Madee

iTrader: (3)

Anyboby have a CRYO2 or N-tercooler system to cool the intake and/or IC? I'm installing a full CRYO2 system on a single turbo; 3 air intake cooling chambers, fuel chiller and dual IC sprayers. It makes good sence but I really am curious how effective it will be. It will be easy to test. Still months away from completion.

DaleClark

iTrader: (55)

OK, my take on all this while we're bench racin' .

Is drawing air from a colder source better? Yes. The big question is, how *much* better?

I think most every forum, especially cars without turbos, beat the cold air argument to death. You really need numbers to go along with the data.

For our cars, the real number that matters is the air intake temp at the intake manifold (or throttle body elbow if you moved the sensor). That should show the actual temps entering the engine, which is what we're most concerned with. This is a whole system - it's arguable that having a very efficient intercooler could offset a hot intake, and having a cold intake could offset a stock intercooler.

At the end of the day, how much does the intake air temp affect power? Does 50 degrees at the intake versus 150 degrees make 5hp difference? 10? 20?

For me, having an intake that's easy to work around is one of the top design priorities. I absolutely LOATHE the stock airbox. I have also seen some rigged cold air setups that would also be a royal pain to remove and reinstall when you're working on the car.

Anyhow, my gut feel is: it's not as big of a deal as people make it out to be. I think a cold air intake will get you more power, but it's not a massive difference.

BTW, one thing that's always cracked me up is there are MANY forums where users are TERRIFIED of putting a plain cone filter on because "you just lose power since it's hot air". Of course, that depends on the car, but dammit, put the cone on and find out for yourself .

Non-turbo RX-7's make a very nice increase in power with just putting a cone on. Every car I've put a cone on had the top end of the powerband wake up SUBSTANTIALLY. That's with a good ol' hot air intake, too. But, that just shows Mazda doesn't make the world's best airboxes - not only are they a pain to service, but they are restrictive.

Dale

Whizbang

i should invest and do a dyno comparison but when i run the cold air, have the tubing extend out of the car 5ft

DamonB

The stock FD airbox is gorgeous. A nice, large plenum type enclosure with a lot of filter area in it that draws cold air from the nose inlet. The restriction in stock form is not the airbox, it's the thin section crossover tube that extends from the airbox to the intercooler duct (the crossover tube is built that way to cut down on intake noise). Once that restriction is removed (by adding AdamC's intake mod for instance) the stock airbox has all the cold inlet air it needs and makes as much power as aftermarket intakes, but without the strange noises (though it is a little louder than stock).

adam c

iTrader: (2)

Yep ^.

The restriction is the way the air has to get into the airbox: Thru the crossover tube, then thru a narrow "bent joint" between the crossover tube, and the airbox. The airbox itself is really nice. It has a big filter, and big outlets.

I think it's pretty amazing that a stock FD makes as much HP as it does with the restrictive tubing to the airbox. Modifying the stock box will give you a BETTER intake than any of the aftermarket cold air intakes!!!

Narfle

iTrader: (16)

Adam's CBI is probably the best modification I have made to the car in terms of performance and pleasure. Ricers cant see it when you pop your hood, either. OMG I can hear the stock BOV!

Kento

While working with the stock airbox (when I had it) was more work than simply undoing a couple of hose clamps on aftermarket filters stuck on the end of some intake tubing, I didn't feel it was bad enough that I absolutely hated working on it (it paled in comparison to replacing the stock fuel filter, for instance...and even that, once you get the procedure down, is bearable). The only thing I did was replace the stock constant pressure clamps with hose clamps to make removal/installation of the intake piping easier. Everything else seemed pretty easy to work with; I never used the bolts that attached the box to the body, since this was with a Greddy SMIC, which butted up against the stock airbox. Now that I have a carbon M2 airbox, it's even easier.
This goes right back to what I stated about people not caring about extra horsepower that's easily obtained (and this isn't meant as a stab at you, Dale). No, it's not 50hp, and in many cases, it's probably stretching to obtain 10hp. But it's easy additional power, as long as you have the option. Granted, if you have a massive V-mount or whatever IC that doesn't allow any room for any aftermarket airbox or enclosure of any sort for the intake, then I could see prioritizing, and not going through the trouble of fabricating something...at least until you get the IC installation sorted (but again, that's my opinion. Personally, I would rather have the coolest intake temps possible for safety's sake when dealing with a forced induction engine, regardless of IC size).

poss

iTrader: (5)

In addition, responsiveness should also be at least slightly increased with a cold air intake.

carbon man

If you make or fit a cold air box and you don't get a gain then you have done something wrong.

I have been designing air boxes for over 25 years,
I had an engine dyno which I used to try to develop a formula for air box size and shape. I was also interested in intake trumpet shapes
I first started using carbon fibre to try to produce better air boxes and that has turned into a business of its own that has been running for over 17 years.
I started to learn about data aquasition to design better air boxes and I have in turn worked as a data engineer for motorsport teams including Mazda Australia and still do work as a data engineer on a teams. I have done data on circuit cars, drag cars, rally cars, motorcyles and boats.

If you can't afford to do the job properly and what you have does what you need it to then no problem, I know a lot of race car that have it wrong but are still competative, I can only emagine how good they could be if they got it right.
I do get upset when I open magazines and see photos of cars that have it all wrong and then people copy them because they don't know any better.

moehler

iTrader: (12)

I have run both with my old set-up (14 psi on the twins). An M2 ceramic painted aluminum box and apexi intakes. I notice zero difference in temps or performance when I switched from the apexi to the M2. In fact it felt as though I lost hp with the more restrictive CAI box.

The argument of a hot night vs cold night is sort of silly. Any car feels better on a cold night, regardless of what intake you use. The question is, how much does a cold air intake lower ambient temps by the time the air reaches the engine. Once everything under the hood is heat soaked (including the CAI box), it doesn't really matter where the air is coming from.

That being said, I agree that a cold air intake in theory is better, but it doesn't seem to make enough of a difference to really matter.

The stock box is nicely designed, but it can't with with most aftermarket intercoolers... I'd take a large IC over a CAI any day.

axr6

Interesting subject.

I think that back in '94 I may have pioneered the fresh air intake by removing the foam between the radiator and the chassis. Build a thermal wall to divide my open intakes filters from the rest of the engine bay and the car run very strong with that setup.

Now, I have the M2 aluminum intake box in my car. I am not all that happy with the size of the intake opening down below. Since I have a C-West sleek headlight and a single touring oil cooler, looks like that I will be able to add a 90 elbow to the side of the M2 box and run ram-air through a 3" flex hose right from the '99 speck bumper intake on the passenger side. This, in addition to the standard intake opening. Probably will patch that opening on the M2 box to prevent the leaking out of the rammed air. Just looking at it from the engine bay today, it should work and should be plenty enough cold air supply.

Albert

'87 turbo II

iTrader: (1)

WTF is a hot air intake?

carbon man

for a comparison a stock RX7 we measured in both street and track work an average intake tempreture at the throttle of 110 degrees C with a dyno measured rear wheel HP 230hp and then the same car fitted with the RX7-SP air box and ducting, the SP intercooler and ducting and carbon turbo hoses we did the same track and street test and we averaged 55 degrees C and the dyno rear wheel HP was 320hp.

in brief 110°c (230°F) = 230 hp
and 55°c (131°F) = 320 hp

If you get cold air and you don't need as large a IC to get the same air temp,
also the colder the air goes into the turbo the more air comes out.
caution; bigger the IC and plubing volume the more turbo lag you may produce, (having a ball bearing turbo may reduce some of this lag)
Non turbo cars cold air boxes make more power if there done properly every time.
Turbo cars if you get colder air you will make more power without doing any changes
but if you have to increase boost or install larger ICs because you didn't get cold air seems to be wrong to me.

Ian.

Marshall

I'm in this boat, but it really depends on the car.

Go here:

http://www.stealth316.com/2-turbotemp.htm

Take a 100F deg day with 2 cars with decent turbos, and ICs:

Car 1 (Cold Air, Good IC), Car 2 (Hot Air, Good IC)
100F inlet temp, 150F inlet temp
137F post IC, 151F post IC

Take a 50 deg day (same cars):
84F post IC, 97F post IC

Bottom line, with a good IC (say 80% efficient with a 1psi drop at 15psi) and semi efficient turbo, a 50 degree decrease in air filter intake temp is worth ~13 degrees post IC. You're talkin MAYBE 5 hp on a 400hp car.

As some have already mentioned, *most* of the "cold night" gains come from allowing the intercooler to work better.

Now, when you have turbos working way beyond their efficiency range (stock ones) running through a shitty IC (stock, ebay), every little bit helps.

Play with the numbers to see if its worth it for you.

On a side note, inlet temp reduction with meth/water is huge!

My .02

dubulup

This is a little hard to swallow...100hp (at the same boost level) simply by changing the intake, hard pipes, and IC

dubulup

spray before the filter?

carbon man

facts are facts, we achieved a less restrictive intake and a cooler intake charge.

If you get colder air at a higher pressure to the turbo you will get a bigger out put for the same turbo.

Efficent IC ducting will make intercoolers work better. The standard FD took its air intake to the airbox from the IC ducting, reducing the air pressure infront of the IC and with the high under bonnet pressure the air dose not want to pass through the IC easly.

Basic, meassure the pressure (vacuum) and tempreture at the inlet of your turbo and meassure same before the IC and then again at your throttle body. Do your changes and do the same meassurements, try as many different combinations as you can, try to get the most efficent. I have, I know the RX7-SP worked because I did the development, I collected the data, I made the parts. Proof is it works.

Ian.

adam c

iTrader: (2)

It won't be at the same boost level. By opening up the cold air intake, and adding an efficient intercooler, the car will easily boost 2-3 psi more than stock. That being said, I still don't see where you get 90 additional HP without removing some restriction from the exhaust. If you did remove some exhaust restriciton, the car would boost another 1 psi.

In addition, I don't see how you can get 320 HP on a stock ECU, unless your ECU is much different than the ones we got in the USA. A stock ECU won't support (for very long) what you would need to reach 320 hp.

Marshall

...err meant to say "throttle body/intake port inlet temp reduction is huge"

carbon man

Yes sorry I omited to say the SP kit also had a stainless steel exhaust system that was less restrictive.

The HP figures I quoted are what was seen on the dyno Mazda Australia tested on (not my dyno) and I don't know what calibration factors they used, but the comparison was the same dyno under the same conditions so I was told. fare test, figures don't realy matter for the test just the gain. I was not there for the dyno tests, Mazda Australia wanted to verify the development I was doing.

It dosn't matter if you don't believe me, what I do works for me, most of the race cars I build win races,

Ian.

KevinK2

Not just the crossover. I measured neg pressure at the box top, in stock form had about -1 psi at stock boost, high rpm. Then put K&N filter in box, about same drop. Then removed crossover, not much gain. Finally ran briefly no filter, still near 1 psi drop into box.

The inlet elbo was most restricting. The Adam mod and RB (IC defeating ) duct both eliminate this restriction.

KevinK2

What were boost level(s) for 230 and 320 runs?

carbon man

I was told they were the same, I belive they were 1.1 bar.

In Australia in the last couple of years the production class racing running under Nations Cup were permitted to run RX7-SP air boxes and plumbing in ntheir FD's but had to retain the standard turbos and IC and there was enough of a gain in just the cold air intake to make it worth the change.

Ian.

adam c

iTrader: (2)

I don't doubt that you have a successful race car. However, your explanation made no sense, and still doesn't add up.

First of all, a stock RX7 (of any 3rd gen) does not boost 1.1 bar. Your car may have boosted 1.1 bar after the modifications. That would account for the 320 rwhp figure. Any properly modified RX7 boosting 1.1 bar should make better than 320 rwhp. In addition, you simply cannot boost 1.1 bar on a stock ECU. Therefore, your car must have had a modified fuel computer. I wonder what else they didn't tell you about what they did to the car??

What exactly do you do with this race team? Make carbon fiber panels?? It doesn't sound like you worked on the car.

DaiOni

The race SP made around (240kw~) 320hp at the flywheel - not at the wheels. The showroom version of the car was advertised at (204kw) 273hp.