velohead66

Hi All,

I have a classic MY98 with a Greedy T518Z tubo fitted.
Car (with a few other mods) produces 225kW at the wheels.
In 'old money' thats 301 bhp at the wheels. (Not sure at flywheel ??)
Also not sure if you'd call that a 300 hp car ?? Would be nice to know, but I digress.

Anyways, the turbo gets quite hot on trackdays, so I was wondering...
what temps I could expect on air intake (impeller) side ?
what temps I could expect on exhaust (turbine) side ?
would octane booster increase exhaust temp ?
would there be heat soak from exhaust side of turbo to intake side ?
what's best way to reduce heat in turbo and/or turbo area ?

Thx.

velohead66

...and would the VF turbos (in classics) be water cooled ?

velohead66

Anyone ?

musso2010

Yes, all VF turbos are water cooled.
To reduce heat, maybe try a turbo blanket and wrapping the pipes.

saiklon

Air intake temps at turbo - more importantly, how efficiently are you running the compressor? Check the compressor map and ensure you are running in a high efficiency region.

Turbine temp: Post 3 of https://www.scoobynet.com/general-te...iming-for.html

Octane booster would actually reduce EGTs if it allows the ability to run more advanced timing. Retarded timing = higher EGTs.

Heat soak from turbine to compressor, not an issue, the biggest component of heat increase for the turbocharged air is due to its compression.

As long as EGTs are ok, (and these are controlled by timing and fueling) there shouldn't be any reason to reduce turbine temps.

If the turbo is running within a fairly efficient region (check compressor maps to be sure) the only worthwhile improvement is improving the intercooler.

All Subaru turbos are watercooled. The watercooling is to prevent oil coking in the center section after engine shutdown, it does not contribute to cooler charge air.

velohead66

That's good to know, have just added a turbo beanie (aka blanket ?), and also thermally coated the down pipe, which is same as lagging the pipe.

velohead66

I've got some bumf on this, so that'll be my bed time reading for the next week !


So, if I get 120ºC air temp after the impeller has compressed it, would that be considered 'hot' or 'normal' ?
Ambient air temp = 30ºC
Post FMIC air temp = 40ºC (so FMIC does a good job)
Boost (I think is) 21 psi , not sure what that is in bar.
Edited...1.45 bar

So would EGT be monitored by ECU ? (ie temp rather than oxygen content)

alcazar

iTrader: (2)

Mine runs an HS TD05 20g, with FMIC on a 2.5 conversion. Never had it RR'd so not sure of the power, but around 400 I'd estimate.

Anyway, it has THREE temperature guges for air:
Ambient, internal/external.
Intake air temperature
ACT or Air Charge Temperature, measured just before the inlet manifold.

When the engine is working hard, as it was the other day, I saw the following:

Ambient temperature: 12 degrees.
Intake temperature: 28 degrees.
ACT: 18 degrees.

My next mini-project will be to get some alloy sheeting and shroud the air filter from the rest of the engine compartment.

If you want advice on intake temperatures, you could do worse than PM Harvey Smith, on here, he posts as harvey, he's done LOADS of actual research on real cars.

trevsjwood

iTrader: (2)

My MD321H at 1.6bar, in wing CAIK, runs at approx 133-136 c outlet temps. It reaches these temps in a fraction of a second on boost and doesn't climb any further. The temps drop away equally quickly as it comes off boost. This is road use and a blast up Santa-Pod. Long sustained runs on a track may be a different story. I've heard of turbo outlet temps up to 200c.
Trev

saiklon

EGTs are not normally monitored by the ECU, and oxygen content is only monitored (and acted on) during closed loop i.e. off boost

velohead66

So, if I'm getting 120ºC at 1.45 bar, that's pretty consistant with yours trevsjwood.
So I guess i've got nothing to worry about then ????

Alcazar, I'm suprised your temps are so low !?
I guess that's because one is before turbo compression, and the other is after FMIC cooling.
I'm not a technical expert, so is the above line correct ?

PS - I did just PM Harvey.

harvey

iTrader: (48)

OK here is some information, some of which may already be on the thread but I hope it helps.
The air inlet temperature should be as close to ambient as possible and to achieve that within the engine bay often involves some insulation and air flow work. Reducing under bonnet temperatures is always worthwhile as it makes it easier to get a reasonable air inlet temperature.
The compressor outlet temperature is typically 150 deg.C on WOT but it can go up to 200 C. on some applications.
Again and obviously, you are attempting to get the air charge temperature just prior to the throttle body as close to ambient as possible. Hence the need for an efficient intercooler
Exhaust gas temperatures should not exceed 930 C. Beyond that and you are entering a danger area.
Increased ignition advance will reduce EGTs and the use of an effective octane booster will allow increased ignition.
The use of methanol in the fuel, as little as 5% will greatly reduce the EGT and also allow for more ignition. Typically 800 C. An alternative method is to use water methanol injection where a water methanol jet fires in to the air stream just before the throttle body. Typical water methanol systems use 50-50 water methanol. There is also a power advantage but not particularly great.
Once the turbo operates outside its efficiency envelope it will create a lot of heat for little or no power advantage.
Turbo blanket on the exhaust side has a number of advantages and I have never come across a situation where the temperature gets too high.
Keep the hot bits hot and the cold bits cold.

velohead66

Yes, it does definately does help.
Thanks for posting harvey, and ALL other posters thanks for posting too.
I'm not a technical expert, and may miss some obvious points.

What does WOT mean, btw ?

harvey

iTrader: (48)

WOT = Wide open throttle.
Here is information on a specific car. STi 3 Wagon with VF23 turbo producing a consistant 335 bhp/333 ft.lbs. The turbo was running to 1.5 bar mid range dropping to 1.4 bar top end. The turbo was operating well outside its efficiency range and any further efforts to produce power only resulted in excess heat.
With ambient temperatures around 15 C. the car was sprinted to 100 mph and the ACT measured at the throttle body was off the scale of the guage at 69.9 deg.C. as we passed through 100 mph. This was repeated several times and was consistant. The compressor discharge temperature was measured rather crudely but was around 170 C.
The car was fitted with OE TMIC.
The car was then fitted with STi 8 TMIC and the experiments repeated with ACTs now in the 40-50 C bracket.
The turbo was clearly operating at the edge of its ability and the solution would have been to fit a bigger turbo.
The car was then fitted with a Hybrid front mount intercooler and ACTs in exactly the same format were now in the high 20s and from the feel of the car it clearly picked up quite a bit of power because the ACTs were now under control.
The same car could regularly achieve EGTs 900-930 C. I am uncomfortable with EGTs of 930 C. and these are measured in the uppipe. Adding water methanol injection reduced EGTs such that they were rarely above 850 C. Other modifications had taken place to the car but the water methanol injection had added about 12 bhp certainly not much more but EGTs were certainly under control. More power was available by running methanol in the tank but the advantage of the water methanol injection was that it was relatively hassle free.
While mapping it is useful to have EGT information and as a matter of course on all my modified cars I monitor ACT and almost always EGT. Other than odd checks on compressor temperature output that is not monitored as I have little control over it and substantially that temperature is influenced by the efficiency operating range of the turbo.

trevsjwood

iTrader: (2)

Harvey, are the above figures running with the W/M injection or was it added later?
With my TMIC and W/M injection I regularly see ACT's within 10-12c + of ambient in the winter and curiously better in the summer at 7-10c+ ambient.
Thats WOT, 6000RPM . 1.6-1.5 BAR, 4th gear, compressor outlet 133c .
Trev

harvey

iTrader: (48)

The water methanol was only added once the car went to front mount and space was available. The effect is on EGTs and has no apparent relevance to ACTs which is what you would expect other than the effect of the reduced under bonnet temperatures.
In Winter the ambient can be very low so obviously in Summer there is less gradient and you are likely to achieve ACTs closer to ambient which is probably 15 degrees more than Winter ambient typically.

trevsjwood

iTrader: (2)

With my W/M injection, running 1 bar of boost with the W/M injection switched off ,ACT'S are double ambient, today ambeint 17c-ACT's 32-34c. With the W/M injection switched on, at 1bar ACT's are pegged back to = ambient 17-18c.
I've no way of knowing what the ACT's would be at 1.6 bar with the system switched off as the safety features do not allow more than 1 bar of boost if the system is not functioning.
Trev

harvey

iTrader: (48)

OK, I understand. It will depend where you are injecting the water methanol and where your temperature probe is located.
On my set up the water methanol is injected just before the throttlebody and after the ACT probe which monitors the air charge temp in the hard pipe several inches before the T.B. Obviously if the probe is after the injection point it will show temp reductions when the water methanol is working.
My probe is intended to give a true indication of intercooler performance without the assistance of water methanol.

I am aware of some guys that are injecting water methanol pre turbo and on some deisle applications this seems to be the fashion. Not advisable in my opinion and I am sceptical about the potential gains from this set up and the potential for long term damage.

trevsjwood

iTrader: (2)

There are number of points where the injector nozzle can be placed, progressivly closer to the cylinder depending upon the intended application, the first being in the intercooler at the intercooler outlet, which is where mine is and is intended to help reducing ACT's.
My temperature probe is in the connecting pipe at the TB end.
Trev