Mods for Merc 4.3L MPFI?

[kyle f]

OK, being that I am a car guy, I think Stock sucks!

With that said, I have tinkered on many a car and tossed all kins of bolt ons at them. I have the 220hp 4.3L FI Alpha 1 on my 2006 Sea Ray 195 Sport with a 19P Stainless 3 Blade Prop.

On the List for the winter is a Wale Tail for the Out board and I am considering a 4 Blade Prop and maybe going up to a 20 or 21 pitch Stainless. I love my power out of the hole as primarily we use the boat for water sports, but we do some high sped trips as well. Any advice here is welcome.

Though main point for this thread is what can I do to the engine... are there bolt ons for this engine they way there are for cars? Such as any kind of Cold Air kits, better air filters, computer programmers, intake manifolds, throttle bodies, heads... etc etc?

Can I use some parts designed for the GM 4.3 Trucks? If so, what year do I need to specify? I woul really like to get inot the 260hp range, or atleast make the boat pull like its got it. Right now I can run 45mph with 4 adults and a 1/2 tank of fuel. Would love to be able to get it up to 50 without losing any bottom end.

 

[Bondo]

Re: Mods for Merc 4.3L MPFI?

OK, being that I am a car guy, I think Stock sucks!

Ayuh,.........

And you've got Alot to learn about Boats,..........

Without some Major internal engine Modifications,.......
You're Dreaming,.... It Ain't gonna Happen,.... Period,..... End of Story.......

260hp,..??..??....
No Way 40hp will get you 10mph...............
That 220hp is about a Good as it Gets for the 4.3ls....

Hole Shot,...... Forget it with the Bigger SSteel Prop........

A 350mpi Might get you where you want to Be...........

 

[Limited-Time]

Re: Mods for Merc 4.3L MPFI?

The only thing better than cubic inches, is more cubic inches!!
Go big or go home.

 

[kyle f]

Re: Mods for Merc 4.3L MPFI?

Wow, now I know what the V6 Mustang guys feel like.


So, there is no way to get power out of a 4.3 because it lacks cubes... and I got a lot to learn?

Go look up... Buick Grand Nationa/GNX

More specific to this engine, look up a GMC Cyclone.

Though, thanks for slamming me without answering anything I asked...what a way to welcome a new member.

 

[Limited-Time]

Re: Mods for Merc 4.3L MPFI?

Dude, no attack meant. Just trying to tell you your dealing in two different worlds. Try this on for size, go down to your local lake or beach and run in 6 inches of water. Then do the same on dry pavement. Now figure how much more power it will take to to duplicate your dry land speed in the water. Just for fun run the National with the rear brakes locked and a parachute attached and see hows long that turbo'd V 6 lasts. BTW welcome aboard.

 

[Don S]

Re: Mods for Merc 4.3L MPFI?

How often does a car go up a steep hill, in first gear only, and under full load, at 4000 rpm, for hours on end.

That's what a boat engine does.

No one was "Slamming" you, just trying to explain the difference between automotive and marine. And this is only the tip of the iceberg of differences.

 

[180shabah]

Re: Mods for Merc 4.3L MPFI?

Yes you do have alot to learn, neither the GN nor the Cyclone have water jacketed exhaust. When you run cams with larger amount of valve overlap, they start to suck water in and that ain't good.

In a boat you need to be more concerned with torque than max hp.

your proposed prop change is not a good idea, it will take forever for you to get on plane(if at all). lugging your engine like that is the worst thing you can do to it.

230-240 hp on a balance shaft 4.3 is about max in a boat. This will either require a serious amount be spent on tuning(there is almost zero, aftermarket EFI support for the 4.3) or convert to a 4bbl carb, new intake manifold and a VERY SLIGHTLY more aggressive cam.

End result = 2-3mph and almost no difference in hole shot.

The whale tail Waste of money, dangerous in some situations. Take the money you are not spending on the engine and get a set of trim tabs.
$100-150 gets Smart Tabs
$500-600 gets manually adjustable Tabs

Toughen up there chief, nobody is trying to attack you, just trying to stop you from wasting a small fortune and possibly destroying your engine.

 

[kyle f]

Re: Mods for Merc 4.3L MPFI?

Yes, I understand all of that. I am a degreed Mechanical Engineer.

All I am saying is... marine or automotive use.. a combustion engine is a combustion engine. More air+more fuel= more power when mixed properly.

I would figure there is a good bit of HP available if cooler air could reach the engine. Breathing inside the engine compartment can't be good for performance. I would think there would be kits out there for the most popular of boats. Not saying that the 195 warrants that spot... but still a way to get cool air... without getting water to, would probably be a benefit. Some sort of header system that smooths the exhaust flow a bit more than the stock manifolds would be nice as well. I know water has to pass through them, but as popular as the 4.3 is on the smaller sport run abouts, I would think something would be available.

I also know that a 4 blade prop is more efficient that the 3 Blade, and adding a whaletail (hydrofoil) helps the holeshot to get up on plane faster. So, I was thinking if I could get 10 or 20 more hp, switch to a more efficient prop, add the whaletail, and just slightly increase the pitch I should keep what I have now on the bottom end and be able to get that extra 5mph on top end. Not just from power, but from better hydrodynamics as well.

I just have to say... Stock sucks and adding anything or more power than stock makes me feel better as a redneck.

 

[superpop]

Re: Mods for Merc 4.3L MPFI?

To answer your question nicely and with a cherry on top, no there is nothing more you can do to your motor to get more speed. A boat motor is very different than a car motor primarily because the boat has no transmission that reduce the RPM's as the boat gains speed. So the torque curve is different on a boat. If you ran the Grand National at 4800RPM's for 2 hours it would most likely explode. A boat motor has been designed from the boat drive manufacturers to provide a pretty specific HP Range and bad things happen when you deviate from this. You could prop it differently but then the top end would suffer for more hole shot or vice versa. Make sure that anything you do is USCG approved or you will have the potential for serious injury or death when the boat blows up. There are several factors to consider when doing anything on a boat with the primary concern being fire and explosion. You already have the most HP that Merc could safely squeeze out of that motor.

 

[pjrogers]

Re: Mods for Merc 4.3L MPFI?

Fairly simple answer: to be useful in your boat, your 4.3L has to make its power inside its RPM operating range, which tops out at, what?, 4,800 I think. The RPM range is important - your outdrive will happily self-destruct if made to spin too fast. To make more power within the RPM range, the engine has to burn more fuel per unit of time than it does now. To get more fuel to burn, it has to have more air going into the throttle body. You can either turbocharge or supercharge in order to achieve the necessary airflow. Since this is a marine engine (ie: it operates in a closed poorly ventilated compartment prone to explosions) anything you add onto the motor has to be marine rated. Google turbocharger or supercharger and marine engines, and you'll quickly learn that the cost of adding one of those things to your little 4.3L will wholly outstrip the cost of re-powering the boat with something that will satisfy your need for speed.

Doing things like polishing the valve ports or installing lightweight titanium this-and-thats that are common in the auto world might add a couple percent more horsepower to your marine engine, but the practical effect of that increase when the fibreglass meets the water, is negligible. That's because the drag of the water on your boat's hull is so great, and increases non-linearly with speed, that a few extra horsepower translates into a speed increase easily offset by a bit of headwind or a ill-trimmed outdrive.

BTW, if no one else says it first, don't waste your $$ on a whale tail. Get a set of SmartTabs instead. I had 'em on our 18' very light weight bowrider with a 4.3LX, and they made a new vessel out of that boat. I'll put a set on our current boat, a SeaRay 23' B/R w/ a 6.2MPI next season. SmartTabs will: make your boat levitate with almost no bowrise out of the hole; allow you to stay on plane at much lower speeds; smooth out the ride in chop; reduce high-speed instability; and allow your boat to track straight at idle. Everything you might read about SmartTabs here is absolutely true. The only thing you have to watch out for is beaching - if the tabs get backed into sand, they're a bear to dig out (DAMHIKT

Cheers, pjr

 

[Tail_Gunner]

Re: Mods for Merc 4.3L MPFI?

Ayuh,.........

And you've got Alot to learn about Boats,..........

Without some Major internal engine Modifications,.......
You're Dreaming,.... It Ain't gonna Happen,.... Period,..... End of Story.......

260hp,..??..??....
No Way 40hp will get you 10mph...............
That 220hp is about a Good as it Gets for the 4.3ls....

Hole Shot,...... Forget it with the Bigger SSteel Prop........

A 350mpi Might get you where you want to Be...........

Ummm what has he been named the Chaumont Buthcer........


But listen close you cant go wrong...."Aside from Soda bottles"...


No matter where you go you will end up in a dead end, boat motor's are pretty strung out already for there application. While it maybe possible to do some electronic ECM stuff no one will touch it due to liability, and as Bond-o once told me your going to run into exhasut flow issue's in the end anyway's, so dont bother and he was right.

Ill give you a real living example going on right here in these forum's, RC const has the very same boat i have, only difference is he has a 350 and 4bl carb doing what RC 300-350?? and i have a 4.3 efi doing 220. And to take it a bit futher he has my old prop which is a 22 pitch 4 blade ss, last i heard he was doing 59 mph with it @ 4800 rpm, i could only get it to turn 53.5 @ 4400 rpm big diff huh. and yes the boat's are identical.

Sometime's the guy's are short, but there is no malice and they give some of the best advice you will find anyplace ohh and it's free, Welcome aboard..just stay away from the Soda Bottle's.....



Hmmm take sometime and relax lot's of good stuff around here like Rubber Frog's BOOM CHICKY WOW WOW Thread............

Or RP's show me your blower thread....

 

[kyle f]

Re: Mods for Merc 4.3L MPFI?

The Smart Tabs look like a good option. The SR 195 is pretty heavy for its size once loaded with gear and makes it difficult to pull a tube or wake board at a lowe speed for the youngsters.

I was reading an artile before that said using both the whale tail and trim tabs is beneficial as well. I mean heck, the whaletail is only $30. The trim tabs aren;t that bad either.

 

[180shabah]

Re: Mods for Merc 4.3L MPFI?

I would figure there is a good bit of HP available if cooler air could reach the engine. Breathing inside the engine compartment can't be good for performance. I would think there would be kits out there for the most popular of boats. Not saying that the 195 warrants that spot... but still a way to get cool air... without getting water to, would probably be a benefit. Some sort of header system that smooths the exhaust flow a bit more than the stock manifolds would be nice as well. I know water has to pass through them, but as popular as the 4.3 is on the smaller sport run abouts, I would think something would be available.

It would be nice, but there really isn't anything out there. If you want to feed your engine coole air, stop over thinking it. Install an additional forward facing scupper with a 3 or 4 inch duct that dumps right infront of the engines ari intake.

I also know that a 4 blade prop is more efficient that the 3 Blade...

Not so. Actually it is the other way around, a 2 blade prop would be more efficient than a 3 blade. However, a 4 blade will provide more initial bite, thus faster hole shot.

and adding a whaletail (hydrofoil) helps the holeshot to get up on plane faster.

True, but they lift from the center and that is inherrently unstable at speed. Also, the faster you go, the more lift that they generate. Guess what that does? Lifts the stern too much, which pushes the bow down. Kills your top end speed, and can cause you to lose control in a turn as the stern comes completely out af the water and the boat pivots on the bow. Lotsa fun on a PWC, not so much in a boat with family aboard.

So, I was thinking if I could get 10 or 20 more hp, switch to a more efficient prop, add the whaletail, and just slightly increase the pitch I should keep what I have now on the bottom end and be able to get that extra 5mph on top end. Not just from power, but from better hydrodynamics as well.

10-20hp is almost meaningless.

The 4 blade prop and the hydrofoil will both decrease your top end. So again, your are looking for an additional 100 hp or so.

Stock sucks and adding anything or more power than stock makes me feel better as a redneck.

All I can say is go ahead and do it, I wouldn't want you to feel bad about your self. Post your results here next summer and we can all help you fix it.

 

[QC]

Re: Mods for Merc 4.3L MPFI?

180shabah is pretty much all over this. For speed, you want less stuff in the water Skip the whales tail, go with the tabs. Get as much weight out as you can. Three blades are better for top speed. You need 'em V8 . . . (notice a pattern here?). Like Don said, no slammin' . . . BTW, welcome to iboats!! It's just that we have answered a brazillion of these threads, and seen a lot of humpty dumpties that needed to be put back together. If you want instant fun, and don't care what happens, go nitrous.

And just to show that we'll challenge anything even from guys that have been around . . . even guys from the home of the best brothers in NASCAR.

In a boat you need to be more concerned with torque than max hp.

That's simply not true. 100% the opposite in a marine application. That's why Marine manufacturers rarely even note torque numbers. Increased peak torque will help hole shot, and more torque at higher revs will raise horsepower, but you need 'em mo ponies to make 'em go fasta . . . I think the rule of thumb between 50 and 60 is $1K per 1 MPH. It gets worse from there . . .

 

[MikDee]

Re: Mods for Merc 4.3L MPFI?

Just as a point of reference, a few years ago, I picked up a 79'-20' SeaRay Bowrider with a 228hp/305 4bbl Chevy Mercruiser that was a clean lake boat, never bottom painted. I used it in salt water on Long Islands Great South Bay. I put late model center outlet risers, and Thru-hull exhaust on it, Champion plugs, Borg Warner spiral core metallic suppression wires, generic synthetic blend oil 10-40W, richened out the carb mixture screws to the max, waxed the hull, ran a 14X19aluminum prop, and kept it in dry rack storage, When it was dropped in the water, it would regularly do 45-48mph at full trim,,, at one time when I put a new 14X19" aluminum Merc Black Max prop on it, I got it to 50mph! I just wanted to show you that a combination of conditions, & little mods do help. It was a great boat, but when fully trimmed out became a bit skittish, because the deepest part of the vee was in the middle of the boat, and it was less vee at the transom, but this did help speed wise. I only sold it to put the money towards a good deal I got on a 79'- 24' SeaRay Cuddy with a 350/260 Mercruiser for some overnighting with my girlfriend at the time

 

[Bondo]

Re: Mods for Merc 4.3L MPFI?

Though, thanks for slamming me without answering anything I asked...what a way to welcome a new member.

Ayuh,........ Sorry Dude,..... No Slam intended,......

With over 13,000 posts,........ All typed with 1 finger,.....
My posts tend to be Short,+ Too the Point........................
Along with Truthful,+ Correct,...............................................Usually.......

 

[Firestar]

Re: Mods for Merc 4.3L MPFI?

Here is a thread on Whale tales. They are dangerous in certain settings. I know from personal experience. Read the 11th post on the thread.
.
http://forums.iboats.com/showthread.php?t=219155

Here is a site to check out for exhausts

http://www.imcomarine.com/pages/exhuast.html

Welcome aboard! This is a great place for any info you could possibly be looking for. There are people here with decades of boating experience. Some of them give the advice sugar coated and others right between the eyes. Either way it's good advice!

 

[rodbolt]

Re: Mods for Merc 4.3L MPFI?

as a nondegreed idiot can I make a few observations?
if you think a cold air kit will help simply make a run at WOT with the engine box open/off.
if it picks up then larger venting for the engine compartment may help.
on the 2,3,4 blade thing.
as you add blades you also add rotating drag. my 130 yamaha will spin my 19"4 blade at 4800 and my 19" 3 blade at 5100. blade shape and cup are almost identical between the two.
with the jack plate I can raise the motor higher,trim it out more,place the tabbs full down and take off with the depth sounder showing 1.8Ft and not hit bottom though.
but mostly without some outrageuos expenditures your not going to get much more performance out of the 4.3.
most props that are not surface piercing dont like shaft speeds over about 2500 RPM.much over 3000 RPM and they tend to cavitate very badly so unless you wish to rasie the package and run surface piercing you really cant go a lot higher on your engine RPM.
dunno how many hours you can get at full load and 4800 RPM with the 7-12 PSI of boost its gonna take before the package self destructs but experience says not many.
whale tails work well on some hulls,not worth a darn on others. some props have holes near the blade root to allow extra prop slippage for hole shot. on most the merc props the size can be adjusted with the use of inserts.
trim tabs work well on most V hulls,bennet makes about the best I have delt with.
I know I have only delt with this stuff about 30 years but I did stay in a holiday inn once.

 

[Limited-Time]

Re: Mods for Merc 4.3L MPFI?

as a nondegreed idiot ........................................... but I did stay in a holiday inn once.

Yes,.......................... but was it a Holiday Inn Express??.............. and was it last night??

 

[45Auto]

Re: Mods for Merc 4.3L MPFI?

Hi Kyle F, welcome to the forum!

I think what everyone is trying to get across to you is that boat performance improvements cost several orders of magnitude more than equivalent automotive performance improvements. They're trying to save your cash from learning the hard way. A slightly more efficient air cleaner (by the way, most boats don't even have an aircleaner - usually a spark arrester at the most - not sure about the 4.3), a couple of HP from a programmer, etc, will not make any difference in the real world to your boat. It would most likely be cheaper for you to sell your boat and buy the same boat with a 350 MAG to get in the performance range (50's) you're talking about then to hop up your 4.3 to get the same performance. And as a general rule, reliability is inversely proportional to HP per cubic inch - not a good thing to realize when you're several miles offshore with a storm coming up and throw a conrod with your wife and kids on the boat... Of course, then you'll want to go 60 so luckily they also make the 496 MAG .......... . And if you want to go faster than that you probably should go over to the Scream-and-Fly or the Offshore Only forums and check them out. You have to have a big enough boat to keep the cubic dollars necessary to go fast from sinking it!

The guys that responded to your post aren't trying to slam you. I've been on these forums for a long time, don't post a lot but do a lot of lurking and laughing at many of the posts. But there is also lots of knowledge - Bond-O, Don S, QC and Rodbolt, just to name a few names I noticed in this thread, consistently give excellent advice based on real world experience. Look at some of the past threads in this forum, do some real-world experiments with a GPS on as many different boats as possible (can't count the number of claims where so-and-so's cousin in law changed from NGK to AC sparkplugs and his 4.3 went from 27 mph on a 14 pitch prop to 65 mph on a 28 pitch ....) and make your own call on who knows what they're talking about and what different mods will do.

I think you'll find that talk is cheap, and many 50 mph boats are really 40 mph boats!

Have fun, enjoy your boat - if you're ever in the southern Louisiana area I'd be glad to show you the good boating spots down here!

Keith