Tune for vararam

[JonnyG2132]

Hmm.. I wonder if I should get rid of mine then before my next tune?

[JonnyG2132]

Also, what does how fast the maff card reads have anything to do with heat soak? The idea of the hsrk is so you can put it in front of the air filter to take it away from heat soak

[G8-4-Speed]

If using the Spectre housing, it doen't heat soak bad at all. Putting a remote IAT sensor in the Vararam scoop does keep it a little cool especially if running the RamAir plate.

[G8V8]

The stock MAF IAT sensor has a long Time Constant (TC). It is something like 14 seconds. That is how long it takes the sensor to register 63.2% of an air temp change. If you are sitting still or rolling on small throttle opening the amount of air passing thru the MAF is small and you can see your IAT reading climb. It you go WOT, for example, a large surge of air passes thru and replaces the heated air with colder, fresher air. Let's say the warmed air was 100* and ambient was 70*. While sitting, the IAT sensor reports 100* air and fueling is adjusted for it. If you go WOT, the 100* air in the MAF, tubing and such is replaced pretty quickly with cooler ambient air sucked in thru the filter. However, the IAT sensor will take 14 seconds to report 63.2 % of the temp change. That is 30* x 63.2% = 19*. So, 14 seconds after going WOT the IAT sensor output will ramp down to reporting 81*, not the actual 70* air the motor is ingesting. In another 14 seconds it will be reporting 74* and so on. By the time 1 TC has passed, you are already more than a quarter mile down the road. See the problem if you are hot lapping and waiting in the que and IATs are pretty high?

The thermistor used by GM is slow because they are cheaper. The thermistor used in the VMS HSRK (the original HSRK) is a better thermistor and it has a TC of about 2 seconds. Most of the Copy Cat HSRK use the same thermistor as stock. They let you mount it in cooler locations but they do not make it respond faster to temp changes.

This matters most if the reported IAT are high enough that the PCM is pulling some timing.