Do alloy OTR's suffer from radiator heat soak?

[BLK-57L]

Do alloy otrs suffer from heat soak from the radiator enough to effect performance???

[whitels1ss]

In a word........No! :)
Buddy I can hear the footsteps of the moderators coming to close this thread!:search:
Plenty of information on the forum about this if you use the search button.
:admin::closed:

[BennyMac]

They do, but only when the car is at a stop. When the car gets moving again and cooler fresh air gets in you will see temps drop.
All OTR's suffer from this but because the said OTR is alloy it will take a little bit longer to cool down.
I have the Areoforce gauge and i see temps sit 2-4deg higher than the outside air when going say 70+kph.
Its only when you hit a set of lights the intake temp goes up and this depends on how hot it is, sitting in the middle of peak hour traffic etc.
So if you hammer it while the air is sitting at say 40deg then there will be some sort of reduced performance.
If it is hot enough you might get some pinging but thats another story.
Do a search on it as there was a thread about it not long ago.

[Woteva]

They do, but only when the car is at a stop. When the car gets moving again and cooler fresh air gets in you will see temps drop.
All OTR's suffer from this but because the said OTR is alloy it will take a little bit longer to cool down.
I have the Areoforce gauge and i see temps sit 2-4deg higher than the outside air when going say 70+kph.
Its only when you hit a set of lights the intake temp goes up and this depends on how hot it is, sitting in the middle of peak hour traffic etc.
So if you hammer it while the air is sitting at say 40deg then there will be some sort of reduced performance.
If it is hot enough you might get some pinging but thats another story.
Do a search on it as there was a thread about it not long ago.

Ever wondered why heatsinks are aluminium? :idea:

[alian]

They do, but only when the car is at a stop. When the car gets moving again and cooler fresh air gets in you will see a fair drop in temp.
All OTR's suffer from this but because the said OTR is alloy it will take a little bit longer to cool down.
I have the Areoforce gauge and i see temps sit 2-4deg higher than the outside air when going say 70+kph.
Its only when you hit a set of lights the intake temp goes up and this depends on how hot it is, sitting in the middle of peak hour traffic etc.
Do a search on it as there was a thread about it not long ago.

+1. I found if you line the bottom of the bottom of the otr with Form Shield and that seem to help heaps.
Cheers Ian

[BennyMac]

Ever wondered why heatsinks are aluminium? :idea:

...Nope...

[Xenon]

Ever wondered why heatsinks are aluminium? :idea:

Because they conduct heat really well?

[BennyMac]

Because they conduct heat really well?

Well there you go.

[O.N.]

Just thinking out loud here and with some thought to it ofcourse.

But wouldn't all these intakes perform better if they were dual layer with a gap inbetween layers and then water cooled.

Ie you have an intake 2in thickness and the same intake shape on top of that 2.5in thickness with 0.5in of water surrounding the whole intake.

1 it wont be a heat sink
2 it might even be colder
3 you also have the option to use an electric water pump to flow water through a small front mount radiator or even a chiller unit.

[feistl]

Just thinking out loud here and with some thought to it ofcourse.

But wouldn't all these intakes perform better if they were dual layer with a gap inbetween layers and then water cooled.

Ie you have an intake 2in thickness and the same intake shape on top of that 2.5in thickness with 0.5in of water surrounding the whole intake.

1 it wont be a heat sink
2 it might even be colder
3 you also have the option to use an electric water pump to flow water through a small front mount radiator or even a chiller unit.

Unless your circulating the water (As you suggested in point 3) any material is eventually going to heat up, and transfer that heat into the incoming air. Shielding would possibly help...

I remember reading/hearing somewhere that every 10 degree increase in intake temp, you lose 6% of total engine power... So best/worst case your talking about a 10% loss of engine power THE FIRST TIME you take off after sitting stationary for a period of time. On a track/drag strip/spirited driving your constantly moving meaning the air temp would stay down.

Alternatively you could spray a CO2 fire extinguisher over an OTR before doing a 1/4 mile run to lower the temp considerably. That said, its not going to lower the actual air intake temp by much.

Any system would be inefficient as the small amount of power gain will be offset by the extra weight of said system.

[BennyMac]

Just take it easy on really hot days as you may also have the A/C on :)

[O.N.]

Unless your circulating the water (As you suggested in point 3) any material is eventually going to heat up, and transfer that heat into the incoming air. Shielding would possibly help...

I remember reading/hearing somewhere that every 10 degree increase in intake temp, you lose 6% of total engine power... So best/worst case your talking about a 10% loss of engine power THE FIRST TIME you take off after sitting stationary for a period of time. On a track/drag strip/spirited driving your constantly moving meaning the air temp would stay down.

Alternatively you could spray a CO2 fire extinguisher over an OTR before doing a 1/4 mile run to lower the temp considerably. That said, its not going to lower the actual air intake temp by much.

Any system would be inefficient as the small amount of power gain will be offset by the extra weight of said system.

if it is true what you say 6% power loss for every 10 degrees then there is a massive amount of power to be gained especially on big power cars, 5kg of water a pump and cooler and a few lines will not weigh all that much.

You also have the option to usesome type of freezer chiller unit that will run on 12 volts.

[gavlotic]

I think it's better to keep things simple.....
most alloy otrs pretty much just fit in vt-vz to begin with

cheers,

Gav

[feistl]

if it is true what you say 6% power loss for every 10 degrees then there is a massive amount of power to be gained especially on big power cars, 5kg of water a pump and cooler and a few lines will not weigh all that much.

Yes, but remember thats 6% power loss for every 10 degree increase in the air intake. Even if the OTR is hot, that may only heat the intake air slightly, and by the same token chilling the OTR wont necessarily cool the intake charge by much.

Plus you would only see the power gain on initial take off from the lights, once running the OTR would be cooled to normal air temp. Plus if you think of how many thousand liters of air are being sucked into the engine every minute, you would need a massive cooling unit to drop the airtemp by much. The only time its worth it is with a forced induction setup as intake charge can be over 100 degrees, so there is a massive difference compared to ambient, meaning its much easier to drop the intake temp with an intercooler.

Basically in short, the amount of weight and cost your talking about is going to give a very small gain in certain circumstances, and no gain (in fact a disadvantage) most of the time.

[morpheousssv]

just hang a wet hession bag over the front = instant cold air intake

[Tyre biter]

Have a look at this thread and will be clear...clear as mud;

http://www.ls1.com.au/forum/showthread.php?t=131251

Clearly the IAT sensor suffers from heat soak - more so in a metal OTR however there remains an unanswered argument as to whether the air in the OTR heats or not to the same degree - my position is not, solely because the more technically minded folks couldn't/wouldn't respond to the observations and questions raised by a number (including myself...oh, and Carnot amongst others). It seems that relocating the IAT from an alloy OTR to another location will absolve most of not all heat soak issues suffered by the IAT, and thereby better measure the actual air temp entering the engine via the OTR.

Cheers, TB

[Woteva]

Because they conduct heat really well?

Umm... NO! Aluminium dissipates heat really well. I'm betting there would be sweet all between aluminium or plastic.

[ASSASIN]

Umm... NO! Aluminium dissipates heat really well. I'm betting there would be sweet all between aluminium or plastic.

To dissipate quickly it must conduct quickly

[Evman]

After trying several different locations I found that moving the IAT sensor into the outlet of the OTR (and thus into guaranteed direct airflow) not only reduces the effects of heat soak at idle but also decreases the time it takes for the sensor to cool down once moving again.

[Xenon]

Umm... NO! Aluminium dissipates heat really well. I'm betting there would be sweet all between aluminium or plastic.

LOL! Scientists, we are not.