Thoughts on hot air vs cold air intakes
 

Hot air vs cold air intakes seems to always be argumentative. I think everyone will agree that cold air is better, it just comes down to how much better and some feel it's not worth it. The hot air guys seem to think that as long as you have a decent intercooler it doesn't matter. I think they're full of hot air :p:

All of us notice the difference in power of our turbo cars between a cool summer night and a hot summer afternoon and that difference is soley due to intake temps! If the difference in intake temps didn't matter you wouldn't notice a change in power. Anyone running a hot air intake is not making the power they should be. End of story.

I have the pettit hot air intake and it sucks and blows. I also have the ASP large IC and while cruising on the highway in 70f weather my intake temp on the PFC was 105f. Thats with hardly any boost.

A while back I used a temp gauge with a remote sensor to see what the temps were like around those filters and its terrible. As soon as you come to a stop the air just bakes. Easily double ambient. It cools when you get moving, but slowly. My intake temps on 80+ days are at least 120+. Worst $/benefit ratio of any mod I've done. The extra $50-$100 for a box seems well worth it.

I absolutely agree. But, the theory goes that, the only time it makes any difference is when the engine is running while the vehicle is at a stand still--e.g., at a traffic light. At all other times, air is flowing through the front of the vehicle and is essentially allowing cool air to enter the intake. I just think 'why make the engine suffer at stops while making it suck in hot engine bay air?'

Although I basically agree with what you said, there IS another factor:

The ability of the IC to cool the air after the turbos compress it. That is also directly related to the temperature of the air passing through it, and may have an even bigger effect than the intake air temperature.

BTW, I run a cold air intake, and a larger IC - see my sig.

having a cooler "starting" temp is a no brainer.

Wow, a new topic!!! Just kidding Damon ;)

I agree. Even while driving at highway speeds, a "hot air intake" wil be sucking hot air that comes off the engine, intercooler, and radiator. That can easily be 50 degrees hotter than ambient. At a stop, air intake temps can be 150+ over ambient.

Well, I do have a "hot air" blitz intake, but I was going to try and fabricate a cool air box just to see what happens. Has anyone tried this before and have any pointer for me?

thanks,
-josh

If that were true I could drive down the highway for hours and immediately pull over, pop the hood and find that the air around a hot air intake under the hood is no warmer than the air outside the car. Wrong!

Well you'd need to be pretty fast, because our little cookers heat the engine bay asap.

Seriously, I cannot argue with you. I have a cold air intake setup and I see it no other way. Traffic these days keeps you idling at lights too many minutes on any trip or commute. Maybe someone can rig up a digital thermometer in the intake to measure intake temps and we'll all know.

Guys, intake temps were measured YEARS ago! http://www.fd3s.net/intake.html#COM

The M2 intake listed was the metal one, not the C/F one. As you can see, even the M2 is much hotter than the stock intake, but much cooler than an open intake. This is why I think the PFS intake is actually the best intake available, it's unfortunate it has to steal from the IC duct to get it's air. And it also makes working on the car a PITA, which is why I run an rx7fashion box now.

Bottom line, IMO, running an open intake is a bad move. There is no reason to, as the box intakes get plenty of air and run much cooler.

I have a similar set us as you: Large M2/ASP SMIC and with 2 4" K&N filters. I also added 3" ducting to channel cold air from the nose up through the gap between the frame rail and the raditator to them along with a home made heat sheild. It sucks hot air from the engine bay into the engine while at a stop.

Does anyone know if an M2 or PFS "enlcosed" intake box will fit with an ASP/M2 Large SMIC?

I don't think anyone argues that there IS a difference in intake temps, but the hot air guys often insist that these differences don't matter because they happen to have a "big" intercooler. Rubbish.

start lower. end lower. physics owns you.

Agreed. Cooler, denser air to the turbos means more efficient (more rapid output rise to controller limit, more output-pressure capability, etc.) turbo operation.

Period.

Won't the IC work more effectively also given cooler ambient air? Meaning that, yes, the cool night air is providing colder intake temps, but I would also expect that the IC is cooling the post turbo air more than it would on a hot day. Plus everything along the path (intake manifold, engine, exhaust, turbos) is going to get better cooling given cold ambient temps.

I'm not speaking to the hot air vs. cold air debate, but I would make an uneducated guess that the difference is probably not soley due to intake temps.

By intake temps I mean pre-air filter...

Is there anyway of getting air from the standard front bumper to the filters. I have the HKS Racing Suction kit but would love to get them some cold air!

I also have twin oil coolers so they're both out.

I've said this many times on this forum, yet people still want to argue with me saying that a big intercooler is just as good!

Good point....and I fully agree with you, of course. :)

yes,there is a way to get cooler air. someone on this forum runs piping thru/under sleek headlight unit, right to the duct for oil cooler.I bet it lower the temps quite a bit.

The old metal M2 or rx7fashion box will....John, give Rick a call. He's running the rx7fashion box with an ASP large now. He is still running the PC680 on the side of the IC.

The PFS should work but it would need to be modified quite a bit.....

Quote :'the PFS intake is actually the best intake available"

You must be on crack, its a horrible unit. One its seriously old technology, second its so restrictive and it just cooks the air. I called it the the PFS hot box.

I have a single turbo with no air box just a K&N filter. My air intake temps are 15c lower then when I ran the PFS equipment.

When my Fd is running the intake pipes on the turbo side are very hot, but on the other side going to the TB its cool to touch. Guess my FMIC works :)

I have the carbon fiber M2 air box. I wonder if it's better than the old metal one. I'd assume the carbon fiber does not asorb and radiate heat as much as the metal box would?

Here is some info on Carbon Fiber for you guys! :)

http://www.everything2.com/index.pl?node=carbon%20fiber

Here are some pipe guards for motorcycles. I would say that the heat protection properties of Carbon Fiber would be substantial.

http://www.motoworldracing.com/wb-06...pe-guards.html

In this link K&N talks about the heat resistance in paragraph 2.

http://www.knfilters.com/Racing/crbnfiber.htm

It is the resin that is laminating the Carbon Fiber fabric that is the weak link for heat. Now a days we have vinylester resin, a cross between polyester and epoxy resins. It is formulated to be extremely heat and chemical resistant. Maybe I need to make a duct that comes from the front bumper straight to the intakes and with a good heatshield for the intake, you should get much improved air flow and intake temps. Also what do you guys think a vented hood would do to change the equation?

I think (imo) the best intake ever made for the FD was the one that was hand made of welded pieces of titanium piping that went down to the corner vent in the front bumper, where the oil cooler in the R1 resides. I cannot for the life of me remember who made that, I havent seen him post in months, and I cant find the thread w/ Search.