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Old 04-10-2015, 06:07 PM   #1
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perkins intercooler question

I've got a early 60s Perkins T6.354m. Having turbo rebuilt currently and shop said I was overheating my turbo on the discharge side. I explained that there is an intercooler with a way to hook up raw water but it hasn't been connected and the reason why I never tried it is in fear of a water leak into my air intake.

anybody have theirs hooked up, not hooked up? Have turbo issues?

had to get turbo rebuilt because it seized recently and I had thought it was due to moisture and still believe it was what seized it but maybe not the only issue in having with it.
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Old 04-10-2015, 07:46 PM   #2
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I've got a late 70s range 4 and it's all hooked up. No turbo issues as of yet but we've only run the boat about 3 hours since we bought it a couple months ago.

The only help I can be is a picture of ours... but the only picture I have is of it NOT hooked up while I was putting in a new-to-me exhaust manifold. I can bother Em if you want a picture of anything...(I'm away for another 2 weeks).
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Old 04-10-2015, 09:11 PM   #3
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I am surprised that in the early 60s Perkins (or anyone for that matter) built a sea water intercooled engine. Could it be set up for coolant cooling which I suspect did exist in the early 60s.

In any case not hooking up coolant or raw water, whichever is bad. The air is compressed to several hundred degrees F by the turbocharger and that heat needs to be removed. Otherwise the combustion temps will get high enough to melt pistons and destroy valves.

Early turbo charged engines had no intercooling. But they did not have enough boost to matter. If the engine was designed to require an intercooler, hook it up right.

Having said that the problems with your turbo are probably not due to a non functioning intercooler. They may be due to sea water backing up into the exhaust side due to a poorly designed exhaust system.

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Old 04-10-2015, 09:34 PM   #4
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Gabe I appreciate the help. That picture doesn't help too much but the fact that you are connected does.....
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Old 04-10-2015, 09:36 PM   #5
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David, the intercooler not being hooked up is been the way its been since I bought the boat in 2011. It wasn't till later that i realized water should be hooked up. I just guessed that it was raw water because the fresh water system doesn't seem like it would connect.
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Old 04-10-2015, 09:42 PM   #6
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I have put around 400-500 hrs on the boat since owning the boat. So i hope i have not damaged pistons or valves because ive just put $4k into engine and id hate for there to be mmore serious issues
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Old 04-10-2015, 09:43 PM   #7
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Reason why i asked on here is because i feel like ive seen it before on here but maybe not
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Old 04-10-2015, 10:03 PM   #8
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The intercooler on my lobsterboat has always been hooked up and it needs it to make the advertised power and prolong engine life by keeping exhaust temps down. It's a Bowman. I'm on my second tube bundle since 1972 and my second housing. Not bad. Boil it out, test it, hook it up. If you need tubes, have it retubed. If it needs a housing, you can make one from 5" PVC or buy one from a Bowman "stockist" There's one in Boston
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Old 04-10-2015, 10:07 PM   #9
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Yea brooksie I think that was going to be the plan. Hopefully what I have is still good
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Old 04-10-2015, 11:15 PM   #10
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Gabe or anybody for that matter, if you could supply me with a photo of what the intercooler is connected to? Water wise. I'll post a picture of what ive got tomorrow
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Old 04-11-2015, 09:03 PM   #11
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here's a picture of what I've got, turbo I at shop obviously but there is a good shot of intercooler <img>http://i.imgur.com/26pqggo.jpg</img> bah you guys can click it
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Old 04-12-2015, 12:13 AM   #12
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hmm, you have a different doohicky in there...

the sunlit connection to your intercooler is connected to the the aft, port part of the exhaust manifold in the attached photo on my engines I think...
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Old 04-12-2015, 12:17 AM   #13
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After a few beers, I'm pretty sure I've got what David is talking about with the coolant cooled turbo.

Sorry to say, I think we're comparing oranges and tangerines
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Old 04-12-2015, 01:38 AM   #14
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I received the following in an e-mail today from a friend who used to participate in this forum. He is a professional marine propulsion, generator, and systems specialist who currently sells and installs an emissions-reducing exhaust system of his own design to the superyacht industry. He happend to read this thread and had the following to say. (Note-- What I myself know about this subject wouldn't cover the head of a pin. I am simply relaying what my friend wrote in case it proves helpful to the discussion.)

-------------

First, there is no way that the discharge temperature is going to damage the turbocharger. The temperature that the intercooler "feels" is the result of air compression that takes place in the volute, the part of the turbo where air accelerated by the impeller is slowed down to convert velocity to pressure. The impeller is not much warmer than the inlet air temperature.

The intercooler is there to reduce the temperature of the compressed air to increase its density and thereby increase engine performance, cooler air is more dense and allows more fuel to be burned during each combustion stroke. That is the whole point of a turbocharger.

The maximum temperature of air leaving the turbo never reaches the temperature required to ignite diesel fuel so the idea that charge air could melt pistons or valves is absurd. Temperature in the cylinder during compression reaches over 1000*F which is probably 3 times what a turbocharger normally produces.

The issue that might occur when the cooler is not cooled is that the tube bundle might be heated beyond its design limits and damage the seals so that when water is restored there may be leakage of water into the charge air space.
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Old 04-12-2015, 09:03 AM   #15
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Marin:

Your friend's note is correct as far as it goes, but it misses the whole point.

Engine manufacturers design an intercooler for two purposes: to improve efficiency as your friend's note indicates, but also to keep combustion temperatures down to safe levels.

If you have a high performance turbo charged engine that has an intercooler installed, that intercooler is designed to reduce the charge air temperature from 3-500 deg F (depending on design boost) as it comes out of the turbo to about a hundred degrees as it goes into the intake manifold. With the intercooler not hooked up to water (whether raw or coolant) that intake air will be hundreds of degrees hotter than designed at heavy loads.

No it won't melt the pistons as it enters the combustion chamber before fuel is injected. Your friend is right about that. But the combustion gasses that result will be hundreds of degrees hotter due to the air starting out hotter. That is what will melt pistons.

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Old 04-12-2015, 09:09 AM   #16
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Quote:
Originally Posted by CaptSoterio View Post
Gabe or anybody for that matter, if you could supply me with a photo of what the intercooler is connected to? Water wise. I'll post a picture of what ive got tomorrow
On my Perkins, the intercooler is the first thing in the seawater circuit. The seacock/strainer is connected first to the to the intercooler b/4 the pump intake.
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Old 04-13-2015, 01:03 AM   #17
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This the reply from my friend in the marine propulsion and systems industry to the comment quoted below. It's long but it seems to address the issue pretty thoroughly. Again, this NOT my area of expertise. I am passing this on as it seems to me to be information from a professional source that people who have an interest in the subject would benefit from reading.

-----------------------

Quote:
"No it won't melt the pistons as it enters the combustion chamber before fuel is injected. Your friend is right about that. But the combustion gasses that result will be hundreds of degrees hotter due to the air starting out hotter. That is what will melt pistons."
Not quite right ... there are components to his misunderstanding that will just add more confusion to most readers.

Air has weight, it has a property called "specific heat" which, simplistically, is the number of BTUs or amount of heat required to raise the temperature of a given mass a given amount. There is a difference between heat and temperature. A candle flame might produce a very high temperature but it will not produce much heat. You can pinch the flame between your fingers and not get burned because there is not enough heat to raise the temperature of your skin to the level that will cause damage.

A turbocharged diesel uses the turbo to compress charge air above ambient pressure, which in the case of a normally aspirated engine will be less than atmospheric pressure. The additional air provided by “boost” above atmospheric pressure provides enough oxygen to support burning more fuel and thereby produce more power than a normally aspirated (NA) engine.

To eliminate the need to add structural strength and weight to achieve this end, the turbocharged engine has a lower compression ratio and the capability of injecting more fuel than its NA cousin. The turbocharged engine also incorporates a slightly different valve timing scheme that provides a period of “overlap” at the end of the exhaust stroke so that both inlet and exhaust valves are open simultaneously for a short period. The purpose of this is to allow comparatively cool charge air to more completely scavenge exhaust gases from the cylinder and to cool the exhaust valves.

Not all turbocharged engines are inter or (more properly) after cooled, but when high performance (and these days – low emissions) is the goal, a charge air cooler increases the charge air density to allow more fuel to be burned to create even more power.

The amount of heat present in the “… hundreds of degrees hotter …” but much less dense charge air is not the reason for higher exhaust gas temperature. The fact that the hot charge air is less dense and does not provide enough oxygen to completely burn the amount of fuel required to produce the power needed for the engine to operate at the load imposed on it means that because it is in effect overloaded, cylinder pressure and exhaust temperature rises accordingly. In addition, the less dense charge air is incapable of scavenging the cylinder as thoroughly and because it has less mass (remember specific heat), is less capable of removing heat from the valves during the overlap period.
A poorly performing turbocharger will cause valve damage related to high cylinder temperatures because it does not produce enough mass (oxygen) to properly burn the fuel required to produce the desired high power output or to cool the combustion chamber and valves during the overlap period. This will happen even if the aftercooler is functioning normally because fuel is still burning during the exhaust stroke.

It is the mass of air, not its temperature that matters most. The fact that they are related is coincidental. As a matter of fact, higher temperature charge air improves fuel vaporization and reduces ignition lag which is a good thing. The bad side is that it also increases emissions and the overall heat load on the cooling system. In the case of a small engine that is not expected to produce a very high power output, the major problem with high charge air temperature is reduced power output, marginal cooling system performance, and higher fuel consumption.
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Old 04-13-2015, 10:09 AM   #18
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Spare for $100. housing alone is worth 3-4 times that.

Diesel Large Cooler Heavy Duty Cooler | eBay
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