4.3L carb Mercruiser upgrade ?

[Tafflad]

I have a Maxum 1800 SR3 with 4.3L carb Mercruiser.

Now I'm assuming that there must be thousands of these engines out there - does anybody make an upgrade kit to boost the hp ?

Bigger carb, rejet existing carb, add supercharger, ... etc.

 

[Tail_Gunner]

Re: 4.3L carb Mercruiser upgrade ?

http://www.edelbrock.com/automotive_new/mc/carbs_acc/performer.shtml

600 cfm, Electric Choke
CALIBRATED FOR PERFORMANCE
Designed and calibrated for optimum marine performance in small-block V8 engines with a variety of manifolds that include Edelbrock Performer, Performer RPM, RPM Air-Gap, Torker II and other brands of similar design. Also ideal for Chevy 4.3L V6 engines with a Performer manifold (see Manifolds) and Calibration Kit #1485. Comes with: Metering Jets ? Primary .098, Secondary .101; Metering Rods ? .068 x .047; Step-Up Spring ? orange (5" Hg).

PERFORMER? MANIFOLDS (Idle to 5500 rpm)
Performer manifolds are dual-plane, low-rise intake manifolds with a 180? firing order and patented runner design that you won't find in other brands. This patented design greatly improves torque over a wide rpm range for excellent throttle response, especially off-idle through the mid-range. Throttle Performers are ideal for passenger cars, trucks, 4x4s, tow vehicles and RVs. There are EGR and non-EGR versions available for most domestic V8 and some V6 engines. Most Performer intakes are 50-state street legal, when used with the correct carburetor and in the correct application. Check the individual listings for detailed information.

And then there's a cam....Only for the brave and well informed..

 

[180shabah]

Re: 4.3L carb Mercruiser upgrade ?

The above is about it too.

It is usually easier/cheaper to just swap a V8 in it's place.

 

[Bondo]

Re: 4.3L carb Mercruiser upgrade ?

does anybody make an upgrade kit to boost the hp ?

Ayuh,...

A Kit,..??..?? Nope....

 

[Tafflad]

Re: 4.3L carb Mercruiser upgrade ?

http://www.edelbrock.com/automotive_new/mc/carbs_acc/performer.shtml

600 cfm, Electric Choke
CALIBRATED FOR PERFORMANCE

QUOTE]




So fitting the carb & intake manifolds is the consideration ... would you know anybody who has done this? .... be keen to find out what improvements they gave.

 

[180shabah]

Re: 4.3L carb Mercruiser upgrade ?

We need to start at the beginning.

What do YOU have now? 2bbl or 4bbl? Regular heads or vortecs?

 

[Tail_Gunner]

Re: 4.3L carb Mercruiser upgrade ?

We need to start at the beginning.

What do YOU have now? 2bbl or 4bbl? Regular heads or vortecs?

Place close attention here and heed his advice

 

[Tafflad]

Re: 4.3L carb Mercruiser upgrade ?

We need to start at the beginning.

What do YOU have now? 2bbl or 4bbl? Regular heads or vortecs?

I have the standard out of the factory mercrusier 4.3L (2006) engine.

So whate ever the standard carb is, that is what I have - no tuning, tweaks or mods have been carried out.

 

[180shabah]

Re: 4.3L carb Mercruiser upgrade ?

You have a 2bbl carb and vortec heads - factory rated at 190hp.

Your engine with an edelbrock 1409(4bbl carb) and edelbrock 2114 performer intake manifold is good for about 215+/- hp. This will set you back $600-700 plus installation, which may or may not require engine removal for access. So figure at least a grand for 25 hp(on paper). This gets you the potential for a 1-2mph increase in top speed and marginal if any increase in planing abililty.

HOWEVER, I believe that your 190hp is severly underated(marketing purposes, gotta sell the MPI's for an extra 2k) and actual power is probably in the 205hp range. Which makes your potential increases even less, but the cost will still be the same. To make any meaningful increases you will need to make internal changes, and the costs will increase exponentially. You will easily spend $3000-4000 on this engine and for marine use the realistic limit is in the 230-240hp range(and this is still with serious risk of reversion) without supercharging wich will add another 3 grand to the bill.

A 5.7 becomes much more appealing at this point. Off the shelf it makes more power than the 4.3 and only weighs 100lbs more. Use an aluminum intake and add a 4bbl and you will be in the 290hp range and recover some of the weight difference.

OR

Sell you boat and get one that already has a V8 and preferrably a Bravo drive. This is probably your best choice, financially.

 

[Tafflad]

Re: 4.3L carb Mercruiser upgrade ?

OK ... good comments and appreciated

When you say it's underrated .. do you mean that it is 'actually' putting out more than 190hp ... or it is capable of that.

A grand for a marginal increase makes little sense, my putting on a High Five prop probably made more difference.

I just thought I'd check ... on a previous car for example, for the cost of a few jets for the carb, and a tweak to valves & timings I got a significant change in performance.


Even did same on sons scooter - new main jet and different variator weights, and removed restrictor and it had massive improvements.

Just thought there may have been some 'trade tweaks' for the 4.3 ... especially as there must be many thousands of them fitted to boats.

 

[MikDee]

Re: 4.3L carb Mercruiser upgrade ?

I had an 86' Celebrity with twin 4.3 V6 OMC Cobras, and back then the 4bbl version was rated for 205hp, and the 2bbl version at 190hp, But, I'm sure that was crank rated HP, nowadays the 190hp, is at the prop, and conservative. I'm sure it would really wake that engine up with a good aftermarket 4bbl combo.

As far as a good cam, I don't know if, or what, is a good factory one to use if it's a balance shaft motor? Aside from some aftermarket cams, all with too much lift to just bolt in without machining the heads for these The 4.3 balance shaft motor is somewhat of an orphan, compared to the cam selection on the small block V8's.

If it's not a balance shaft motor, then one of these tried, & true, proven factory cams will bolt right in, using all your existing parts, & give you about 25hp! So, combined, we're talking about a 50hp increase, not too shabby!

http://www.gmpartsdirect.com/performance_parts/store/catalog/Category.jhtmlCATID=304.html

 

[Tafflad]

Re: 4.3L carb Mercruiser upgrade ?

>If it's not a balance shaft motor

How would I tell what type mine is?

 

[MikDee]

Re: 4.3L carb Mercruiser upgrade ?

>If it's not a balance shaft motor

How would I tell what type mine is?

It should say in the service manual, or maybe the owners manual. Chances are, if it's a 06 motor it is. The auto, & truck motors, have been balance shaft since 1992 I believe, but marine engines usually lag behind in technology, I think the reason is, it has to be a tried, and proven design first, before it goes to marine.

I wish someone would come up with some info or part numbers for some GM hi-perf factory cams for the 4.3V6, (It's like top secret info?!) I'm sure there must be some out there, especially a marine version Because, I have a 95' Chevy S-10 pickup with a 4.3 TBI balance shaft motor, with a dull stock cam, I'd like to upgrade myself!

 

[180shabah]

Re: 4.3L carb Mercruiser upgrade ?

'92 is correct for the introduction of the balance shaft. Merc, VP and OMC got those blacks at the same time because that is all GM was building. The lag is due to "stock on hand" at VP, Merc and OMC. No sense trashing all of those '91 engines just because of a change for the new year. Same thing happened in '96 with real vortec heads. I have a '96 boat, but te engine is a "left over" '95 with the old style heads on it.

There are performance cams out there for '92+ 4.3's. Plan on spending at least $350 for one. However there are a couple of limitations. First, the vortec heads are more prone to reversion (sucking water in through the exhaust)than the old style, so cam selection really can't get to aggressive. Second, the heads themselves have a max lift of approx .470(from memory, but it's close) without machine work, but you still have the reversion issue.

Se we are still talking about a realistic maximum of about 230hp (at the prop).
Of course - you could remove the engine cover, dog house, hatch(whatever you have) and convert to dry exhaust and go for about 300hp, but again a 5.7 would still be cheaper, safer, and much more practical. Plus it just sounds sweet.

 

[180shabah]

Re: 4.3L carb Mercruiser upgrade ?

....Because, I have a 95' Chevy S-10 pickup with a 4.3 TBI balance shaft motor, with a dull stock cam, I'd like to upgrade myself!

The weak link here are your heads. Probably the worst heads GM ever used - EVER

They just don't allow any flow. You've probably noticed there is not much power after crossing 3500RPM. Even with the stock cam, a set of vortecs will really wake it up. Of course that also will require a new intake manifold. And since you've got it apart it just makes sense to upgrade the cam. Just get one from a big name(Comp, Crane etc.) and they usually include a PROM at no charge.

 

[Tafflad]

Re: 4.3L carb Mercruiser upgrade ?

The weak link here are your heads. Probably the worst heads GM ever used - EVER

They just don't allow any flow. You've probably noticed there is not much power after crossing 3500RPM. Even with the stock cam, a set of vortecs will really wake it up. Of course that also will require a new intake manifold. And since you've got it apart it just makes sense to upgrade the cam. Just get one from a big name(Comp, Crane etc.) and they usually include a PROM at no charge.

Is there one company I can go to to get all parts needed .. I am not in the US, so would prefer to use a single US dealer that would have all necessary parts.

Realistically ... to be worthwhile am I looking at new carb, heads, intake manifolds & cam.

This sounds like a significant job ... covering the mechanics swap over would be reasonably OK, what about set up information ? .... timing for new cam, tuning for carb ?

 

[180shabah]

Re: 4.3L carb Mercruiser upgrade ?

This is not an "upgrade" that has much industry support, so if you must do it, you will have to piece it together. There is no kit. As for shopping from a single retailer, I'm sure it is possible, but you will need to know what you want, including part numbers, before hand.

I know I already said this, but the best you can hope to net is about 30 or 40hp, IF you do everything mentioned above at a cost of $3000-4000USD. 30-40hp WILL NOT make a significant difference(maybe 3+/-mph and almost no change in acceleration) in a boat. This just doesn't sound like a great "investment".

I still think a V8 swap(or a different boat) would be a better solution. Just as an example you could look at the 5.7 vortec engine - Gold package from michiganmotorz. It includes manifolds, carb, and ignition for $5000USD. You could reuse your starter, alternator, PS pump, coupler etc. from the 4.3, they are the same for both engines. Sell your 4.3 to recover some of the cost. Buy a new upper unit with a 1.47:1 gear ratio from SEI and sell your old upper and probably break even or possibly even make money on this one.

Then go enjoy a 100hp boost for the same or less money, plus it will have increased resale value with the V8 in it. And sound WAY better.

 

[MikDee]

Re: 4.3L carb Mercruiser upgrade ?

The weak link here are your heads. Probably the worst heads GM ever used - EVER

They just don't allow any flow. You've probably noticed there is not much power after crossing 3500RPM. Even with the stock cam, a set of vortecs will really wake it up. Of course that also will require a new intake manifold. And since you've got it apart it just makes sense to upgrade the cam. Just get one from a big name(Comp, Crane etc.) and they usually include a PROM at no charge.

The worst heads for the V6, I don't think so? From what I understand the TBI (mine), & the CPI, on the 95' 4.3 have the same heads, and they're not bad, not as good as 96' Vortecs, but the main hp difference is the better Cam in the CPI motor. I'm really just looking to get more torque out of it mainly, for towing. It's bad enough the 2WD Automatic all came stock with a 3:08 rear!

Quote from a reply at the S10forum, where the 4.3 V6 is discussed mostly:
"1994-?95 TRUCK WITH TBI OR CFI, EXCEPT HEAVY DUTY: The top angle for the intake seat was changed from 8? to 30? and the throat was opened up from 75? to 80? to give a 10% increase in intake airflow for better performance in ?94. The same heads were used on both the TBI and CFI engines through ?95."

Also, The TBI "Z" code has 160hp, and the CPI "W" code has 195hp, The 95' "W" cam must produce the extra 35hp.

 

[BrettBBonner]

Re: 4.3L carb Mercruiser upgrade ?

While I know this is late, but I did this maybe 8 years ago. The magazine "Trailer Boats" did an article about this. The Trailer Boats article said better fuel efficiency, higher speed, but slightly less torque and slighly longer time to plane.

My runnabout boat is a 1991 180SE Glassstream. It's a heavy boat for that much original engine. I chose to upgrade in the hope I could get pulled up easier on salom. I'm a big guy - OK - fat guy.

The manual that came with the boat was a 1990 manual. My engine was a 2bbl. If I remember correctly, it was rated for 175HP and called the 4.4L. I believe Mercruiser offfered a 4bbl that year rated at 195HP called the 4.3LX. The LX had a higher gear rating as well. Anyway, I replaced the manifold and carb and used the 4.3L calibration kit. When first testing, I had to go 2 steps richer on the jets to keep it from missing at full throttle. You have to buy these separately.

Well, it made a BIG difference. Much lower fuel burn when cruising and messing around. Much faster time to plane. Much higher top end. I have both an Aerostar and a TorqueShifter variable pitch prop. I had to increase the upper pitch of both to keep from overspeeding the engine. I don't use the TorqueShifter anymore, but I had to run out the stops from 22 inches all the way to 26 pitch. The TorqueShifter is overall a faster and more efficient prop than the Aerostar, but the Aerostar doesn't vibrate. The Aerostar shifts from 17 to 23 pitch.

Experienced boaters can't believe the boat is a 4.3L.

My only problem is the engine leaks oil from the intake manifold around the distributor as a result of this upgrade. I just bought a new gasket kit and the task this winter to get this resolved.

I do recommend this upgrade. It is well worth it.

 

[gettin'even]

Re: 4.3L carb Mercruiser upgrade ?

If you are looking for the power that a V-8 has to offer, you may be money/effort ahead selling your boat, and buying a boat with a V-8.
If you are looking for a few extra ponies, I would suggest contacting a custom cam builder, and have him grind an appliction specific cam. He will also tell you what carb and intake combo to use.