Cold-air intake for track days

Discussions relating to Turbochargers, Superchargers, Induction, Engine Mods, Exhaust Mods, and other items specifically to make your MX5 or Roadster put out more power.

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WideOpenThrottle
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Cold-air intake for track days

Post by WideOpenThrottle » Fri May 17, 2013 2:53 pm

Will have this ready as a unit to drop in [with a different pod filter] at the track after i remove the light assembly there just incase its illegal for the road.

Just need to locate some bolt holes and source some rubber edging as it has sharp edges.
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Cold air intake for track days 001.JPG
Cold air intake for track days 003.JPG
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Post by warrior » Fri May 17, 2013 4:33 pm

Very smart, just don't run it in the rain, but very smart
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Post by WideOpenThrottle » Fri May 17, 2013 5:52 pm

Thanks-I try not to do track days in the rain...there's enough to concentrate on when its dry! :D
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Post by Timmo » Mon May 20, 2013 12:38 pm

hmmm I would think that the extra drag from not having the headlight cover there would more than negate any advantages of a cold air intake.

It would be better to get an old headlight cover and fashion a vent into it for use with your trackday intake so you get the best of both worlds.
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Post by WideOpenThrottle » Mon May 20, 2013 1:33 pm

I had thought of that too but seeing as my turbo will be drawing in air so fast that it will swallow up any turbulence! :lol:

I have seen a few race cars at track days doing this so turbulence is probably negligable?
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Post by Furai » Mon May 20, 2013 4:33 pm

I would imagine the drag would only lose you a couple KMs at 160+? Drag doesnt really have much effect until about 80K isnt it?

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Post by WideOpenThrottle » Mon May 20, 2013 5:24 pm

Should't be any drag if this picture is to believed!
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Post by 2low2c » Mon May 20, 2013 9:32 pm

i have 3 things to point out here
1 on a turbo car if your intercooler is sized corectly this will make no differcene at all as the air leaving the turbo is alot hotter than the intake i run my filter directly on the turbo with no effect on performance from when i had it boxed.
2 if you wre to run it like that and it did force air in you could find it may run lean .
3 if your drawing is corect it would be in low presure zone in which case you could starve the turbo of air.
just my thoughts

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Post by Timmo » Mon May 20, 2013 9:38 pm

Yeah but you are comparing a smooth surface, where flow can remain fairly laminar, to an abrupt hole where air is smacking a surface perpendicular to its flow getting into all sorts of trouble since there are no easy escape paths for it.

Remember that the influence of drag is squared with speed so a couple of HP increase via the intake is going to be negated at fairly low speeds.

I just think, with a bit more work you can get the best of both worlds :)

(that's a picture of a FC RX7 too innit?)
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Post by siren676 » Mon May 20, 2013 9:40 pm

Cold air intakes dont really make any noticeable difference to power levels


http://www.youtube.com/watch?v=gCi2yo4UqPI
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Post by WideOpenThrottle » Tue May 21, 2013 8:24 am

Read this...http://auto.howstuffworks.com/why-insta ... intake.htm

I am not after more HP by doing this just after a cooler place to obtain air as my filter is normally mounted behind the top of the radiator and this position is where under hood temps are the highest and probably with slow moving air.

Why do so many people heat shield their filters if obtaining cold air is not relevant?..i for one cant & dont want to put my filter in a heat shield that is still inside a hot engine compartment.

I have done tests on my car which shows it doesnt hiccup occaisionally at motorway speeds by
[1]...removing the passenger headlight cover.
OR
[2]...placing the air filter down by the bottom of the radiator.

Ever noticed that during winter or even when its raining your car seems to run better?

Will take my car to the local wind tunnel today and test the air flow over the head-light covers.
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Post by Furai » Tue May 21, 2013 8:49 am

Maybe for my NA car winter is better but the intercooler does that for turbo doesn't it?

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Post by 2low2c » Tue May 21, 2013 9:06 am

turbo cars run better in colder tempretuers because the intercooler is colder not the incoming air.

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Post by WideOpenThrottle » Tue May 21, 2013 9:20 am

2low2c wrote:i have 3 things to point out here
1 on a turbo car if your intercooler is sized corectly this will make no differcene at all as the air leaving the turbo is alot hotter than the intake i run my filter directly on the turbo with no effect on performance from when i had it boxed.
2 if you wre to run it like that and it did force air in you could find it may run lean .
3 if your drawing is corect it would be in low presure zone in which case you could starve the turbo of air.
just my thoughts
1..Was your filter when boxed sucking hot air or was it fed cool external air?
2..Its already forced by way of the turbo so i imagine i would have to drive at light-speed to cause this air to drive the turbo faster than what it already spins via the exhaust gasses.
3..The speed of the car causes an increase in air pressure at the front...the remaining sheltered/lower pressure air is still normal surrounding air pressure.
Sheltered spots are not starved of oxygen otherwise every race car that drives in the sheltered lower pressure slipstream of the car in front would suffer engine damage...and they dont!
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Post by WideOpenThrottle » Tue May 21, 2013 9:27 am

2low2c wrote:turbo cars run better in colder tempretuers because the intercooler is colder not the incoming air.
??? if i source the air from outside the engine bay then this incoming air is colder!..and this applies to NA and FI.

Once the air is moving through the intake system i am of the opinion that cooler air at the start is better then trying to cool engine compartment air.

We might be splitting hairs but if it works for me thats whats most important
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Post by Donovan » Tue May 21, 2013 9:34 am

Just to put my two cents in, which actually amounts to very little, since I know very little, but I thought the whole point is to try and get as much air into the manifold as possible and as cold as possible.

Cold air is denser than hot air, so contains more oxygen for the same cubic amount, therefor better cleaner bang?? Much the same as running a car as close to sea level will net more HP than running it up at a high altitude because the oxygen in the air is so thin?

The colder the air you can get into the intake the less the intercooler has to do, so couldn't you either do a smaller intercooler with the coolest place for your intake, or a larger intercooler with a not so great intake point as far as air temp goes, and still get the same result?

As for the low pressure point, would have thought that if the turbo is trying to suck in more air than is actually there, going to run into some problems, but someone with a bigger brain than mine would need to work out the volume of air present at various speeds compared to the volume of air the turbo is sucking in.

Guess another trick to cooling the air temp down, is either a water sprayer on the intercooler, or a water injection system on the intake manifold, you just have to make sure that the injector atomizes the water enough that it helps things, rather than damage.

So, like I said don't know much about it or whether what you have there is good or bad, but just thought I would put my perspective on it.

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Post by marcellarius » Tue May 21, 2013 9:46 am

But compressing the air heats it significantly, hence why an intercooler is necessary. Variation in intake temperature probably has no [significant] effect on temperature at the throttle body.

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Cold-air intake for track days

Post by jif » Tue May 21, 2013 9:46 am

from the manufacturer's perspective, warm air is good - the engine will warm up faster and fuel atomisation is better. Both good for emissions and fuel economy ratings.  And most normal people never wring every last hp out of it ;)

but for max power, yeah cold *dense* air is clearly better.  Experimenting with the intake placement made this really obvious in my case (in front of radiator vs next to engine block)


another 2c...

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Post by WideOpenThrottle » Tue May 21, 2013 10:20 am

Yay! for Donovan & Jif...great minds think alike! :D
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Post by Timmo » Tue May 21, 2013 11:58 am

Don't get me wrong, obtaining cold air is a good idea! But the question is whether adding the cold air intake is a step backwards in terms of overall performance. The options as I see them are:

Non-cold air intake = base HP & base Cd = baseline 'speed'
Cold air intake with headlight cover removed = higher HP but higher Cd = possibly slower
Cold air intake but with more efficient ducting = higher HP and negligible change in Cd = possibly faster.
Ex: 1991 BRG NA6, 1998 White RS, 1997 Wine Merlot M Edition

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Post by WideOpenThrottle » Tue May 21, 2013 1:27 pm

Wind tunnel test complete...see results on new thread :D
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Post by WideOpenThrottle » Tue May 21, 2013 1:52 pm

So now that i have tested the air-flow characteristics it would seem a vented headlight cover will be supplying "positive cold air"with minimal turbulance.
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Post by warrior » Tue May 21, 2013 5:15 pm

are you guys being serious? OF COURSE colder air into an engine produces more power, That is why people run intercoolers.
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Post by warrior » Tue May 21, 2013 5:25 pm

2LOW2C, you are not 100% correct about intercoolers. If the air flowing across an intercooler is say 28c on one day then on a winters day 10c the intake temperature WILL be lower on the 10c day. An intercooler can only produce air at the temperature flowing over it (or close to it). So that is why (even with an intercooler) turbo cars have more power on cooler days.
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Post by WideOpenThrottle » Tue May 21, 2013 5:25 pm

http://www.youtube.com/watch?v=gCi2yo4UqPI

These guys proved it does make a small gain even if they weren't convinced!

But an incremental gain is a "gain".
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