compared to the others too. I am guessing the 500 or so extra lbs compared to the Stingray for example must slow it down somewhat. It sure takes chop good though.

 

[mthieme]

Re: How fast does your 4.3L V6 push your boat?

that ray looks like an srv 190.....thats exactally what the boat in the hull ext thread is/was.......fantastic boat !

it came stock with an inline 6

Yep. Right on both counts. Thanks for noticing.
She was repowered in '89 with a NEW OMC 4.3 and NEW I/O...fresh water cooled too. The interior was original and pristine...garage kept.
The previous owner had the transom redone to accomodate the new I/O. It's about 3/4" thicker than factory.
I have the receipt - just shy of $10K.
It was then rewired and had the aluminum fuel tank replaced with a plastic one. It had 20 hours on all that when I found her...it didn't even have under the doghouse.
The guy died and his son sold it. I wrote a check instantly ($3,500). No brainer.
Did I mention the tires on the trailer still had the stickers on the tread - including a spare?
She's been an excellent boat. I've taken her all the Chesapeake and been out in 5'-6' seas.
Only in the past two years have I had to put any money into her...new interior, some options (radio, electronics, bimini, swim platform, replaced zinc fittings, cleats, chocks with SS, starter, PS heat exchanger, PS pump).

 

[mrmushroomman]

Re: How fast does your 4.3L V6 push your boat?

1995 Sea Ray 4.3lx (205hp). I can hit 50-52mph with rpm's at 5000-5100. Yes i know it's a little high. I am running a 23 pitch aluminum prop. I'm thinking of trying out a 21 pitch to see if i can get wot rpm's down a little. That is with 2-3 people and half tank of gas with ski locker full of equipment.

 

[fivetaylor]

Re: How fast does your 4.3L V6 push your boat?

92 Sea Ray 200 BR (20') with 4.3LX (4bbl) (Recently purchased)
SS 21" Pitch prop.
Spec sheet says HP is (205/175 HP) assuming 175 at the prop.

Top speed of 48MPH (4800 RPM) (GPS and Speedo) with 2-3 people.
Top speed of 44/45 MPH (GPS and Speedo) with full load (8 people).

Cruises nicely at a bit over 30MPH at ~3500RPM.

 

[Pierutrus]

Re: How fast does your 4.3L V6 push your boat?

1995 Sea Ray 4.3lx (205hp). I can hit 50-52mph with rpm's at 5000-5100. Yes i know it's a little high. I am running a 23 pitch aluminum prop. I'm thinking of trying out a 21 pitch to see if i can get wot rpm's down a little. That is with 2-3 people and half tank of gas with ski locker full of equipment.

Going down in pitch will raise your rpm's @ WOT not lower it.
With my 21 pitch alum, my WOT rpm's are at 5000.
I have a 23 pitch alum that I bought to try out and it put WOT at around 4300.
So I'm gonna run it down to the prop guys and have them re-pitch it to 22 to see if I can bring up the rpm's to around 47-4800. That would be the sweet spot.

 

[mthieme]

Re: How fast does your 4.3L V6 push your boat?

1995 Sea Ray 4.3lx (205hp). I can hit 50-52mph with rpm's at 5000-5100. Yes i know it's a little high. I am running a 23 pitch aluminum prop. I'm thinking of trying out a 21 pitch to see if i can get wot rpm's down a little. That is with 2-3 people and half tank of gas with ski locker full of equipment.

That's a lot of rpm for that motor.
My 21P gives me 4400 rpm which I'm happy with, but I'm 170 hp.
Trade ya!

 

[QC]

Re: How fast does your 4.3L V6 push your boat?

A 21P vs. a 23P will make your RPM go UP . . .

 

[DaveM]

Re: How fast does your 4.3L V6 push your boat?

Interesting stuff. My 1994 Volvo looks to be the one filling in the bottom of the power band with 160 hp.

VP 4.3L GL-SX, 2bbl carb and 17 pitch prop pushes my 20' Excel to 43 MPH (speedo only, no GPS) at 4800 RPM.

 

[MikDee]

Re: How fast does your 4.3L V6 push your boat?

Those little high output 4.3 V6's can really kick butt!

I had a 79'- 20' SeaRay bowrider with a 305 4bbl/228hp Mercruiser (that was a lake boat), no bottom paint, and I waxed it, plus I ran thru-hull exhausts, synthetic oil, idle screws out to highest speed (richest point), and the best I ever did, when fully trimmed out, with a brand new Black Max aluminum prop on it, was 50mph!

There's must be something to that 6cyls. larger 4" bore, less cylinders, less friction idea!

 

[Hiliner222]

Re: How fast does your 4.3L V6 push your boat?

1974 HiLiner Gypsy- 3500 lbs avg running weight- 1998 4.3 LH 4bbl 205HP Alpha 1 GenII 1.62 gearing. WOT should be 4400-4800 according to the OEM manual. This is a great thread for me because I just spun a prop a few weeks ago and have been tring to find the perfect new one. I am now running a 15x15 3 bladed aluminum prop that gets my RPM's up to 4000 max. I cant get the top end speed over 30.0 via gps. Think I may be underpowered?

 

[mrainey889]

Re: How fast does your 4.3L V6 push your boat?

1990 Rinker V180, 175hp 2-barrel 4.3 liter v-6. With a 20p 4-blade merc prop I am hitting about 44-45mph (gps verified) trimmed out. I might get 46mph on glass water lightly loaded. Currently I am over-revving about 200rpm (5000rpm), however the only other prop I own is a 23p 3-blade that came with the boat that I recently had rebuilt. My guess is that is too much pitch, but one of these days I will try it out and see what happens.

Mike

 

[642mx]

Re: How fast does your 4.3L V6 push your boat?

Those little high output 4.3 V6's can really kick butt!

I had a 79'- 20' SeaRay bowrider with a 305 4bbl/228hp Mercruiser (that was a lake boat), no bottom paint, and I waxed it, plus I ran thru-hull exhausts, synthetic oil, idle screws out to highest speed (richest point), and the best I ever did, when fully trimmed out, with a brand new Black Max aluminum prop on it, was 50mph!

There's must be something to that 6cyls. larger 4" bore, less cylinders, less friction idea!

The 4.3's do run pretty good. I have a friend with a 21 foot Sea-Ray bow rider with a 305 V8. Loaded he can only run 46 mph, with just 2 people and low fuel he can get 50 mph. Of course I don't rub it in when I come blowing by him with my V6....lol.

 

[Dante04SRT]

Re: How fast does your 4.3L V6 push your boat?

I was a little confused when we took our 2007 20' Ebbtide out for the first time. I thought it should be doing faster than 44-46mph at WOT with the 21p prop. I knew it was heavy at 2900lbs, but I still thought 50 was attainable. Oh well. I guess thats the price you pay when you've only got a 2bbl on a boat that will hold 10.

 

[mthieme]

Re: How fast does your 4.3L V6 push your boat?

I'm amazed to hear all these numbers. So far, mine is the second slowest. Everyone seems to be 10-15 mph faster, but no one seems to be passing me.

 

[jkust]

Re: How fast does your 4.3L V6 push your boat?

I read in a boating magazine recently that the same boat/engine set up run in salt water will boast higher top end due to more buoyancy versus fresh water. Seems like common sense but I have never run in salt water. Anybody actually experienced a difference?

 

[acke61]

Re: How fast does your 4.3L V6 push your boat?

91 Rinker open bow, unknown rpms because my gauge is 1500 rpm off or so...

21 pitch alum prop 48mph on speedo...

my boat was repowered in 2005 with a jasper crate motor so i'm unsure if its a 175 or 190 hp... def not 200 or 210 because its a 2 Barrel