Gang- While at the Indy Speedway Museum a few weeks back, I had a chance to see a number of Miller race cars close up. As I think most of you know, these things are simply spectacular in every aspect - and virtually jewels in both design and construction. Anyway, one of the featured displays was the car in the photo below that used an intercooler. Seeing it got me to thinking about intercoolers in general, and I'm curious if any of you engine builders, etc. have had any experience with them. And if so, what are your thoughts on their potential application on a rod? If I understand correctly, their purpose is to pre-cool the fuel charge, increasing it's density - and thereby, performance. I know they were used (and maybe still are) on aircraft engines - and ***ume they are especially suited for that application since planes operate at al***udes where the surrounding air is very cold. I suppose they also worked well in long-distance races (Indy 500, etc.) where the cars are at speed for long periods of time, with air constantly moving over the exposed portion (as per the Miller set-up in the photo). I say "worked", as I don't believe they are in general use for that type of racing any longer. My question is - could there be any practical application for intercooling on a hot rod? Either when racing, or perhaps even to enhance overall performance (and/or fuel milage?) during regular driving, especially on the highway. I recall guys packing ice on top of their intake manfolds at the drags to accomplish the same purpose. That's obviously not going to work for everyday driving, but I wonder if there might be any practical way to get some benefits from intercooling. If nothing else, something like the Miller 'cooler would sure look *****in' on a rod! Ideas or comments anyone?
Grand Nationals, along with other turbocharged cars, have used them with great success, but you already knew that
are you referring to normally aspirated engines, or forced induction? just speculating here I would think you may want to be carefull with too much cooling on the naturally aspirated engines as one of the effects of turning a liquid to a gas is refrigeration if you separate the engine's heat from the intake charge you will already have a condition where the fuel/air is below ambient temperatures, which could conceivably lead to icing inside the intake tract if further cooling were induced if you mean cooling the pressurized charge in a forced induction system then it might make more sense as the act of pressurization causes heat, just the opposite of the naturally aspirated system
A buddy of mine used one on a 8-71 supercharged big block in a roadster. He said it really helped solve the detonation problem he'd had before. The only downside is that it lifts the blower up another four inches or so; on his deuce it wasn't too big a deal, but on some cars it might be a headache.
I run an intercooler on one of my cars. It is not normally aspirated though. Plenty of people use them on forced induction cars but I would agree with the above post that it would probably not function as well on a normally aspirated car. Also the power you may gain will probably not be worth the effort of buying an intercooler and then mounting it in a position and fashion that works properly and looks good. Long story short would not even consider it unless it had forced induction.
I always thought the down side of an intercoller for a roots style blower was the price. They often go for a couple -o- G's. 5-7 lbs. boost you should be able to get by w/o it. Would be nice to have one though!
60s Style is correct. Unless you live in the Mohave Desert an intercooler on a normally aspirated engine, used at normal or cool temps, is likely going to result in carburetor icing similar to what aircraft experience at al***ude. Most aircraft use some sort of carb heat to offset this problem. The principle works great in lowering the heat caused by compressing air in a 'charger setup but it would hardly be worth the trouble on an unblown motor unless you're planning on driving in very hot weather only. It might work okay with port fuel injection but I suspect it still wouldn't be worth the h***le.
I am getting ready to install one on my fairlane once I finish welding it all up....but I am slo runnign a turbo which really likes cooler air.
Unless you're running forced induction air, no gain with an intercooler since it's cooled with ambinet air the same temperature that's going into your carburetor anyhow. All methods of forced induction heat the air, thus the advantage of intercooling.
"no gain with an intercooler since it's cooled with ambinet air the same temperature that's going into your carburetor anyhow" Not so strictly speaking. An intercooler on a normally aspirated engine might well indeed lower the temperature of air entering it if the heat transfer capacity is large enough. The principle is the same as an air conditioning system. Heat is removed from a liquid coolant by a "radiator" of some sort which then absorbs heat from inside the vehicle. Water is used a coolant in an engine which dissipates heat through a radiator into the ambient air. A properly designed "radiator" will lower the temp of any coolant or air going through if the heat transfer capacity is sufficient. By suffiicient of course usually means a big enough radiator. And that's all an intercooler is. Since an air to air system is not nearly as efficient at rapidly removing heat as a liquid to air system the size of the heat transfer device and/or the air volume has to be fairly large to do any good. In short you could indeed get a drop in intake air temps on a N.A. engine with a properly designed system but it would be just as big a packaging h***le as a turboed setup if not actually worse, would provide little practical advantage, and in cool or cold temps the ****er might well ice up a carburetor. If it sounds illogical that an intercooler would drop the temp of un-heated ambient air just remember that this is easily accomplished by have a much larger volume of ambient air p***ing over an adequately sized heat transfer device than is actually going into the engine. The principles are simple but the execution in the crowded confines of an engine compartment is what is a big pain in the rear.
"What do you use to cool with, if it ain't AMBIENT AIR?" You can create liquid hydrogen with enough heat dissipated into ambient air. Admittedly this requires enormous energy input and huge heat transfer devices but ultimately the heat removed must be dissipated somewhere. Even if the heat is removed by a liquid cooling loop from a body of water that heat will eventually end up in the ambient air. The situation with an automotive intercooler is at a far remove from that required to liquify gases but the principle is exactly the same. And even an air to air system requires energy input to remove heat in the form moving air with fans or forward vehicle motion which for sure requires energy. Maybe not much in the overall scheme of things but not zero. Again you can easily lower the temperature of an ambient air stream with a large enough volume of the same ambient air moving through an adequately sized heat exchanger.
"Duh. ... The original subject was about "Street", as in cars, not ocean liners or trains." Yeah it was----Intercoolers for un-turboed engines---waste of time.
Go back and look at the photo in the original post, and CAREFULLY read it! Stan292 isn't talking about cooling the AIR coming in, he's talking about cooling the FUEL before it get to the carb. That big cooler on the side of the Miller is a finned aluminum radiator that the fuel runs through. Everyone here is getting confused with a modern term -- the intercooler used mainly for turbo charged engines since the act of compressing air also heats it up. Don't some drag racers still use a "cool can" for the fuel to run through under the hood? Same principal, except for long distance Indy driving.
The picture did fool me. The unit on the side looks pretty big for just a fuel cooler. Stan292 did say "fuel charge" which was perhaps just ambiguous enough to throw us off track. The original post also mentioned packing ice around intake manifolds which would cool the whole fuel mixture not just the fuel itself as in the case of cool cans.
I don't understand the point of cooling the fuel. Sure it gets denser, so you have more fuel going into the engine, but can't you get the same results by jetting bigger? either way your getting more fuel into the motor, right?
Cold fuel means that as the it atomises into the airstream it will to some degree result in a cooler overall fuel/air mixture which would in fact be somewhat denser although the advantage in a street car is probably minimal. Bigger jets will make the mixture richer but won't make a noticeable difference in the density of the mixture. Racers needing every last jot of power may see a difference using cold fuel but using a radiator style cooler on a typical street car, cool cans not being practical, is unlikely to be worth the trouble unless underhood temps are high enough to worry about vapor lock.
Without giving a complete lesson on the Fundamentals of Physical Science, Ill just point out that moving air doesnt change temperature unless it is heated or cooled by some outside source, that is it doesnt heat or cool itself from within. Air p***ing through ductwork is going to change the temperature of the ductwork to its temperature, unless of course, the ductwork has more m*** than the moving air, which wouldnt be the case, except in extraordinary cir***stances, for example; in a nuclear reactor. Therefore, air moving through a heat exchanger(radiator) regulates the internal temperature of the container(radiator), with that temperature being prone to balance with the temperature in the other side of the heat exchanger. In a normally aspirated Street Machine, ie, a car, the Ambient air going through one half of the heat exchanger, opposed by Ambient air moving through the induction side, will be basically balanced in a matter of seconds and of course, (a wash). Your phrase at end of sentence (is probably minimal) is overstated. A more correct ****ysis would be (not worth a hill of beans), making this entire discussion of using an intercooler on a normally aspirated street machine moot. Do you have direct knowledge of a normally aspirated street machine with a functioning intercooler that improved the performance to a measurable point?
Hey, this thread is starting to get good! A couple more notes on the subject - It's quite likely (almost a certainty, I'd guess) that the Miller in my photo was indeed a supercharged motor. I hadn't thought about that, but the technology was definately available then, and Miller was on the leading edge of supercharger savvy. I went to the Miller (club) website, but there was no difinative info there - although there was a mention of notable performance gains due to advancements in intercooling technology. I know famed automotive engineer and writer Griff Borgeson published a lengthy book about the Millers. I'll stop by the library tonight and see if I can find it. In any case, I always thought intercooling took place between the fuel supply mechanism (carb, injector, etc.) and the combustion chamber - blown or not. Is that correct? Intercooling aside - Bugman raises a good question. Is it possible the "ice packing" method isn't so much to cause a denser charge, but to drop its temperature enough to provide some cooling in the combustion chamber. I know water-injection was used in military and racing aircraft engines for that purpose (combustion chamber cooling). How that translates to power, I don't really know. Don't stop now guys - let's have some more discussion. Even after 61years, learning is still fun!
Probably blown. For intercooling to work you need a difference between the cooling medium and exposure time. There are some on the market that use A/C evaporators or dry ice in the water tank, but in the SE the core would quickly become clogged with ice from our 80-90% humidity. You could cool the fuel, but is is only 1/13 the weight of the air, so not a lot of help with charge cooling. Best charge cooling is probably thermal coating intake valve faces. If you think about stem clearances, you see exhaust needs more as it is hotter. But intake has more area exposed to combustion so it is being cooled by A/F mix, or the A/F mix is being heated by the valve.
Yes, any motor with an induction intercooler will be supercharged. As stated somewhere before, using an intercooler on a normally aspirated (not being forced by a turbo or a supercharger) Intercooling is of no value. In a forced air system, when the induction air is compressed, the result is heated air. That's where the intercooler comes in. Ambient air is drawn through one side of the intercooler radiator, the compressed/heated induction air through the other side. The flow of the ram ambient air cools the heated induction air, increasing it's density which results in a more dense combustion mixture that it would have been if left uncooled. Applications differ; but picture if you will, a Blower with carburetors sitting on top. The fuel is introduced before the air is compressed. If an intercooler is used, it will be below the blower, a part of the intake manifold. On the other hand, if the induction air is turbocharged, the fuel will be introduced to the induction air after it is compressed. Now, realize that one of you guys find this setup at a swap meet and will adapt the fuel metering device from an intercooled system to a non-intercooled application. The jets in the injector body on the turbocharged application will have to be changed to compensate for the difference in air density that it was set up for. In theory, the carburetors sitting on top of the blower will not have to be changed, because the air/fuel ratio was determined before it was compressed. Eh?
"Do you have direct knowledge of a normally aspirated street machine with a functioning intercooler that improved the performance to a measurable point?" Nope never heard of one and don't expect to.
Gale Banks ran a non turboed car with one of his Harrison intercoolers and an ice water tank at Bonneville. That's one of the few forms of racing where the weight penalty didn't hurt. But if you ***ume even a slight pressure drop through the core and compare it to the increase in density, I doubt it was worth it.
"you can easily lower the temperature of an ambient air stream with a large enough volume of the same ambient air moving through an adequately sized heat exchanger." This is stiill true but only in a strictly theoretical sense. "Adequately sized" is the trick phrase. It'd probably require an intercooler the size of a doghouse or larger to see even a small difference in a car. Fugedaboudit. You could see a significant difference if you used an AC compressor/condenser setup but that'd likely rob more power than a cooler charge would give. Probably a lot more. Fugedaboudit twice.
There are on the market a few devices that are essentially naturally aspirated intercoolers(like the NX Ntercooler). they work like a standard intercooler, buy N2O or CO2 is run through them. As it expands from the liquid to a gas inside the intercooler, it cools down and that in turn cools the air p***ing over it. they are momentary use, because the gas is consumable, but the chilling effect on the incomming air is quite pronounced.
No; with turbo chargers you want to run the compressed air through the intercooler before you introduce the fuel, for one main reason - if you have pipes & intercooloer full of fuel & it backfires you'll get a m***ive explosion. Also it would tend to seperate the fuel from the air. With a blower on top of the engine, you have no real choice but to put the intercooloer under the blower & run the fuel through it. ~ Paul aka "Tha Driver" You braggin' or complainin'?
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