Max power for IO Holiday

boatnut74 · Sep 24, 2011

I have an 18' 1973 Holiday I'm currently restoring. I have a few choices for power but not sure which I want. I havn't read anywhwere about max power for an IO. My capacity plate says engine and drive not to exceed 710 pounds. My first option is stick with the 140hp 4 cylinder. It has plenty of power and performs just fine. Next I have a 165hp inline 6 in good shape it runs fine. It is 8" longer than the 4cyl so I would have to sacrifice a little deck space. My other option is a 4.3 V6, I'm pretty sure it would make it haul butt. Motor mounts would have to be fabbed up but I think I have all that figured out already. I don't get real crazy at the lake, I just want something reliable and with enough power to get me back to shore if a big storm comes up.

Bwana Don · Sep 24, 2011

Re: Max power for IO Holiday

I'm pretty sure mine says 140 hp max. It's a 1970 (reg says 71 but it's wrong) Offshore 18"4".

If I had a choice I'd go with the straight 6, possibly the 4.3 depending on the fit and fab work. I've heard those I6 are very reliable. Whats the power on that straight 6? I'm guessing 160-170 horses. My 4 cylinder is in the boat and runs well, so it stays, but I always dream of more ponies, always.

boatnut74 · Sep 24, 2011

Re: Max power for IO Holiday

Straight 6 is 165 hp.

Bwana Don · Sep 24, 2011

Re: Max power for IO Holiday

I've often fantasized about the I6 or 4.3. Having 165 horses would be nice, you'd hit about 50 mph imo.

jasoutside · Sep 24, 2011

Re: Max power for IO Holiday

Have you got the I6 and V6 both on hand Drew? If you do, wow! Talk about options!

Bwana Don · Sep 24, 2011

Re: Max power for IO Holiday

I think the outdrive is geared different for the I4 vs a 6 cylinder. If you have the engine and outdrive to match your good.

The 4.3 is 2/3 of a small block Chevy, great motors. I've heard the I6 will last forever so it'll be a tough choice. Does the v6 take up less room than the inline?

elkhunter338 · Sep 24, 2011

Re: Max power for IO Holiday

How much do you run the boat.
I run 60-100 hrs a year on the main engine and those extra 2 cylinders will cost you money in gas and at almost $5 a gallon that will add up.
If you don't need the extra hp for towing a skier I would stick with the 4.
I have a 140hp in a 21' cheiftain and happy with the results. Troll all day on a few gallons of gas, go 40 miles on about 10 gallons, cruise at 20-25mph does just fine. I would not put the I6 in because it will take up more deck space, my deck is already almost too small for 4 guys to fish. All those motors have been put in the starcraft i/o's at some point so your choice. Choose chevy/chevy or chevy.

boatnut74 · Sep 26, 2011

Re: Max power for IO Holiday

Bwana Don said:
The 4.3 is 2/3 of a small block Chevy, great motors. I've heard the I6 will last forever so it'll be a tough choice. Does the v6 take up less room than the inline?

The V6 would be shorter and a little wider. It would't take much to fab up the motor mounts either.

jasoutside said:
Have you got the I6 and V6 both on hand Drew? If you do, wow! Talk about options!

Yep, I got all 3 setups. The only thing I'm missing is the original outdrive from the I6. Other than that I have the wiring, guages, controls ect from all 3.

elkhunter338 said:
Choose chevy/chevy or chevy.

Yep, I think I'm gonna go with a chevy on this one

jasoutside · Sep 26, 2011

Re: Max power for IO Holiday

boatnut74 said:
Yep, I got all 3 setups. The only thing I'm missing is the original outdrive from the I6. Other than that I have the wiring, guages, controls ect from all 3.

Well, in that case...

I'd say go with the V6 since it's complete. Now, only do that if you are amped about the new motor mount challenge. It's obviously a fatter set up so it'll be a little bit of a squeeze on each side of the doghouse.

Or,

The I6 if you want something a little easier to install and a little more space at the stern. Course ya gotta find an outdrive on this option which is a bummer.

I don't think you can go wrong on either one of these choices, really just what piece of the puzzle you are looking to avoid ya know.

boatnut74 · Sep 26, 2011

Re: Max power for IO Holiday

jasoutside said:
Well, in that case...

I'd say go with the V6 since it's complete. Now, only do that if you are amped about the new motor mount challenge. It's obviously a fatter set up so it'll be a little bit of a squeeze on each side of the doghouse.

Or,

The I6 if you want something a little easier to install and a little more space at the stern. Course ya gotta find an outdrive on this option which is a bummer.

I don't think you can go wrong on either one of these choices, really just what piece of the puzzle you are looking to avoid ya know.

I'm really leaning toward the V6 at this point. I did some measuring and such and I don't think motor mounts will be a whole lot different than what I got now, just a little taller.

jasoutside · Sep 26, 2011

Re: Max power for IO Holiday

boatnut74 said:
I'm really leaning toward the V6 at this point. I did some measuring and such and I don't think motor mounts will be a whole lot different than what I got now, just a little taller.

Well, you have one in the front now and you'd need to go to two, one on each side though eh?

boatnut74 · Sep 26, 2011

Re: Max power for IO Holiday

jasoutside said:
Well, you have one in the front now and you'd need to go to two, one on each side though eh?

Yep, It's got the one in front now. I did a little measuring and I think I can do something similiar. Put the 1.5" thick piece across the stringers, then build it up on the ends to meet the motor mounts, maybe 4" high or so. I think I might have to move the stringers out an 1/8" or so due to the width but thats no biggie.

jasoutside · Sep 26, 2011

Re: Max power for IO Holiday

The V6 will move that 18 foot Holiday!

Bwana Don · Sep 26, 2011

Re: Max power for IO Holiday

elkhunter338 said:
How much do you run the boat.
I run 60-100 hrs a year on the main engine and those extra 2 cylinders will cost you money in gas and at almost $5 a gallon that will add up.
If you don't need the extra hp for towing a skier I would stick with the 4.
I have a 140hp in a 21' cheiftain and happy with the results. Troll all day on a few gallons of gas, go 40 miles on about 10 gallons, cruise at 20-25mph does just fine. I would not put the I6 in because it will take up more deck space, my deck is already almost too small for 4 guys to fish. All those motors have been put in the starcraft i/o's at some point so your choice. Choose chevy/chevy or chevy.

Nicely written Elkhunter. That gives us a pretty good perspective on the 140 HP chevy. I believe this is a great little engine.

The allure of horsepower is very great though. I hope boatnut does what makes him happy. Go 4.3, go 4.3, go 4.3, I wouldn't mind seeing a v6 in an 18 footer. I really wouldn't mind that at all.

elkhunter338 · Sep 26, 2011

Re: Max power for IO Holiday

There are some days I wish I had some more hp, but those days are maybe 1-3 a year when I could cruise 30+ mph. Most days when I pull into the gas pump I am satisfied with the little 4.
If I had my choice I would choose the 4 or the v-6 depending on which motor I thought was in best shape and I could get running for the least cost.

Lyle29464 · Sep 26, 2011

Re: Max power for IO Holiday

I put a 350 in the same hull. no problem at all. had to make the front mounts and make the engine cover 4 inches wider. Had a 1:5 drive and ran a 23 inch prop. started to plane around 1600 and on a full plane at 2200 gas use was not bad till the back half of the carb opened around 3500

boatnut74 · Sep 26, 2011

Re: Max power for IO Holiday

That 4.3 actually does pretty good on fuel. We used it all summer in our 19' glasser tri hull and would burn 1.5-2 gph running hard, tubing and skiing all day. That little 4 cylinder is a great motor though. I just like horsepower

CheapboatKev · Sep 30, 2011

Re: Max power for IO Holiday

Bwana Don said:
Nicely written Elkhunter. That gives us a pretty good perspective on the 140 HP chevy. I believe this is a great little engine.

The allure of horsepower is very great though. I hope boatnut does what makes him happy. Go 4.3, go 4.3, go 4.3, I wouldn't mind seeing a v6 in an 18 footer. I really wouldn't mind that at all.

Bond-O has a V6 in his Starcraft..There are pics around someplace..Cant miss it..Its painted Catepillar Yellow..lol

Bwana Don · Sep 30, 2011

Re: Max power for IO Holiday

CheapboatKev said:
Bond-O has a V6 in his Starcraft..There are pics around someplace..Cant miss it..Its painted Catepillar Yellow..lol

He's got an Islander right? How big? Does he have a thread showing the install?

jasoutside · Sep 30, 2011

Re: Max power for IO Holiday

Bwana Don said:
He's got an Islander right? How big? Does he have a thread showing the install?

Yah, he has a 22' Islander. There is a random photo floating around here and there. If you check alpheus' thread I think there is one there.

Max power for IO Holiday

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