I've been looking to buy a boat with a carbureted 2000 5.0l mercruiser motor.
Just wondering if any of you vets here have heard of anyone swapping out the carb and putting on an LB9 TPI setup on it (which I already have from another motor). Other than a different air filter setup and wiring harness mods and fuel pump, I dont *think* there should be much more to it. Its to be used exclusively in fresh water, so corrosion isnt too much of a concern for me (or should it?).
Any input would be greatly appreciated (before the guy sells the boat to someone else, or puts it away in storage).

 

You'd have a torque monster in the boat with the TPI IMO.
It would probably be easier than retro fit on older car. I've put a TPI in a 37 Chevy, a 40 Chevy, a 35 Dodge, a 58 vette, a 67 Firebird, and a Ramjet in a 41 Chevy Pickup.
If you read this site and all the tutorials on it, you can put a TPI on a tractor if you want to.
Another good tutorial on retro fits is www.chevythunder.com.
Be sure and put pump in tank. Shouldn't be problem. I had a Master Craft with 350 and almost put TPI in it a few years ago.
The Ramjet is made by Mercruiser from what I hear and I bought the marine version for my 41 pickup project from someone that worked at the Mercruiser factory.
Get a harness from S10Wildside, use heated O2 sensor, and drop EGR, VATS, and cannister. You'll be good to go.
Also, probably with the extra torque, you can go up a prop pitch size and use a little less gas and have a better top end.
Most boats with car engines usually top out in the 4500 rpm range.

 

Thanks for the great info Scuzz. Sounds like you definitely know your boats! Any reason you didnt put TPI in your Mastercraft (not that it would most likely have needed it!)?
Is it easy to retrofit a pump in tank? The ones I've used before were external in line units.
Another question, do you know if Mercruiser were using 5.0L Gm or ford blocks in 2000? i'm buying it long distance, and the guy selling isnt very good at relaying info. I think they used Ford in the "old days" and then GM later on, so I should be good to go.

 

I considered installing a high-flow TPI on my 25' cuddy cabin a few years back. Problem with boats is that they are under a heavy load all the time, so the tuning has to be right on or they self-destruct quickly. To properly tune an engine you need wide-band O2 data. I was never able to figure out how to sample the exhaust on my set-up since it gets water injected into the exhaust. I've watch my friends have to re-build their engines 3 or 4 times a season cause something wasn't just right.
Moral of the story is leave marine engines alone unless you enjoy building and rebuilding engines more than being on the water!

 

I'm putting TPI on my friends boat. It was originally a 5.7 4 barrel engine ... the thermostat housing looks like a big problem as does lack of an o2 sensor. He is going to run closed cooling so can't help you with wiill it corode question.I would think running cold water through motor all the time would also keep TPI in open loop.

 

Lack of an O2 sensor will keep the ecm in open loop.

 

stingray 5.0 liter could have been either ford or chevy. Mercruiser used both one thing I would ask the guy is when was the water impellor chaged. This drive water up from the outdrive to the water pump ... PITA to change and to have it done it's expensive ... NEVER run it without a garden hose attached to the outdrive or you will disintegrate the impellor. Also verify the sterns hydraulic lifts work and don't leak. If they do leak the trim feature won't work properly.

 

Thanks for the info guys.
Hmmm....this might be tricky after all, hadnt thought of the effect of constant cold water cooling, as well as the O2 sensor. I'm going to have to look at how mercruiser does their factory MPFI/EFI setups for some pointers I guess.

 

Cold water coming into the block has no effect on closed loop. That's what the thermostat is for.
I would recommend to go go a closed cooling system because it will eliminate the trouble of having a speciali thermostat that can bypass water to the exhaust manifolds.
Also, the TPI should be sufficient for that application even though the 305 would most likely have a radical cam and practically open exhaust. You might have some trouble tuning it to idle well but it will make decent power, especially if you lower the temperature in the ECM too (marine engines run at 160F).

The O2 sensor can be installed in one of the risers so that water doesn't get on it. That way, you can run in closed loop.

Hope this helps.
Lou

 

Rock Valley Auto sells a kit to put GM TPI pump in about any tank. On the deeper boat tank, I would think you'd just extend the pump down more and lengthen the pump brace. I've used them in several tanks.
I had thought about making the water circ like car, instead of sending cooling water to the exhaust manifolds. I've been told by boat people that a lot of boats in Florida run enclosed water systems to keep the salt water out.
The reason I didn't do project was simple. My back went out and I couldn't ski anymore, and then I bought property on a really shallow lake in Alabama, and sold it and bought Sea Doo. So sad after that.
When I was hanging with all the inboard boat people several years ago, most boats came with Ford engines, and Chevy was optional. I haven't been around real boating in 6 or 8 years now though. Ford sold their setups cheaper back then.

 

I thought about the same thing on my 90 Chaparral. It has the 260HP 5.7L GM motor. From all the headaches of converting I ended up putting on a Cast Iron Bowtie intake "High Rise" from GM. I also rebuilt the Q jet and changed the Thunderbolt advance module from a V8-22 to a V8-24A. I'm getting 55mph right now on the GPS and I'm hoping to add some more mods over the winter. Jump on www.speedwake.com to get some more good combos on the SBC. I've been there for a few months and its an awesome site.

BTW Ford discontinued their marine use in the early 90's

 

You will also find that the 2000 model 305 probably has Vortec heads. The TPI Vortec base gets $$$$.

 

False, On a wet system as he is going to have water that gets pumped up though there and into the exhaust. The only way, and I can post a pic is to have an o2 welded right where the head bolts to the iexhaust manifold. Its an partial obstruction of flow for one cylinder but its the only way I have seen is unless you spend thousands on a dry set of headers.

 

I have done them in the exhaust crossover passageway on Marine TBI conversions.

 

Hmmm, risers are jacketed and the water flows up in the jacket, not in the exhaust stream. The water is dumped into the exhaust stream after it exits the riser so it's not a problem to have the O2 on the vertical wall of a riser.

Lou

 

Yes it is. water jackets are around the center exhaust stream. You drill anywhere on the side of the riser going up and you are going to be drilling into a jacket. Heres a pic of a manifold. Picture the riser now with the same openings going up.

 

Right. That's why you buy risers or manifolds that already have a provision for an O2 sensor (for FI engines) or you simply make it work through the jacket. I'm not saying it's trivial but it sure is doable.

In any case, a fuel injected 305 with a radical cam and good heads should yield what, 250hp? 280?

Lou

 

Can you lead me to a company that sells them? All newer EFI Mercs run no 02's and I cant find a supplier anywhere. I've seen custom but its $$$$ and frankly not worth it.

 

The Ramjet setup is an outgrowth of the marine industry. Mercruiser in Tulsa is where I heard they are made. I bought a marine version from a guy that said he worked there, and the intake was brass plated in the water circ part. Also, it didn't have a port drilled for power brake vaccum. The ecm and harness that comes with them did not have a oxygen sensor at first.

 

I am doing this conversion but I am not using a TPI. I am using an Edelbrock TBI to MPFI intake. It bolts right up and you can use the Merc thermostat housing. It should feed the boat just fine since it was meant for a 350 (boats a 305). I used it on my truck at one time, but since I built my 383 I went back to TBI and have learned how to tune.

Fast 355 said that he did this conversion and put the 02 sensor in the EGR port. I am going to make a plate up with a bung welded to it and give it a shot. If anything I should be able to use the wideband so I dont burn the motor up.

When I pulled the Intake I found a roller block. So I have installed the factory LT4 cam and valve train out of my Vette. I have also done some serious work to the heads, 081 castings.

 

Did you take any pictures of the port work for all to see?

 

96, Do you have any idea what manifolds you are going to run? I've narrowed it down to 3. Revolutions, IMCO Thumpers and the Super Offshore brand sold by CP Performance. In the future I would love to do aluminum heads and intake to free up some major weight.

 

I was going to run the stock manifolds for now. Those things do weigh a ton!!! It seems like you could gain a lot by going aluminum. The factory intake was cast iron, so I am gaining a little by running the MPFI setup. I was looking for a way to run threw hull exhaust but everything I find is major $$$. I will take a look at the manifolds you posted.

 

Here are some pics of the 081 heads. I literally spent hours porting and gasket matching these things, on and off for 3 weeks. I cut down and tapped the heads for ARP studs, cut down the valve guides (they are good for up to .550 lift with the LT4 retainers), 5 angle valve job, unshrouded the valves by hand, cleaned up the chambers, and new springs to handle the lift. I bought a set of 1.6 roller rockers from Summit, thats the biggest expense so far since I did all the head work myself and I already had the studs lying around. I decided not to shave the heads since I am running a .020 thinner head gasket.

One thing I wish I would have changed were the exhaust valves. They have a bigger diameter stem than intake and are really fat at the base of the valve. They also weigh a ton. I would have had to install new guides, so I left them.

 

i work as a boat mechanic and i would not advise this. You can get a complete marine EFI/PCM set up off ebay for a steal. I have one on a merc 305 and it is great.

 

The factory marine ECMs are VERY lacking. The TPI or the Edelbrock MPFI setup will both work well on a boat. The TPI setup makes peak power around 4,600 rpm and the Edelbrock manifold does too.

 

I've been looking on ebay for 6 monhts already have havent found one. Only kit I found was 1800 bucks and used a 730 ecm.

 

Can you elaberate....I dont see any reason not to do it. I have all the parts lying around. You can find GM ECM's way cheap, and if you can tune them, they are better than any aftermarket ECM you can buy.

 

I am thinking about doing away with the stock y pipe and running the exhaust out the sides of the boat, since I dont have any room out the back due to the swim platform.


http://www.cpperformance.com/detail.aspx?ID=372

Here is a pic of my rig..

 

I'm also going to get the sides exhaust but I am leaving my stock y pipe in there and using Corsas Q&Q Plus system so it can be noisy and quiet when I want it. Are you going to be running any spacers between manifold and risers to stop reversion or will the cam be mild enough to avoid it?

 

Lt4 cam does not have much overlap. It should be mild enough to keep water out of the heads.

 

Ehh. I bit the bullet and got a cam also lol. Converting to roller too. But I am staying with low lift for now as I dont want to mess with my heads yet. I'll let you know how it goes!

Also posted a pic for good measure.

 

Hi guys I have a '99 Rinker Captiva 192 here
4.3l Mercruiser V6
Is this gonna be a Ford or a GM block?

thanks for any help

 

GM Block.

 

The 4.3 is DEFINATELY GM, it is 3/4 of a 350.

 

Here is a short video of the boat running. I have the lower unit off installing a new water pump so it doesnt hurt anything to run it a little without water hooked up.

 

I posted earlier about a 4.3l V6 which we ascertained was a Chevy block and having looked at it since I realise I was stupid-it's got GM stamped on the side
anyway, it's carbed, does anyone know what the carb would be?I'm sure it's not a GM carb
I keep the boat 110 miles from my home so I can't check it right now
Would this take TBI or TPI systems?also what would be the best way to tune it?I reckon the tiny carb is the limiting factor, what carbs will fit to it?
I think it's rated at 190hp right now.
BTW I'm in the UK and paying 11 dollars or so a gallon so fuel economy is a fairly important