Question; when you say stock tune starts to pull timing at 120° do you mean act or engine temp? I'm guessing act and so I am basing my next two comments on that.By icing down the IC etc, you're keeping the ACT's down which in turn prevent timing from being pulled both by the act's being high and getting high enough to cause detonation.
Stock tuning has timing being pulled starting at 120F and by 180F will have 8 degrees pulled. From the datalogs I've seen of several cars, the knock sensor starts kicking in by pulling timing at around 145F, and if its severe enough you lose a full 8 degrees.
Cold air is denser than hot air, so you get more O2 in a cubic foot when the air is colder, which means more power. I'd say you would be taking a very big risk by adding timing based on how much you have iced everything down.
Ricardo, I don't think your going to gain anything on a dyno by icing the motor down, unless you have a way of colling the ACT's down to like zero degrees before the pull, and keeping them there, which has no benefit anyway because you wouldn't be able to run that tune on the street.
Fraser
Question; when you say stock tune starts to pull timing at 120° do you mean act or engine temp? I'm guessing act and so I am basing my next two comments on that.
I don't see where you say you can keep the act's pretty low on the dyno but not use that tune on the street. Or did you literally mean "zero" because keeping the act's under 120° is doable.
So then at what point does icing down become redundant? At what act's is it no longer a benefit? I am able to keep the act's pretty reasonable but I still ice at the track primarily because everyone else does. But I've never measured what exactly it does. Am I wasting my time or what?
Ira
I mean the ACT's, and yes I was literally talking 0F .
I'm going to use my car as an example here since I have hundreds of logs including alot from the track. The one prominent thing I've noticed is just how much ACT's climb per run and that seems to be pretty constant, no matter the starting temperature.
For instance, with the DIC setup I have now, I see on average about a 25 degree rise on each pass. That doesn't seem to change with starting out at 110F or 100F or 120F.
Allowing the car to cool down and helping it out by icing it down can help because the starting temperature can keep you out of the zone where timing gets pulled and/or detonation kicks in. How much of a difference in the ET's will it make between starting out at ambient temperatures say 75F or 100F, that I don't know.
I don't ice anything down, I'll usually let the car sit for 20 minutes or so, and maybe run the IC fan for a bit to cool the IC down quicker.. but I'd rather be racing more and seeing how consistent the car can be. I'm not scared of running several back to back runs where I see my ACT's drop down to about 100 or so in the staging lanes and seeing it go to 125F down the 1/4. You've seen what I average .
If I was to completely ice the car down and let it sit for an hour and a half I might nab that 13 but thats not really telling me the truth of what my car can really do, in my mind anyway.... I'm a driver, not a sitter .
Sitting on a dyno, that all changes because you don't get the airflow to cool things down like you would at the track, and I was seeing temperature rises of 35 to 40 degrees on a short pull in 3rd gear.
Fraser