Do After Market Air Intakes REALLY Work?
Jason Lancaster | Aug 20, 2007 | Comments 26
The modern internal combustion engine is, first and foremost, a pump. It pumps in an air/fuel mixture, and it pumps out power, heat, and combustion byproducts. If you want to improve the efficiency of any pump, one method is to remove any restrictions placed on intake or output. When it comes to most engines, that means intake and exhaust. Since we’ve already covered the Tundra Exhaust System, we’ll focus now on the intake system.
First of all, Toyota’s factory air intake system is excellent. It’s a great compromise between the need to move high volumes of air into your engine and the need to keep overall engine noise down. Keep in mind, a modern engine operating at peak efficiency will require nearly 14 times as much air as the amount of fuel it burns (read all about stoichiometric air-fuel mixture). At 65mph, that’s about 32 liters of air per second. Moving 32L of anything in one second requires a powerful pump, and it’s a miracle of modern science and technology that engines do this without making a tremendous sucking sound. How is this accomplished? Engineers use a small baffling chamber called a silencer which is tuned to dramatically reduce the “swoosh” sound that a heavy-breathing engine should be making.
Obviously, the need to reduce intake noise also reduces efficiency. Since the advent of computer modeling, automobile engineers have managed to abate this loss in efficiency quite a bit. In fact, a factory air intake from a vehicle manufactured in the last five years or so is nearly as efficient as the best after market kit — at least in terms of air flow. So why bother with replacing the factory air intake if it’s so good?
1. While it is small, there is an efficiency loss with a factory air intake. The fact is factory intakes are designed to be quiet first and efficient second.
2. If you add any other performance equipment, like an upgraded exhaust, you’ve changed the characteristics of your engine enough to see a respectable gain in terms of performance.
If you add an after market air intake (sometimes referred to as a cold air intake, or CAI) respectable gains usually equal 3 to 5 hp and 5 to 10 lb-ft of torque. However, when you combine this with gains from an upgraded exhaust, you’ll see a total gain that’s greater than the sum of the parts.
Additionally, you’ll experience better fuel economy, and in most cases you’ll enjoy noticeably better throttle response. Remember how we said a Tundra at 65mph breathes about 32L of air per second? That’s at sea level. For every thousand feet of altitude above sea level, your engine requires another .8 L of air — per second. Obviously, if you live at higher altitudes you will see greater performance gains.
After market air intakes improve performance and efficiency because they’re not designed to be quiet. Therefore, adding one will increase engine noise. While most people we know don’t mind the extra “womp” when they mash the throttle, if you’re not interested in making your interior a little louder than an after market air intake is not for you. After market air intakes also can improve performance and efficiency by pulling air from below the vehicle. The concept is that air near the engine compartment is slightly warmer than the rest of the atmosphere, so pulling air as far away from the engine as possible will result in cooler, denser air entering the engine. Obviously, when you’re trying to help your engine get as much air as possible, dense is better.
At this point in time (July 2010), we have yet to see an after market air intake that offers this benefit on the Tundra. All of the kits we’ve seen pull the air from the same location as the factory intake (just above the wheel well). This is a pretty good spot to pull air from, and there’s little risk of ingesting water at this location, so it’s doubtful we’ll see any kits that pull from below the Tundra.
When buying an after market air-intake kit:
- Make sure the kit is offered by a reputable after market manufacturer with a full research and design department. There are many companies on the internet producing air intake kits that have no business doing so. Adding one of these garage designed kits, at best, won’t improve efficiency.
- Consider buying an after market kit made from plastic. Because plastic has a lower heat capacity than metal, it will insulate the incoming air from the heat of the engine compartment better than a metal kit.
- Insist on seeing dyno results before purchasing a kit. Some kits do an excellent job of adding low-end performance, but do so at the expense of top end performance, or vice-versa. Make sure you study the dyno graph to make sure you understand how your engine’s performance is going to change.
- Make sure you understand what type of filter comes with the kit and the maintenance required on that filter. Some kits have dry filters that must be replaced, other kits have a light coating of oil and must be thoroughly cleaned every 25k-50k miles (like this K&N air filter for the Tundra)
- As far as pricing goes, expect to spend $250 to $400 for a decent kit.
Bottom line: The factory Toyota Tundra air intake is fine as-is. However, if you plan to upgrade your truck’s exhaust system, if you add a performance modifying computer chip, or if you’re willing to trade some engine noise for a slight improvement in gas mileage, buying an after market air intake kit makes sense. If you live at higher altitudes, you should consider adding an after market air intake to your Tundra regardless. While there will be more noise from the engine, you’ll also feel more power, better throttle response, and improved fuel efficiency.
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Filed Under: Toyota Tundra Accessories
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Don’t fall for this folks. If you do want/ need a CAI, DON’T buy a Volant. The product is Junk and the Customer Service is worse.
Myersob,
I’m not sure if you’ve read the recommendation, but we don’t suggest any particular brand here, or even that everyone buy an intake.
i bought a trd cold air intake to go with my flowmaster exhaust and i felt a small increase in horsepower from the cold air intake but no in cab suction noise. lil dissappointed but my truck is faster
[…] Re: First Time Tundra Owner – Clueless About CAI’s There is a lot of threads about this but you should read the attached link. By far seems to be the most informative on if a CAI works or not and which ones are good. Read for yourself and decide what you think. I just installed an AFE in my truck. So far its ok I guess but only had it a few days and they say to give the computer some time to adapt. Like Gorilla says though, expect most of your power to come from the top end. Then ask yourself if 10 HP is worth about $300. The more you read the easier it will be for you to make a decision whether or not you want to spend the cash for the HP and the sound. Some love it, some dont. It is personal taste more than anything I think. Do Air Intake Kits Work? | Tundra Headquarters […]
I recommend you DONT BUY TRD CAI!!! IT FAILED for me,,,READ THIS,,i have some things to share about the TRD cai as i havent seen much feed back about it. I am compelled to tell my story/oppinion of the TRD cai. I have a 08 tundra dc 5.7 w/35k on it. I had a trd cai installed on purchase and the other day I went out to clean the filter and found leaves and debre on the wrong side of the filter stuck on the screen filter at the top of the air box, bad deal to say the least. Upon further investigation, the seal was fine and in place properly- what happened is the engine side of the lid had warped for some reason(heat) and was bowing out enough to allow leaves ect to directly pass the filter. Typically, you dont have to clean these very often; it appears to have been leaking for over a month. To make matters worse the dealer i bought mine from- mark miller in slc utah will not refund, and will only replace the lid. In additon, they are making me wait 7-10 days(i got rid of the stocker) and their remedy for the problem was to wrap the lid seam with masking tape and send me on my way…pretty shoddy bs in my opinion . john miller was the service guy in charge of my truck this day,,,, i let him know it was shoddy ect but to deft ears, long story short save yourself the aganoy i have gone through and get a AFE or Volant even though both have their ups and downs. I have never read of either one of them failing,,, and i found out the hard way you cant count on TRD cai. I have pics but i dont know how to load them from here, and if you are one of the unlucky owners get rid of it and keep your eye on the inside(engine side) of the lid and watch for this or you will regret it!! O yea and also i never have overheated my truck so cant blame the failure on that!! I am going to contact TRD next cuz in my oppioion they need to recall.
Had my AFE Stage II Lifetime filter and never needs oil for over 2 years with no issue other than the instructions are pretty lame.
Thanks for the feedback on the 08 Tundra in UT. I am in the area and was considering the same CAI. I will do some more research now.
I have a questions with regards to the the phrase “making your interior a little louder than an after market air intake”.
How much is a little? What is the best rule of thumb to combine say the afe intake and the TRD cat back dual system on a 4.7L ?
Ralph – It’s like the difference in engine sound between having your window rolled down and having it rolled up…but that’s with the windows up. Does that make sense? It’s louder, but not unbearably so. You just notice it a lot more. The TRD exhaust system sounds pretty good – louder, but most people say there’s no drone. As for how loud, it’s definitely more noticeable. If you’re really concerned about noise, neither options is a good fit.
Jason,
Thanks for the reply. I actually have the TRD cat back dual exhaust already (came with the ’07 DC I just bought). I was curious to see what “extra” noise would be associated with a CAI install.
Also, I am one of the few with a 4.7L and after test driving a few 5.7L the “get up and go” feels comparable to that (at least to me) with the exhaust system. I was curious as to what the combine hp gain would be with the exhaust + CAI? Is it worth the addition of the CAI (since I think I can live with the noise factor after your explanation) to marry it with my exhaust?
Thanks,
Ralph
Ralph – For sure. I think you’ll find that the two together are better than just one, but there’s no reason not to try one at a time.
Most people like the exhaust because of the additional torque (10 to 20lb-ft), throttle response, and rumble. The air intake usually doesn’t add more than 5-10 hp (and marginal torque), but it DOES benefit gas mileage. Honestly, I would suggest a CAI for the fuel benefit alone. An extra 1-2 mpg can add up to a lot of money over the life of your truck, especially when gas prices start creeping back up.
Jason, which one would you suggest for the 4.7L ? I saw on your cold air intake blog that your pick back in 2007 was the AFE, is that still your pick?
If all are equal with horsepower gain, which is the best for fuel economy?
[…] over at Tundra Headquarters had a helpful reply in his comment section to my question. Do Air Intake Kits Work? | Tundra Headquarters I would still like to know what gain comes from the combination of the TRD exhaust and a CAI? […]
Ralph – The kits are all pretty much the same in terms of HP (at least based on our testing), but the Volant kit (which we tested first) had the best performance. Unfortunately, the quality on the Volant kit wasn’t that great. K&N’s kit is a bit of a joke IMHO – you basically have to put it together before you can install it, and the pipe clamps they supply are cheap and need re-tightening. aFe’s kit has good quality, but some people don’t like the fact it pulls air from both the fender and the engine compartment. Of the three, I like the aFe kit the best, with the Volant being my second choice.
There is one glaring mistake in this article.
If stoich. is 14.7:1, how can increasing air intake increase fuel economy? If you have to keep the same air/fuel ratio, sucking in more air means…
I’ve yet to see an independent, trustworthy, before/after dyno test backing up ANY of the claims of the manufacturers in regards to CAI. Frankly, the manufacturer claims seem outlandish, given that an old school 250HP motor can expect to gain less than 10% in HP output with 50’s technology exhaust, given a free flowing air induction setup.
Air filters are easy…less filtering equals more flow, and more power. Easy to prove on the dyno. “Intake systems” (man I hate that phrase), if they worked, should be equally able to stand on their own.
Mike – The air intake doesn’t impact the efficiency of the engine’s combustion process by giving it more air – it works because your engine breathes with less effort, which means you get more air faster, and that in turn means less time spent accelerating.
I’ve tested a few of these air intakes, and they’ve universally increased fuel economy *provided* the owner doesn’t drive harder…which they often do.
As for your point that manufacturer horsepower claims are outlandish, I wholeheartedly agree. The best dyno runs from all of our tests show 10hp or so, and the worst show no gain. Our average run fell somewhere in the 5-10hp range – nothing that ever came close to 15-20 hp gain promised.
The intakes do work better than a filter alone – we’ve tested this too. How much better? 1-5 hp. Nothing to sneeze at, but does it justify the expense? Unless you factor in the “cool” factor, it probably doesn’t.
The best bang-for-the-buck performance add-ons we’ve ever tested are the TRD supercharger and then the Unichip Tuner. Everything else has come in a distant 3rd (or worse).
[…] above quote came from here. There is some good info here. Read through these and see if this helps. Do Air Intake Kits Work? | Tundra Headquarters aFe Air Intake Toyota Tundra Review with Video Sound Clips | Tundra Headquarters After reading […]
i bought a G force chip and got less economy and performance (WAY LESS)PLEASE GIVE ME SOME SUGGESTIONS ON ECONOMY PRODUCTS.
larry – my best suggestion is to avoid products that sound too good to be true. G-Force promises that their “chip” can work wonders for a grand total of $50 (or something like that). Is it *really* a surprise that it didn’t work as advertised?
Jason
I’ve seen a lot of guys on here complaining of of the low-end torque loss. Is it true? and does that mean slower of the line?
Peter
Peter – Not necessarily. Every torque curve on the air intakes we tested was a bit different, but for the most part none of these intakes had an appreciable effect below 3000 RPM. My opinion is that air intakes can neither help or hurt performance off the line.
jason would you recommend the the dry filter or the oil filter for the afe cold air intake?
I’ve been reading your reviews on these systems and I am convinced that the afe intake is the one I’m going with. Just confused on which filter to get now..I noticed on your review of the afe intake you used the oil filter why?
al – I like the dry filter, mostly because cleaning and re-oiling the filter can be hard to do correctly. If you use too much oil, your MAF sensor gets coated in air cleaner oil, then it doesn’t work anymore.
We probably used the oil filter b.c that was what they sent us. 😉
Jason, I have the stock air box in right now and i put a drop in K and N filter in and also removed the Hipa filter that the stock air box has for gas vapor emissions or whatever its for. Would i still benefit from removing the stock and going with the Volant setup or no. I dont mind spending money on my truck but want to make sure Im going to get some type of performance increase doing so.