View Full Version : heat soak?

09-21-2005, 09:57 PM
well i have a custom intake for my 2.8, but i still havent made a heatshield (lazy). When i start my car in the morning, it pulls really really nicely, and it just feels like it doesnt wanna stop. Then after about 20 minutes of driving my car starts to feel a lot slower and more sluggish, i floor second gear and it feels like im not hitting the throttle at all for the first like 2 seconds. Anyway, is this from heat soak? Im planning on just getting an EVO intake so that i can have a nice heatshield so i dont have to worry about anything. But i was wondering, if i do get an evo intake, will my car always drive the way it does on cold mornings?

Yeah i know my question sounds kinda dumb but i have no other way to put it...[a4]

09-22-2005, 06:23 PM

09-22-2005, 07:08 PM
heat soak is related to intercoolers for turbo charged engines

09-22-2005, 07:39 PM
N/A cars suffer from heat soak as well, not sure if a cold air intake is the answer tho. Drawing in cool air is definately better, but if your car is heat soaked it's not going to make as big of a difference as you might think.

Howard Hughes
09-22-2005, 07:57 PM
Well despite your car being non-turbo....I would say yes it makes a difference....cold air is denser and makes more power right fellas??? So having cool air in your engine bay that becomes hot after "20 mins" you lose that combustion.

Get yourself that heatshield I would think it would make a difference.

09-22-2005, 10:11 PM
I didn't think that a N/A car really got heatsoke. Well at least nothing like a forced induction car.

09-22-2005, 10:51 PM
well then what would be the explanation for my car running really well in the morning, and then turning lazy after a few minutes of driving....

I cant really recall but i think this has only been happening since i got the intake, and my biggest question is, will my car always be running the way it does right when i start it up if i get a heatshield, or will it just not turn quite as lazy.

09-23-2005, 07:24 AM
This is from Audi World. I think it is the solution to your problem.

Insulating the Air Mass Sensor Choy Ngee Hoe 2000
Note: Upgrade performed on a 1997 Audi A6 2.8L

Let me share with you a really cheap way to make your car response better, especially after hours of driving, and in hot wheather like what I have here in Malaysia all year round.

The basic principle is, cooler air intake improve engine power output. But what many do not know is, your engine must know about it in the first place.

What triggered me was, when I drive the car long enough, high speed, hot day, the car power felt like not as good as in the initial part of the journey. Kick down was also somehow retarded. After I stopped for a while for meal break, the car power seems to come back.

The Audi A6 that I have is using an air mass sensor to measure the amount of air mass intake, and adjust fuel mixture accordingly. Upon examining of the air mass sensor (right after air filter housing), I can see some thin wires running across the cross section of the opening. From here, I guess that Audi is using "hot wire" method to measure air mass: when the relatively cooler air flow pass the electrically heated wires, the amount of air passing through can be derived by the amount of heat energy taken away from the wire.

Audi is drawing cool air by running a duct from the top of the front grill to the air filter box, which suppose to draw the coolest air possible. What I found was, after hours of driving, heat from the engine started to heat up the air duct, as well as the air mass sensor (made of aluminium). The housing of the air mass sensor is especially hot, hurt if touch (must be over 90 deg C). Theoretically, this external heat would affect air mass measurement which mistakenly assume higher air temperature due to hotter housing, result in overly-lean air-fuel mixture. I can feel it, I think you can too, when you start driving when the engine is cool, you feel better response and the car is more torqy. After some time (30 minutes, maybe, on high speed), especially in hot summer afternoon, you would feel the car become less powerful. But in actual fact, temperature of the external air drawn are both approximately the same.

What I did was to wrap the air sensor housing with thick cloth to act as heat insulator. Amazing, I have that "morning power" feel all along the journey!! Kick down is more responsive on high speed. I guess Audi control kick down when the engine is too hot to avoid over loading. And the sensor housing was just a little warm when touch (may be 40 deg C), but the air hose is still very hot, taking heat rediation from the engine.

I went further to insulate the whole air induction system, including the air filter housing - they are black in color and prone to absorb more heat. It feel a little better after that, but not as much as after I insulate the air mass sensor.

You should try it. It cost you almost nothing. I did not have the mean to measure actual output change, but the power improvement feel is quite apparent.

09-25-2005, 08:16 PM
what should i use to wrap it, just cotton material?

10-10-2005, 07:08 PM
wouldnt wrapping it in cotton material just insulate the heat in even more????

10-10-2005, 07:11 PM
Just don't forgot the marshmellows!!! [eek]
For the campfire, formerly known as your A4, that your about to start! [rolleyes]

10-10-2005, 08:08 PM
no seriously, i really want some serious input on this...someone?

will it actually catch fire?

am i supposed to use something else....?

10-10-2005, 10:14 PM
if you want to reflect radiant heat try foil tape in the ducting section of the hardware store. it's basically shiny metal tape. reflects heat. bam

10-11-2005, 07:13 AM
sooooo no other material, such as cotton??

10-11-2005, 07:18 AM
Originally posted by MR VTEC
Just don't forgot the marshmellows!!! [eek]
For the campfire, formerly known as your A4, that your about to start! [rolleyes]

10-11-2005, 10:05 AM
umm..why are you flooring your car before its up to operating temp?

10-11-2005, 10:08 AM
I would consider a layer of "insulation material" followed by a few layers of that shinny tape. And be sure it is very fire retardant. I don't know like that pink fiberglass stuff walls????

Howard Hughes
10-11-2005, 10:17 AM
Just use turbo heat wrap...

10-11-2005, 11:08 AM
Originally posted by k0mpresd
umm..why are you flooring your car before its up to operating temp?