Cold Air Intakes

[Jason]

The purpose of this topic is to ask a couple simple questions about gas mileage:

1. Do / can cold air intakes increase mpg, or is that a myth?

2. Does / can adding an aftermarket electric fan to a vehicle with a traditional clutched fan?

3. Does / can an aftermarket ecm programmer increase mpg?

The vehicle in question is a 2008 Dodge Ram 1500 with a 3.7 and an automatic six speed transmission.

Thanks in advance for your help.

Topic

[Lorrin Barth]

I’ll take a stab at #3.

The real purpose for an aftermarket computer tune is get an engine that has been heavily modified to run. Otherwise the computer will be seeing inputs from sensors that are out of range. A tuner fixes this.

There are tunes for mileage. Now, I’m not a truck guy but since trucks are popular I’m sure these exist for trucks too. The thing is there has to be room in the factory tune to make adjustments. If the factory tune is pig rich then a tune could provide more gas mileage.

But you have to think about how trucks are used. A rich tune protects the engine when you pull that big load over the mountain. The leaner you go the more dangerous the tune if the engine has to work hard.

[valde]

1. No. Unleash you push throttle so much that ECU goes to open loop or to full throttle. And even then cold air intake doesn’t lover intake temperature that much. And other times it hurts MPG. This is with naturally aspirated gas engine diesel or turbo is different but it’s unlikely that you get MPG gains with those either.

2. Yes. Traditional fan takes engine power always. Electric fan only when needed. But MPG gain is going to be very small.

3. Yes. But it may wear everything faster and gains are small.

[Jason]

I appreciate the responses, I’ve been looking for ways to increase my mpg, but have been coming up short. The most given answer is to change your driving habits. To that end, I’ll say I’ve never been hard on my Ram. I’ve only gotten it up to 5K rpm twice, and those were passing situations on the interstates. I usually hover around 2-3K while getting to speed and then set the cruise control to hold it at the lowest possible rpm, around 1500-1900 on average.

Even with this I still only get about 17-19 mpg. I also know the Ram is a heavy truck and the 3.7 must use a lot of power to get up to and maintaining speeds. This is something I have accepted. At least I know there are not going to be really many things I can do to increase it.

Thanks very much for the replies.

Have a blessed day

[EricTheCarGuy]

As for cold air intakes, it’s a complete waste of time.

Electric fans do use less power than engine driven fans but you need to hook them up correctly.

As for MPG, this may also help.

http://www.ericthecarguy.com/faq/finding-and-fixing-the-causes-of-poor-mpg

Lastly, that’s a big heavy truck, try not to expect too much.

[Jane]

Cold air intakes cannot work as the air can bypass the fan blades. You need some form of air screw such as a super charger or turbo charger for this to work. This works in such a way that no air can escape past the impeller. On some cars there is a secondary air injection system which is mostly tied in with the EGR system. This is just there to help efficiently start a cold engine though, not for more power but to reduce emissions.

Note the air compressor housing at the middle front of the engine. This only runs for 15 seconds at start up time.

Attachments:

• IdlecontrolsystemV6320.jpg

[Wayne]

[quote=”EricTheCarGuy” post=91024]As for cold air intakes, it’s a complete waste of time.[/quote]

Love ya, but afraid that show is just that..a show. Factory box is set for the tuning done. “No-tune” CAIs are a complete waste and actually dangerous, as they’re usually leaning out the mixture across the board, but they tested 0 that were “tune required”. As in to re-tune the ECU/PCM to take advantage of the different intake, either made for a specific CAI, or line of them. Which they failed to actually test or even mention. And then, testing on a turbo? Seriously? It’s already set to crank in as much air as it can muster in most cases. Making the straw larger at the tip isn’t going to help when you’ve compressed the rest to max already.

Dyno runs are also a good gauge of overall HP, but not the be-all-end-all as they’d have you believe in addition to the above. A trip to their local drag strip with and without would have been a far better real-world debunking, but I noted they didn’t do this either.

I assume mainly for the same reasons news outlets tend to exaggerate or hype, for ratings. And I think the gist was to debunk the “cold” aspect with a stock setup, rather than an overall gain for certain rpm ranges with a proper re-tune on a stock NA setup, especially with larger engines. The advantage of a CAI is a mislabeling really, colder air may help when there are truly significant temperature variations between the factory and CAI setup, but the real gain is usually in the dialed to 11 setting of the tune for larger gulps of air from a CAI vs. the factory intake.

They could still be essentially not worthwhile, that’s still up for debate. I will say this however, I’ve set a tune for my own to a smaller diameter CAI by mistake once, which tripped the lean condition codes if that’s any indication. Overall horsepower may not be affected between a high performance tune for a CAI vs the stock airbox in most, but it’s fairly obvious to me with a tune you can get access to more air faster for off the line use with most CAIs if not mid-range.

I’d yank the CAI I have tomorrow if I thought the stock airbox would do exactly what the CAI does with the appropriate tune. I have yet to see or hear anyone actually show/state this with any solid reasoning/de-bunking.

My take:

1. Do / can cold air intakes increase mpg, or is that a myth?

Tune does it, CAI will help throttle response in most cases, but if you just slap one on, all you’re doing is leaning out the mixture, likely causing detonation at WOT (wide open throttle). If you use one with a tune, if you can keep your foot under tight control, you can, but they’re usually for added performance.

2. Does / can adding an aftermarket electric fan to a vehicle with a traditional clutched fan?

Yes, and no, lessens the belt drag, much like underdrive pulleys. Same deal as tune, if your self-control is awesome, then yes, but it will be near negligible to you, a few miles extra gained at best for a tank. You will get a bit more power off the line. A handful of HP added at most.

3. Does / can an aftermarket ecm programmer increase mpg?

Yes, it can, but see response 1 for caveats.

[Jonathan Stiver]

All of those CAN boost mpg but it’ll be negligible at best. CAIs will increase efficiency if done properly due to less heat & resistance. Just sticking a pipe and cone filter on your throttle body won’t though, especially in warmer climates. The more expensive kits are routed through the fender well or somewhere away from the hot engine. Same goes for ECM tuning, stock parts are designed to work reliability in any and all conditions so there’s room for more aggressive tuning but generally only chipped ECMs will do this, not a “magical box” for $20.

[valde]

To really understand CAI we need to divide it into two things 1) colder intake air 2) less restriction on intake
1) This will make engine more efficient but only if you use power (you don’t have to use max power but close to it). With less power needed colder air is bad thing cause you engine will have more power so you will need less throttle so engine will be less efficient. So for steady feet cruising you would get better MPG from hot air intake system (that has its own disadvantages). Stock system is somewhat designed to work like that so that when you use less throttle air is going to be warmer than if you use more throttle.
2) This will only help if you use power (you don’t have to use max power but close to it). And there is slight change that this will cause engine to run lean on full (and close to full) throttle (if it’s not tuned). It will also make engine run leaner on lesser throttle values but effect will be smaller and actually good for economy.
And many CAI systems don’t work at all they may have both hotter air and more restrictive than stock system.

[Jonathan Stiver]

^^^ Excellent post!!! That’s it right there. I remember the Honda Gen I Insight owners would route their intake pipes right near the exhaust manifold for maximum mpg, but a large part of their gains came from that particular engine being able to run in a ‘lean-burn mode’ under the right conditions

[Jeremy]

My Duramax in stock form pulled 20mpg.
Cold air intake
Aftermarket turbo horn
Aftermarket exhaust manifolds/up pipes
5″ MBRP exhaust, no muffler
30% over injectors
Airdog lift pump
Built trans for 1,000hp
EFI Live custom tuning
Edge CTS insight moniter for boost/EGT/fuel pressure

Now I get 22mpg on my conservative tune.
Was 2mpg worth all the money? Hell no!
Was it worth all the money when I leave a corvette in my smoke cloud from light to light? Hell yes!!
I love harassing all the little imports. They get nice and peeved when they get dusted by 7,000lbs of truck.

[Lorrin Barth]

On forums where car owners are removing stock electric fans and replacing them with slim fans they sometimes get into overheating problems because the stock fan moves more air. Stock fans are removed when people add a bigger manifold or turbocharger – usually both.

So, I’d be hesitant to go with a replacement electric fan over whatever the stock equipment is unless I could somehow know before hand the replacement is up to the job.

[Author]

Replies