inlet temps and coolant temp relation
Discussion
Morning learned PH'ers,
Is there a correlation/link between inlet temps on a forced induction vehicle and general engine temps (coolant/oil temps)?
Specifically, does improving the general cooling of the engine (more efficient radiator, addition of oil cooler) have any effect on the actual intake temps?
Say on a hot track day, if you can maintain the engine oil/water temps at a steady temperature (rather than creeping up), will that have any impact on actual intake temps (and therefore retardation/knock etc) or are the two "separate" in that respect?
I would assume (maybe wrongly?) that high intake temps would "leech" into the cars cooling system and raise water/oil temps, so I wondered if it would work the other way around?
Is there a correlation/link between inlet temps on a forced induction vehicle and general engine temps (coolant/oil temps)?
Specifically, does improving the general cooling of the engine (more efficient radiator, addition of oil cooler) have any effect on the actual intake temps?
Say on a hot track day, if you can maintain the engine oil/water temps at a steady temperature (rather than creeping up), will that have any impact on actual intake temps (and therefore retardation/knock etc) or are the two "separate" in that respect?
I would assume (maybe wrongly?) that high intake temps would "leech" into the cars cooling system and raise water/oil temps, so I wondered if it would work the other way around?
None technical, experience only. My Sylva turbo race car runs in the tropics, typical ambient air 33+c Track high 40 to 50's, I had an air intake under and just in front of the turbo but in the flow of hot air from brakes rad, inter-cooler etc, put in an air pipe to pick up from front of the car to feed the turbo, noticeable increase in power but no measurable effect on water temp. two weeks ago I ran without the air intake pipe, as we couldn't refit it following an accident, noticeable drop in power but no visible increase in water temp. I suppose the air temp under the bonnet is in the 50's pick up at the front of the car its mid 30's.
In theory , (I suppose), the higher intake temp must go some where (isn't that the first law of thermo) but its not visible even on a temp gauge that reads l in numbers, you'd never see it on a needle type temp gauge.
What I do know is lowering the intake air temp made a difference to power and the feeder pipe will be back on for the next race.
I did a few calculation on air density at these temp, and there was a significant increase in oxygen getting to the engine from the denser air.
I'm not a scientist so I'm not saying I can support these observations to get a PHD just my simple calcs based on Boyls law from my O levels.
In theory , (I suppose), the higher intake temp must go some where (isn't that the first law of thermo) but its not visible even on a temp gauge that reads l in numbers, you'd never see it on a needle type temp gauge.
What I do know is lowering the intake air temp made a difference to power and the feeder pipe will be back on for the next race.
I did a few calculation on air density at these temp, and there was a significant increase in oxygen getting to the engine from the denser air.
I'm not a scientist so I'm not saying I can support these observations to get a PHD just my simple calcs based on Boyls law from my O levels.
The general engine temperature shouldn't make any difference, as long as you have a cold air intake and keep the incoming charge air reasonably well protected from heat sources on the way in. If you're taking in hot air from the engine bay then of course the hotter everything is the hotter your charge air will be.
Engine metal temps (and hence average coolant temp) has a direct bearing on charge air temperature, but generally only after it's entered the plenum or inlet manifold. One of the reasons most modern cars use plastic parts in the intake system (clean and dirty side) is not just for low mass and cost, but also to limit upheat from the engine itself.
If you measure intake air charge temp in the lower end of the intake runners, you can easily see a 10 degC upheat at low loads, and 3 to 5 degC at full load.
Most really high performance race cars run with low average coolant temps in order to minimise the upheat
If you measure intake air charge temp in the lower end of the intake runners, you can easily see a 10 degC upheat at low loads, and 3 to 5 degC at full load.
Most really high performance race cars run with low average coolant temps in order to minimise the upheat
Berw said:
None technical, experience only. My Sylva turbo race car runs in the tropics, typical ambient air 33+c Track high 40 to 50's, I had an air intake under and just in front of the turbo but in the flow of hot air from brakes rad, inter-cooler etc, put in an air pipe to pick up from front of the car to feed the turbo, noticeable increase in power but no measurable effect on water temp. two weeks ago I ran without the air intake pipe, as we couldn't refit it following an accident, noticeable drop in power but no visible increase in water temp. I suppose the air temp under the bonnet is in the 50's pick up at the front of the car its mid 30's.
In theory , (I suppose), the higher intake temp must go some where (isn't that the first law of thermo) but its not visible even on a temp gauge that reads l in numbers, you'd never see it on a needle type temp gauge.
What I do know is lowering the intake air temp made a difference to power and the feeder pipe will be back on for the next race.
I did a few calculation on air density at these temp, and there was a significant increase in oxygen getting to the engine from the denser air.
I'm not a scientist so I'm not saying I can support these observations to get a PHD just my simple calcs based on Boyls law from my O levels.
I have actually toyed with the idea of fans to exhaust the engine bay of the mojo through the bonnet slats I've fitted...on the plus side, on a decent run it eventually warms up the metal gear lever and seatbacks In theory , (I suppose), the higher intake temp must go some where (isn't that the first law of thermo) but its not visible even on a temp gauge that reads l in numbers, you'd never see it on a needle type temp gauge.
What I do know is lowering the intake air temp made a difference to power and the feeder pipe will be back on for the next race.
I did a few calculation on air density at these temp, and there was a significant increase in oxygen getting to the engine from the denser air.
I'm not a scientist so I'm not saying I can support these observations to get a PHD just my simple calcs based on Boyls law from my O levels.
Kccv23highliftcam said:
I have actually toyed with the idea of fans to exhaust the engine bay of the mojo through the bonnet slats I've fitted
Have you managed to position them in a low pressure zone? I used wool tufts to see how effective the vents are on mine. It was very strange to see the tufts sticking up six inches into the slip stream at high speed.I know nothing about the Mojo, but my Phoenix when it came to the tropics had a Lotus 900 in it, ran rather hotter than I liked and we looked at all sorts, one issue was getting hot air out, we put side went behind the front wheels sorted that, but a big issue was hot air coming back round the side of the rad, so we boxed the front of the rad,
My car, with no fan, runs at a constant 85c in the high temp here, and I'm happy with that, but as I say if I run air from the engine bay to feed the turbo I do feel a loss in power.
My car, with no fan, runs at a constant 85c in the high temp here, and I'm happy with that, but as I say if I run air from the engine bay to feed the turbo I do feel a loss in power.
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