PDA

View Full Version : Engine Swap


H20skeefreek
01-11-2005, 09:33 PM
I currently have a '85 w/PCM 351 and PowerSlot Transmission. Just toying with the idea (wouldn't do it anytime soon) but what would it take to bolt up a LS1 Corvette Motor to my PowerSlot? I assume it could be done with the appropriate bell housing? do the current boats with 350's use the same PowerSlot transmission? or is it different?

I know a guy, who knows a guy that always is picking up totalled vettes.

JimN
01-11-2005, 09:48 PM
How are you going to calibrate the ECM to run this when the car computer is set up for closed loop? This means that it wants to see input from an O2 sensor, not to mention the transmission. The car ECM is made to stay inside the passenger compartment, not sealed for exterior mounting.

Not trying to shoot you down, I'm just saying.

H20skeefreek
01-11-2005, 09:51 PM
How are you going to calibrate the ECM to run this when the car computer is set up for closed loop? This means that it wants to see input from an O2 sensor, not to mention the transmission. The car ECM is made to stay inside the passenger compartment, not sealed for exterior mounting.

Not trying to shoot you down, I'm just saying.

Like I said, just toying with the idea. No reason to get rid of what I have, except for my carb is giving me trouble right now.

how do the newer boats do it with ls1's and other marinized computer controlled automotive motors?

JimN
01-11-2005, 10:52 PM
The marine ECM is made for open loop, meaning the fuel delivery isn't quite as controlled for emissions as the motors with an O2 sensor that indicates exhaust content. These controllers are designed for wet environment and the program is based on dyno and on-water testing. If you want to do the LS-1, just make sure the program is correct. There isn't a call for your boat but it would be possible to get it. No idea of the cost, though. Malibu had about 75 catastrophic failures the first year they offered the LS-1, due to their thinking that they had the right program even though the right one was offered to them. They didn't.

H20skeefreek
01-11-2005, 11:21 PM
The marine ECM is made for open loop, meaning the fuel delivery isn't quite as controlled for emissions as the motors with an O2 sensor that indicates exhaust content. These controllers are designed for wet environment and the program is based on dyno and on-water testing. If you want to do the LS-1, just make sure the program is correct. There isn't a call for your boat but it would be possible to get it. No idea of the cost, though. Malibu had about 75 catastrophic failures the first year they offered the LS-1, due to their thinking that they had the right program even though the right one was offered to them. They didn't.

OK, OK, OK.....I'll just forget it :) Hopefully I can get my carb problems worked out, then I won't be thinking of using my engine for an anchor :eek:

Lance
01-12-2005, 09:30 AM
What are your carb problems? With the the right rebuild kit, a decent set of tools, the correct overhaul / repair manual, and a little patience the rebuilding of a holley carburetor is within the reach of a lot more people than you might think.

I have never been a gear head but had good luck when rebuilding the 4160 off my 87 prostar that had problems with the secondaries opening, gunked up passages on the accelerator pump, and one other thing that I don't recall now (problems from lack of use). My advice would be to get a kit fro skidim, buy a holley overhaul / rebuild manual, invite your most mechanically inclined friend over, and go for it.

The worst case scenario is you need to have it professionally rebuilt or replaced which will be money way ahead on an engine swap.

H20skeefreek
01-12-2005, 09:37 AM
what aren't my carb problems, this thing sucks. Nah, it's under control, my mechanic is meeting me on the lake tomorrow to get her figured out. Like I said, I'm just toying with the idea, i don't have the time or money for a swap, i just think it'd be cool to have this old boat, then open the engine compartment to a Corvette motor. But then I'd get even more "wow, that must be really fast, what's her top speed?" questions.

east tx skier
01-12-2005, 11:35 AM
You can get a carb professionally rebuilt for around $200 including parts. Run fresh gas through it regularly, and it'll last you a long time before it needs to be rebuilt again.

A new PCM fuel injected GT-40 engine will run you about $6,500.00 from skidim.com. I can't imagine what an LS-1 would cost over that. I just know it's not in the skidim catalog.

Here's the scale of how to spend your money as I see it:

A can of Stabil/Seafoam is cheaper than rebuilding a carb.
New Carbs are cheaper than new engines.
New Engines are cheaper than new boats, and ...
Boats are cheaper than women (that's for Rick).

JimN
01-12-2005, 12:02 PM
Lance- you listed the parts, kit, tools and mechanical friend. YOU FORGOT BEER!!!!

Why not do it the way Doug has and tweak the carb and intake. If you want to go farther, rework the heads and put in a a hotter cam.

ski_king
01-12-2005, 01:05 PM
Interesting thread…….

I have had been thinking in the back of my mind, what I will do if and when I will need to refresh my engine. My boat has a 82 351 PCM 240 HP somewhere around 650 hours.

I have kicked around the following ideas:

1) Get the present block rebuilt: Cost ?????
Add GT40 head: At $695 per head, (way too expensive)
Replace the exhaust manifold and riser: $550 (cant believe the original ones are still ok)

2) Buy a new base engine from SkiDim: $3150
3) Buy a new base engine with GT40 Heads: $3350
Both the above will still need the $550 exhaust parts and reuse my existing carb, water pump, etc.

4) Buy a new PCM 351HO Carb engine from Ski Dim: $5600 complete engine
5) But a new 351 GT40 Fuel Injected engine from SkiDim: $6500 complete engine

The cost of going with a new engine is pretty steep, but considering on what it would cost to get a new boat, not too bad.

Has anybody out there updated to a new block or maybe even switched over to a fuel-injected engine?

east tx skier
01-12-2005, 01:41 PM
As powerslot suggests, the GT40 heads would also be a great improvement on the 240 hp 351.

As Jim mentioned, I recently swapped intakes for a little torque/hp boost. I haven't done anything further simply because it's a lot of money to spend for something that is a want rather than a need.

At a certain point, with all the add-ons, at least in my case, I could've just bought a bit newer and gotten the 300+ HP fuel-injected engine. But what fun would that be.

At this point, inasmuch as I'm still making boat payments and will be expanding the family, I've become satisfied with what I've got.

My recommendation would be to rebuild that carb and go skiing. If this were a year-round sport, I don't think our boats would have nearly as many add-ons.

skimax
01-12-2005, 02:12 PM
I rebuilt the carb on my 85 PCM 351 about 11 years ago, ran fine for the next 4 years. Then it started acting up again, I bought a new carb from skidim for $395 and sold my old carb to a local carb shop for $100.
It was the best money I ever spent, it ran like a brand new boat...and it still does today.