How much HP increase by cooling the intake air?

[710]

Does anyone have any info about the HP increase in an NSX by chilling the intake air? I actually notice a large difference in performance when its cold compared to when it’s hot, as we have all known for a hundred years and we all know why, too.

From my experience, small increases in power can’t be “noticed” by the seat of the pants (like when you chip an car, for example, it's psychological. The noise from the new exhaust system etc.). But I notice a difference in something when it’s cooler. So the power, or engine response or whatever must be much better.

I’ve been thinking about this for a while. If I use an air conditioner compressor, driven by a different gasoline engine not connected to the engine (thus not any sapping power from the engine) to cool the air drastically, can I get 30 extra HP from a 3 litre engine?
This might be really cheap to do. And NO changes in the engine (chip, sensors etc) would have to be changed.

The whole idea of getting more power is to burn more fuel (ok, efficiency too, like changing to headers, but I’m not talking about that here). With a stock engine, we are burning the maximum amount of fuel currently possible.
If you charge a motor (by super or turbo) you can burn more fuel. This means more power.
If we burn more total fuel by adding an extra small motor, we would achieve that.
It would only be powering when we are on full throttle. It would be idling most of the time, just enough to keep the gas compressed I guess. If it stops working or it breaks, our engines would still work perfectly. No down time.
Would this work? I don’t know much about air conditioners.

Peter

 

[menuserve]

sounds interesting....

 

[clr1024]

as an approximation believe that for every 11 F degree drop in temperature there is about a 1% increase in horsepower. I guess I could break out my thermo books and do the theoretical calculation but I really don't feel like going there on a Saturday morning. Calculations for FI would be different.

 

[clr1024]

The idea in achieving power is to increase mass flow through the engine. Adding things like intake headers and exhaust, without getting into the dynamics of the exhaust etc, allow for more air to be suck, squeezed, lit/combusted (banged) then blown out of the engine.
The limit on NA engines is determined by the atmospheric pressure and temperature at which air is coming in. This is not true with turbos and superchargers as you can adjust the pressure(biggest factor) then temperature(second biggest factor) with which they cram more air into the cylinder to which you add more fuel to keep your A/F ration constant which in turn creates more power. This is why turbo/supercharger cars suffer less at higher elevations

 

[1BADNSX]

The SAE correction factor is proportional to ((Temp + 460)/536.4)^0.5 when Temp is in degrees Fahrenheit. So a 10.6 degree reduction would increase the power approximately 1%. Same thing clr1024 said.

Bob

 

[710]

So if I reduce the temperature 30 degrees F, I would gain 8HP. Hopeless.
Then the increased power or responsiveness or something I feel when it’s cold and wet is purely psychological.
Thanks for all the input.
Peter

 

[Bob Kenney]

The question is are how much can you drop the temp of a rapidly moving air mass as it passes through the cooling coils? How much cooling capacity do you actually need to gain noticable HP. Have we also considered the humidity factor? Colder temps + more humidity = more safe timing advance. Just some questions to ponder.

 

[IsR]

Interesting... making air denser by using temperature reduction. Thought about it when I was still modding engines(MR2 and GTR).Don't think car air conditioner is 'cool' enough to chill your intake to get the performance increase. Check out this web address, have similiar goal

http://www.cryofuzion.com/

 

[1BADNSX]

Don't think car air conditioner is 'cool' enough to chill your intake to get the performance increase.

If somebody tried the ac method, I think the second law of thermodynamics would show you would take more power running the AC than you would gain.

Bob

 

[liberty1performanc]

it's not just the fact that you can get more power from the coolness but you can run more timing and increase the power increment even greater(like Bob Kenney said).on my civic I’m running 30psi out of a pt67-76 and some races don't allow for intercoolers. those races I’m retarding the ignition 10 degree's and having to pull about 15% of the fuel which brings me down to about 21 degrees of advanced ign. now when I have the water to air cooler on I’m able to run 32 degree's advanced ignition at 9000rpm's and I have well over 45whp difference(this is all done on 9:5 compr. ratio).as far as setting it up with an ac system I don't know how that would work, but why don't you just try running water/meth injection. I’ve set one of them up on a na s2000 and we were able to get 18whp with out touching the timing and when we advanced the timing a little we received 27whp, not to mention there will be a lot less r&r to get up and running.

 

[710]

If somebody tried the ac method, I think the second law of thermodynamics would show you would take more power running the AC than you would gain.Bob

my whole point was to run the AC pump from another engine separate to the NSX engine. So adding cubic inches, if you know what i mean.

The question is are how much can you drop the temp of a rapidly moving air mass as it passes through the cooling coils? .

Good point. Air resistance.

Have we also considered the humidity factor? Colder temps + more humidity = more safe timing advance.

yes, I was thinking of that too.

Well, i guess nitrous cools the air too, eh? i'll try that.

This car (NSX) should have 400hp.

it's not just the fact that you can get more power from the coolness but you can run more timing and increase the power increment even greater(like Bob Kenney said).on my civic I’m running 30psi out of a pt67-76 and some races don't allow for intercoolers. those races I’m retarding the ignition 10 degree's and having to pull about 15% of the fuel which brings me down to about 21 degrees of advanced ign. now when I have the water to air cooler on I’m able to run 32 degree's advanced ignition at 9000rpm's and I have well over 45whp difference(this is all done on 9:5 compr. ratio).as far as setting it up with an ac system I don't know how that would work, but why don't you just try running water/meth injection. I’ve set one of them up on a na s2000 and we were able to get 18whp with out touching the timing and when we advanced the timing a little we received 27whp, not to mention there will be a lot less r&r to get up and running.

Wow, good info. Thanks.
If I turbo, means 8:1 comp pistons and new ecu. But I don’t want to pull a good engine apart. And I’d lose the responsiveness of the engine. Well a little. My Cosworth has very little turbo lag. Has the stock turbo. Maybe on the NSX twin turbos would be ok.
But if I did the engine, I’d prefer the stroker kit to 3.8l litres over a turbo. That would be 400hp (with 11.2:1 pistons. Here we have 98 octane gas everywhere).
But it’s $15,000.

You, know it’s a real pity we didn’t get a Euro version with hi compression pistons here!
But it’s the same engine as in the USA. Bummer.

Is the map exactly the same on a Euro NSX as on the US one?

Does the ECU advance the timing constantly using the knock sensor? Pretty risky, I’d think.

Peter

 

[QuadCamSix]

I have looked at systems like this before but never on an NA application. Here is how an active charge cooler is setup.

On a FI application the ac compressor chills a resiuar of coolant down to very low (subzero) temperatures. This super cold fluid is then pumped through an air to water intercooler/aftercooler to achieve lower than ambient charge temperatures (grater than 100% cooler efficiency). The AC compressor runs constantly, cooling the fluid unless the throttle is depressed fully. At WOT the compressor cuts off, thereby removing its power robbing load from the engine. That way the system does not take more power than it makes because there is only a load when off throttle. The resivuar acts as a thermal capacitor and if sized correctly will never allow the incoming air to get above the ambient temperatures.

This is all with forced induction applications though. The cost and complexity of the system would be wasted on the few horses you would gain without boost.

Jim