Is running coolent to a turbo required?

[TSi Kid]

I've heard different things from some of my local friends but is coolent really necessary, or is running oil alone good enough?

 

[TSi Kid]

i bought my gsx a few weeks ago and it had an hx35 turbo on it and the guy i bought it from had the coolant lines blocked off and it ran fine but i swapped it for a stock turbo since everything else was stock... so now its got coolant goin through it and works just the same

its not a matter of performance of the turbo its the longevity of it

Your logic is very flawed. For one thing the way I drive my GSX most of my driving is within five minutes of where I am. Another thing is I bought a turbochared car for a reason, if I had to baby it for the last five minutes of every drive or sit and wait for it to cool I would go out of my mind. Why not just get a civic that I can get on the whole way and still have better fuel economy?

maybe i'm wrong but you seem like the kind of kid that floors it everywhere and beats the breaks off his car. If you can't baby your car for the last five min of your drive then i feel bad for your car

Like I said in my above post, this topic has been discussed and argued about not only on this forum but on other car enthusiast sites as well.

Scotts right. I could type up another paragraph of the EXACT same information just worded a bit differently so I'll save myself the trouble and just use Scotts post.

gofer you must love that emoticon haha

Another thing is I bought a turbochared car for a reason, if I had to baby it for the last five minutes of every drive or sit and wait for it to cool I would go out of my mind. Why not just get a civic that I can get on the whole way and still have better fuel economy?

i know NA hondas that would smash on you and get better gas milage while doing it

 

[gofer]

gofer you must love that emoticon haha

I like using that emoticon when the threads going absolutely no where, I'm glad Justin posted though since he probably has more experience tearing apart turbos then anyone on here.

Turbo from the factory vehicles (Evo's, STi's, 911's) have a warranty their cars have to live up to. Of course they'll do anything and EVERYTHING to keep the oil from coking whether its necessary or not, if it extends the life of the turbo past their warranty then its good to go as far as they're concerned.

 

[Ninja GSX]

Then you my friend would be a prime example for a turbo timer user but my logic isn't flawed in that statement. It's true in the fact that if you just drive out of boost for a little before you shut off then there is no need to sit and let it cool down.


So aside from detergents and a higher weight, what's the difference between diesel oil and gasoline oil WTF I personally run Rotella 15w-40 which stated diesel AND turbocharged vehicles.

So since my TiAL MVS has liquid cooling ports on there, does that mean it's necessary to run those too

If that oil is rated for both gas and diesel then you aren't going to have problems. But diesel oil is different in terms of the wear compounds that are added to it as diesels have a different operating range. An oil that is intended for use in a gasoline engine is formulated for the particular conditions it will encounter. But you could still get away with it.

Just like how you could use 10w40 in an eclipse transaxle and transfer case. It is the same weight oil. However transaxle oil is specifically formulated to have much higher sheer strength to deal with the sheering action that occurs where gears mesh. You can get away with it for a while but you either need to change your transaxle oil much more frequently or don't plan on your transaxle lasting as long.

With your choice of oil I would say you are taking a bigger risk running an oil that has minimum viscosity of 15 weight. Even if you live somewhere warm like I do you are going to have to go easy on your engine as it warms up and gets oil circulated. If you live a climate that gets cold you are asking for increased wear. The reason why they started using 5 weight oil back in the late 80's is because modern engines have much tighter clearances so they need that lighter weight oil to get properly lubricated on start up. But you can get away with it just don't be surprised if your engine doesn't last as long.

I got this off of the net about your Tial :

17-7 PH Stainless Steel actuator spring gives consistent pressure at high temperature, resist "relaxing" at temperature to 900F (483C).

From that I would deduce that if you want it to give consistent spring pressure don't let it get hotter than 900F. Due to it's use and location I think that device just might be able to get hotter than that. So if you are not taking advantage of the designed in ability to cool it, it may not be consistently functioning the way the designers intended it to. That spring may be relaxing above 900F causing you to lose boost. I'm not saying it is for sure but it just might.

Did I say otherwise towards this? I know how liquid cooling is beneficial but it's still NOT required.

Here is another thread dealing with removing coolant from turbos.
http://www.dsmtuners.com/forums/newbie-forum/379750-can-i-overheat-my-turbo.html

My post is #10 and pay attention to paragraph #2, it's saying what you already said

I read that thread. You are making much better sense there. Though it seems like you are missing a little bit of the operational theory of how a cooling system works. While you are accurate in describing part of the process as convection currents, but that is not really the proper term for the operational cycle of a cooling system after shutdown.

The proper term for the system is thermal siphon. There are actually two thermal siphons in the cooling system. The overflow tank works through thermal siphoning. When the coolant expands the radiator cap allows it to flow into the overflow tank when it cools it it is drawn back into the radiator.

The other one is the cooling system itself, which is purposefully designed to continue to operate after shutdown. How long? As long as it takes for the engine to cool down. if it takes minutes or hours to properly cool the cooling system will continue to cool the turbocharger. Because of the way that cooling systems are designed. After reading your post this is something I'm not certain you (or some of the other posters) realize. Here is why I say that.

You are correct in stating that a thermostat will close after the coolant cools shutting down the flow of coolant. However not all parts of an engine like a turbo may not be sufficiently cooled when that happens. So how did the engineers deal with that? Simple. Heat rises, so they put the thermostat at the high point in the system. If the thermostat closes trapping coolant in the turbo and the coolant begins to boil, the heated coolant will rise through the system, reopen the thermostat and reengage the thermal siphon. This is how that system can continue to operate long after shutdown and ensure uniform cooling.

One of the keys to making this system functional is the location of the radiator hoses. Thermal siphoning is why cooling systems are designed with an upper and lower radiator hose so coolant flows from the top down instead of side to side. As hot coolant rises up into the upper radiator hose it will then flow into the upper part of the radiator, where as it cools it descends through the radiator towards the lower radiator hose. As the heated coolant flows out of the engine to the radiator it will draw the cooled coolant from the bottom of the radiator back into the engine.

Thanks to the thermal siphon system, which I don't think most people are aware of, I would have to say that liquid cooling beats the hell out of a turbo timer. As I think about it more I would even say that a turbo timer is probably one of those useless devices that takes advantage of people who just don't know any better. You would do better to liquid cool and rig your cooling fans to a thermostat with a continuous power supply that will allow them to operate after shutdown.

Then I suggest you never get a non-water-cooled turbo.

I don't have a water cooled turbo, mine is liquid cooled. There is a difference. If live in a warm climate you may be able to get away with running pure water, but you are asking for problems. Your cooling system isn't going to cool as well because antifreeze can absorb more heat.

So what about guys who are currently using diesel oil in their gasoline engines, and have been doing so for years and years? What are the negatives to this other than having a clean engine and well-protected turbo system?

When I worked at Precision Tune doing thirty minute tuneups and oil changes they had us rushing so much that I once started up a car before I put the oil back in. I ran it for a little while before I realized my mistake and it didn't break anything. If I could get away with that I am sure you could do a lot better using some kind of motor oil.

There are differences in the chemistry of gasoline and diesel motor oil. But some are rated for use in both. I don't remember the specifics but diesel only uses ZDDP while gasoline uses ZDDP and secondary ZDDP. There are different wear inhibitors because the operating ranges are different.

Then your logic is very flawed, because in my years of rebuilding turbos I've seen many water-cooled turbos that suffer the same oil coking issues that non-water-cooled turbos suffer from. If water cooling eliminated oil coking, then my repair business would probably be cut in half....but it's not.

Actually you are making the case for liquid cooling. Because if even with the extra cooling, coking is happening what would happen without it? I don't think you can make the case that eliminating cooling is going to make that situation better. But I can make the case that eliminating cooling could make it worse.

According to Exxon oil coking increases dramatically as metal temperatures exceed 225 degrees Celcius. Turbo's get a lot hotter than that. That is why you need liquid cooling to continue cooling after shutdown. Also the higher the temperature the harder the deposit.

http://www.exxonmobil.com/lubes/exxonmobil/emal/files/TTopic6_OilCoking1.pdf

Hell I've seen stock 14B's that were oil coked inside so badly that there was no way for oil to enter the turbine-side journal. Might even be able to post pics if you're curious.

I would be interested in seeing it.

Another factor to consider that doesn't get mentioned in these discussions is the effect of coking in the turbo on the rest of the engine. I think it would be safe to assume that as it builds up those coke deposits are going to be worn down and break loose. So as coke deposits shed it is released into the oil and carried into the rest of the engine. Shedding is probably how turbo's that have had their liquid cooling disabled are able to keep operating. It can't be good for overall engine longevity.

Hmm....Porsche mentions having had to switch over to water cooled turbos due to a significant number of turbo failures due to oil coke issues. Turbo timing I think is a dubious effort. Heat soak occurs AFTER the motor is shut off. Subaru even goes so far as to have siphon action draw coolant thru the turbo on engine shut off.

So what is being recommended goes against Mitsubishi, Subaru, and Porsche engineering practice, and I think these companies know a thing or two about turbo failures taking into consideration their long and successful history of motorsport racing. Clean synthetic oil, proper oil temps, sufficient oil pressure, and coolant flow are your friends. Overkill is highly underrated.

Thanks for mentioning this because I was going to discuss this in one of my earlier posts. Actually Porsche went to liquid cooled engines because of tightening emissions standards. In order to deal with the extra thermal expansion their air cooled engines had looser clearances, which resulted in a lot more blow by and oil burning during warm up.

When the engineers design a turbo with liquid cooling I would expect them to factor that in when determining optimal clearances in relation to thermal expansion.

All liquid cooled cars are designed to thermal siphon after shutdown. Subaru just goes to the trouble of pointing it out to the uneducated because most people don't know what it is and it makes it appear that they have done some extra engineering that their competitors haven't. See my previous post to get a fuller description of how thermal siphoning is designed into cars.

its not a matter of performance of the turbo its the longevity of it

I wouldn't be so sure that it does not affect performance, especially over time. But it most certainly is a matter of longevity for the turbo and even for the rest of the engine parts that could be affected by coke shedding from the turbo.

maybe i'm wrong but you seem like the kind of kid that floors it everywhere and beats the breaks off his car. If you can't baby your car for the last five min of your drive then i feel bad for your car

Touche. I am a bit of an overgrown kid. But as much as I like to take advantage of my cars performance, I try not to beat on it too much. I can't afford to be breaking things. The last two miles to my house is a huge 35mph speed trap. On a Friday or Saturday night I can see four or five cops laying in wait. Since I put the new turbo on I do try to give it a cool down which that drive is good for. But commuting 25 miles to work in Miami traffic can be a bi*** adding a cool down drive into that commute is not practical.

gofer you must love that emoticon haha


i know NA hondas that would smash on you and get better gas milage while doing it

Trust me. Every time I fill up with premium fuel I think about how I had wanted to put a K20 into a 96-99 hatchback before I saw a GSX with 80K for $3800 and changed plans. I still might get one.

 

[TSi Kid]

Actually you are making the case for liquid cooling. Because if even with the extra cooling, coking is happening what would happen without it? I don't think you can make the case that eliminating cooling is going to make that situation better. But I can make the case that eliminating cooling could make it worse.

he's not adding to you, its more of a rebutle. That regaurdless of being water cooled you'll still get oil coke if you don't let it properly cool down. I'm sure that beating the shiz out of your water cooled turbo and then immediatly parking it is a lot worse then running no water to the turbo and babying it for the last 5 miles of your drive, especially if you have a TT setup

 

[burningforce]

I remember running oil cooled fp greens back in the days with no problems you just have to run a good synthetic and let it cool down for a few minutes.

 

[jrohner]

From that I would deduce that if you want it to give consistent spring pressure don't let it get hotter than 900F. Due to it's use and location I think that device just might be able to get hotter than that. So if you are not taking advantage of the designed in ability to cool it, it may not be consistently functioning the way the designers intended it to. That spring may be relaxing above 900F causing you to lose boost. I'm not saying it is for sure but it just might.

Water in the center section of the turbo isn't going to cool an external wastegate. What does this have to do with this discussion anyways?

 

[gofer]

He's talking about the cooling ports on the new Tial MV-R...

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[Ninja GSX]

Water in the center section of the turbo isn't going to cool an external wastegate. What does this have to do with this discussion anyways?

Because he asked me this question. So I was responding to it.

"So since my TiAL MVS has liquid cooling ports on there, does that mean it's necessary to run those too "


The impression he is giving is he thinks he is smarter than the Engineers who designed these devices. The Engineers (guys who went to University) who design these components don't unnecessarily design cooling into a component because they don't know any better or they are just guessing it will help the component function better but they haven't done any testing to see if their guess is accurate. It costs money to add that extra complexity.

If a cooling system is part of the design then the engineers are going to factor that into a components operational parameters when designing the rest of the system. For example if you are designing a clean sheet new design turbo and it is going to be liquid cooled instead of oil cooled, a good engineer is going to factor that in when determining how much oil is going to flow through that turbo. If you no longer need oil for cooling you can reduce the flow rate and send more to the engine.

That is why you need to be cautious when re-engineering components. Because you are second guessing someone who probably knew a hell of a lot more than you do and had access to millions of dollars of testing equipment to do testing that you don't know about.

He's talking about the cooling ports on the new Tial MV-R...

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Exactly. If you look at the new design compared to the old design you can see that the new one has been designed to be compact so it can fit into a tighter space. I would be willing to bet money that in order to do that they had to make some changes to the design that require extra cooling in order for it to function as well as or better than the old design. If you look at it you can see that in addition to the coolant ports they also added four rows of cooling fins.

Because of the cooling fins I wouldn't be surprised if at lower boost levels it worked okay without coolant. But if you were going to take it to the limit of it's designed performance envelope you would want to run coolant through it.