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Old 08-08-2003, 08:43 AM   #1
skuttledude
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Join Date: Jan 2000
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Location: Southern Ohio USA
Vehicle:
2008 Lexus IS-F
Ducati Monster 800

Default How you know your getting "heat soak"

Sorry for the noob question, but this is my first turbo car and was wondering how you know you are getting heat soak.

It was really hot yesterday afternoon, with high humidity and I was running my AC at medium and felt that the car was "lagging" a little bit. Some slow traffic too made it difficult to get fresh air into the intercooler/ Of course the AC on didn't help but it seemed a little more than usual.

I tried the IC water sprayer a little bit but couldn't tell an immediate difference; don't know if that would even help at all.

Did I just answer my own question or is there a way to tell if you are experiencing heat soak.

Cheers,

Davis
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Old 08-08-2003, 09:07 AM   #2
happasaiyan
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Default

your slowness was primarily from the a/c being on. heatsoak will affect your car..but no where near the degree the a/c does. a/c on makes you feel like the n00biest driver. lol.
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Old 08-08-2003, 09:19 AM   #3
skuttledude
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Ducati Monster 800

Default

Quote:
Originally posted by happasaiyan
your slowness was primarily from the a/c being on. heatsoak will affect your car..but no where near the degree the a/c does. a/c on makes you feel like the n00biest driver. lol.
The noob thanks you

Davis
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Old 08-08-2003, 11:16 AM   #4
dsmperformance
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Default

With the conditions you described, heat soak will occur very rapidly since there is a lack of airflow to the intercooler. The way your car was running would definitely be a sign of heat soak. The AC robs a ton of power also. A combination of using the IC spray and moving faster will help dissipate the heat and regain some lost power. Personally, I don't like to run my car very hard when the IC is heat soaked.
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Old 08-08-2003, 11:37 AM   #5
CloNeGTS
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Default

I have to disagree on the A/C having the most effect comment. I have rarely driven without the A/C on since getting it and I notice extreme differences in power when coming from a standing start especially.

If it is a quick stop sign after driving at a decent speed (assuming this is a no heat soak situation), very little attention is needed to get a clean, no bog start.

However, if the car is sitting still for longer than a minute or so with the engine running (assuming a heat soak situation), you have to really think about not killing the engine when taking off. If I don't think about it ahead of time, a 'normal' clutch-gas transition will bog the engine to the point where it would die if the clutch was not pulled back.

I think this shows the effects of heat soak pretty substantially. Regarding the water spray, since that is a reactive action in this case, the results of the spray come after the time it's needed. If you are thinking about the heat soak while you are still sitting at the light, give the IC a good 3-4 second shot with the spray. It does make a difference when you take off.
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Old 08-08-2003, 01:16 PM   #6
skuttledude
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Default

Good advice guys. Thanks

Davis
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Old 08-08-2003, 06:25 PM   #7
mazdman
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I've got a SECS unit & have page 5 set up with the (4)
data items:

KC - Knock Correction (Haven't seen any yet)
BP - Boost Pressure (15.8 psig max so far)
IN - INtake temperature
& can't remember the 4th right now. But I have observed
the following:

The I/C heat soaks pretty quickly once the air speed drops
below about 20 mph & then cools off pretty quickly once
you get up around 55-60 mph. I've also sat in traffic & watched
the IN rise to above 118F & sat and sprayed the I/C for a good
6-7 seconds steady & saw no change in the IN. The TMIC is
good for steady driving at speeds above 45 mph, but sucks
in slow speed/stopped conditions. When I see how high the
IN gets I'm hesitant to drive the car hard until it drops at least
down in the 90's. What it needs is a couple of small fans
mounted on the bottom side of the I/C that kick on above
a certain temp like the rad or a FMIC.
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Old 08-09-2003, 10:16 PM   #8
'04 STi
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Default

[quote]Originally posted by mazdman
I've also sat in traffic & watched the IN rise to above 118F & sat and sprayed the I/C for a good 6-7 seconds steady & saw no change in the IN.


Spraying the intercooler when sitting still will do next to nothing. If you're not moving, the evaporation will not occur quickly enough to cool it significantly.


Bill
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Old 08-10-2003, 11:48 AM   #9
mazdman
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Default

[quote]Originally posted by '04 STi
Quote:
Originally posted by mazdman
I've also sat in traffic & watched the IN rise to above 118F & sat and sprayed the I/C for a good 6-7 seconds steady & saw no change in the IN.


Spraying the intercooler when sitting still will do next to nothing. If you're not moving, the evaporation will not occur quickly enough to cool it significantly.


Bill

The I/C sprayer is or should be spraying a fine mist of H20
over the I/C. The heat transfer coefficient of evaporating H20
is much greater than that of liquid H20. Therefore, spraying
the I/C while @ rest when the metal temperature is higher
should cause greater evaporation & therefore a greater
cooling effect not less if the mass & size of the droplets is properly
sized. Since this is not occuring then the
nozzle needs a greater atomization effect & mass flow so that the I/C
spray is effective @ slow speeds or when stopped, when it is
most needed. Also the heat transferred by such a small mass of
H20 @ rest is negligible compared to the convective heat loss
of a much larger mass of air once the car is moving. I'll try to
get more data @ speed by maintaining a constant velocity &
then spraying the I/C & monitoring the intake temps.
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Old 08-10-2003, 12:14 PM   #10
RichQY
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Default

i believe i read the manual on the psI^3 site that

the IN intake temperature is the temp of air going in the air box. not actualy intake charge temperature.. which means it shows the temp in the air box area, spraying the IC won't do anything to reduce this IN number.
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