joshworthy21

I just recently purchased an AEM Bruteforce HD intake with the hopes of a little better MPG"S, power and sound and i have great turbo whistle now and a little more power but to my surprise my mpg's have dropped significantly

i know i know with my mods and driving it to see how much more power i have now i will most likely get worse mpg's but i babied it for 2 full tanks and hand calculated 11 to 12 mpg and before the mod it was more like 15 to 16 in town and 18 19 highway.

Anyways i was just wondering if anyone else had experienced this and if anyone had any advice how i could save even a little bit at the pump thanks.

Alpo

I put the *****`s whistler on mine.
No increase nor decrease in mileage.....just the whistle.

And the quality of an Amsoil air filter.

Sorry no help.

fitzydog

yea the turbo sounds great but I just got a urge to check my mileage real close a couple of months ago and realized that I lost at least 1 mpg with the "Cold Air Intake". Really it sucks hot air from the engine "the whistler" anyway; which I had. I have the amsoil drop in factory spot and it has been great. Solid 20 mpg everyday running 70-74 mph. later

chipmonk

no way a CAI can cause you to loose 4-7 mpg. there's something else going on with your truck. most people (myself included) either see no change, or a slight increase with their CAI. BTW, i have an AEM brute force as well.

Dieselnick

If that is one of those AEM dry filters, they don't flow very well. I took mine off and put an S&B filter on the AEM tube. Now it flows and spools much better.

Nick

XLR8R

Hot underhood air ingested by the CTD generally doesn't incur a performance or mileage penalty (excluding triple-digit ambients ), since excessively cool charge air lowers combustion chamber temps to the point of reduced efficiency.

CD in NM

My first mod/change was a drop-in Amsoil filter, my mileage increased a little. Then I installed a complete aftermarket CAI, the Icebox, and my mileage increased a little more.

There has to be something else taking place for your mileage to be that low. My 2006 is getting right at 20mpg empty and 15-16 towing heavy.

CD

CamperAndy

You know that is not true on both points. The delta temp extremes on intake from cold to hot is about 200 degrees f. Unlikely that you would see both extremes but one extreme would be someone in Alaska or Northern Canada (-60) to someone in the deserts of the southwest (+140 death valley).

Those poor guys in the -60 have their own issues but once a truck that gets the core temperature up to 185-195 range will run more efficiently then the truck in the hot climates. If it were not the case then there would not be a market for inter-coolers.

Turbo efficiency is directly connected to both intake restriction and intake temperature. Increase either and the turbo produces less boost and thus the engine produces less power for a give fuel flow. Now back to the combustion efficiency of colder intake air, this is looking at the combustion act itself after the turbo has done what ever it can do to the intake charge. The compression cycle alone raises the cylinder temp to about 900 degree C and the combustion of the fuel raises it to around 2500 degrees C. That makes the head inlet air temperature variable a very minor ratio component of the overall combustion temperature cycle assuming the same boost pressure at the head. There is much more effect on combustion efficiency from timing, duration and number of the injection events then from the head inlet temperature itself for a given boost pressure (which has a much greater impact on overall efficiency).

Back to the OP - the CAI verse the stock intake should have only a minor impact on performance of a 3rd gen truck and this can result in a minor improvement in mpg. It should not have a negative impact under any condition unless the CAI has higher restriction or has a higher inlet temperature due to its location.

Performance

I have an AEM Workhorse HD intake now and saw no change in MPGs. Before the Workhorse, I had a Bruteforce and also saw no change in MPGs with it either. The intake wouldn't have caused your big drop in MPGs.

Sprinter17

Wow that does suck, I just calculate 12.5 mpg pulling my fifthwheel 1200miles this week, and I was hoping for more.

Ram Daddy

Swap it back out for the stock one and see if it goes back up....

XLR8R

Actually, the CTD's optimum ambient intake temp range is 60-90*F (those are Cummins' specs, so don't shoot the messenger )... too cold = excessive cooling of combustion chamber; too hot = insufficient air (O2).

This phenomenom is readily observed when too much water/meth is injected - or nitrous, or both (shock cooling) - or either if injected too close to the piston crown; and also during cold weather dyno testing.

It may be helpful to think of this in terms of the engine's core temperature: excessively cool charge air absorbs more core temp thermal energy, so a portion of the compression cycle's heat is transferred back to the combustion chambers' surfaces, and thus unavailable for the ignition point/combustion process.

Of course, low temperature-induced charge air densification is beneficial, but only up to the point of diminishing returns (which is far less than for a SI engine), since the heat of compression absorbed by the intake charge is the ignition source.

Charge-air coolers (intercoolers typically are used between stages of compression) are effective and desirable because they reduce charge air temps from 350-500*F+ down to <75-175*F.

Also, all else being equal - when intake restriction is increased, boost must increase; and if intake temperature is increased - boost (pressure) will also increase, although it will be primarily expansion boost. Try to think in terms of air mass instead of air volume... in a static model, we don't care how large the container is - just how many molecules of oxygen are in there; in a dynamic system (an operating CTD), we don't care how large the pipe is - just how many molecules of O2 are passing through per unit of time. Ideally, we want the maximum number of hot O2 molecules possible... obviously, there's a trade-off between heat & quantity.

We have performed extensive testing of the Super BHAF on our '05 CTD for boost, differential & power. It uses enough Cummins-spec air flow & filtration to support close to 1KHP and almost 2K ft-lbs of torque; it can either draw underhood air or high-pressure cowl plenum outside air via it's cowl induction hat. There is no measurable difference between the two sources of intake air, although the engine runs better at the track on a hot day with the cowl induction and runs better on a cold day with underhood air.

CamperAndy

Both of those items are true to a degree.

ISO ratings for performance are corrected to 59 degrees F so Cummins using 60 as the optimum intake temp makes since as does the 90 degree upper limit. Above 90 degrees the turbo efficiency starts to go down hill and produce less boost but I doubt that Cummins lists the reason that below 60 results in combustion cooling.

Also quenching the combustion with a cold charge of water or NO is separate from the statement that cold ambient's drop combustion efficiency. This phenomenon can be reduced by heating the water prior to injection. No way to really improve the NO cooling factor unless it was injected pre turbo so that the NO is heated/blended to match the air charge. You would still get the added O2 from the NO but the density boost would be negated. So would not be as beneficial as injection in the air horn.

joshworthy21

Yea i know i pulled my 12 foot trailer that i use for my plumbing business for like 1/8 of one of the two tanks but the trailer only weighs like 4500 lbs fully loaded. There must be something else going on maybe i just didn't check it right before the intake install but even the lying overhead display seemed to go down after install???

Anyways did the muffler delete today and filled up again which by the way was $146 and the low fuel light wasn't even on yet so I'll run another tank and see what happens. I mean I know that an intake and free flowing exhaust aren't going to give me a major mpg increase but even with my 37" tires and 6" lift I would be gettin better mileage than 11 - 12

MOTONATE

What a great idea.........