1989 Mercruiser 4.3 V6 2Barrel 175HP - UPgrade Question

[jmw129]

I would like to know what amount of HP increase I should expect if I did the following change out on a 4.3 2-Barrell rated at 175hp..

Put rebuilt or used 4.3 Vortec heads + 4 barrel Carb, and intake designed for 4-barrel & added performance.

How much HP increase should I expect?

Can I get the heads, intake, and 4-barrel carb off a GM 4.3 (Auto) application? Junk yards maybe my best friend for this upgrade I hope!

The parts would come from various sources to keep cost down to the min as I realize people can waste alot of money on these parts if they are not careful (my opion) of course. I could be wrong.

Thx!

 

[Struc]

Re: 1989 Mercruiser 4.3 V6 2Barrel 175HP - UPgrade Question

Marine manifold is a good idea. Carb must be marine. Anything out of a boneyard will be for some sort of fuel injected engine.

http://www.michiganmotorz.com/vortec-intake-manifold-1996current-p-91.html

Heads are the same - get them off Ebay, Craigslist, boneyard, etc.

 

[Howard Sterndrive]

Re: 1989 Mercruiser 4.3 V6 2Barrel 175HP - UPgrade Question

typical power increase about 20HP going to a 4 barrel.
I don't understand the part about heads. You should already have vortec heads on that 4.3

if salt water not an issue, you can use an Edelbrock EDL 2111 aluminum intake and the Edelbrock 1409 carb - that's a popular combo for converting to 4 barrel. They have a kit to de-tune the 1409 carb to V6 cfm's

 

[thumpar]

Re: 1989 Mercruiser 4.3 V6 2Barrel 175HP - UPgrade Question

Vortec heads didn't come around until 96. The intake is different for standard and vortec head so decide on heads before you go to upgrade the intake. One thing to keep in mind is that the 92-95 engines have the vortec name but are not the vortec 8 bolt intake heads so watch out when looking.

 

[jmw129]

Re: 1989 Mercruiser 4.3 V6 2Barrel 175HP - UPgrade Question

Vortec heads didn't come around until 96. The intake is different for standard and vortec head so decide on heads before you go to upgrade the intake. One thing to keep in mind is that the 92-95 engines have the vortec name but are not the vortec 8 bolt intake heads so watch out when looking.

So basically any set of heads that are Vortec need to be 96 & newer? How much HP will I gain by replacing the heads, adding the intake & carb?

Just want to make sure the 96 or newer heads will bolt-up on the 89 block?

Let's say I get up to the 205hp to 230hp range after these improvements.... Will the engine feel stronger than a V8 stock that has 205hp - 228hp stock?

 

[thumpar]

Re: 1989 Mercruiser 4.3 V6 2Barrel 175HP - UPgrade Question

The only real way to verify if they are vortec heads or not is the 8 bolts for the intake. The earlier ones that might have vortec labeled valve covers may not be the true vortec heads. When it comes to boats you need to make sure because engines and parts can sit on the shelf from year to year.

For HP gains I have not idea. There are alot of things to consider. But I would put a somewhat modern 4.3l against a not so modern 305 anyday, plus the fuel use will be less.

 

[mxcobra]

Re: 1989 Mercruiser 4.3 V6 2Barrel 175HP - UPgrade Question

if it was me, I would have a qualified machinist port and polish the heads-with the bigest valves that will fit.
Put a high rev cam in, with stiff valve springs, and roller rockers and lifters, then force feed the fuel and air with the carb and intake from post #3

 

[thumpar]

Re: 1989 Mercruiser 4.3 V6 2Barrel 175HP - UPgrade Question

if it was me, I would have a qualified machinist port and polish the heads-with the bigest valves that will fit.
Put a high rev cam in, with stiff valve springs, and roller rockers and lifters, then force feed the fuel and air with the carb and intake from post #3

Be careful with the cam. If you get a little wild you will end up sucking water in from the cooling of the exhaust. If you go with other than standard marine cam you better have a mechanic that knows boats very very well.

 

[jmw129]

Re: 1989 Mercruiser 4.3 V6 2Barrel 175HP - UPgrade Question

typical power increase about 20HP going to a 4 barrel.
I don't understand the part about heads. You should already have vortec heads on that 4.3

if salt water not an issue, you can use an Edelbrock EDL 2111 aluminum intake and the Edelbrock 1409 carb - that's a popular combo for converting to 4 barrel. They have a kit to de-tune the 1409 carb to V6 cfm's

Are you talking just the 4-barrel by itself will increase 20hp or 4-barrel with intake?

Earlier thread showed that I can increase 18hp from Mich. Motors with just the intake.. so I assume you're saying 38hp increase with the combo right?

I'm trying to keep this upgrade very much cost effective $300-$500 max with used parts.

Common sense say's that is the most I should spend otherwise a used V8 is the next step.

 

[Bondo]

Re: 1989 Mercruiser 4.3 V6 2Barrel 175HP - UPgrade Question

Are you talking just the 4-barrel by itself will increase 20hp or 4-barrel with intake?

Earlier thread showed that I can increase 18hp from Mich. Motors with just the intake.. so I assume you're saying 38hp increase with the combo right?

I'm trying to keep this upgrade very much cost effective $300-$500 max with used parts.

Common sense say's that is the most I should spend otherwise a used V8 is the next step.

Ayuh,... It's 'bout 20hp, for the Carb, 'n Intake swap...
Ya can't bolt a 4 bbl. carb to a 2bbl. manifold, 'n expect that kinda hp increase...

If ya go with the Carb, Manifold, 'n Vortec heads,... Figure 'bout 35/ 40hp increase...

 

[jmw129]

Re: 1989 Mercruiser 4.3 V6 2Barrel 175HP - UPgrade Question

Ayuh,... It's 'bout 20hp, for the Carb, 'n Intake swap...
Ya can't bolt a 4 bbl. carb to a 2bbl. manifold, 'n expect that kinda hp increase...

If ya go with the Carb, Manifold, 'n Vortec heads,... Figure 'bout 35/ 40hp increase...

Now can I get the 20hp increase with a stock 4.3L manifold & 4-barrel carb?

These I can find fairly easy. The heads are a pain.

 

[Bondo]

Re: 1989 Mercruiser 4.3 V6 2Barrel 175HP - UPgrade Question

Now can I get the 20hp increase with a stock 4.3L manifold & 4-barrel carb?

These I can find fairly easy. The heads are a pain.

Ayuh,.... That's correct...

If ya add the heads later, you'll need another intake manifold though...