How much does a cold air box actually do?
 

I have the Apex'i intake on my FD, and driving anywhere except the freeway the intake temps can get pretty hot. The power FC controller reads as hot as 70 degrees Celsius at times. I think that works out to like 150 degrees Fahrenheit or something. I see all these guys with single turbos and they just have the air filter right on the turbo sucking in hot engine bay air, so is a cold air box really that important? Will changing to a cold air box give a noticeable increase in power or response? Opinions, or facts anything would be apprieciated!

The air still has to pass through the intercooler. It has been shown to help in a previous thread, but the intercooler is the major determining factor.

I agree. The intercooler is a big deal! But the one thing I do know, is that the lower the charge temps(air is more dense), the more power you get. Now for you to feel the difference; I don't think your ass dyno is that good!

well, with a larger turbo I believe they create more heat than say the stock twins. So I dont think putting a cold air intake on it would really do to much. But on something that would not increase the heat as much it would probably make a little bit of a difference.

But like Larz said. The intercooler is what does the most. So if you have a solid cooler than you should not have to worry about it.

This was proven over 8 years ago..... here's the data again:

http://www.fd3s.net/intake.html#COM

Wrong. A larger single turbo runs much cooler than the stock twins.

really? damn I was off on that one.

Reasoning for it? I am guessing because they are sitting side by side?

They heat while the secondary pree spools, too.

well thats what I figured because they are packed together. I didnt really think about that when i posted.

Obviously running a filter right off the twins would be a terrible idea. (am I going to get owned on this too?)

You learn something new everyday!

ok so to branch off this.

How would say the heat temps differ from a T-88 and a T04B?

That was sorta where I was headed with the initial post but forgot about 2 turbos in 1 spot making more heat.

Who cares as a T-88 is a worthless turbo on an FD....unless it's a pure drag car (and then it's just outdated compared to newer quicker spooling turbos). Most of the heat from the twins is due to their small size and the cast iron manifold design. In general, any single turbo running in its efficiency range will likely run at nearly the same temp.

Don't forget, the damn heat shields don't help anything either.

haha, the point wasnt about using a T-88 I just wanted to know if there was a heat difference. It was just easier to reference. I was just looking for the answer you gave in the second half of your post.

i saw much cooler intake temps vs my buddies car on a several hour drive. i have the m2 box with m2 med ic and he had apexi open intake and blitz smic.

I find the M2 aluminum box I have is a BIG help for autoX-style applications where the underhood temps are hot and engine bay is heatsoaked. In this type of driving I find the box a significant improvement. I am more or less stock other than this.

IMHO, cold air is one of those things people get really excited about. I've seen people go to bizarre lengths for a cold air intake - cut holes in the hood, you name it.

On a non-turbo car, it's a good idea, but IMHO there really isn't gonna be that big of a horsepower difference. On a turbo car, the compressor design and intercooler efficiency really sets the bar as to what your intake temps will be.

Many times a cold air setup just isn't practical due to space limitations. In general, as long as it's pulling air from a relatively cool part of the engine bay and not from, say, directly over a hot manifold, you're doing OK. This is what Corky Bell told me many moons ago when I had a good long talk with him.

The link to the intake temp test by Dave Disney from back in the day is interesting, but it would be more relavant to see a change in temps the *engine* is seeing. That would tell you if the air the engine gets to ingest is helped by the airbox.

My primary design criteria for an intake is that it must filter well, must be easy to remove to work on the car (I HATE the stock airbox for this!), and needs to look decent and not like something I made with duct tape and dog poo.

Dale

But wouldn't you agree that the intake temp drop before the turbo will also have the same relative drop at the engine?

And because of this drop before the turbo, wouldn't it help to switch to a CAI?

"The third-generation RX-7 had come off Mazda's rigorous development test programs on the bench and on the demanding Global Road Circuit section of the Miyoshi Proving Ground with flying colors. Yet, there was one arduous test left undone. When the car was taken to a race track near Tokyo known
for its tight turns requiring short bursts of speed followed by fierce deceleration, the pride of Mazda's rotary rocket team quickly cooked its powerplant when pushed to the limit. Subsequent investigation revealed that air temperature at the entry area had risen as high as 50 C (122 F). Fresh air for the engine's consumption was taken from the single intake that also fed to the air-to-air intercooler. On wide-open driving, air flow reversed its course from the intercooler and went straight into the engine's intake.
The intercooler was acting as an inter-heater! In the updated RX-7 with a designed fascia, fresh air is taken through a separate, dedicated duct guided by a newly installed air-guide. Air temperature at the engine's intake entry area has been halved to about 25 C ( 77 F), which adds about 7 kW (10bhp) to the output. "
http://www.rx7.net.nz/newrx7.htm

long talks? you mean like cover to cover? :tonque:. I think it should be required that any turbo car owner read that book cover to cover before modifying their car :tonque:.

Lot's of good info in this thread already, no need to repeat it :bigthumb:.

so if i wanted a cooler intake temp, greddy's intake system wouldn't be for me right? Greddy's intake would allow more air than a stock air box but not cold air, correct.