FormulaRX

Hello all! I tried searching already and could not find the answer so please just a simple answer will do for me instead of telling me to use the search function again. I obviously don't have an FD or I would just pop the hood and look. So are the stock twins water or oil cooled? If they are water cooled, there's no need for a turbo timer right? Thank you!

AMRAAM4

water cooled..and turbo timers are worthless. (this right from the mouth of a well known RX7 mechanic/tuner I will not name so as to protect him from flammage).

twinturborx7pete

iTrader: (3)

they are both.

FormulaRX

both? so they have oil feed lines as well as water lines through them? I was under the impression that any turbo cooled by oil "SHOULD" ideally use turbo timers to prevent oil cooking during shut off but the guy above said it's worthless

rx7onfire

iTrader: (10)

So tell me why turbo timers are worthless?

SpeedKing

iTrader: (4)

He will tell you to drive without boost a couple miles or so from your destination, then shut it off when you get there, hence no need for a turbo timer to idle the car. However, not everyone has the patience or is soft-of-foot to always do that.

twinturborx7pete

iTrader: (3)

yes they have both lines running through them. You don't really need a turbo timer if you drive smoothly before you shut it down.. idling for a long time isn't good for any car.. all you are doing is increasing the underhood temps

FormulaRX

so say if we were to upgrade to an aftermarket single turbo setup, we can get one that's 100% water cooled right so then we could just block of the stock oil lines?

turbojeff

iTrader: (30)

Only if you have some magic stuff that allows the turbo to spin a 100,000+ rpm without any lube.

t-von

iTrader: (8)

To add to this, letting the car sit up and idle does nothing to cool the car down (especially the oil coolers). You need the air flow. After I drag my car, I always take a short little drive as soon as I finish my run(no boost). The engine coolant & oil will cool down much faster this way. Also carbon build-up is accelerated while the engine is idleing.

live2drive15

iTrader: (4)

I always drive slow for the last 2 mile stretch before I get home. That is if i'm not driving slow already.

FormulaRX

Drive slow? In an FD? I don't think I'll be able to do that once I get mine HAHA! All joking aside, thanks for the info guys ... yeah i just don't like toying with turbo timers cuz on my previous car Audi A4 1.8T I had a turbo timer cuz the turbo was strictly oil cooled and even though it's set to go off by itself, I still have to stand there and wait til it turns off (the slowest 2 minutes I've ever experienced) cuz I just don't trust it for some reason...don't want to go into my house and come out an hour later seeing my engine still running. Thanks for the info guys

live2drive15

iTrader: (4)

Punch it all the time and when your motor blows you'll figure out how to drive slow heh

FormulaRX

nah if the motor blows, then I'll just throw in a street ported rebuilt one and drive faster

anyway, yeah I never understood the point of the turbo timer even when I had it on my old Audi...if there's no incoming air then sitting there idling would increase engine temps rather than lowering them. I know that it's to prevent the oil that's sitting in the turbo from cooking itself when you turn it off hence the reason the engine is kept running to circulate it but wow what can 1-2 minutes do...it'll still cook the oil after the timer turns the engine off cuz after hard driving, those turbos glow a faint orange...would need at least an hour to cool down if not more.

AMRAAM4

Even if oil cooled, what is the point of idling a car to try and cool the turbos? AS stated, it just increase underhood temps....and don't you finally have to shut it off at some point???

dgeesaman

iTrader: (7)

Teflon car wax!!!

brancato1

Does an "Oil Cooled" turbo even exist? They are all oil lubricated, and some are water cooled.
Car manufacturers almost always water cool thier turbos, to aid in turbo life, but water cooling is not needed... just nice to have.

jeffrored92

I might be off the mark a bit here, but I was under the impression that the turbos require a finite time to spin down after boosting. I have no idea how much time that is, but apparently it's a little while, long enough to damage the turbos if the oil is not flowing.

I thought boosting, then shutting down the engine straight away (without idling or gentle driving) could leave the turbos still spinning after shutdown, but with no oil/coolant flowing. This could lead to overheating and coking the oil.

Not saying this is how it is, because I'm not sure, just throwing it out for comment.

Here, I found one site that has this info posted on it so I know that I'm not making stuff up.

http://www.majesticturbo.com/glossary.html

KevinK2

majestic note is for oil cooled turbos. translation: let it idle 30 sec to let rpms drop, but better to let is idle several minutes to cool the very hot center housings, and avoid coking.

My thermocouple tests on an oil cooled turbo showed cool down idle was much more effective if one of the rad fans was blowing air across the turbo area while idling.

Oil only turbos use a large flow of oil through center housing cavities for cooling. For water cooled tubos, water fills and flows through the cavities, and oil flow is restricted, and does less cooling.

Turbo times are not very effective with FD's, unless fans are blowing some air across turbos. This is beacuse very little water flows through the tubos at idle, since the supply line port is near the return line port at the WP hsg.

Sled Driver

iTrader: (9)

The turbos are water cooler & oil lubricated.

A turbo timer is not needed & as previously posted will not actually "cool" down the car or turbos. The longer your car runs the hotter it will get due to lack of airflow (until your fans kick on)

In the old days turbos were not water cooled & the housing would glow red hot for a long time. If you shut down the motor with "hot" turbos the oil would boil away & coke up the oil passages. Lack of lube would seize/score the turbo bearings.

Fast forward to modern times......

Water cooled housing & synthetic oil. Both keep the oil from cokeing & clogging the passages.

Yes, you shouldn't shut down your motor after a 1/4 mile run or fast laps on the track. As stated numerous times, prior to arriving at your destination. Drive without boosting for 3-5 minutes.

As far as your turbos needing time to "spool down". Pull your "Y" pipe or intercooler pipe off. Start your car.

Damn, them little suckers are spinning away at idle. Granted they arn't going 100K rpms, but they are in motion.

BlaCkPlaGUE

Couldn't have said it better myself.

With water cooled turbos you do not need a turbo timer.

FormulaRX

thanks for all the useful information

CANRX7GX

iTrader: (1)

Some guy tried to tell me that I was a fool for not having a turbo timer in my FD... I got frustrated trying to explain at first and ended up laughing.
He said" if you don't have a turbo timer you'll cook your turbos"
anyhow, your questions have been answered!! so no point in me saying things again

adam c

iTrader: (2)

OMG!! A bunch of people on this forum all agreeing that turbo timers are worthless. Every time I preach this, some young fools start argueing with me.

Can this thread be a sticky

RoadRaceJosh

Engine oil cools and lubricates the turbo bearings. Porsche 930s have no water with which to cool the turbocharger nor do most turbocharged aircraft or diesel engines. Idling the engine is done strictly to cool the turbocharger bearing housing enough so that the oil does not coke. Water cooled turbos are pretty much always below the coking point as the bearing housings don't get much over 220°F. This is why turbo timers are of little benifit with a vehicle with a water cooled bearing housing. If you have enough coked oil in the bearing housing you will starve the turbo for oil and burn up the bearings or clog the outlet and blow the seals. So yes, turbochargers are oil cooled except for the no longer produced Aerodyne.