yeah, best bet is the plastic style ones like the FIPK with a surround on the filter. plus those bends do suck97predator said:yes an intercooler/radiator is much different than a hollow tube. the fins increase the surface area through which heat can transfer, giving a higher transfer rate and while keeping pressure up. a hollow tube has parabolic velocity profile. the air near the inner wall will be hotter than the air in the center. the hotter tha intake tube is, the hotter the air charge becomes throughout. once the car is moving the underhood air draws heat of the tube, cooling the intake flow. this in effect with drawing air from outside the engine compartment will create some power. but i htink the greater beneffit is the smoothness of the air flow of a metal tube vs the stock squiggly plastic.
Much higher than ??? Well, you are right that it does conduct at a relatively high level, that's true. Actually what I meant to say was that aluminum is great at dissapating heat. So it may absorb heat pretty easily, but it also looses it very quickly.RysRed96GT said:actually, aluminum is a much higher conductor of heat
302 coupe said:90% of the air flows though the centermost 75% of the diameter approximately.
302 coupe said:Why the factory heats the throttle body- that I have no idea, maybe its to improve cold weather idle quality, as the air would be moving slowly enough to actually be heated.
CatmanJJ said:Well can we at least agree that most popular CAI don't do much of anything except on boosted applications ie 03+Cobras and other blown Stangs? On N/A bolt on SOHC 4.6s I think they're good for mostly cleaning up the engine bay at best.
i would personally never buy something for 150 bucks that can only give me about 3 hp maybe...even risk losing some power from bendsCrimsonCobra_01 said:so you guys are sayin that a new cold air kit aint worth it then? cause if so then thats 150 bucks i dont need to spend
302 coupe said:the problem is that at the metal/air interface, the air velocity is zero. So yes, the air will get hot, but its not flowing either. 90% of the air flows though the centermost 75% of the diameter approximately. I could go into formulas and graphs, but if you really want to know, go to the library and read a book on heat transfer. Why the factory heats the throttle body- that I have no idea, maybe its to improve cold weather idle quality, as the air would be moving slowly enough to actually be heated. Once air gets flowing, it couldn't care less what temperature the pipe is that its flowing through-unless its really long and really hot. Anyway, under normal circumstances it doesn't make a difference.
RysRed96GT said:similiar to the reversion principle of large exhaust pipes
they heat the throttle body? im confused...
hognutz said:your right an intercooler is differnet I am just saying I don't buy you velocity theory... ...Now if you can show me actual intake temps I will shut up. I have a feeling you are just running on your own logic.
Aaron 4.6 said:Well I spent some time this week putting together my own simulation of air temperatures based on the analysis that GulfCoastMustang presented late last week. He may be the only person that cares about the blood and guts, so the rest might prefer to simply skip to the results below.
Method- I used a simple heat balance just like GCM did setting mCpdT = Q = UAdT
System assumptions were CAI diameter of 3” and length of 28”, air inlet temp of 75F and ambient engine compartment temp of 145F. Tube thickness of .12” (might be a little too thick but it doesn’t affect the results) and a thermal conductivity of 16 W/m*K for steel.
I took the relevant properties of air (thermal conductivity, viscosity, density, heat capacity, Prandlt number) and used cubic spline functions in MathCAD to interpolate values over a range from –10 to 260 F.
Natural convection is hard to figure for the engine compartment, because no one knows exactly how air moves in there. Typical h values for natural convection are around 5-6 W/m2*K however, but I assumed 25 W/m2*K just to be safe.
Calculating an overall heat transfer coefficient at 200 CFM (flow rate at 2500 RPM) gave us U=2.6 W/K, which is pretty small (I used Dittus-Boelter to get hin values for the inside of the pipe). The overall temperature rise at those conditions is about 1.6 degrees F. Now at a worst case assumption where convective heat transfer is SO robust that the wall temperature is steady at 145F, the overall temperature rise is 7 degrees F (hin, which becomes U, for the inside of the pipe is 70 W/m2*K).
If you look at the Densecharger, which is made of ABS plastic, the thermal conductivity drops to about 0.9 W/m*K and the overall heat transfer coefficient and overall temperature increase goes practically to zero.
What it all means. There is no significant temperature effect introduced by a CAI, no matter which brand you buy. Unless your filter is exposed to engine bay air, a stock airbox, steel CAI, or plastic CAI will all have approximately the same inlet temperature to the intake plenum. Thus the ONLY benefit you should expect to see from a CAI is the performance increase gained by having a smooth pipe instead of rough rubber as the conduit for inlet air.
quiksilver98 said:I don't know whats up with you u guys getting hot air, I was happy ever since I installed my cold air intake. felt like 20 hp. Me and my uncle installed it in about an hour and when we where done. I took it out for a test drive and he said he felt a big difference.
no way to get 20 hp, unless there was a gerbil stuck in ur stock air hose...quiksilver98 said:I don't know whats up with you u guys getting hot air, I was happy ever since I installed my cold air intake. felt like 20 hp. Me and my uncle installed it in about an hour and when we where done. I took it out for a test drive and he said he felt a big difference.
YallarStang said:Why not just alleviate the intake tube all together and clamp a filter onto the throttle body?
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