'Oil cooled' turbos

[nick.parker]

Hi,
Is the concept of an 'oil cooled' turbo a load of rubbish in regards to a performance petrol engine? I found some info on the internet that seemed to indicate any 'oil cooled' turbo will eventually suffer from coking, whereas water cooled cores, so long as cool down procedure is followed after hard driving do not reach oil coking temperature.

The bigger turbos of the KKR range dont have water cooled cores, but the smaller ones do. Is there any logic behind this? Lots of the Ebay stuff (Im sure its crap) is also not water cooled.

Cheers, Nick

[Billzilla]

All turbos are oil-cooled.
Some are water-cooled in addition though.
There's no problem with using an oil-cooled one, you just have to let it all cool down a lot longer after parking. When the engine is running there's enough oil flow through the turbo so the oil isn't in there long enough to be 'hurt' by the high temperatures. So you just let it cool down for a few minutes and they're fine.

[Pube]

Id like to think all turbos are oil lubricated not so much as oil cooled

[roadsailing]

feel free to think what ever you like, but something has to keep the bearings cool.

of course it lubricates the bearing too

[Endless]

You'll also find most of the big name jap turbos are oil cooled/lubricated only.

[nick.parker]

Id like to think all turbos are oil lubricated not so much as oil cooled

This was my opinion too, but if all the oil 'cooled' turbos died really quickly then it doesn't make sense that you see so many for sale on ebay etc.... However, I have noticed that almost all factory turbo'd cars have water cooling.

All turbos are oil-cooled.

How well does oil conduct heat? I guess quite well since we use oil in frypans.....but is the turbo going to cool more as a result of radiation and convection cooling....?

[The Real Roadrunner]

nothing wrong with oil only trust/ mitsubishi turbos are still like this and alot of the journal type garrets also.
the main reason behind watercooling is the ball bearing turbos only require around 2lpm of oil and dont want any more than that or they blow turbine seals.
if its advertised as roller and oil cooled it would last about 6 months before it died.
most ebay turbos ie chinese are crap, the reason they dont prvide turbo maps is half the time they dont even know what theyre copying add to that they make different trims from the same wheels and it gets more confusing.

here is a good one for you, customer bought one in to be fitted so i did it after long arguements
he took the car out and complained it was laggy and made less power than stock.
removed turbo and sent it off for assesment, out of balance badly , much time spent but got it high speed balanced bolted back on.
took it for a drive and the thing went hard, came on boost well i was impressed.

but by the time al this was done the guy could have bought a bb garret so what was the piont in being tight in the first place.

my 2c

[thechuckster]

the Corky Bell book Maximum Boost has a nice graph comparing oil-only core temps and oil+water core temps - against the temps that oil will coke or charcoal at.

Water-cooled housings (unless abused significantly) didn't reach the temps that oil would die at.

[30psi 4agte]

I like the water cooled cores.

A oil only core will be fine for drag use and cruising the streets but if track work is the go then id go for the water cooled core.

Constant hi rpm will send oil temp skywards add to this the heat that a turbo is producing and ........ well you get my drift.
Extreme oil temps will not only damage a turbo but also will do its thing to the engine bearings.

A water cooled will provide some form of tempreture stability.
Cooler oil temps = longer oil life and engine life.

CHUCK: how did the oil only core fair?

[SIKTOY]

If oil cooled is only good for short running times how is it that 99% of truck turbos use oil only cooled cores
My truck turbo runs at full boost (30psi) 90% of the day 6 days a week and has no problem at all

My friends truck runs 35-40 psi on his 600hp cat motor and has been doing for 6 years


my2c

[wilbo666]

CHUCK: how did the oil only core fair?

No where near as good as water cooled.

He might have the page scanned

Cheers
Wilbo

[thechuckster]

oops - must find photocopies of the book <blush>, will try to post tonight

[Mr DOHC]

turbonetic thumpers are all oil cooled

they are 1500-2500hp turbos

[thechuckster]

yeah - but they don't get (ab)used for long durations (e.g. doing heavy-duty circuit laps) so the heating 'duty cycle' is comparatively low.

[SIKTOY]

yeah - but they don't get (ab)used for long durations (e.g. doing heavy-duty circuit laps) so the heating 'duty cycle' is comparatively low.

Like I said before chuck my truck turbo (garret) runs at full boost for about 10 hours a day so your theory of non water cooled turbos not lasting isn't so strong