Engine comparison ??'s

[Reel Poor]

I am lookin to repower my boat and have some questions about the differences between sterndrive, bobtail, and inboard engine configureations. I know these "engines" are the same. Im wondering what bolt on accessories may be different. When searching Im finding that the inboard setup is a little bit cheaper than the sterndrive (mainly Mercruiser, Crusader, Marine Power) and this is what raises my question. Keep in mind Im taking out two running motors and will have any accessories that I may need to convert these engines to fit my application. All the engines Im looking at are GM based smallblocks.

 

[Haut Medoc]

Re: Engine comparison ??'s

Changing to anything other than you are all ready set up with will be costly...<br />Exhaust configurations would be different....If you have an I/O, I can't see doing anything but sticking some new/remanned engines & call it good.....JK

 

[cobra 3.0]

Re: Engine comparison ??'s

Aren't true inboards more forward in the boat(like on a MasterCraft ski boat)? Do you even have room for that? Plus you will have to plug those big holes where the I/O's were...I dunno seems like a lot of work and $$$. And then the hull design is usually different too...

 

[mkast]

Re: Engine comparison ??'s

Inboard engines use a transmission, Borg Warner, with an outdrive like a TRS or a TR. The engine data plate will have a MIE designation instead of MCM.

 

[Reel Poor]

Re: Engine comparison ??'s

Thanks guys, but your missing my question. Im not trying to redesign my boat it is an I/O setup and its gonna stay that way. Im asking what are the accessory differences that make each of these enginges destinct to its particular application. I know the difference in drive design and engine location in each application. Im asking why a difference in price. It has to do with standard bolt on accessories, surely. ie; with or without bellhousing?? includes gear reduction?? exhaust risers turned around??? Just what exactly? What am I not getting on the inboard engine that I would get on a sterndrive engine? <br /><br />Im removing two running I/O engines and if I can bolt on some of my hardware to an inboard engine and save about $600.00 on each engine, thats what I would like to do. What will have to be swapped?

 

[TilliamWe]

Re: Engine comparison ??'s

Reel Poor, I have often wondered the same things. From photos, it is all the bolt on stuff, exhaust manifolds, risers, p/s pumps, that look different to me. I would think if you got a "base" Crusader, all you would do would bolt on all your "Mercruiser" or VP stuff.

 

[Reel Poor]

Re: Engine comparison ??'s

Thats what im thinking TilliamWe. Surely someone on here that does engine installs or repairs on inboards and I/O's would know for sure. I have worked on many I/O's but very few inboards, and have never bought a crate inboard engine. I know the engines are the same.

 

[Don S]

Re: Engine comparison ??'s

Sterndrive bobtail engines come with exhaust Y's, couplers, bellhousings, shift cable plates for helm to lower shift cables, shift interrupt system of Alpha and probably a few other things the straight inboards don't have.<br />I don't see many inboard repowers, and the last one I repowered (as I recall) didn't have bellhousing, exhaust system shift system etc.<br />So yes, it might save some money to go with the inboard and change what needs to be changed. But you also need to realize both Mercruiser, and Volvo sell NEW Long blocks. Maybe you just asked the wrong question??????

 

[Reel Poor]

Re: Engine comparison ??'s

Thanks Don Im wanting to upgrading power from a 5.0 TBI to a 6.2 MPI and need more than a long block, but dont neccesarily need all the parts that come with the stern drive unit, based on what you said it includes. I would be happy to buy just the engine fuel system and exhaust manifolds.<br />Thats why I was asking about the inboard unit.

 

[QC]

Re: Engine comparison ??'s

Soooooo, it sounds like the inboard would meet your needs, right RP? Other than the shift cable plate linkage, your 5.0 stuff should work? Are the manifolds the same up to the risers?<br /><br />Can I help test? You need somebody to help you watch guages, right?<br /><br />Pretty cool, you ask a question, and I help by asking a lot of questions Really just wanted an excuse to offer to help test

 

[Reel Poor]

Re: Engine comparison ??'s

QC thats the conclusion I came to also. Gonna need the linkage plate, maybe. The risers should be the same, I think they just install them backwards.<br /><br />

Can I help test? You need somebody to help you watch guages, right?

I think I can handle the guages, but I will need someone to hang off the swim platform and tell me if my props are turning to fast. Dont want to burn a hole in the water ya know.

 

[QC]

Re: Engine comparison ??'s

Originally posted by Reel Poor:<br /> I will need someone to hang off the swim platform and tell me if my props are turning to fast

Roger. I'm all over it.

 

[QC]

Re: Engine comparison ??'s

RP,<br /><br />I'm confused about something. Your boat has Volvo drives right? You're gonna put the Mercs in front of them?

 

[Reel Poor]

Re: Engine comparison ??'s

Yea QC Like I said Im really after the engine and fuel assembly. I have any bolt on accessories that I'll need off the volvo package I took out. Yeap already out.<br /><br />May have to do a little wire work to connect it to the boat, but I'll do that on the boat side of the harness.<br /><br />I have also been looking at the volvo 5.7Gxi 320hp. I still have lots of questions. But they have to do with technical design specs and not mechanical specs. Dont really know where to get the answers. Questions like where does volvo get there 320hp from. Why does it take Mercruiser 377 ci to achieve the same power. Which motor is really the best the Volvo 5.7Gxi Or the Merc 6.2? Both are rated at the same hp. Are cams grinds, timing, and fuel componants made specific to volvo or merc specs to give different hp ratings? Duh, sure they are but what exactly is the difference? If so, then Volvo or Merc are not common GM engines with subtle differences. I do know that the 6.2 liter block is built only for Mercruiser.<br /><br />I would like to see all the cam, timing curve, and fuel flow specs. Sure would help me make a decission.

 

[QC]

Re: Engine comparison ??'s

That 236 SSi I put the SmartTabs on has the Gxi 320. Runs real strong. Pushes that boat to 53. If you saw our boats side by side you'd think I'd be more than 2 MPH faster . . .<br /><br />I was confused about the tech side of that discussion as well. But they get more out of 5.3s (automotive) stock now, so it's not an air issue. I think it is mostly marketing on Merc's part. You can charge more if it's bigger. Same reason I think they both have the 5.0. It doesn't cost any less to make the 5.0, so why have it? Because it makes the 5.7s worth more.<br /><br />That's my spin. What's the max input capability of your drives? SX drives right?

 

[Reel Poor]

Re: Engine comparison ??'s

Yea SX....I think i've read 400<br /><br />The Volvo stuff is just soooo expensive. Supply and demand thing I think.<br /><br />Ive heard that the Volvo 5.7Gxi vs Mercruiser 6.2 in the same boat will out run the Merc?????<br /><br />I'm still researching. It may be the Volvo's.

 

[Reel Poor]

Re: Engine comparison ??'s

oooops