It can be even more---I don't think I ever got better than a 13.4 in that car when I ran it with stock thermo--meaning running it at the 215 degree range it runs at stock. the example I gave was where I had to wait in line with the car running, and by the time I got up there it was idling for so ong it got up over my desired launch temp.

 

That is the kicker with the ice. How hot does the car get waiting, burning out, and staging? It still helps by lowering the initial temp of the intake though.

 

I understand how an engine being cooler makes a difference...but heres my thought behind it.

Lets say that on an average 70 degree summer night, you make a pass and ice the intake in the garage area. The idea is that cooling that intake cools the engine intake air, and that would be fine if you were to cool the engine as much as you wanted then to immeadiately make a pass..but when you put a bag of ice on an engine that is scalding hot to the touch, you ARE cooling that manifold, but the rest of the engine isnt getting any cooler, so the ice is battling the heat moving through the metal of the engine, into that manifold. Ive tried with the stratus (there is no way to ice the intake on the demon or mirada), and im not sure that i got enough gain to bother with making a mess of the engine and staging area. For instance, after i make a pass, if i ice my intake...thats what, maybe an hour? The engine will likely not cool too much in that hour... When they call my class, I have to drive the car back to the lanes, then idle my way through the lanes, then do my burnout, then stage...and make my pass. Id have to think that in all of the pissing around between when I leave my "pit stall" and when I actually stage to run, the engine bay heat will have heated that intake right back up.

This is an interesting point...and I have done it with the stratus, as one of those "it cant hurt" things...but i dont know that ive noticed as much of a difference. perhaps the stratus is just too slow for anything to help...I do know that with the mirada, it makes a big difference on a very hot day to keep my fuel lines nice and cold.

 

Icing the intake is not to cool the whole engine. It is only to cool the intake. The reason why is that air runs through the intake and if the intake is cold the air becomes cold. Air is more dense when it is cold. The fuel system then compensates for more air with more fuel. More air and more fuel = more HP.

And why can't you ice the intake on the Demon? You can on my 318 Dart.

 

i understand why you do it. my point is that you ice it before you run, and the only thing cooled by the ice, is the manifold...but then by the time you stage, you dont think that the heat being transferred through the engine has heated it back up again? i think that you agreed with my point in your previous post..i was just long winded...

as for the ice on the demon, how do you situate it, and how big of a bag of ice are you using? on my 340s, the fuel line is too close to the manifold to put a bag of ice there, and on the other side, the linkages are in the way...

 

A lot of the gain from icing the intake depends on what the intake manifold is made of. The way I see it, there are two characteristics that matter here: Thermal conductivity, and specific heat. Thermal conductivity is obvious-how well does a given substance conduct heat? Specific heat is a measure of how much thermal energy it takes to heat a substance (and conversely, how much cooling it takes to lower it's temperature.) Well, our plastic intake manifolds may get hot, but they don't hold much heat. I'd venture to say that after a few seconds of running, the air rushing through them cools them down quickly. Try this: Get your truck engine warmed up, and shut it off. Pop the hood. 10 minutes later, put your hand on the intake manifold. Now, put it on a cylinder head. And finally, put it on an exposed part of the block. How long could you hold your hand on the manifold? The head? What about the block?

See what I'm saying? Last time I took the truck to the track, I took my thermometer gun and had a look for myself. The manifold cools off very quickly, the heads less so, and the block takes a long time.

Now, aluminum holds more heat than plastic, and iron holds more than aluminum. It stands to reason that the higher the specific heat the manifold substance is made of, the more benefit you'll get from artificially cooling the manifold. Also involved is the thermal conductivity. How easily does heat from the heads soak the manifold? Not very easy if it's plastic, very easily if it's aluminum, and somewhere in between for an iron manifold. With aluminum, it's easy come easy go. With iron it's not as easy to heat it up, but it takes a bunch of cooling to get rid of the heat once it does get hot.

So, I think that there won't be much benefit to icing most plastic intakes because they simply don't hold that much heat to start with. If you wanna see some benefits, I'd recommend cooling the block and heads. I'm going to be trying rubbing alcohol in a garden sprayer, since alcohol evaporates much faster than water. It will cool surfaces faster and have less chance of dripping on the track, since it will boil off much quicker.

 

As to our plastic intakes, it does not hold heat. When I was in the engine compartment, the engine itself was hot to the touch yet I could put my hands on the intake and it was not even warm.

BadStratRT, I have heard that people just dump ice onto the intake to get around the problem of where to put ice. Gasket material can also offset the heating of the manifold.

Yes, the engine heats the manifold back up after icing. But if you start with an intake temp of 50*, then the engine heats it up 50*, you are know at 100*. But if you don't ice and start it at 80* and the engine heats it up 50*, then you are at 130*. Granted, temp rising does not work perfectly like my example, but the cooler it starts off the cooler it will be when you get to the line.

Small block Mopars have the intake sitting right on the engine where big block Mopars have the gap under the intake, which really helps offset the manifold getting hot.

 

Oh and BadSratRT, you may want to look into a cool can. You route your fuel through it and it cools the fuel down.

http://store.summitracing.com/partdetail.asp?autofilter=1∂=MOR-65125&N=700+115&autoview=sku

 

i run an airgap, so i also have a gap under my carb...and on the mirada im already running a cool can. even with that gap, the manifold still gets REAL hot when after a run on a hot day. what track allows people to run with melted ice coming off of the engines? at a few of the tracks ive been to, they have people in the street class lanes to make sure that youre not melting ice all over the place, and ive seen them toss people for it...theyre very strict about that.

v8440, i didnt think about the intake manifold makeup...every vehicle i own right now has an aluminum intake...except for the ramcharger. i used to ice the stratus when i ran, but i stick to the cool can with the mirada..as unless im hot lapping, i dont have to use the fans or water pump, even on very hot days.

 

My point exactly. That's what I was encouraging people to find out with their bare hands to help them understand why icing a plastic intake probably won't make much difference.