Changing engines

[jdb11386 1]

I have mentioned this before, but I am seriously considering changing engines in my enzo. I know everyone thinks I'm crazy for even wanting to do it, but sometimes my ideas are a little wild and I'm use to the abuse. Anyway I have an ls3 engine with a good vvt cam sitting on the stand in the shop, that is ready to go in something. My question is does anyone have or know where to find used pcm zr engines or ls indmar engines from a totaled boat or an engine that blew. The main things I am needing are exhaust manifolds and a few accessory pieces. I really havent found any cheap manifolds. I have tossed around the idea of taking zo6 manifolds and turning them upside down and using my existing risers and have an exhaust shop fab up an adapter to connect the two, but I really dont want to go that route, I am trying to use as many bolt on parts that were meant for a boat and try not to do to much fab work. The wiring doesnt really bother me, ive got a wiring harness and pcm and I dont think i'll have to cut up too many wires. Basically I'm trying to do this as cheap as possible but do a nice job. Right now I'm in a position where I want to pull the engine in my boat but I'm not going to until I know for sure I can do this at a reasonable price.

[DarksideR 1,679]

Is this just for fun, or are you doing this for a reason???

[jdb11386 1]

More or less for fun. The reason would be more power and a smoother engine. There is nothing wrong with the the black scorpion 330 engine and that is why I'm making sure I have everything covered before I go any further. Plus who wouldnt like a nice choppy idle on a boat, especially with the sideswipe.

Edited April 2, 2013 by jdb11386

[superdtf 68]

I think you should talk to these guys: http://www.michiganmotorz.com/

[PayCheck 20]

I wondered it it was stupid to super or turbo charge a marine engine. There is an option in the 2013 centurion catalog for a supercharged motor. Is there any way to add horse power with a different air intake for these engines? I have weird ideas too, don't feel like alone jdb

[Overby Marine 54]

Like you said, Manifolds are going to be your bigges hold up. If you really want to make any power you need something like PCM's header system on the XS550 seen here: http://www.pcmengines.com/XS-550/ However for the type of power that engine would make with a mild cam you can probably go with stock LS based exhaust from a PCM/Indmar.

 

Also keep in mind you need water cooled exhaust. Your Z06 exhaust would be waaay too hot to have in an enclosed engine bay, in my opinion.

 

Beyond that your engine mounts should probably bolt right up. same goes for tranny, fuel lines, etc.

 

Getting all of the gages and whatnot to work may be a challenge as well, as most automotive sensors work off of 5v reference signal whereas most sensors on your merc work off of ground impedence. (temp, oil pressure, etc). So you may have to buy some gages to complete the setup.

 

Would for sure be a fun project, I'd like to take a look if you decide to pull the trigger. I wonder what your torque curve on the LS3 would look like as compared to the merc? You may would have to re-prop.

 

Joe.

[superdtf 68]

Joe's post reminds me of the torque curve problem. My brother's in-laws kinda accidentally forgot to winterize their 25 foot cuddy; it had a 454 Merc. So the dude has a buddy with a performance machine shop, and the buddy owes the dude. So the Buddy builds the 454 up all roller and balanced and cammed etc. But the torque curve was too top-heavy. He took it out on the water and it would barely get on plane, but once it did, 65-70 mph. So they propped down, better out of the hole, but it could cavitate at speed if you hammered it, and that juicy range of the torque curve wasn't really helping. So they ended up pulling it back out, different cam, timing, etc (the Buddy ended up consulting a marine guy, I think the Michigan Motorz guys), and they got it running very nicely.

 

Moral of the story: Thousands of dollars and hundreds of hours later they got a marginal improvement over the stupid stock Merc 454.

[Overby Marine 54]

Yep, unless you have some kind of variable valve system you have to give up low end power to make top end, and visa versa. For a boat you would like something with a flat torque curve that makes power from say 2000 rpm on up. Depending on the cam in his ls3 though he could have just that.

[CenturionSkier 43]

How about just ordering one of these from MerCruiser Repower. It would hook up easily for sure.

 

http://www.mercurymarine.com/repower/mercruiser/remanufactured-mercruiser-products/plus-series/383-mag-inboard-4v/

[jdb11386 1]

I don't know exactly how the manifolds work but I think the water only goes through the collector. I don't think the water would be allowed in the lower part to sit on the valves every time you switched off. But they aren't terribly expensive so that's a minor holdup. The beauty of these engines is the variable valve timing. Its like having two camshafts. I really don't have to suffer low end torque. on paper I should be right around 450 HP and 450 torque with a somewhat conservative tune. That brings me to my next question, how are the newer boats with drive by wire set up? Do they still have a cable that runs some kind of module just like the gas pedal in a vehicle controls? If not I'm going to have to fab up something to keep my engine drive by wire to utilize the variable valve timing pcm.

 

Sent from my XT901 using Tapatalk 2

 

 

[jdb11386 1]

I don't know exactly how the manifolds work but I think the water only goes through the collector. I don't think the water would be allowed in the lower part to sit on the valves every time you switched off. But they aren't terribly expensive so that's a minor holdup. The beauty of these engines is the variable valve timing. Its like having two camshafts. I really don't have to suffer low end torque. on paper I should be right around 450 HP and 450 torque with a somewhat conservative tune. That brings me to my next question, how are the newer boats with drive by wire set up? Do they still have a cable that runs some kind of module just like the gas pedal in a vehicle controls? If not I'm going to have to fab up something to keep my engine drive by wire to utilize the variable valve timing pcm.

 

Sent from my XT901 using Tapatalk 2

 

 

[jdb11386 1]

 

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Edited April 4, 2013 by jdb11386

[Troy. R 198]

Jdb,

The throttle/perfect pass issue you brought up was the first thing I thought of when I read this thread. Your Merc is a mechanical throttle/perfect pass and I'm sure your ls3 is electronic. I would talk to the folks at PCM to figure out how to resolve this. I'm sure you'll have to change out your PP to a drive-by-wire system or go to a Zero-off system.

Sounds like an interesting project. Keep us posted.

[jdb11386 1]

Yea everything I have is fully electronic and I want to keep it that way. If I have to change over to drive by cable that means a different throttle body and didn't wiring harness and computer, and I might lose the VVT and have to go with a different cam but I'm not sure about that. My big question is how does the drive by wire work on the pcm engines? Is there a sensor right there at the throttle lever on a separate wiring harness or do they still use a cable that goes to the back to control a module there at the engine. I know they still use a cable for the transmission.

 

Sent from my XT901 using Tapatalk 2

 

 

[Troy. R 198]

I would think they use a throttle position sensor similar to a car, but that's purely a guess.

[Overby Marine 54]

Boat manifold are water jacketed. There is not any water IN the exhaust until you get to the elbows, however the exhaust tubes are surrounded by cool water.

[jdb11386 1]

Boat manifold are water jacketed. There is not any water IN the exhaust until you get to the elbows, however the exhaust tubes are surrounded by cool water.

Ok that makes sense. If you look at Indmar's ls3 they have a nice header deal that looks really expensive, and it doesn't look like the water gets in them until the very end of the header. But I think I'm going to use the old style zr manifolds before the cat style. I can get them for around 750 for everything minus the studs.

 

Sent from my XT901 using Tapatalk 2

 

 

[superdtf 68]

Another dude to talk to is the guy at Discount Inboard Marine (skidim.com). I think his name is Kurt or Bruce (something with a "u"). He's really laid back and helpful.

[jdb11386 1]

Well I talked with PCM and had a few questions answered. It looks like i'm going to have to fab up a way to run the throttle to utilize the perfect pass and keep it drive by wire. PCM nor indmar use the factory gm engine wire harness' so if I make this work it's all going to be custom if I want to tune the engine correctly and use my computer and harness.

[jdb11386 1]

I talked to the guy at michigan motors and he was pretty helpful. He basically told me to forget about everyone else's equipment and use what I have and things will be a lot cheaper and easier, which is what I was thinking, but it's nice to have reassurance.