danish

Ive been all over the net but i cant find out what heatsoak is. I just hear its a problem with the SRIs. I was about to get the Injen SRI since its easier to install but i just heard about the heatsoak problem. What is heatsoak? and will it be a problem with an Injen SRI?

CGTSX2004

iTrader: (1)

Heatsoak is when the heat in the engine compartment causes your intake air to be heated up, negating the effect of having an SRI to bring cooler, denser air for the engine to combust.

danish

So what are the consequences of this to the car? Does it just make your SRI into a normal intake or does it actually hurt the engine?

chuson

Heatsoak happens mostly on SRI. The intention of any "intake" mod is suck in big volume of air than stock OEM intake. However, due to the design of SRI construct beside the engine, it's suckin' in hot air. More, the heat from the engine bay is crowded around the intake so the whole tube is getting hot somehow. That's how heatsoak formed.

danish

Gotchya. So about the consequences of this, what are they?

CGTSX2004

iTrader: (1)

No real consequences other than the supposed performance gains are severely reduced.

sluggercz

If an intake is sucking in hot air it is taking in less air than a cold air intake would. The hotter a given amount of air is the more volume it takes up. So, if it gets hot less would be available to go through the intake pipe and therefore you would not be getting the max amount of air you could have if you had a cold air intake.

rmpage

Heat soak is a condition where intake and cooling system parts become heated to the point where it takes them a significant of time to cool down again. A common example of a situation where one would encounter this is sitting in traffic on a hot summer day. Without cool air circulating through the engine bay, heat radiates and convects from the radiator and block and is imparted upon the intake and intake manifold. While this happens, the coolant system is also being heated higher than the ideal condition, evidenced by the fan running on a high duty cycle (or even continuously).

Others have already explained why heat soak is bad. If you have a CAI and the intake piping becomes heat soaked, the air coming in the filter may be cool but by the time it flows through the piping and intake manifold to the ports themselves it is very hot. This hot air is less dense (as the guy above me said) so it results in a lower manifold pressure, causing the ECU to squirt in less fuel, which results in a loss of power. Further, the hot intake charge is more prone to detonation during the compression stroke, so the ECU also retards ignition timing contributing to further power loss.

In hot weather it can take several minutes of driving at a decent speed (say >30mph) until enough air is forced through the engine bay to get everything cooled off again. Some ways to cut down on heat soak are to shield intake parts from sources of radiant heat, like by wrapping intake piping with reflective tape and coating exhaust manifolds with ceramic or wrapping them. Any vehicle will heat soak if you sit still for long enough though.

As an aside, I've long wondered if relocating the TSX's IAT sensor would be worth trying. When I installed my Injen I was surprised to see it right behind the radiator, which made me wonder if the thermistor could become heated above the temperature of the air and cause the ECU to retard ignition timing unnecessarily. I've watched IATs in the summer heat soar above 130F at a stoplight and stay that way for minutes after I get moving. Not that I don't trust Doug to not have thought of this but I am curious.

danish

Alright, so i can buy this SRI and not worry at all about engine problems like i would if i bought a CAI and worried about hydrolocking? (dont tell me i can only hydrolock if i drive through a river because in my neighborhood, cars sometimes have to go through water deep enough to concern me with a CAI)

clee109

just get Injen's, heatsoak wont hurt the engine or damage it at all. With injen when the rainy season passes you can switch it to CAI if you feel the need but the performance difference between SRI and CAI isn't much to offset the pain of installation and cleaning the filter