How fast does your 4.3L V6 push your boat?

[MikDee]

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?

I kinda thought this was true myself, I think saltwater is denser. I have no way to prove this, but I've boated on salt water all my life, except for the last 6yrs, after moving from Long Island to Pa. it's been fresh water lakes ever since.

 

[mthieme]

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

Sound theory, but in practicality, I think the difference would be negligible.

I did some hydrostatics work for the Navy back in the late 80's. The boats, T-AGS-39 & 40 were 499'10". I forget the tonnage. But I remember the difference between plopping the boat in the middle of Salt Lake (whose salinity varies - forget what numbers I used) and fresh water was 4". One heckuva difference I thought. I suspect if proportionately shrinking the numbers down to a 20' runabout, the performance would not make a noticeable difference.

 

[jkust]

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

After reading the posts, it makes me wonder if the Stingrays really break 60mph with a v6. I was seriously considering buying one this season before buying the Chap. I played around with the speed calculator on the Stingray site and adjusting the prop to a standard 3 blade alum prop, 195l model, same 190hp engine, full fuel tank and matching my boat's weight and my altitude, it is almost dead even with my Chap. It seems to me that either the calculator is conservative or they get their speed from their light weight since the calcs seem to disregard the effects of th Zplane hull and higher transome height or alternatively weight is not as much a factor as I thought. I hope to someday take my boat out with a nearly empty tank and all alone to see if there is any increase in top end.

 

[642mx]

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

Sound theory, but in practicality, I think the difference would be negligible.

I did some hydrostatics work for the Navy back in the late 80's. The boats, T-AGS-39 & 40 were 499'10". I forget the tonnage. But I remember the difference between plopping the boat in the middle of Salt Lake (whose salinity varies - forget what numbers I used) and fresh water was 4". One heckuva difference I thought. I suspect if proportionately shrinking the numbers down to a 20' runabout, the performance would not make a noticeable difference.

At 50 something MPH there isn't much boat in the water. I agree that it wouldn't make much (if any) difference....

Here is whats in the water at 52-54 (can't remember how fast I was going)...

 

[mthieme]

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

There you go!

Looks like you're on a nice calm river.
I'm on the Chesapeake, there's almost always a chop. I don't care what kind of boat you have, at a certain speed you start skipping like a rock over the waves!

 

[642mx]

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

There you go!

Looks like you're on a nice calm river.
I'm on the Chesapeake, there's almost always a chop. I don't care what kind of boat you have, at a certain speed you start skipping like a rock over the waves!

That picture was taken in the canal that connects Kentucky and Barkley Lake. 80% of the time its like glass in the canal, 20% of the time you can barely get thru it alive....lol.

 

[45Auto]

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.

I know what you mean, Mthieme! If you ever get to run against lots of these boats in person, don't be surprised if their boat is having a bad day and "it's just not running right" because they still can't pass you!!

There's an old saying if you've ever done any type of motorsports competition - "WHEN THE GREEN FLAG DROPS THE B.S. STOPS!".

 

[achris]

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

43.1 knots... 19" Vengance prop, one up....

Chris...........

 

[642mx]

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

I know what you mean, Mthieme! If you ever get to run against lots of these boats in person, don't be surprised if their boat is having a bad day and "it's just not running right" because they still can't pass you!!

If anybody thinks my numbers are inaccurate. Come to Southern Indiana and take it for a ride.

 

[Desjer]

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

Sea Ray 185 - 2004 - 190HP 2 barell carbie.
44-45 MPH (speedo not GPS verified). I changed from 23P factory supplied prop to a 4 blade solas 19P because we do a lot of watersports. Much better hole shot now. Top speed didn't seem to change much, but WOT is now 4800, previously about 4300 with 23P prop.

 

[wca_tim]

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

original bone stock 1988 2bbl 4.3 in same boat as above... 48-49 at 4800

new engine, not far from stock, but best combo of stock parts, a little higher compression, 4bbl, good manifold, etc... top speed 60-61 under perfect conditions... )probably 50 hp more than original, and set-up, propped better)

typical top speed under normal conditions and with normal load 55-57

current set-up with 385 ci stroker, normal loading propped for all around, upper 60's. (most likely approaching 200 horsepower added)

ideal conditions and best speed prop, 75+ (so far)

bottom line: a lot of what I've read on here and in other places regarding horsepower and top speed for i/o set-ups is spot on. first upgrade, say 5 mph from hp increase, and another several from set-up, etc... Second upgrade roughly 200 hp, pushing 20 mph increase....

and I'll echo what 45auto eludes to.. most 60(s) mph boats - especially i/o set-ups... are 50(s) mph boats

 

[achris]

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

If anybody thinks my numbers are inaccurate. Come to Southern Indiana and take it for a ride.

I don't disbelieve you.. I would love to run the numbers through a program I wrote....
What size prop are you running?

I'm doing 43.1 knots with a 19" back wheel, 1.62:1 leg and pulling 4800rpm... I get 11.7% slip and a 3.2 degree angle of attack....

Chris.........

 

[180shabah]

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

18' Mariah bowrider with 4.3LX(that's 4bbl - 175hp at the prop) and a 21" Hustler prop
Last tested run was:
1/4 tank fuel, no passengers and glass smooth water

50.1 mph(GPS) at 5050RPM(Dash Tach)
Normal load is 48MPH and 4800RPM +/-

 

[achris]

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

18' Mariah bowrider with 4.3LX(that's 4bbl - 175hp at the prop) and a 21" Hustler prop
Last tested run was:
1/4 tank fuel, no passengers and glass smooth water

50.1 mph(GPS) at 5050RPM(Dash Tach)
Normal load is 48MPH and 4800RPM +/-

Those numbers look good... I get 12.4% slip, and 3.5 degrees angle of attack
I assumed you have a 1.84:1 leg ratio...

Chris.........

 

[642mx]

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

I don't disbelieve you.. I would love to run the numbers through a program I wrote....
What size prop are you running?

Its a 23p Mirage Plus.

 

[mthieme]

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

Those numbers look good... I get 12.4% slip, and 3.5 degrees angle of attack
I assumed you have a 1.84:1 leg ratio...

Chris.........

Cool program.
Curious about all the variables you have programmed in there.
Everything but the layer of barnacles I'll bet (?).

 

[wca_tim]

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

Its a 23p Mirage Plus.

642mx,

I believe your numbers... that's a light, well made hull and should fly with a light, strong-running 4.3 in it...

My best all around performance with the v-6 was with a 23" laser 2, fastest top end was with a vented 26" turbo, but it didn't hold well in turns so I ran the laser the most.

Currently running a 27" mirage plus and best top end to date is with a 29" hydromotive quad iv... I'm running an 1.81 gear ratio.

Before you have your mirage labbed, ou might try a hydromotive quad 4 in 23" or so. I was always told that my check (light, ca. 1400 without power and drive, 17' 6" balsa-cored, padded v-hull) would run faster with a bowlifting prop, so when I tried a neutral / sternlifting hydromotive and it handled like a dream, ran fastest top end, etc... I was suprised. After a little more playing, I will probably wind up with a labbed hydromotive or a bravo. I still porpoise a little with the mirage plus that's on it now.

Hope this is helpful...

 

[180shabah]

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

Those numbers look good... I get 12.4% slip, and 3.5 degrees angle of attack
I assumed you have a 1.84:1 leg ratio...

Sorry, forgot to list the ratio, 1.84:1 is correct.

 

[mylesm260]

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

1988 Regal Medallion 195
19.5' Open bow

Originally came with 2bbl 4.3 rated at 160? hp and when I bought it it had a 19P prop.


Switched engine out for 200 HP (rated in automotive application) vortec 4.3 and switched to a 23P prop

I believe my setup is very close to the current generation of the marine 4.3 (rated at 226 HP)

http://www.gm.com/experience/technology/gmpowertrain/engines/specialized/marine/2009_4300_Marine.pdf

63 MPH (gps) @ 4900 RPM with just me in it

with 5 ppl in it it tops at about 55 mph @ 4500 +/-
with 8 ppl it has a hard time breaking 50 (or at least it did that day)

 

[MikDee]

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

1988 Regal Medallion 195
19.5' Open bow

Originally came with 2bbl 4.3 rated at 160? hp and when I bought it it had a 19P prop.


Switched engine out for 200 HP (rated in automotive application) vortec 4.3 and switched to a 23P prop

I believe my setup is very close to the current generation of the marine 4.3 (rated at 226 HP)

http://www.gm.com/experience/technology/gmpowertrain/engines/specialized/marine/2009_4300_Marine.pdf

63 MPH (gps) @ 4900 RPM with just me in it

with 5 ppl in it it tops at about 55 mph @ 4500 +/-
with 8 ppl it has a hard time breaking 50 (or at least it did that day)

Now That's Cookin!

Wish I knew the specs on that cam? I'd like to put it in My 95' S-10 4.3 TBI which has a pathetic stock roller cam, & balance shaft, rather then any balance shaft Comp cam, thats only available with .500 lift
But, it's like top secret to find the specs, & part # of the factory cam!