4.3 2bbl. Trying to get a few more mph!

[walleyejunkie889]

Hey fellas, I have a 92 trophy 2359 with a 4.3 2bbl. Of course these earlier trophies were very underpowered and tough to plane. Mine will cruise at about 21-22 mph. Is there any way possible to add 2-3 mph to my cruising speed? I saw some mods involving the fairly easy 2bbl to 4bbl carb and intake swap. Looking for any input!

Thanks
-Nate

 

[Mischief Managed]

Assuming you are not at WOT already, just push the throttle a bit further forward until you get the extra 2-3 MPH

 

[Rick Stephens]

There are a lot of mods available for the 4.3 from intake and carb, fuel injection, Vortec top end (all by itself the Vortec heads add 25 HP or so)

All of them depend on how deep yer pockets are.

 

[walleyejunkie889]

There are a lot of mods available for the 4.3 from intake and carb, fuel injection, Vortec top end (all by itself the Vortec heads add 25 HP or so)

All of them depend on how deep yer pockets are.

Well Rick, looking to spend within 500-1000 on it. More or less anything short of upgrading to a 350(unless I find a good used complete setup). Would that 20-25hp gain get me there? Or be hardly noticeable?

 

[Bondo]

Ayuh,... Welcome Aboard,...... What are yer rpms at Wot, 'n with what pitch prop,..??

A rebuilt set of Vortec heads, a matchin' intake, 'n a 1409 carb, is what I'd do,.....

 

[walleyejunkie889]

Bondo, I'll get back to you on WOT rpm this week. Not sure of the prop pitch. The stamped numbers aren't obvious so I'll look at it tomorrow. As for the head swap, what will I need besides an upgraded intake? Cams? Electronic fuel pump?

 

[Scott Danforth]

Your cam and fuel pump is fine. However as Bondo indicated, Vortex heads, 4-bbl inake and a 4-bbl carb will get you a few more ponies

 

[walleyejunkie889]

If I added the heads, the 96 and newer intake manifold would be needed, correct?

 

[Scott Danforth]

yes

 

[walleyejunkie889]

With a wot run I can get it to about 25mph at 4800rpm. Cruise 21ish @ 4k. Can't quite make out the prop but it says 18-16440-16. 16 pitch I believe. Any input on prop selection or do these rpms seem good?

 

[NHGuy]

Verify the combustion chamber size on the heads, get smaller chambers because they make higher compression. Search around for a thin marine rated head gasket set too for the same reason. Vortec heads are very efficient and since boats have relatively cool running temps you can go for a couple of extra horses with those choices.

 

[Bondo]

16 pitch I believe.

Ayuh,.... Do the Vortec swap, 'n ya might be comfortable with a 17" pitch, possibly taller,.....
The 4.3 likes bein' proped to 4800 rpms,.... Wild, trimmed, 'n Flyin', maybe touchin' 5 grand occasionally,...

Sounds like a big heavy hull,... gonna take a big blade prop to push 'er,...

Which gear ratio ya got in the drive,..?? 1.8:1,..??
If the 1.6:1, droppin' to the 1,8:1 might help,....

 

[HT32BSX115]

Hey fellas, I have a 92 trophy 2359 with a 4.3 2bbl. Of course these earlier trophies were very underpowered and tough to plane. Mine will cruise at about 21-22 mph. Is there any way possible to add 2-3 mph to my cruising speed? I saw some mods involving the fairly easy 2bbl to 4bbl carb and intake swap. Looking for any input!

Thanks
-Nate

Don't forget that you have a nearly 24ft (very heavy) boat powered by a V-6.

With your current power, it IS underpowered.

Regardless of what you do to that engine (excepting a supercharger) , your cruise is not going to change much.

You would however get a much better holeshot and cruise performance by going to a 350.
(and for a big heavy boat like that, I would also go to a Bravo III)

All it takes is money!