Question on Turbo cooling

[Grrrrrrr!]

Basic questions is, should I change the -4 fittings out for -6 fittings to get more coolant flow through the turbo core.

Application is club level racing and trackdays, car wont be used much on the road.
Turbo is a kinugawa td05-18g, going on a 3sgte.

Can see two possible outcomes:

1) More cooling = less heat making it thru to compressor side, = cooler air out of the turbo. Also due to better flow the turbo will cool down a lot faster on slowdown lap and wont need to run turbo timer as long or at all in the pits, and under lid temperatures might be lower.
2) More $ for parts, but wont do diddly squat except suck more heat into the cooling system.

Thoughts?

[Vertigo]

Do you know for sure that the flow isnt restricted by the core itself?

[Grrrrrrr!]

Its a pretty big cavity in there with m14 threaded fittings, so it'll flow way more than AN4 fittings will.

[Vertigo]

In that case, more cooling is always going to help.

[Dell'Orto]

I guess as long as it isn't passing through so quickly it doesn't get a chance to draw as much heat out as it might otherwise do, can't be a bad thing.
What do Evos use sizewise?

[Vertigo]

Velocity of the water means very little really - in fact, should help cooling efficiency if it is faster to pass through the core.

[Stott69]

As for the timer idea, is that not for the oil side of things? I was under the impression that a turbo timer was so the turbine had stopped spinning be for you stop oil flow over the shaft and bearings?

[sergei]

As for the timer idea, is that not for the oil side of things? I was under the impression that a turbo timer was so the turbine had stopped spinning be for you stop oil flow over the shaft and bearings?

no, that's for the oil not coke in the housing. Pointless for water cooled turbo.

[KinLoud]

I guess as long as it isn't passing through so quickly it doesn't get a chance to draw as much heat out as it might otherwise do, can't be a bad thing.
What do Evos use sizewise?

Faster flow is better
Heat transfer is proportional to the difference in temperature between the hot part and the cooling medium (water or air) - if the flow is slow then the cooling medium heats up too much and the temperature difference decreases - so less heat is transferred.
An extreme example is seen at burnout competitions...
200kw car can overheat pretty quickly during a burnout because the radiator can't dump enough heat even with big electric radiator fans.
Same car could have no problem at high speed as the airflow only heats up a small amount due to high airflow.

[Al]

As for the timer idea, is that not for the oil side of things? I was under the impression that a turbo timer was so the turbine had stopped spinning be for you stop oil flow over the shaft and bearings?

no, that's for the oil not coke in the housing. Pointless for water cooled turbo.

Oil won't coke it's not 1985 anymore.

Turbo timers just waste gas.

[Flannelman]

I think I need to add here on turbo timers and their intended purpose.

Many years ago, Caterpillar bulldozers were hired to do the earth moving at the Meremere coal mine. These machines operated from 6am to 12 midnight without fail. Then, the upgraded models were introduced. These were the new Turbo Diesels. However, the head life was found to be very limited. In a short time, the cast iron head developed cracks. All conventional methods were tried to improve service life by more cooling, bigger oil lines ect. While these methods did help, all it did was extend the life from a fortnight to a month.
Desperation set in, so all external panels were removed to try and improve the heat extraction. The first night this was done, the heat became obvious. The turbine housing was found to be glowing to the extent that the "shadow" of the impeller inside the housing could be seen. This info was then given to the mechanics who instantly told all drivers when work has finished to let their vehicle idle for 5 minutes. This cured the head cracking problem.
So, what was happening was when the engine was shut down immediately when the turbo was red hot, the head became the heat sink.

While this case is an extreme (slow moving, hard working earth moving diesel V fast moving, low working grocery getter) the timer is there to eliminate the heat sink the head becomes, even more so as most performance turbo road car engines are aluminum. This has a greater heat transfer rate than cast iron.

There is also the case of the BA XR6T that got turbine wheel droop because he gave his car a performance drive, then shut it down straight away.

Turbo timers have a place. These are just two reasons why they are needed.

[Al]

Not convinced.

Sounds more like Cat made a shit product and there is far more to the Ford story than turning the car off once after a hard boost.

[Flannelman]

History is there to teach those willing to learn.

For everyone else, there's MasterCard

[MAC_HATER]

My turbotimer is 50\50 used if i really give it hell and dont have a few minutes of gentle cruising before shutting it off

And if its a friggen cold morning and I want the car to run a bit longer to warm up

[Grrrrrrr!]

Oil won't coke it's not 1985 anymore.

Turbo timers just waste gas.

Any oil (even group IV synthetics) will coke if you shut down hot, 5 or 6kgs of cast iron manifold glowing red after a good thrash; thats a shit-ton of heat to get rid of, and MR2s aren't known for great engine bay airflow. I don't think the <2 minute cruise back to the pits is going shed all that heat by itself. Turbo timer will be getting used for at least another minute once back in the pits.

[85AW20v]

...... thats a shit-ton of heat to get rid of, and MR2s aren't known for great engine bay airflow. I don't think the <2 minute cruise back to the pits is going shed all that heat by itself. Turbo timer will be getting used for at least another minute once back in the pits.

The only time my engine bay fan came on in the AW was in the pits after hard track use on a hot day and you're right - the cool down laps didn't help dissipate much heat except for maybe the brakes and mine is NA not turbo.

[thegreatestben]

I've never had any of my mr2's creep up in temp, not even at the track.
The 7agte was no different either, 13L+ of coolant with everything in top order (plus water wetter just cos) is pretty good at cooling a 1.6L 4 cyl

[Akane]

I'm with Al on this one.
Bought used Garrett turbo, installed it without any water cooling - the lines ain't even hooked up. Done my share of events, burnouts, skids, spin outs on track and stall the engine etc. Took it to phothog to disassemble and a rebuild after 10,000kms - just because I felt like it.

He found the core and bearings to be in good condition, he was puzzled as to why it needed a rebuild, but he did it anyway.

Please do share your experience on wrecked turbos because you didn't have a turbo timer installed....