So the main benefit of this would be to avoid fuel cut in cold weather right? It that's right then it would seem that just using bigger injectors/AFC would accomplish the same thing. Even though your IAT would read cold, the AFC would decrease the Hz signal sending an overall lower MAF reading to the ECU and you wouldnt be bothered with constantly adjusting the IAT signal.

 

Well, the downside to airflow correction is that you are constantly finding that balance between acceptable timing, enough fuel, and lack of fuel cut. If you're fooling the ECU into thinking there's less air (and at 40 some degrees outside, that's a lot of air density compared to 80 degrees), you're running the risk of running lean + exaggerated timing... I'll tell ya, my DSM sure doesn't like it . I like this idea though... any other thoughts? Todd.

 

So the main benefit of this would be to avoid fuel cut in cold weather right? It that's right then it would seem that just using bigger injectors/AFC would accomplish the same thing. Even though your IAT would read cold, the AFC would decrease the Hz signal sending an overall lower MAF reading to the ECU and you wouldnt be bothered with constantly adjusting the IAT signal.

Actually has 2 main benefits. 1st benefit like you said fuel cut during cold weather. 2nd is when you have a CAI tucked underneath the fender. The kn filter is sitting outside away from the engine bay, but the MAF is not. Now the engine is ingesting cold air, but the MAF is telling the ECU that the IAT is XX deg f because the MAF is still mounted inside the engine bay. Delta temp is huge enough to affect timing if you would let the car idle for too long or do part throttle duriing traffic.

Another point is that would you rather have all hc's removed or just play around with the temperature to delay fc. It's up to you to decide. Personally onece you remove the hc's, ECU doesn't adjust the fuel curve linearly.


Check out the diagram at:
http://www.dsmtuners.com/forums/showthread.php?s=&threadid=23115

 

If we wrap our maf up can we get lower temps???

 

i insulated the maf and still get 20 deg f difference.

If we wrap our maf up can we get lower temps???

 

This seems like a lot of work to accomplish a tiny amount of "benefit". I find it very hard to believe, at least in a 1G set up, that the MAF is going to register a substantial difference between ambient air temperature due to "heat soak".

The reason why is that the MAF is being bathed with cold air from outside, and if you route a CAI the "heat soak" would be reduced by a continuous supply of cooling air flowing into the engine.

Nevertheless, let's assume an actual soaking conditions exists. How much impact would it have on air density?

Turning to our old friend the Ideal Gas Law, pV=nRT, a change in temperature, dT, will result in a change in molar concentration, dn, if volume and pressure are held constant.

Let us assume a volume of 22.4 L, since that is the standard volume of 1 mole of gas at STP (1 atm, 0 deg C). This reduces the amount of math needed.

p = 1 atm = 1.013 x 10^5 Pa
V = 22.4 L = 0.0224 m^3
R = 8.31 J/mol-K

We must convert the temperature to Kelvins to work properly:

40 F = 5(40-32)/9 C = 4.4C = 277.6 K
80 F = 5(80-32)/9 C = 26.7 C = 299.8 K

Therefore d 40 F = d 22.2 K

Now: dn = dT (R/pV)

So: pV/R = (1.013 X 10^5 Pa)(0.0224 m^3)/(8.31 J/mol-K) = 273.01 Pa-m^3/(J/mol-K)

since 1 Pa = 1 N/m^2 and 1 J = 1 N m then

pV/R = 273 mol-K

so a change of 22.2 K (40 F) gives a change in density of 0.0813 or about 8%. The question is, does this difference in temperature really exist in a system with CAI and the standard MAF?

I find it hard to believe that this is the case, since the MAF is *in* the air stream. if anyone has real-world numbers, i'd be surprised at a difference larger than 20 F (11 K = change in density of 4%). Once agian, it seems like a lot of trouble to "fool" the ECU to gain, what *at best* is 4% tuning ability.

That does NOT relate to a 4% change in power, mind you. The actual power gain may be substantially less than 4% for all this work.

 

Just freeze it...................with Co2



http://www.designengineering.com/cryo2_cryogenic_air_intake.html

 

The website offers scant information other than " Dyno testing showed a reduction in intake air temperature of more than 35%"

Now, I'll go out on a limb here and offer that dT in this case is a value of 35% of ambient air temperature, but I don't know what scale, or what value ambient was. Let's give the folks at Design Engineering the benefit of more doubt and say that ambient air was 85 degrees and that we'll use the Farenheit scale. This makes thier numbers better than using other scales.

At 85F, 35% is 29.75 or 30F, or (5/9)30F = 16.66C or we'll round to 17C. Now, as before, we are interested in exactly how much denser this colder charge is given that dT = 17C = 17K.

Since dn = dT (R/pV) = dT/273 = 0.0623 , a 6.23% increase in air intake density. Remember, that only works out under the best conditions. Your performance may vary.

If we take ambient air temperature to be room temp (68F), the performace is even lower: 4.84%

Air density is not directly translateable to horsepower, a lot of factors affect final HP. Let's assume that an increase in 5 HP is realized by this system, and that's optimistic. You're still gaining it at a cost of $26/HP, not counting costs of gas.

The Hahn turbo kit for the NT 4G63/420A will provide 100 HP improvement for ~$2300. That's $23/HP. Get the turbo, it's a better deal.

If you already have a turbo, a 35% decrease in intake temp is going to do very little under boost, since temp increases with boost level (A difference of about 500F increase at 14lbs of boost*, so 30F/500F = 6% decrease). A front-mount intercooler is far more efficient than a cryo-bulb, for about $900, with no consumeables.

If ads are to be believed, you can gain ~40HP, which translates to $22.50/HP. Still a better deal.

*dP(V/nR) = dT. Therefore since n = 1, dP (V/R) = dT. dP = 14.7 psi = 101.3 kPa = 101,300 Pa. R =8.31 J/mol-K. 1 Pa = 1 J/m^3.
V = 0.0224m^3, therefore dT = 101,300 (0.0224/8.31) = 273.06K

dT (F) = dT (K)(9/5) = 491.5F

 

Just to let you guys know i didn't abandon this project yet. I'm just waiting for the weather to get better. I'll keep you guys posted on the results.

 

I must be missing something, you guys where talking about getting colder air in by using a CAI type setup. And the problem was that the mas would "heat soak" giving a wrong IAT at the maf, right?

Well wouldn't it be better to mount the maf with the filter in a CAI setup. given you have enough space. Water shouldn't be a problem if you mount it all correctly because you don't want the filter to get wet either.

However wouldn't the maf be design to work properly at the same temp as the inside of the engine bay. This is were the engineers intended to put it. Not sure only speculation.

And about the cryo intake, wouldn't it be better to have that cold air after the MAF. If you think about the rate of temp rise do to compression and airflow over hot parts, then reduceing IAT at the maf wouldn't net as much of a gain as after the maf becasue the air would 1. not be as hot so the cryo thing wouldn't reduce the temp as much. 2. the cold air would suck up more heat becasue of the difference in temp before the turbo, which is hot.

 

I must be missing something, you guys where talking about getting colder air in by using a CAI type setup. And the problem was that the mas would "heat soak" giving a wrong IAT at the maf, right?

Well wouldn't it be better to mount the maf with the filter in a CAI setup. given you have enough space. Water shouldn't be a problem if you mount it all correctly because you don't want the filter to get wet either.

However wouldn't the maf be design to work properly at the same temp as the inside of the engine bay. This is were the engineers intended to put it. Not sure only speculation.

And about the cryo intake, wouldn't it be better to have that cold air after the MAF. If you think about the rate of temp rise do to compression and airflow over hot parts, then reduceing IAT at the maf wouldn't net as much of a gain as after the maf becasue the air would 1. not be as hot so the cryo thing wouldn't reduce the temp as much. 2. the cold air would suck up more heat becasue of the difference in temp before the turbo, which is hot.

The stock mas and intercooler locations were design for economical purpose. However once you start modding parts like bigger mas, more efficient intercooler, shorter intercooler pipes, and any parts affect IAT, what was the original intent of the design?

The ideal location would be right on the manifold itself, but what do I know?


Here's a diagram of the relocated IAT:

www.dsmtuners.com/forums/sho...&threadid=23115