air intake
 

i have a 88 t11 and i wana get the alium. shroud that gose around it instead of the plastic, we can i get it?

if you mean a cold air box there is no inexpensive or even reasonable place to get one, much easier to make it yourself.

there is only 1 or 2 aftermarket sources for "cold air intake boxes", one costs $400 and is carbon fiber and the other i haven't seen in forever, aside from that the only option is to be creative and make one yourself.


the only question i have to ask is: "why bother?"

there is no cold air flowing anywhere near that area and even the ones i have seen that were done well will barely make it worth the effort.

^That's not entirely true. There are lots of cracks from the hood + lights. There's also that hole where the washer fluid filler neck is. If you take that out then you'll have a decent amount of air that is colder than the surrounding air that's hot from the engine.

dose anyone have one that they wana sell :)

Aluminum is a terrible material to make an intake out of. Make your own out of cardboard for better results. (I wish I was kidding)

http://www.mariahmotorsports.com/
http://corksport.com/

I assume that's because you think that the aluminum will cause massive heat transfer to the intake charge. In actuality, there is very little heat transfer because straight-wall metal doesn't transfer heat very well, and at the typical rotary engine's flow rate of 250-400cfm there is little time for the heat transfer to take place. Aluminum is a very good material because it is cheap, light, corrosion resistant, malleable, weldable, and it is easily fastened with rivets, screws, or bolts. Cardboard is great for making a mock-up of an intake for planning, but it is too moisture sensitive and fragile for permanent use.

I was mostly kidding about the cardboard... however, I DID think aluminum would cause excessive heat soak for intake tubing and air-boxes. Thanks for inserting your knowledge into me. My plan was to fiberglass/CF a box for my car or vacuum form one out of ABS/Acrylic. I'm assuming those would heat-soak less than aluminum. And in an NA.. every ounce of improvement is needed.

Hey aviator... Having thought about it some more....I have a question... Why, if aluminum doesn't heat soak very well, are most heat sinks made from arrays of sraight-walled aluminum? The purpose of a heat-sink is to heat-soak. Seems like the same think we are trying to avoid...

Heat sinks are NOT made to heatsoak, they are designed to transfer heat from a concentrated area (the CPU) to a larger surface (hence, the fins) where it can be disbursed, usually by forced air (i.e., a fan).

Aluminum dissapates heat very quickly, steel and cast iron tend to hold, I would assume that a plexiglass or acrylic would be the best way to block off the filter assuming that it would hold upto the heat in the engine bay.

They are designed to ABSORB heat as fast as possible so the fan/ambient air can pull it off.

Yes... dissipates it very quickly.. which means that it would dissipate it right into your air-stream.

I'm not saying I'm right.. I'm just saying, the logic of heatsinks makes me think aluminum is a bad material to use.

well thanks guys this is great so it is worth gettin one.

Gonna have to agree with micaheli... the way you explained heat sinks make this idea sound even worse.

"They are designed to transfer heat from a concentrated area (the engine) to a larger surface (the aluminum box) where it can be disbursed, usually by forced air (i.e., the intake air) resulting in a hotter intake air."

^ My aluminum intake piping gets very warm and sometimes hot to the touch. Im pretty sure its effecting the intake temps. Especially the intake manifolds as well.

Though not asthetically pleasing, would heatwrapping the intake pipe be a good idea?

Both of you are missing (or ignoring) a very important factor about heatsinks though.
Heatsinks are in direct contact with a very hot heatsource- in fact, extra care is taken to maximize this contact (thermal paste/lapping the CPU).
The heatsink is then designed to maximize the surface area available to force cooling air through it.

I did not make the analogy that an aluminum heatsink was comparable to an intake shroud/box, I was simply commenting on micaheli's statement about heatsinks in general.

Evil Aviator was absolutely correct about the general nature of heat transfer as it relates to sheet metal -of any composition- basically, it's not a factor.

@Tsuka- where did you get the idea that heatsoak- to whatever degree that it IS occurring- is coming from the attachment of the intake box to the engine?
My understanding is that air, heated by passage through the radiator, is the culprit.

Lots of auto makers are using plastic to make their intake manifolds now, this has gotta tell you somethin. Even my Slk, which is supercharged, has a partially plastic intake manifold.



"Plastics Make It Possible" I know you've seen tyhe commercial.

True enough, but the temperature differential between both sides of the aluminum CAUSES heat transfer in metals. It doesn't matter how hot the heatsource is, it doesn't alter the properties of the material. The aluminum is in direct contact with the hot-hot-air, and the moving air inside the intake would be acting EXACTLY like a heatsink. Carrying off the heated air. The ONLY thing cooling down the intake piping/cold air box would be the air moving through it. Heatsinks are exactly that.

We're all friends here. :) no worries
Sheet metal, bumpy metal, cast metal, it doesn't matter.. the only difference is the efficiency that it dissipates heat due to the amount of surface area created by the shape of the metal. The fact is that it DOES transfer heat and that affects intake temperatures and air density. Making cardboard (sarcastically, but accurately) a better insulator than aluminum... although definately not a practical material. Something like corrugated plastic would be great, but highly oversized.

Again... I might be wrong.. but I have yet to see real data indicating this. So, feel free to prove me wrong. I live for it. :) Perhaps we need to take this offline and let this guy have his thread back too.

OP: sorry for the hijack!

The heat soak isn't significant, but I do not see anything wrong with using other material.

When I was a very young boy, many toys were made out of metal. Now toys are mostly made out of plastic. It must be because of heat soak. ;)

I can't teach you 4 years of thermodynamics in one internet thread. I would if it were possible, but I'm afraid that you are going to need to either take my word for it, take some college courses on your own, or just keep your own incorrect yet harmless opinion on the subject.

BTW, what are you going to do about the metal upper intake manifold, lower intake manifold, and throttle body that are all made out of ... METAL :bigeyes: ... and would obviously "heat soak" much more than a little intake box? :)

I see your point, but I'm pretty sure you just called an SLK a toy. :)


Oh.... playing the "I took this in college" card eh? Thats cool. I took psychology for 4 years too... doesn't make me an expert, but I'm pretty sure you are what they call in "the biz" a "dick". Hehe. okay.. I don't really think that.. but it sounded funny in my head.

I painted them black... so they LOOK cool. :) And honestly, I'm not looking to make a HUGE difference with the material I make the box out of.. or the intake piping... but, I have an NA right now, every teeny bit of power/efficiency I can muster up counts. Any NA owner will agree with that I think.

Upon "finding" some more information, I admit defeat! clokker sent me this: http://www.specjm.com/toolbox/engine...n/81-1-ISD.pdf

Great information about exactly what Evil Aviator was talking about.... Heat soak would occur, but in such small amounts it'd be virtually unmeasurable. Good stuff to know. but I'll probably still use fiberglass/CF due to ease of shaping and availability (I have a bunch somewhere).

Good job EA, looks like your 4 years of classes paid off. You stinking jerk. :) j/k, we'll all friends here.

To be more accurate Micah, I don't believe that data I sent you addresses the amount of potential heatsoak- which is at least partially dependent on the delta T between ambient and intake air- so much as the difference that the duct material would make.
A small point to be sure, but it can't be denied that any intake will suffer from some degree of temp increase- it's just that the material the intake is made from isn't going to be very significant.

Once reasonable steps have been taken to introduce the coolest possible air, I think the next most beneficial move would be to concentrate on engine bay air extraction.
In other words...more bang for the buck trying to lower engine bay temps rather than insulating against them.
Nip the problem in the bud as it were.

Right, right that data you sent me made me realize I should be focused more on the design of the air-box rather than the material its made of.

That was a multi-level remark. Congratulations on picking up on the most sophisticated point.

BTW, I was actually considering a SLK myself. It's the only new car that I like. However, I decided to drive my truck for a few more years and wait and see if a new RX-7 hits the market.

No, it's the "I'm not a professor, and I can't see how it is possible to explain the concept in a single internet post" card.

Black absorbs heat! :rlaugh:

Sorry, I couldn't resist.

I disagree with that plan. I don't care much about engine bay temps as long as components are not getting ruined by the heat. My focus would be on pressure, which is where most homemade CAI's fail miserably.

so this box is a bad idea? theres alot of back and forth going on.

Yeah, sorry about that... cold air box = good idea.

My advice was predicated on the idea that intake temp was still the primary concern- i.e., it's easier to maintain a lower DeltaT intake variation by lowing the engine bay ambient than by trying to insulate.
Since the average CAI makes no pretense of actually pressurizing the charge that seemed outside the scope of the discussion.

Trying ot get enough pressure from a CAI to actually be worth speaking about will be pretty difficult. Trying to find a location for a scoop of some sort would be one problem, then building the scoop to allow the airflow to velocitize and smoothly enter the intake tubing would be another issue.

Personally, wrapping CAI piping or box with ceramic insulation would be easier to me. I suppose to lower the engine bay temps would be to cut / add vents in the hood.


Evil Aviator, I wouldn't say homemade CAI fail at getting pressure since most of them, including mine, are not designed to get pressure. They are designed to duct outside air into the engine. Now if you were desinging a CAI for pressure and you got nothing, then I would say it failed.

Certainly wrapping insulation is easier and I'd like to see what effect it might have.
I have no way of measuring intake temps but I'd guess the difference would be very small.

Venting the hood would not only be at least as effective lowing the intake temps but also have the added benefit of lowering the coolant temps, assuming that the venting was designed to extract rad air outflow.
Hence my "more bang for the buck" statement.

If you buy the stuff with the reflective foil and ceramic insulation, depending on how fast the air is moving in the intake piping, im sure there would be a pretty good difference. My intake piping gets pretty damn hot at times.

I would personally like to see a vent system that actually did substaintially lower the engine bay temps and coolant temps. Getting the hoods with the whole center as vents, probubly would be the only venting system that would be worth talking about.

I'm sure it does but that's the whole point of the link I sent Micah...it's basically irrelevant.
In Micah's link look at page 5.
The temp difference in that test between plain sheetmetal and 1" thick insulated material was 4°F...over a 100 FOOT duct length.

Now, given the duct's poor heat transfer capability, the high airflow volume AND the short duct length what do you think the difference might be...a fraction of a degree?

By all means, go ahead and wrap your ducts...it certainly can't hurt but I'd be skeptical of any claims that it helps much.

You make a good point. 4 degrees, even if that was per foot, would make almost no noticable difference in power.

Well that's exactly the problem. Everybody is so gung ho about lowering temperatures that they completely miss the point that pressure also has an effect on density. I am not talking about ram air, but rather what you guys would call a "restriction".

See above.

4degF = about 1/2% hp difference

I know pressure effects density and also know that restriction can lower it. I do agree that some so called CAI I have seen seem to be just as restrictive if not more then the stock intake system. On that note I do agree with you.

First of all, saying ALL CAIs or AAIs are restrictive in your terms is incorrect. Yes ANY intake will have some restriction but the point that you seem to be trying to make is that they are usless because they are so "restrictive". This is one reason why I used 3.5" ID piping insteaf of 2.5" or smaller like most people do.

Like I said, nothing very noticable.

.

Forget all that aluminum garbage, some of those ceramic tiles of the space shuttle would be perfect. YaY

You mean the ones that fall off and need replacing every flight?
Yeah, those would be perfect.

I'm sorry a little off topic. But it's so much fun to watch you guys all but rip each other's limbs off, but still be so polite it qualifies as nice.

yea they do blow off, kinda reminds me of somethin. O yeah, apex seals.

I can prove that you did in fact design yours for pressure, and this also follows my main point that people are so wrapped up in "cold" air that they totally forget about pressure.

Given that: The stock intake system already ducts outside air into the engine.
Your goal was: Duct outside air into the engine? That doesn't make any sense because it did that to start with.

Therefore, your actual goal was: Design a new intake system that ducts in the EXACT same temperature air as before, but with less pressure loss.

So, using your own reasoning, if you designed a CAI for colder temperature, and you got the exact same temperature as before, what have you hopefully gained?.... That's right, pressure.

Therefore, I say back to you, if you designed the CAI for pressure, and you got nothing, then I would say it failed. The dyno will prove this, because if the temperature remains constant, there will be absolutely no power gain if there is no gain in pressure.

headlight vent FTW

I see what you are talking about now. I even mentioned the "positive pressure" helping in my old thread. For some reason I was still thinking "ram air".

Yes, but the air box is more restrictive then what I could have. Im sure my filter isn't helping and if I replace that with a K&N im sure it would flow better then the stock box. Anyways, my stock box was out of there when I first got the car 6 years ago, just starting out, following friends and what they said to do, later I learned, and when I had the time, years later, I built what I built.

I do 100% agree.

Now removing the stock air box and building a CAI that is lower in restriction, is already a pressure increase, but thats the issue, I suppose you could say, everyone is building their CAI for increase in pressure because restriction lowers it and thats what people try to minimize is the restriction. Although, like you have said in the past, some CAI are so convoluded, they may not have gained anything at all.

Yes, that's exactly my point. Ironic, isn't it? :)


Now there is also the issue of momentum, but I won't go into that. ;)

Ya sorry, I didn't think of it till now after remembering what I read about a couple months ago. Kinda clicked, felt stupid after.:uhh:

Oh come on now, lets :) I first asked if you were talking about velocity but thats only 1 product of momentum.

so lets talk :)