Mahjik

iTrader: (1)

Cold air is good, however, the intake is not cooling anything; the IC is. It will never be below ambient temp at the intake (i.e. if it's 90 degrees outside, the best you'll hope for is 90 degrees coming in.... It still won't be like a 50-60 degree day).

Many old school guys have done testing and found the intake (barring not be restrictive) made no difference with an efficient IC.

Cold air intakes aren't as useful on turbocharged cars as they are on NA cars.

dubulup

whoa - never thought I'd disagree with so much of what you've said?!?!?!


so you think there is no difference in trying to compress cool air and compressing hot air?

and the second statement...

DaveW

IMO, a cold air intake provides cooler, denser air to the turbos. Therefore, if the peak boost is turbo-limited, the cooler air should enable higher peak boost. Even if higher peak boost is not desired, the turbos will work more efficiently with the cooler, denser air, and arrive at the desired boost level sooner.

You are correct, a cold air intake is not as important on a turbo car with a good IC, but it can still provide some benefits.

Mahjik

iTrader: (1)

Have you seen the exhaust turbos?

ManGaZeRo

iTrader: (1)

Just curious did any people that installed the apexi intake remove that foam between the rad and frame?

Mahjik

iTrader: (1)

But the thing is, you aren't going to get any colder than ambient temp. If it's 100 degrees outside, you aren't going to get lower temps than that. The intake boxes just reduces the amount of engine air that is brought in at low or idle speeds. At speeds, it really doesn't matter; more is better at that point.

There used to be plenty of dynos around showing no gain from switching different intakes between boxes and open air (on the stock twins). The only difference was shown in the restriction of the stock (and some other) boxes verese other box designs and open air intakes.

Theory and actual results sometimes don't always go hand in hand. I agree, that in theory, cold air boxes should provide better power. In reality, on the stock twins, it just doesn't make a noticeable difference.

RX7-2JOCK

I love the cold air duct John made for me. I see cold temps all day. On the drive home from tunning at Ground Zero I was getting readings off of my PFC as low as 10 Celsius, not sure what that equals in degrees. The cold air system is actually in two pieces, the duct, and the piping to the compressor housing. John also painted the duct black for me, you can kinda see the glare in the last pic.

Mahjik

iTrader: (1)

Unless you relocated the IAT, then you are reading your intake temp after your IC which really doesn't show what your intake per say is doing.

Ideally, you'd have a sensor just after the intake before the turbos, and then one after the turbos before the IC and then once after the IC (like where the stock IAT is located). That would truley show you the benefits of any changes in the intake (or IC for that matter).

adam c

iTrader: (2)

There are lots of situations where a cold air intake can make a huge difference, when compared to an open intake. How about this example:

It's 75 degrees out, and you have been driving your car hard. 220 degrees coolant temp. You come to a red light, and are waiting for it to change. A guy in a older modded Mustang GT pulls up next to you, and wants to race. The light finally changes. Which intake do you want?

Intake "A" is an open intake. In this sitaution, is will be pulling in very hot air from under the hood. This air will probably be close to 250 degrees.

Intake "B" is a cold air intake. It is sucking in 75 degree from outside the car.

In this situation, there is a 175 degree difference in pre-intercooler intake temps. That is significant.

ptrhahn

iTrader: (9)

I'd suggest that what you get "out", i.e.: what your intake manifold air temperature is, is always affected by what you put in.

There's no way anyone can tell me that, no matter what temperature air is fed into the turbos, that the same temperature air comes out, and is then subsequently cooled by X degrees by the intercooler. Think about it. You see cooler intake temps on cold days because colder air entered your intake, was warmed by a certain amount through the turbos, then cooled a certain amount by the intercooler.

I'd dare say that the underhood temperature in any FD is a damn bit hotter than any ambient temperature... even at 100 degree ambient temps, thats still 100 degree air going in the turbo, not 180-200 or whatever the engine bay temp is.

Say you take 100 degree air, add 200 degrees through compression, thats 300 degree air into your IC, that may drop that temp 50%, netting you a 150 degree intake charge. Somebody's going to tell me that if you feed 200 degree air in the begining of that equation that your still going to get a 150 degree charge?

Cgotto6

iTrader: (8)

Thankyou Mahjik, thats what I said on the first page of this thread.

Mahjik

iTrader: (1)

Guys, you can argue this until the cows start flying, but it's not going to matter. You can't say that a 40 degree temp difference at the intake is going to equal a 40 degree temp at the manifold.

While I don't have the formulas, I would expect the temp change from the turbos to be a more complex equation than just "adding 200 degree to the intake temp". This is more likely the reason that the intake temp plays such a small roll on turbo charged cars verses NA cars.

If the cold air boxes made THAT much of a difference, there would be a much larger market for them over the open intakes and that's just NOT the case. The fact is, if you want to lower your intake temps (which the ECU measures at the manifold): get a better intercooler. A cold air intake isn't going to do squat if your IC is 40% efficient.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/who-makes-best-intake-system-42550/

dubulup

Where is Max Cooper?

he has a detailed spreadsheet where you can enter temp values, efficiency %'s, blah blah blah...and it calculates how much difference pre-turbo air temp makes; pretty neat info.

As for my belief...I have a single (open intake) SMIC'd/WI'd FD. Hot days in traffic, I have seen very very hot temps 150+F. Radiator fans blowing on my intake sure doesn't help. Of course once I get into boost that drops quite a bit (wind, WI, etc), but I'm still not happy with those #'s and think they can be lowered more with some ducting and box work.

Now, maybe I'm picking up 2 1/2 hp at 8k rpms but at least my air is cooler and my mixture is further from detonation. With these cars I would think everyone was in agreement any and every little bit will help...what ever it is.

coolvette

Will that cold air setup work with twins? i guess you have to go with a single air cleaner for both turbos.I where doe he drill the hole for the duct?

seven samurai

step one: buy two small ice chest
step two: port box one with hole on each side above midway line
step three: connect intake lines two ported holes
step four: add a bag of ice to bottom half of box one DO NOT PASS MIDWAY LINE(very Important unless you have a bypass valve) WITH ICE
step five: put bag of ice in box 2
step six: put box 2 in trunk or rear compartment
step: seven drive
step: eight take Ice from box two and replace bag of ice in box1 as/if needed
ha ha ha ha

POS7

I have a question, although this may seem like an unsophisticated way of testing air temps. The pfc reads off the UIM IAT sensor (I believe), so cant you just compare an OAI with a CAI using readings off this sensor in similar conditions?

By similar conditions, I mean similar weather conditions at 1. car fully warmed at a highway cruise 2. car fully warmed at a complete stop. You can use 2 different tests.

Mahjik

iTrader: (1)

Sure if you have the same car with the same conditions on both tests. It will be hard to dupicate the test and make sure all the variables are the same aside from the intakes, but it's possible.

However, I'll bet that a more efficient IC makes more of a difference on intake temps than a cold air intake. Now, if you can create a true ram air intake, that would be more beneficial.

Mahjik

iTrader: (1)

If you are talking about RX7-2JOCK's setup, you'll never get that kind of piping through there with the stock pop-up lights.

Madmax670

I would like to hear what Max Cooper has to say, someone mentioned he had done some research on this topic. Before I start making a nice CAI I would like a little more information, anyone want to fetch him?

poss

iTrader: (5)

Turbo inlet temperature and it's effects on compressor efficiency is not up for debate. It's math people!! Don't argue, just smile and nod. Cold air is better for making power, period.

jic

iTrader: (1)

yupp...need cooler air somehow..my RE sucks up HOT air in the compartment
too bad i cant use my stock airbox...wont fit with my smic

mibad

I mounted a heat shield on the stock airbox mounts to keep the hot air from blowing on the Apexi Intakes. I also wrapped the metal portion of the intakes with exhaust wrap. They stay much cooler now. I blocked off 3/4 of the opening that fed stock airbox so more air would flow thru the IC. Then I ran flexible 2" tubing from under the car up along side the oil cooler, under the head lights, and directly to the Apexi.

7 BOUND

Noooooooo Dude You Have To Get The Arc Cold Air Intake Box, You Dont Have To Pay 500 For It You Can Find It On Ebay For About 250 To 300 Maybe Less, But Man I Do Hard Runs And Ther Not Even Hot Just Warm, You Have 2 Filters One On The Bottom And The Top Just Heat Shield The Coolant Hose Under It Or Just Go Without And You Will Love It
Have A Good Search

coolvette

this thread is a couple months old how did it come back?I will check out the arc.

impactwrench

Mine