Hey, Just found this forum, And hope it helps

Okay here it is I'm try t build a single turbo system for a merc 3.0 stern drive motor i know.. I'm crazy, But the boat is paid off and I just want alittle more speed. I have all the tools, And can build stuff pretty easy, So with your help I think I can do this.

Now my questions are,

I know I will need to make a new manifold for the turbo setup, My big question is can i use just any turbo? as I'm pretty sure you cant run water threw the turbo..
and as for as carb tuning and all that good stuff.. I want to only run around 4-7 pounds of boost.

Lemme know guys.. ha ha I know this a crazy thread.

 

I was hoping and planing on running a tubro kit like this http://cgi.ebay.com/ebaymotors/T3-6...ryZ33742QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

and then this intercooler

http://cgi.ebay.com/ebaymotors/Univ...ryZ33742QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

I'm not going to be much help turbo wise(I'm still learning), but as far as your application do you have an enclosed engine compartment? If so dry turbo headers won't be an option. 3.0 is that like a v-6??

 

Hey. Yes it is a inclosed hatch, And its a inline 4cyl

 

sell the boat and build 1, what you're talking about doin is gonna cost alot more than just what that kit costs you'll 100's just trying to make the carb work , then you've gotta deal with exhaust and heat. not sayin it wouldn't be a cool project, but man, i turn wrenches for a living and wouldn't wanna try it.

 

Hey. Thats the thing. I dont want another boat, I love this one. And I just want some more speed. I found a garret turbo that is watercooled. That will help alot with heat. I can build the mount very easy with how my riser setup is on the motor. I just need carb help. Im going to buy the webber carb for the motor. Will help with tunning. And I will run the msd 6al. Heat is the only thing. But I have alot of space in the hatch, Its the same engine hatch for the v-8s. So I have alot of room. And I will be running the small garret. I should be able to run 4-6psi of boost. I bet that will net me around 45-60 hp. I really want to make this work.

 

Your manifolds now are water cooled right........................Just don't want to see the 4th of July early.

 

yes my manifold is watercooled.

 

please remember, Im new and dont know too much.. lol

 

You didn't specify if you want to make it a blow through or a draw through so be aware that there are only a handful of turbos that can be used for a draw through system. Most don't like having a vacuum on the compressor side.
If you go with a blow through then the carb is going to have to be a special unit also.

On a 4 cylinder the piping is pretty simple so that's a plus for you.

 

i dont know what blow through is?

 

Go to a book store and read up on turbo systems first.
Maximum boost is a good book and there are several others out there.

Having fab skills is going to be a huge plus for you but you need to understand the basics of it so you don't waste time and money going off in the wrong direction. You might not do too bad with a draw through system. Their simpler but you'll need a turbo with a vacuum seal on the compressor. A Rajay turbo from an old Gale Banks system would probably work on a 4 cyl. and be cheap.

 

I picked up the book "turbocharging performance handbook" to day, They did have the other book. My question is, How do I pick the right size turbo. You talked about the rajay turbo. Is there only one size?

 

Picking the right size turbo can cover quite a range.
The book should tell you something about determining the engines cfm air flow.
The compressor maps determine what cfm will apply to your size engine.
Look for something with about a 55 - 60 mm compressor inlet (inducer) for a 4 cyl.
Rajay is one of the few manufacturers that made a turbo capable of running a draw through system. Turbonetics is another.
Read up on it and all your answers are in the books.

 

Ha it shouldnt cost you too much. I did this on my 2.5 liter Mercruiser which is the same as your engine just less stroke. Below are some pictures. My turbo is off an old Saab 900. I rebuilt it with a $50 Ebay rebuild kit. It's a T-25. I had it up to 15 psi before I blew the head gasket out. I was nearing 40 mph with that thing before it blew. Intake temps were over 220 degrees because I could boil water on the intercooler. Now im rigging up a water cooled intercooler with raw lake water. I sealed up that Rochester 2 barrel and put some monster 88ish Holley jets in the thing to make it a blow thru carb. Before turbo max 26 ish mph. Now it should run 40 unless it blows up again. Fun times. 1974 VIP 17' runabout.

It was reliable all summer at 5-10 psi. It was when I had some tequila in me that I figured it would be fun to turn it up to 15 and blew the head gasket out. I used a 3 liter intake manifold just like you have. I used JB weld water weld putty to seal up the water jackets where it would usually leave the manifold. I then drilled a hole in the back of the manifold and tapped a water outlet there. This lets only exhaust go through the turbo, and the water re-enters the exhaust turbing after the turbine side of the turbo. It works great. You will also need a boost referenced fuel pressure regulator and an electric fuel pump. I found some random electric fuel pump from a honda. Set your idle fuel pressure around 4 psi for that little rochester. It will go up 1 psi for every pound of boost. Buy a manual boost regulator off Ebay for like $15. You can turn that little knob and adjust your boost on the fly.







Mailboxes painted with flames for cold air into the doghouse. Ghetto as hell. Whole thing probably cost me $400 in parts. So yes it can be done cheap and ghetto as hell if you want.

 

Can you call me.. .. I have some questions if you had the time.. Thanks man!

 

Don't ever use a dry turbo headers in it.

 

This is a great thread! i have been thinking about doing this to my 19.5 open bow with a 4.3L. Your right trying to gather info is difficult because every one just says it will be too expensive or we are stupid.... Especially on the Marine forums....

 

Hey...
Back at it! Im about to score a good running complete 3.0 I will be using this engine to test. .I spoke to a guy in CA that will "seal up" my carb for me. I will be running a small garett water cooled turbo. A air to water intercooler with raw water from lake. Will update as this comes along.. I have all winter. I plan to weld the water ports off the exhaust and re route them after the turbo.

Question. Would the turbo take lake water for cooling? If I ran a filter? Or should I run a closed loop system for the turbo? water temp would be around 65F. Would that hurt coming into a hot turbo?


LET ME HAVE IT BOYS!!

 

looks good
couple of things
whats your max rpm ?