Let me start out by saying I'm frugal, thrifty... ok I'm cheap. I don't want to spend $300 or more to upgrade to a cold air intake setup, but (if I can) I would like to improve upon the factory setup.

I'm focusing my attention on the air supply before the turbo... primarily to reduce air restrictions and change the turbo sound to get a little more noise out of it.

Currently, I have the factory plumbing and air box with an aftermarket K&N filter. The filter inserts into the factory air box with an increased surface area over the factory filter... by creating a "cone" shape that extends into the box with a flat, plastic bottom.

Over the weekend I removed the intake plumbing to have a look...
1) Inside the lower elbow in front of the turbo I found "fins" that appear to direct airflow into the turbo. I removed these. Are they needed or do they help move air into the turbo?
2) I removed the silencer ring. It didn't noticeably change the turbo sound.

I'd like to remove the baffles from the connecting down pipe, but don't want to destroy them in case I decide to re-install later. The pipe also has ribbing on the side which would seem to be counterproductive to efficient air flow.

So, I'm looking for a replacement for the connecting section of downpipe between the two elbows before the turbo. The pipe seems to be about 5 1/2" OD and about 8" long. I've seen online (link) where a 12" aluminum section of 5 1/2" tubing can be had for $30 (after shipping). Not too bad, but can I find something at HD for less? Any ideas?

I've thought about taking a piece of metal A/C duct I have left over from a previous home improvement project and cutting it to size. Then using double-sided tape or silicone sealer and pop rivets to seal and secure the pipe where it is split. I'd include a strip of metallic duct seam tape over the outside of the seam for good measure (directed away from the block/exhaust).

Another modification I have considered is to open the bottom of the air box to allow more flow into the box. I've seen other posts/projects where folks have added a drain flange and some 3" or 4" PVC pipe to pull in air from outside the engine compartment. I have the plumbing materials in my junk box, but does the flange and PVC pipe really make that much difference? Could one cut a big hole into the bottom of the box and cover it with screen to prevent critters from entering? Would it make a difference in airflow volume?

My truck currently has no aftermarket modifications. With the $400 monthly payment, it'll probably be that way until the note is paid off!

Be kind... I told you I was cheap (and maybe overly descriptive). I expect there are others reading who are looking for inexpensive (or free) improvements... besides, tinkering is fun!

Thanks,
John.

 

First off, the K&N filter is known to cause damage to the turbo. They are poor filters at best, and combine that with oil and bad things happen when your sucking 800+ CFM thru them.

The vanes in the lower elbow have been reported by Cummins/Holset to make the turbo up to 30% more efficient, so I would put them back.

I have about $350 into my intake and I am very confident I got better results than any CAI out there, for less money.

GDP intake horn; improved airflow at all rpm, most noticable in mid range. It provided a lower peak boost, quicker spooling, and cooler IAT's.

Airaid MIT; improved low boost airflow, quicker spooking, lower CAI, louder turbo (but not annoying), and cooler IAT's

Both of those can be had for about $318 from GDP plus shipping.

Home Depot CAI; improved airflow at high rpm and high boost levels (my filterminder rarely moves now) : $15ish


The OE airbox is more than adequate for stock hp, even up thru 400 rwhp the stock works as good as a CAI. If you do a few mods you will probably only notice a very small difference in the mid range, and a slightly quicker spool.

 

I'm a tightwad myself and made my own intake using parts from Airflowonline.com and a BHAF...

 

Do you have you BHAF shielded?

The OE setup runs about 10-15* above ambient under normal cruise, and +40* or so when running 30+psi sustained towing.

The setup I have now runs 8-12* above ambient under normal cruise, and +40* or so when running 30+psi sustained towing.

If the BHAF isn't shielded and the IAT's are higher I would suspect you run higher EGT's due to the BHAF. For every 1* increase in IAT you get a 1.5* rise in EGT for the same fuel/boost load.

 

No shield and EGTs stay well in check. Remember, I have an early 04 which is known to have lower EGTs...
I will have my SRT10 hood back soon and then lots of hot air will escape from under the hood and lots of cool air will be coming in.....

 

I guess my point was more that a BHAF on a 3rd gen is probably not an upgrade unless you are outflowing the confines of the stock setup (over 450 rwhp)

 

you could always do what I did.....wait for an AFE stage 2 in like new cond come up on ebay.....got it for around 125-150 bucks cant remember.

 

AH64ID, I'm not sure I agree with you there. The BHAF has such a large surface area that it has to breathe better than a stock filter in the airbox. Add to that my custom torque tube and there's no way I will believe that it is not helping me any. Plus it looks cooler than the stock airbox. Doesn't that count for anything???

 

Okay, looks do count!!

The stock setup is plenty for 450+ rwhp (personally did/saw the dyno to back that statement) and an aftermarket filter/intake won't do much, if any, better. So if you're not out flowing the stock filter than a larger filter won't do much.

You do lose the "baffle" so you gain a little there on spool, but for the cost its not worth it. Then on the 04.5+ setup you lose the lower vanes which are like a TAG and do help.

The issue with a BHAF on a 3rd gen is it draws in hotter air than the stock setup, the hot air doesn't compress as well and causes a rise in EGT's. While EGT's may not be an issue for you the performance isn't at its full potential.

If you had access to a scan tool that would show IAT you could look at it and see how much hotter the BHAF will run than a stock or modded stock setup (or you could prove me wrong.. that would be okay too).. but the fact remains that colder air is better, and I am confident there isn't a setup that will do better than what I have (with the stock IC, but I would only see gains at higher boost levels considering how cool my intake air really is).

 

You may be right. I'm not racing so I'm not too worried about it. My EGTs always stay well in check no matter what I'm doing with the truck. I have, however, been thinking about making some kind of forced air setup to use with the new hood. Probably not a true Ram Air setup but at least a way to direct some cold air towards the BHAF...

 

From what I read...
1) It's recommended I return the plastic vanes to the lower elbow.
2) The expensive, aftermarket, washable K&N air filter reportedly does not flow as well as other choices (maybe worse than stock) and could suck oil into the system causing other issues. If I keep the stock box, do you have recommendations?
4) Upgrade the Modular Intake Tube. Why Airaid? Would straight piece of aluminum tube do just as well?
5) Upgrade the air horn. Maybe down the road. I see where this would help, but my focus for the moment is before the turbo.
6) The Home Depot CAI could improve performance... some. The Airaid MXP box looks like the factory box with a hole cut in the fender side, the lid removed, and the HD CAI downpipe added... with a bigger, better filter. Maybe I should get a better filter and add some additional "inlets" to the factory box.

I'd like to improve HP & torque, but I don't want to go crazy with it as I'm not making major drivetrain upgrades anytime soon. While more HP & torque would be great, the truck meets my needs in it's current form.

I'm looking to make small, inexpensive improvements. And I like to tinker.

Thanks,
John.

 

Answers in red.

Good luck. Here is the link to my HD CAI install.

https://www.dieseltruckresource.com/...n-t272967.html

 

AH64, could you show me any graph or statement from Cummins where they state the diffuser makes the turbo more efficient, rather than reduce the noise as was originally stated by Dodge. If it were something important for flow, it would have to be directly inline with the flow, not before a 90 degree turn. I know that the makers of the T.A.G. claim some things like that, but it never shows up on the dyno, or fuel mileage. For power and economy I would modify the stock box, and upgrade the filter. Actual cool air increases mpg and h.p. Big open filters sound good, but hurt both, below a power level that many will never reach. A formed silicone hose to replace the factory elbows and diffuser would probably be better for flow and temps. A modded stock box, 6.7 air filter, and the intake manifold air horn would cover your needs cheaply. I hate to tell you, that other than a couple of peak h.p. you probably still would gain little. I do think the air horns pick up some power low boost however.

 

I am not sure were talking about the same part. The one I am saying to keep is in the lower elbow, it is the 90* turn, not before it. It simply aids the air in making the 90* corner by directing it in multiple places not just one. The upper baffle is the one primarily designed for noise reduction, and mine has been replaces with a Airaid MIT with good results.

I think the stock lower elbow with the directional vanes is a better setup than a silicone hose without vanes, it deals with fluid dynamics.

The top end gain is minimal, in fact I didn't even notice one. With the 3 intake mods I have done I do have physical changes I can account for, and they are all in the bottom end and mid range, with the exception of better flow on the top end from the HD CAI.

I read the statement from Dodge/Cummins some time ago, and never book marked it, I have searched several times to re-find it and haven't been able to.

 

When did they start using anything in the lower elbow. Mine is an 2003 and it has nothing in it. Are you speaking of the silencer ring, which to me looks like a velocity stack. I could actually believe that it would help flow. I would advise John take a look at the PSM web site also. I have an AFE and mine and I am switching back over to a PSM clone modified factory assembly, and probably a cool blue hose.