Power Loss from running Hot.

[anonymous-user]

I race a SR20 Det, with a big turbo up-rated everything, and 350+ at the wheels, in a Sylva Phoenix, Car always ran perfect at 93c.
However following some instruction I got faster and stared to push the oil temp up. Put in a bigger oil cooler and repositioned it from drivers sill behind the front wheel to the nose infront of the water radiator and intercooler.
5 laps in (25km) the engine has now started to run hot, and after 10 laps is up to 103c. Not enough to boil over or do damage, but there is a noticeable drop off in power. (around 1.5 secs a lap). Falls back to 85c on the cool down lap.
I've already decide on the cure and the oil cooler will now sit on the front splitter in front of the front wheel with air ducted in, this duct will mirror the one on the other side that feeds the Turbo.
But I was surprised at the power drop, OK the car was hot but at 103 it was within the operating range of the coolent. I'm assuming that the hotter air was reducing the effect of the inter cooler, rather than any mechanical inefficiencies, due expansion, any one else got experience of this.

[Boosted LS1]

Yep, You need to ensure that the air can exit freely from the cooler and reposition it back by the front corner as that's a really good place for a cooler.

If you're driving harder/faster have you checked the coolant situation and airflow? If you're running at higher revs everything in the engine bay will get hotter including the compressor inlet. Has the turbo been specced for the revs that you're using? Hot air can definately cause a power loss on a turbocharged engine.

Edited by Boosted LS1 on Thursday 3rd September 10:18

[stevieturbo]

Berw said:

I race a SR20 Det, with a big turbo up-rated everything, and 350+ at the wheels, in a Sylva Phoenix, Car always ran perfect at 93c.
However following some instruction I got faster and stared to push the oil temp up. Put in a bigger oil cooler and repositioned it from drivers sill behind the front wheel to the nose infront of the water radiator and intercooler.
5 laps in (25km) the engine has now started to run hot, and after 10 laps is up to 103c. Not enough to boil over or do damage, but there is a noticeable drop off in power. (around 1.5 secs a lap). Falls back to 85c on the cool down lap.
I've already decide on the cure and the oil cooler will now sit on the front splitter in front of the front wheel with air ducted in, this duct will mirror the one on the other side that feeds the Turbo.
But I was surprised at the power drop, OK the car was hot but at 103 it was within the operating range of the coolent. I'm assuming that the hotter air was reducing the effect of the inter cooler, rather than any mechanical inefficiencies, due expansion, any one else got experience of this.

the 10deg may not make a huge difference, but what tuning changes are taking place over 100degC if the tuner was never wanting the car to be run that hot ?

IMO just stick a cooler stat in it and ensure your radiator is up to scratch. Although with only 350hp most OEM rads should cope pretty well

Although with a swing of 93-103-85...just what stat is even in there ?

[anonymous-user]

stevieturbo said:

the 10deg may not make a huge difference, but what tuning changes are taking place over 100degC if the tuner was never wanting the car to be run that hot ?

^^^ This. A LOT of tuners, fairly sensibly, start pulling out boost and retarding the ignition if coolant temps climb above 100 degC.

I tend to use 110 to 115 degC on a modern engine before i calibrate that sort of power clipping in the EMS calibration.

[anonymous-user]

Thanks for the info, you confirmed I am on the right track, will re=position the oil cooler, my car is completely bespoke, in terms of most things including the turbo, inter cooler and rad, we can sort most things but some times just nice to confirm I am going the right way.
Couple of pictures, the oil cooler was in the sill behind the passenger wheel, worked great for years, but the I had a few lessons and was holding higher speed through the fast bends, Oil temp went up and pressure down, moved the oil cooler under the radiator in the nose, and started the temp problems, will relocate it to sit on the splitter in front of the front wheel.

thanks

[PeterBurgess]

By any chance are you running waterless coolant?

Peter

[Boosted LS1]

Berw, that's a nice looking car. It must be a lot of fun :-)