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Old 10-01-2018, 15:17   #1
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Can I Turbo a Stock Diesel?

Hey all you engine nuts! Back from a long break, bringing with me a very interesting question:

Is it possible to put a Turbo on a completely stock diesel engine and have it produce more power while at the same time not blowing up?

Background:
A Turbo is a compressor that runs off of exhaust gasses and squishes more air into the compression chamber that there would be on a naturally aspirated engine. More air = more power.


The engine I plan on doing this to is an impressively indestructible Universal M-18 with 1200 hours on the clock. If you remember how I used to post tons of threads about Catalina 27s, you'll probably have already assumed the engines in a Catalina 27 right now. That's correct, and whether its age or just how its always been, the boat feels super underpowered. I would fiddle with the propeller pitch or the similar, but after recently buying a Mk3 Jetta TDI (that's VWs Turbocharged Direct Injection engine for all you normie Toyota drivers) I know exactly how I wanna fix my problem.

The plan:
You have to tap into the exhaust for the turbo to work.
so imagine this

Except with a turbo connected inline.
Charge side can run directly into the intake
I dont plan on cranking boost up to 20++ Psi. Only five to 8 Psi at first, Ill start small and work my way up safely till I get the results im looking for

Now, for the questions I have.
(Note: If at all possible, avoid just being like "Bad idea, stupid, 14hp is enough power for a 27, ect, ect". Answer my questions if you can, give some valid reasons why it can fail or work, and maybe a short and sweet reason as to whether or not I should do it.)

Now, calling all Diesel experts:
1 What Is a good size turbo? Engine displacement is like 550cc, 14hp, 2 cylinders
2 Will it be neccisary to upgrade the injectors size?
3 What do you guys think is the max Psi this engine can handle safely in its stock form?
And the golden question
4 Will stock rods, rings and valves even be able to handle boost?

Tell me what you guys think, and anything I may have missed. Interesting topic to me at least
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Old 10-01-2018, 16:57   #2
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Can I Turbo a Stock Diesel?

Of course you can turbocharge a normally aspersed Diesel, itís the not blowing up part that is hard.
Actually if done correctly a turbo will be easier than normally aspirated, the reason is that there is valve overlap, during this period of valve overlap a turbo will blow air right through the engine, cooling it slightly.
Now your problem is several fold, first determining how much margin all your parts have and not exceeding the margin, and as you have already said you will have to upgrade your injection system.
If you really want to go down this road, the only real safe way to do it, you end up with only a marginal power gain, and then whatís the point?

Look at the GM 6.5 Diesel to see how a turbo can be added to a basically stock NA Diesel.

A turbo or any other modification to increase horsepower is all about getting more air into the engine, fuel is easy. Then of course the engine has to be able to handle the increased power, and do so continuously and that is the hard part. You can put say a stock Honda Accord on the bottle (nitrous oxide) and probably almost double itís power output and not blow it up, but the key is you only stay on the bottle for seconds at a time, not minutes.

So bottom line, yes with enough money and time it can be done, the question is why?

Oh and turbocharging a two cylinder engine is tough, real tough, it has to do with the long interval between exhaust pulses, itís only been done successfully once that I know of, by Honda on their odd 650 V twin decades ago, others have done it Iím sure, I just donít know who has
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Old 10-01-2018, 17:05   #3
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Re: Can I Turbo a Stock Diesel?

This may be of some interest to you.
http://isromac-isimet.univ-lille1.fr...finalpaper.pdf
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Old 10-01-2018, 18:15   #4
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Re: Can I Turbo a Stock Diesel?

yes and add Intercooler also very simple set up
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Old 10-01-2018, 18:47   #5
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Re: Can I Turbo a Stock Diesel?

Many years ago I was going to turbo wife's Pinto woody station wagon. I was looking to create a real sleeper. I had access to a small industrial RayJay turbo capable of 30 plus
PSI. The engine had a fresh rebuild and I figured it would hold together for a while. Long story short I got rid of the car and the wife. I think I did the right thing and came out ahead in both cases. Just because you can do something doesn't always mean you should.
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Old 11-01-2018, 01:19   #6
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Re: Can I Turbo a Stock Diesel?

Engines I have experience with have a lower compression ratio for turbo models and they have bigger injectors, higher volume water pumps, bigger heat exchangers. Turbo models use 3 -4x more fuel at rated hp. So with any boost, and stock injectors, it will be running lean. A good way to burn out the piston tops and valves. With bigger injectors you'll use a lot more fuel. Hull speed is going to be the determining factor of how fast you go. Once you're going at hull speed, it takes many times more hp to go a knot faster.
The other big issue is exhaust gas temperatures. A natural engine has metal alloys not designed for the high EGTs a turbo produces. So you'll wear rings, cylinders and valves much faster. You may not be able to properly cool the engine. Even if the coolant temp stays at normal, you're still eating metal with the high EGTs.
Engines of the same basic design, but turbo and natural models, turbo engine life between overhauls will be about 1/2 to 1/4 of the natural.
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Old 11-01-2018, 01:52   #7
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Re: Can I Turbo a Stock Diesel?

Quote:
Originally Posted by Sailuke View Post
the boat feels super underpowered.
Q1. So can you reach hull speed and can the existing engine reach full revs in gear with a clean hull? if so I am not understanding your problem.

What I do know is you are in for a heap of pain, as Lepke explains turbo engines normally have lower compression ratios so you can squeeze more air into the cylinders which along with more fuel makes a bigger bang. So are lower compression pistons available for your engine and are you able to do a piston replacement?

So what is the answer to question 1?

Pete
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Old 11-01-2018, 06:33   #8
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Re: Can I Turbo a Stock Diesel?

Diesels or high compression based engines long story short if you don’t over rev the RPMs it will not hurt a diesel engine to push more air through life of the engine will be shorter simply because the engine is engineered to burn A certain amount of fuel. Meaning stock engine naturally aspirated will last 3000 gallons. Same engine turbo will last 3000 gallons you will just have the ability to get there faster shorter amount of hours. it will do no good to add more power if you were reaching your RPM range but if you had more power and a bigger wheel You could keep your rpm’s in the same factory spec range and put more power in the water. May need to add larger injectors also.
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Old 11-01-2018, 07:38   #9
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Re: Can I Turbo a Stock Diesel?

Quote:
Originally Posted by Sailuke View Post
Is it possible to put a Turbo on a completely stock diesel engine and have it produce more power while at the same time not blowing up?

You might want to compare the cost ($$$, study, time, fabrication, effort, etc.) to the cost of simply replacing the engine with something you think might be more suitable... and then flogging your existing engine to recoup some of that later cost.

Not a recommendation, just a thought...

-Chris
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Old 11-01-2018, 08:17   #10
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Re: Can I Turbo a Stock Diesel?

Definitely worth pricing out an engine swap. If it's close, I wouldn't mess with the complications of a turbo.

Also, as mentioned, check the WOT RPM. If it's not reaching the rated RPM, you probably need a different prop (assumes clean bottom and prop in good condition). If you hit hull speed well below cruising RPM, a lower pitch prop can make a huge difference.

14hp is probably adequate to get to hull speed in calm conditions but if you are fighting headwinds or waves, it's probably a little light on power but not drastically.
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Old 11-01-2018, 09:22   #11
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Re: Can I Turbo a Stock Diesel?

You can turbo anything, thereís even a YouTube video or two of a turboíd literoid single cylinder engine.....but, imho youíre not going to gain much by putting a turbo on what youíve got. Unless you can cobble something together for free, and then change the prop for free I think youíre wasting cash that could go towards a three cylinder engine with a little more oomph. Even then though your boat is only going to go so fast.
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Old 11-01-2018, 09:28   #12
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Re: Can I Turbo a Stock Diesel?

Don't waste your money with the turbo BS.
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Old 11-01-2018, 10:49   #13
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Re: Can I Turbo a Stock Diesel?

If I was buying a sailing boat and there were two identical ones except one with a turbo engine and other with a NA one, I would chooce the NA engine boat every time. Better reliability, cheaper to maintain, less heat in engine room. A motor boat might be another story but a sail boat is not a motor boat..
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Old 11-01-2018, 11:01   #14
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Re: Can I Turbo a Stock Diesel?

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Originally Posted by ErikFinn View Post
If I was buying a sailing boat and there were two identical ones except one with a turbo engine and other with a NA one, I would chooce the NA engine boat every time. Better reliability, cheaper to maintain, less heat in engine room. A motor boat might be another story but a sail boat is not a motor boat..
I agree.
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Old 11-01-2018, 11:12   #15
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Re: Can I Turbo a Stock Diesel?

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Originally Posted by ErikFinn View Post
If I was buying a sailing boat and there were two identical ones except one with a turbo engine and other with a NA one, I would chooce the NA engine boat every time. Better reliability, cheaper to maintain, less heat in engine room.
x2. Also consider the effect of added power on your existing drive. Will the transmission handle the added power or is it at the or near the limit of what it can handle. More power...more heat...more wear...etc. Affects more than just the basic engine.
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