Turbochargers
 

Ok guys, I want valid technical reasons why I can’t put turbos on a big block. on my boat. I’m not looking for go with prochargers, or any other week just don’t do that’ answer. Hard technical reasons or obstacles that need to be overcome

There is only one obstacle, keeping the turbo housings cool enough so that you don't burn it to the water line

water cooled turbos should do the trick in my mind...they are getting more and more common in automotive applications. I’ll need to get some numbers on temps...

The problem you have is that with water cooled exhaust and water cooled turbos, you are loosing so much of the exhaust force due to cooling. Your best bet is to use insulated cast iron manifolds with insulated turbo jackets. But then you need to ventilate the hell out of your engine compartment to protect everything else. The cast iron manifolds will grow less and hold heat better.

Well the exhaust gasses won’t be cooled until after the turbo... water going through the impeller will destroy it..My thought was dry exhaust to the turbo, and welding up the holes internally for water draining. Then weld a couple fittings to bypass the water around the turbo to the tips. Then just having the cooling water run through the water jackets inside the turbo casting that re already there... I got plenty of ventilation holes I can actually use a fan to force air through on the side, plus I have goo gobs of room in the bilge.. I could probably have an 8/71 blower on the engine without cutting holes in my hatch.

Heat dispersement
 

Well the exhaust gasses won’t be cooled until after the turbo... water going through the impeller will destroy it..My thought was dry exhaust to the turbo, and welding up the holes internally for water draining. Then weld a couple fittings to bypass the water around the turbo to the tips. Then just having the cooling water run through the water jackets inside the turbo casting that re already there... I got plenty of ventilation holes I can actually use a fan to force air through on the side, plus I have goo gobs of room in the bilge.. I could probably have an 8/71 blower on the engine without cutting holes in my hatch.

Do you have water cooled exhaust housings? (Water surrounding the entire exhaust)

my motors are out, and I’m redoing everything..I understand there are dry headed setups, where there is a jacket around the tube, then I would bypass around the turbo, and connect the water to the tops to go through the transom

You need to cool or blanket the housing. Not just circulate coolant through the center cartridge for the bearings. Far from impossible, but not very easy either.

I have no input to your Q, but saw this the other night.

https://www.racingjunk.com/Turbos/18...&from=search#3

This is bench racing/ imagination but.
Why not look at the closed cooling and jacketed exhaust of the Mercury 1350/1650 engines for inspiration? I'd expect that with those, the exhaust manifolds are hotter than straight lake water cooling. That would allow more exhaust heat transfer to the turbo than cold water exhaust jackets. You would have to use exhaust manifolds that can take heat though.
If you blanketed the turbocharger housings and placed some temperature probes inside the engine bay during development you could decide just how much engine compartment air movement would suit your setup. Maybe start out by driving it with no cover. Then add parts to the cover til you like how it works. You will want temperature and pressure probes all over the place.
Your intercooler will probably need to get the cooling water first, then whatever it passes through could go to the heat exchanger. If it's too hot they can get separate cooling water feeds.
I would love to build something like that but I think I'd try to do it with a bigger LS engine.
On the LS there are not as many marine exhaust choices though, so that could be a problem.
Once you have your design you can do the final engine cover with the air movement you need.

Heated water
 

Well my thoughts were something along those lines.. I use thermostats in my motors, so taking the water from the engine into the exhaust jackets would be around 160. I’m thinking if I plug a bob into the exhaust jacket, and run a hose to a bob on a jacket around the exhaust housing of the turbo, then another bob opposite to run the line to the tip, the water would be hot Enough getting into the jacket. I would have to weld a partition into the jacket so the water doesn’t just stay in side and swirl around. Intake and outlet ports would be right next to each other, but on opposite sides of the internal divider.

I'm installing some Gentry Engineering Twin Turbos right now. Carson Brumett is the Gentry guy. (626) 792-6410. Super, top-level turbo guy (and nice guy). In the end, 10 psi of boost at the head doesn't know if the turbo was water-jacketed, blankleted, supercharged or procharged. For safety and proper packaging, definitely need water-jacketed turbo exhaust housings in an enclosed area, particularly if you have 4 of them! There are several new makers of water-jacketed housings, there are used sets of Gentry and Banks if you can find them, or get new Gentry's from Carson, but be ready for sticker shock. In my research, I've even seen some guys fab up stainless "water cooler" that go over regular exhaust housings, so the options are endless as your imagination and wallet.

I was lucky enough (after 2 years of searching) to find a matched set of Gentrys from intake to exhaust tails, but they are getting rare. Water leaves the exhaust manifold, into the exhaust housing, over to the double-walled exhaust tail, and out of the boat.

Good Luck! These are my first ever turbos, kind of excited to see what happens!

Few people have done twin turbos successfully here, over the years.

Check300 rings a bell in my mind. Do a search.

Ad far as 10psi at the head doesn't matter how it got there ? Huh ? Sure does. And just, or more, important is when it get's there.

I didnt think it was possible to create a secondary cooling method. The turbo housings crack dont they?

Turbo option is amazing. Its obvious they work, MERC RACing uses them as the biggest power maker. On modern two valve v8's they are great but mutli valve they really rule. Putting together a compact water cooled and oiled package is very complicated and it is expensive because the equipment to do it is all custom. But then again I put a metric 496 mag ho and im making 1300hp with a hopped up Procharger. AS I SIT HERE AND THINK ABOUT IT. i ALREADY HAVE A PLATFORM FOR IT ON MY MOTOR. I have the block ECM system I would just need to fit a couple of turbos with water cooling.....where would I introduce water into the exhaust jacket with torching my engine room. How would i use the intercooler. 588 needs lost of exhaust. rightnow i produce almost all my power very low in the rpm scale.

https://cimg6.ibsrv.net/gimg/www.off...482bcef864.jpg

Turbos are done all the time. Checkout BoostPower or Carson Brummet. Problem is few do it so the price is reflected accordingly.

I called both.. no one answered. No one has returned a call.

Hi SB. I respect your motor skills, but I think you are trying to make this too complex. My answer was after all the charge density, speed and velocity, volumetric efficiencies were calculated and debated, etc etc. -- if there is 10 psi of boost at the valve ready to go, that cylinder doesn't care where it came from; be it a roots blower, turbo, or ProCharger. When we drag raced flatbottoms, it was "Boost is boost".

Now more to the point; the issue was raised whether cooling the turbine exhaust housing adversely affected the exhaust boost efficiency to the point you might consider not running a full water-jacketed turbo housing in your build philosophy. My reply was intended to express my belief that if a wet turbo and a dry turbo both produced an end product of 10 psi boost, all else being the same, the motor doesn't care where that 10 psi came from. Safety has to be NO.1

For years I had qualms about turbos too, in fact, it kept me from attempting to live with one up until this point. With the availability to the public of better and better computerized fuel and spark management, and the success of the long line of turbo Merc Racing engines, I thought I'd give it a try too. We're supposed to be having fun, so right now, turbos seem fun. Ask me later, you might get a different answer! LOL!

Text Carson at that number I gave you. He'll get back as soon as he can.

https://cimg3.ibsrv.net/gimg/www.off...32bc9cb01a.jpg
I used water cooled heat shields to control the temp under the engine hatch.

WHat ECM are you using? What block how much boost total. compression?

I knew this was the place to go! Lol... I heb a ton of questions..are those heatshields welded to the exhaust housing? Are your headers water cooled what did you use to run the water to the tips? Did you use automotive headers? Or did you use marine and modify the ends? Sooo many questions

This is a tall deck bow tie race prepped block at 572 ci. Very low compression and 25#'s of boost on 110 octane.

The heat shields were covering the housing but not touching them as we didn't want to cool the housing itself. The headers used are Dana Marine headers. We fabricated the exhaust pipes out of 6" stainless. CMI made me a set of 6" exhaust tips.

Boost is not boost. 10lbs from one turbo will not make the same power from 10lbs of a different turbo.

Keep the exhaust short before the turbo, and don't go too big on the pre turbo piping.

Make sure to size the exhaust housing correctly or you will have trouble spooling or high exhaust back pressure.

You don't need a lot of camshaft. Let the turbos do the work. Watch overlap.

Like stated, try to find someone that has a good working combo.

I have to do this work thing, unwound love to contact you about this later...I’ve got a set of 509’s, blower pistons, that I need to put the top end on:. I have a bunch of technical questions, with your setup, because I believe you’ve done exactly what’ve want to do... I was thinking of welding jackets on the turbo, but I love the 25 lbs of boost, you have to be in the 4 digits for horsepower. And if the bilge temps are in good shape, i would love to pattern mine after your build

1730 hp at 25#.

Many of the big diesels use a wrap or blanket. There’s a black wrap that marine exhaust out of Florida uses, I can put my hand right on the 8” pipe of 2000hp Mtu’s while the boat is cruising. I’d look into using that if you’re not using jacketed housings

Here you go.
https://cimg1.ibsrv.net/gimg/www.off...4a63ce618.jpeg

Beautiful. Do I see belt driven fuel pumps ? If so, who’s ?

Im a small nobody in the turbo world, but Ill give you my experience so far. Gale Banks made the turbos for the Mercruiser 475 package. These were water cooled turbo housings and it was a draw thru system using a rayjay turbo. M&W made a bolt on kit using Rayjay turbos and water cooled housings and their kit was a blow thru into a box that that carb sat in. On my Scarab, I have the foundation of the Mercruiser 475 package except my exhaust housings have water cooled heat shields and rayjay turbos.

Great article:
https://www.msn.com/en-us/autos/enth...7l5?li=BBnb4R5

That's because of turbine efficiency/set up. 10PSI in the intake manifold is 10PSI in the intake manifold. How you get there is what will change the output to the crankshaft. An engine will respond differently based on turbine housing/wheel sizing, supercharger drive losses, ect.

A turbo engine with 2:1 backpressure will make less power than one with 1:1 backpressure at the same boost level for this reason.

Exactly right. At 25# of boost we had 25# of exhaust back pressure.

TomFTM--Thanks so much for the picture. I have those exact exhaust housings, but a different internal wastegate setup. (diaphragm in the housing) I wasn' sure what the small cast "bungs" were for, as mine were plugged. I see I can convert mine over to a more modern wastegate. Pictures of Gentry stuff can be hard to come by. Thanks Again! That's what I aspire to for my engines to be.

Offtopic--- My intercoolers are a bit different but do have the large water inlet and outlet like yours. Are you running you water from the pump there first then out to the motor, or are you pulling water from somewhere else?

Thanks!

sent you a PM...or are we now calling it a DM? Whatever. Sent you a message

Boost is fickle thing, if you efficient intake heads etc. boost will measure lower than what others may say. I know on my motor a blower that would traditionally produce 8lbs only produced 3#, I had to get a different blower to get any numbers above 4#. my heads and intake flow very well. there is an art to boosted flow and very few grasp it. Most engine builders just dont care how heads, intake flow when throwing boost at motor. it is pretty well admitted by them.

Does anyone know who makes the Mercruiser turbos? I have looked for a performance watercooled turbo but I can't find anything. For a while Tial was making water cooled housings but they don't now. Thanks.