v6 power up

[jdcook]

I have been considering changing the engine my boat, but after thinking about it and getting some opinions I think that i will try to beef up my current engine. its a 1988 GM 4.3l v6.<br />my question is what are some ways that i can accomplish this. I would like to do whatever i can to maximize hp.<br />any suggestions would be helpful,<br />thank you

 

[LubeDude]

Re: v6 power up

Just add two cylinders and a four barrel, it will be better in the long run.

 

[jdcook]

Re: v6 power up

is there an advantage to add a 4 barrell carb to the v6 or is it to small

 

[ZmOz]

Re: v6 power up

It will give it more HP, obviously. You could also probably get a better cam, maybe increase the compression ration and advance the timing, although you would have to run premium fuel.

 

[Boomyal]

Re: v6 power up

There is no substitute for cubic inches, especially in a marine application. Modified carburation and higher lift cams can move your torque range out of the ideal for your boat. Appeal to the knowledgable GM/Merc gurus to see if your outdrive and intermediate housing would accomodate a larger marine convertable engine.

 

[ZmOz]

Re: v6 power up

Yeah, more displacement is really what you need. I don't know much about inboards, but seeing as a 4.3 is just a 5.7 without two cylinders, it can't be that hard to make fit. Also you can use an automotive 350 long block if you want, and use most of your existing accessories.

 

[bluewater19]

Re: v6 power up

Anything you can do to hop up a 350 can be done with the 4.3 also. most of the time using the same parts. I swapped from the stock 2bbl to a 4bbl and gained 4mpg on the topend. This is on a heavy cuddy cab. I am getting ready to rebuild my motor this spring and getting 200-220hp should be no problem.

 

[TwoBallScrewBall]

Re: v6 power up

As far as I know, the 4.3 and the 5.0/5.7 use the same mounts. I know for a fact that they do in a truck. I can't see where there would be a difference in a boat, as long as it's using the side mounts and not a front mount. The bellhousing also bolts right up. Most accessories should fit from the 4.3. You'll need a carb and distributor. <br /><br />If you're dead set on the 4.3, look around on google, you can get that v6 up to 300hp easy with a stroker kit, cam and pistons, but you'll be running 93 octane to do it.

 

[LubeDude]

Re: v6 power up

Originally posted by huminski:<br />If you're dead set on the 4.3, look around on google, you can get that v6 up to 300hp easy with a stroker kit, cam and pistons, but you'll be running 93 octane to do it.

The only problem will be the lack of torgue. It will be hard to prop correctly to utilize the HP. Without enough torque you will need a smaller pitch prop to get on plane, then when up you will run out of pitch. A torque pitch prop would be in order then.

 

[Walt T]

Re: v6 power up

Those 300 hp V-6s usually get those ponies up above 5000 rpm. Thats great for auto racing and totally irrelevant for marine use.

 

[Trent]

Re: v6 power up

Also, If he has an Alpha drive its not going to handle over 300 ponies. She will come apart.

 

[DJ]

Re: v6 power up

The GM engines went to Gen+ heads somewhere in the mid nineties, I believe.<br /><br />I also understand that they are a direct bolt up.<br /><br />Once the higher flow heads are installed, it handles a 4bbl very nicely.

 

[Walt T]

Re: v6 power up

DJ speaketh the truth

 

[jdcook]

Re: v6 power up

wow, thanks for the info.<br />i have decided to rebuild the engine, add a 4bbl carb and new cams. going to have everything checked out and replaced what needs to be replaced. <br />i figure while i.m in there i may as well have it all checked out.<br />if i can bump my hp to 200+ and add a ss prop, then i will be one happy boater.<br />once again thanks for the responses.

 

[DJ]

Re: v6 power up

jd,<br /><br />You'll need the Gen+ heads and a four barrel manifold/carburetor to get 200 ponies. I'll bet you can find them on e-bay.

 

[jdcook]

Re: v6 power up

dj,<br />thanks

 

[andeline1]

Re: v6 power up

jdcook,<br />Wondering how it turned out? I may do the same!

 

[waterone1@aol.com]

Re: v6 power up

It has been my experience that "performance" cams generally improve performance in one area of the rpm curve, while sacrificing it in another. High lift cams may get more air/fuel mixture into and out of the cylinder and will work fine in <br />automotive applications, but when was the last time you drove a car at 4500 rpms for an hour straight ? In my opinion getting high flow heads or having porting work done on your heads along with a better intake manifold and four barrel(or if money isn't an issue...fuel injection) and perhaps thru hull exhuast is the most you can safely do to a marine engine without affecting dependability.

 

[Chris1956]

Re: v6 power up

jdcook, I may be a bit late with this but, Mercruiser made a 4.3LX 205HP V6 in 1988. I am not sure of the difference between the 205HP motor and yours other than the 4 bbl carb. You could probably do some research on the part numbers(heads, cams, pistons etc.) for the two motors on www.dougrussell.com, and come up with a good guess as to the differences.

 

[paulrfrancisco]

Re: v6 power up

As most every is stating, you may get more HP with a high lift cam, but maybe try looking into the techniques to increase torque throughout the RPM range... High torque is just a good no? Look at diesels... Can't you choose a cam that provide the torque in the proper RPM range... or the HP in the proper range?