One of the things that always bothers me about CAI (both Injen and AEM) is that they use polished steel or aluminum tubing.
Now, I believe they give gains and add a few horsepower, and I also understand why they use steel or aluminum (to "resonate" the air better for higher flow).

The problem, as I see it, is that aluminum or steel are BETTER heat conductors than plastic (which is what the stock intake is made out of). That means they get hotter faster and take a little away from the benefits of a true CAI right? I mean have you ever tried to touch the polished part of a CAI after your engine has been running for a while? You can't! This is not true for the stock intake.

So are any of these systems (Injen or AEM) insulated in any way? I heard the Injen comes with a heat shield which doesn't look like it does much.

Thinking about this issue, I came across these insulation pieces for CAIs http://www.thermotec.com/products/full/11600/11600.html

anyone ever try them? I cant imagine it hurts, other than taking away the cool look of a polished intake.

It make me wonder why CAI manufacturers don't design intakes with low heat conducting piping. Just my 0.02

RaymanZ

 

I have thought about this too. This is what I have found out. When at speed, the air is traveling very fast through the intake. If you have ever put your hand in front of the intake and moved the throttle body you will feel the massive suction the engine creates. Because the air is moving so fast it doesn't really pick up the heat that is absorbed by the intake pipe. I may change a little but, I don't think in would make much of a difference. What does make a difference is the temp of the air the intake sucks up. If you just get a cone filter with no effective heat sheild, you will just be sucking hot air.

 

Um, I beleive the air does pick up much of that heat. Just the same as the air blowing over your radiator. Faster air just draws more heat away.... but less per molecule.

 

 

Sorry, that link I posted was incorrect,, should be:

http://www.thermotec.com/products/full/14500/14500.html

 

Sorry, that link I posted was incorrect,, should be:

http://www.thermotec.com/products/full/14500/14500.html

RaymanZ

 

Being the previous owner of a 2001 Mustang Cobra, I think I have a different take on things around here. The Nissan 350Z crowd is SIGNIFICANTLY less performance minded than the Cobra crowd. There are much fewer complains of things like "I don't like how you can see the muffler in the Borla exhaust" etc. etc. and more talk of gaining raw power. For better or worse, Z owners are significantly more image-conscious. Actually, I would say that this tends to be truer of imports than domestics across the board.

Products like theIce-Man intake system would never do [relatively] well in the 350Z scene. This is an intake that's plastic and ugly, but gets better results. If this were on the market for us, I'd hedge my bets on the comparitively inefficient metallic AEM and Injen kits consistantly outselling it SIMPLY BECAUSE OF ITS LACK OF BLING FACTOR.

*shrug*, I ain't trying to hate on my fellow Z brothers, it's all a matter of personal taste. Whatever floats ur boat

 

I agree with you 100%. That is why I haven't got a CAI, still waiting for the perfect one, how shinny it is does not factor in to my desision. What year Cobra did you have? My friend (CMJ) traded his 99 Cobra in for a 350Z.

 

You said you belive that air does pick up much of the heat, about how much? If it is allot then wouldn't the performance go down? If there are no performance gains from CAI why do they sell them and why are people buying them?

 

I personally believe that there are indeed performance gains for the current CAIs out there. I just feel that they are far from optimal because of the air partially reabsorbing the heat from the metal tubing.


RaymanZ

 

Most if not all CAIs draw in air close to the ground. We all know that hot air rises, and cool air sinks to the ground. Temperatures under the hood often exceed 150 degrees F. A term often used to describe this is heat soak . You may think that on a hot day the air just above the asphalt may be equal to or greater than the air in the engine compartment ... generally, this is untrue. (It's really damn hot in your engine, trust me). Most CAIs show gains of 5-10 hp (some less, some more, like real restrictive Honda intakes). Besides getting cooler air, CAIs also straightens out the airflow, thus increasing it. More air to your engine = more power. Now back to the original discussion ... yes the metal tubing heats up quite a bit (it is mostly for show), but that still doesnt heat the air nearly as much as a normal intake that draws in hot and stagnant air in the engine compartment would. There is a tradeoff though ... CAIs risk hydrolocking your engine ... if you drive through a large enough puddle, the close-to-the-ground intake may suck up water as damage your engine. The question is is that extra couple of HP is worth the risk? That's up to you. Hope this helped ...

 

 

Ever heard of anyone's car more than stalling due to a puddle? And someone who isn't a friend of some guy's aunt who's neighbor who this happened to and then posted it online? Anyone? *looks around*

Didn't think so.

Either way, a non-metallic intake would still bring in significantly cooler air.

 

AEM intakes have a zirconia powder coat finish on them which is supposed to help prevent heat soak...I dont know how much cooler it makes them degrees wise, but it does keep them cooler than a non coated aluminum tube used as an intake.

As far as hydro locking your motor due to a cold air intake....you would have to submerge 70+% of your filter in water to get enough vacuum to actually hydrolock and damage your motor.(we are talking a big puddle folks). I know it sounds crazy but it DOES happen. I have personally replaced multiple heads, rods, and pistons due to hydrolock from cai's.

Hope this helps out, Mark.

 

Well, it all depends...

The thing about less heat per molecule, forget it. The average temperature of the air charge AFTER it has gone thru the piping is what matters. I agree the temp difference should be minimal, but I also think that these systems should and can be easily improved. I wouldnt recomend using a plastic pipe. I would recomend using some kind of insulation. One aspect not mentioned about the steel piping is that its easier to mold to the engine compartment. Using plastic, it would be moire likely that you would have to use "elbows" or tie ins to achieve the different angles, thus, in the end, decresing air flow due to pressure changes. Ill write more later, Im at work....

 

If some of you are concerned with the heat from the polished intake pipe, you can get thermal resistant paint and spray the inside of the pipe. They do come in a spray can. Usually the DIY'er spay inside and out, but...I hear that spraying inside and out keeps the pipe from absorbing much heat at all. They say that you can touch the intake pipe even after the engine bay is completely warmed up.

Also, amount of heat transfer is proprotionate to the difference in temperature (~100*F maybe?), thermal conductivity of the transfer medium (intake pipe), and surface area of the transfer medium. Essentially, using the thermal resistant paint would reduce the thermal conductivity of the medium. I don't know how it would affect airflow though...BUT reducing intake temperature is always a good thing right?

 

I think that metal Vs. Plastic is a stupid argument, a guy who recently closed his site (i know it hurts my point not to have the data but it does hold tru) calculated that:
on a 24 inch long 3 inch OD pipe
Fixed to a 2.5L 164 HP 156 TQ motor at max VE
the air was in the tube roughly .023 seconds

But also consider this, all of the air for each cylinder goes through the CAI very fast, once it hits the IM (heat transfer through heads anyone MUCH hotter) it slows and spends CONSIDERABLY more time heating up in the IM, through the TB, into the IM, into each runner, past the heat soaked heads and valves....

A company I know makes Pheloic (heat resistant plastic, reduces IM heating dramatically) spacers for IM's on mazda and honda motors and have seen nice gains.

Ben

 

I'm assuming that 2.5L engine was the KL03 in 2nd gen. Mazda MX-6's and Ford Probe GT's. Actually I know it's from that car because I used to own an MX-6 LS ... a cone filter strapped to the IM dynoed generally with a 2-5 hp LOSS while a custom CAI, or hotshot intake, would dyno a 5-8 whp gain. These engine bays were small and produced lots of heat, thus the heat soak would decrease power. The cooler, more dense air from the CAI worked quite nicely, but I would have disagree about the Phenolic, or pheno spacers seeing nice gains ... they actually keep the IM cool, but tend to only prevent losses in power by minimizing heat soak more than adding a few extra ponies. Not sure about the Honda engines tho ...

 

No disrespect or harm intended, but I think CAI systems for the Z are worthless. I just cant believe claims to power gains.

The stock system is a great setup and it is not restrictive at all.
In fact it is obvious to see that Nissan designed it as a CAI anyway.

First, look at the placement of the intake! At speed the air will rush right up and into that intake channel.

Second, reach inside the channel, and feel the amount of space on the filter that is exposed to open air. All of it! I am not surprised by the dyno posts that show CAIs losing power!

Third, other "techies" On this forum have noted that even under moderate throttle there is still positive pressure in the airbox at speed! You cant say that about an open filter element like those on CAIs

Then look at the real smart guys on this forum like Chebosto. He is souping up his car, but his intake is staying stock.
I am no engineer, but between Those with profound mechanical experience, and my own observations, I will never get a CAI for the Z. We are all better off, just finding a way to get better flow to the stock intake, ie. shielding it from radiator heat.

I think so many take the plunge and buy the CAI for their Zs because on other cars, they really do make a difference.
Not on the Z though

I am Joust75 and thats my perspective!

 

There is no KL03 only KLDE
Well most people do not dyno with a cold motor/IM, thus 99.9% of dyno's were done with a warm motor thus a hot IM, with the addition of Phenos now the motor is warm but the IM is cool and gains were seen. Technically you are correct, not power was "added" but i would equate it to a set of pully's or a FW in that is still increases performance and is a measurable amount.

Do you have links of any lind or proof of positive pressure in the stock IM, cause simply looking at the intake and thinking "gee that LOOKS like air will run right into the front of the intake" is not a valid argument. oooooh if aerodynamics were that easy!

I only ask cause I have seen a lot of CAI Vs. STOCK arguments on here and my home board (www.probetalk.com) but NEVER any solid evidence, LOT's of opinion and guesstimates form smart guys but nothing concrete.
Ben