Gang- O.K., I'm gonna try this again - from another angle. I started a thread a few days ago that included this question, but it sort of got lost amid a very interesting discussion about intercooling. Hopefully, this more direct approach will result in some answers/discussion about this specific procedure. Here goes. Back in "the day", it was common for drag racers to pack ice (mostly "regular" crushed stuff, but sometimes "dry" ice too) on top of their intake manifolds just before making a run. Some guys even fabricated metal "dams" at the front and rear of the manifold to allow using greater quantities of ice. I understood the concept was to cool the fuel charge and therefore cause it to be more dense (providing a greater fuel charge to the cylinder than would "normally" occur) - but perhaps that's not the case. In fact, I'm not aware of any actual performance comparisons, and have to admit it may just have been something that seemed like a good idea, but really had little or no effect. We were just kids back then, and were pretty suseptible to adopting ideas we had read about in the drag mags - or heard mentioned during "bench racing" sessions at the local drive in. I'm sure some of it (O.K., a lot of it - LOL) was just B.S. Is anyone else familiar with the ice-packing "trick"? Is/was it effective in increasing performance? Is it still in practice today? Comments? Opinions?
It is effective and still in use today. I believe the sanctioning bodies have rules against it though. Mostly to keep water off the track. I'll look at a rule book later.
You know dude, that is my understanding also. My father told me when he was a youngster all the serious drag racers did it and when he explained it too me like that it makes sense. Colder air, colder fuel, better delivery, stronger fire in the cylinder. That being said, I don't have any solid evidence that it works, only that the theory is strong. Most of what he tokd me about the pros was that they all used dry ice and that crushed ice was for mostly the weekend warriors (ie. "street racers" at the strip). I know that when it's colder and damper outside my personal cars tend to run stronger, so it only goes to say that the ice should make a difference, if applied properly to cool everything back down before the next run. I'll be watching this post to see what gets said, hopefully it should be interesting.
It is still done, and it works. It is used to keep the intake manifold from getting hot / heat soaked. If the intake is cool, the air going into the cylinders is significantly more dense. That means more oxygen, and the potential for more power. I've seen cars lose 3-4mph in the quarter when they get heat soaked, but a 30min wait with ice on the intake gets the trap speeds back up. Be careful that you don't let water drip onto the track, you will get kicked off.
for bracket racing consistency is important, I think this might have been a big reason why the trend started....just about the same time that bracket racing became dominant in sportsman classes....
I used to do this many years ago but gave up on it. You'd wait 2-3 hours to make a pass and as soon as you pull out of the burnout box and the starting line official sees a single drop dripping under the car, you're told to shut it off and get it out of there. I'm sure it helps get the heat out of the manifold, but in the staging lanes you should keep one of those super absorbent micro-fiber towels and soak up the water before you attempt to run.
It's done more for the air part of the mixture (A Gas) than the fuel part of the mixture (a liquid) Gasses expand and contract due to heat much more than liquids. As the air cools down the oxygen molecules come closer together...cooler air = more oxygen molecules per cubic inch. (they are packed in tighter) With more oxygen, you can now add more fuel to get that elusive perfect power making mixture ratio of oxygen molecules to fuel molecules. The same theory as rejetting for altitude. The thinner air has less oxygen molecules to start with at any temp.
Moroso sells a little cool can that runs your fuel line through it before the carb. It is supposed to be a little more efficient and without the danger of getting water on your tires at a high rate of speed.
"It's done more for the air part of the mixture (A Gas) than the fuel part of the mixture (a liquid)..." Aha! It's an "air" thing, not a "fuel" thing. Now that makes sense! I don't think any of us thought about re-jetting to add additional fuel that could be "supported" by the extra oxygen. Obviously, we didn't really understand what was going on, so we didn't take full advantage. Oh well - too late now. LOL Thanks for the clarification Tommy. As far as the "drip" problem for current racers. It seems like there should be some heat-resistant "plastic bag" style containers available somewhere that could be filled with crushed ice, sealed, and then just layed on the manifold.
Guess I've been wrong for a long time then because I always thought it was to cool down the intake and carb to prevent the fuel from vaporizing when it touches the hot internal surfaces of the carb and intake. I think we've all dealt with vapor lock before.
Could you just hose down your intake with CO2(like from a fire extinguisher or spare air shifter bottle)? That would also cause a chilling effect, but wouldn't leave anything to drip. You could also modify the heat riser and shoot CO2 under the carb just before the run. It wouldn't chill the whole intake, but it would be better than nothing.
Actually, it's better if the fuel vaporises faster. luquid fuel will drop out of suspension and cling to the manifold walls. Also, liquid fuel doesn't burn, the vapors do. Vapor lock is a different thing entirley. Thats when the fuel boils or turns to vapor before it gets to the carb. fuel pumps suck at pumping gasses instead of liquids.
If it's heat resistant, how is the ice going to absorb the heat from the intake? Yes. Anything that will pull heat out of the intake is a good thing. A lot of people use dry ice (frozen CO2) instead of water since you won't get any drip. The downside is that the temperature difference is so drastic that you stand a good chance of cracking something.
you could also use a small can of freon .....some of the stock class drag guys were doing it .....then ihra got on them .....brandon
I always liked the guys that would put coats over their rear tires to keep the sun off them in the lanes then do 20 seconds of smoke in the bleach box and a 1/4 track burnout followed by 4 or 5 dry hops before they run. As for the dripping on the track: Drips cause cars to hit things like the lights, the tree, the starter, the wall, the guy in the other lane, the tow vehicles on the sidelines, dumb assed camera men, etc. All these things cause delays that piss off the sponsors and cause the TV people to miss or adjust their commercial time slot. Sweeping the pieces of you up after the crash also causes the track and organization's insurance to go up. Please abide by the rules and don't cause the organization and track to lose the profits these rules were designed to protect.
Tuner show the other day showed just about what you describe. They documented how to cool the air in the intercooler with a CO2 shot, and one of the products offered by the same company was an insert by the MAF where they just ran the CO2 through, cooling the intake air.
Cool cans are still legal at NHRA strips. Ice on the manifold and spray cans with a cooling effect are now outlawed. Was used most often when making record runs or heads up races. Pete
Was used most often when making record runs or heads up races. Pete[/QUOTE] along with huge vacuum leaks......and draining most of the oil out....anything to win a class race......hahahah brandon
How about for land speed racing? i'd think you'd get more benifit on a land speed car because the motor is under full load for a longer period of time, especially with a gas spray system because you could use it while on the run.
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