better breathing

Darthyota · **Joined:** Wed Apr 06, 2011 6:12 pm **Posts:** 11

is there anyhting a guy can do to make the 2.8L crd liberty breath better thats relativly cheap or even bolt on?

bhc04 · **Posted:** Wed Apr 06, 2011 6:52 pm

Yep, check out the Noob Guide on this forum.

Darthyota · **Joined:** Wed Apr 06, 2011 6:12 pm **Posts:** 11

i did and i saw the factory air box mod or what ever but i was thinkng more like a cold air intake and exhaust id also like to know if offing the cats will set off a code

LibertyCRD · **Posted:** Wed Apr 06, 2011 8:42 pm

There are recent threads about cold air intakes (I think the thread was titled "air box sensors" or something like that) and there are muffler threads all the time. Just poke around a little.

FWIT though...I've tried almost everything you can do to the exhaust and intake on these and have seen virtually no increase in power or economy. So I'm of the opinion that in the real world, you're better off using the stock airbox and an aftermarket muffler at best.

dgeist · **Posted:** Thu Apr 07, 2011 10:55 am

I think the best things that can be done are:

- Use a good air filter that still filters. Most of the higher quality filter elements (stock size) pass plenty of air for the power generated by the VM 2.8. Granted, if you put some kind of twin-turbo and larger injectors on, you're on your own...

- Replace the stock muffler (a carryover from the gasser with backpressure and all) with something appropriate for a diesel (either straight or free-flow aftermarket) and get rid of the diameter restrictions at the joints of the exhaust.

- Monitor your negative pressure with a simple gauge at the air box. I don't have the link, but a simple mod will tell you if your intake is struggling to get enough air (based on the pressure gradient in the box).

Dan

Darthyota · **Joined:** Wed Apr 06, 2011 6:12 pm **Posts:** 11

so no ones ever done a full 3" turbo back exhaust?

NotPicky · **Posted:** Thu Apr 07, 2011 3:31 pm

I have to agree with LibertyCRD. Air box mods and or an open exhaust yields very little improvement if any in the economy department. Now if you want sound they help. I can really hear the turbo through my intake.

I believe the stock 2.5" exhaust flows more than enough for a stock engine with a muffler delete or straight through muffler. Sound really good with just a CAT. I've seen and heard clips off of YouTube of people with 3" exhaust. I'm going to convert to 3" when I change turbos and add fuel.

Here is a pic of my Cold Air Intake. It consists of the heat shield off the K&N kit for a 3.7L Liberty. A 3" to 4" exhaust adapter and a soon to have AFE Pro Guard 7 dry filter (72-90055). It has a K&N filter now (RE-0870). I'm going to have to redesign it when I get a custom tune because I just deleted the MAF sensor. So I'll just mod the tube to house the MAF. Heat shield kit, filter, and 3" to 4" was about $175. I just called K&N direct and ordered the shield and hardware. The filter was from Advance Auto Parts and the exhaust adapter was from our International Trucks Dealer

wolcott · **Joined:** Thu Nov 10, 2005 4:16 pm **Posts:** 108

One thing you can do is put on the older model airbox, which has a higher intake than the stock unit. I have done this and have extended my air filter change from 5000 miles to 10,000 miles. It takes in much less dust and works better in heavy rain. No difference in mileage or performance.

ajk381 · **Posted:** Fri Apr 08, 2011 4:29 am

I have full 3in from just after the first 90 at the turbo (cant get closer cause of v-band) with a hooker aerochamber and the big air filter. Turbo is super loud and it grunts. I think it added power cause it gets up and goes off the line and is stock except that. Ill see how it is this spring with windows down but ive liked it all winter. And these im sure are just like any turbo vehicle where bigger is better for intake and exhaust.

Darthyota · **Joined:** Wed Apr 06, 2011 6:12 pm **Posts:** 11

ajk381 wrote:

I have full 3in from just after the first 90 at the turbo (cant get closer cause of v-band) with a hooker aerochamber and the big air filter. Turbo is super loud and it grunts. I think it added power cause it gets up and goes off the line and is stock except that. Ill see how it is this spring with windows down but ive liked it all winter. And these im sure are just like any turbo vehicle where bigger is better for intake and exhaust.

do you have pics of your set up? and why couldnt you get closer then the first 90* elbow after the turbo?

CATCRD · **Posted:** Fri Apr 08, 2011 7:20 pm

The turbo outlet itself is only 2.5", so a bigger exhaust pipe like 3" ain't gonna help. Best bang for your buck would be to just hollow out your cat and replace your muffler with a straight-through style having true 2.5" inlet/outlets. It won't set any codes. I always chuckle at these cummins guys with pipe diameters several inches larger than their turbo outlets.

Glend · **Posted:** Fri Apr 08, 2011 8:36 pm

A 3" exhaust is a waste of money on the Vm 2.8L. As mentioned the turbo flange restriction (above) is one issue, the other is the laminar flow of gases in the pipe. The gases in the 2.5" pipe will flow better (ie faster) than the 3" pipe (which allow pressure decreases due to its increased diametre). Stick with the 2.5" exhaust pipes but get rid of all the restriction flanges, and the muffler. Make sure you cut out the flange between the muffler and the Cat as that stops it down considerably. That and a Magnaflow or even stright pipe or similiar is all you need on the exhaust side. On the intake side, again the turbo inlet diametre is a factor, but you can deliver as much air as possible to that opening by doing some airbox mods, including using a Ram air type snorkel which will deliver some postive pressure to the inlet at speed. There are arguments that say that with a turbo any sort of forced induction (like ram air) is a waste as the turbo will grab what it needs. I tend to favor a benefit in forced induction and run a 90mm airbox opening (in the original opening spot) and an Airflow snorkel coming in from the side. The front opening can be blocked off for water crossings.

Radman · **Posted:** Mon Apr 11, 2011 10:54 am

In my 10 years experience with modding Diesel Vehicles (Mostly VW) any intake / exhaust mods yield minimal gains IF any. Usually not worth the cost and extra noise. Keep in mind these are not high revving motors so stock system flows plenty for its application. What may be gained is lower EGT's due to better flow = faster cooling on the exhaust side.

Squeeto · **Posted:** Mon Apr 11, 2011 3:05 pm

(1) is the cat
(2) is a flex coupling

(3) is the muffler of course

Where exactly are the restrictions that can be honed out or cut away?

dgeist · **Posted:** Mon Apr 11, 2011 4:51 pm

Squeeto wrote:

(3) is the muffler of course

Where exactly are the restrictions that can be honed out or cut away?

The #4 flange is the one that narrows down to near 2" (more like 2-3/16"). When I say "I", I mean the muffler shop with me standing off to the side. I cut about 1 inch before it (just before where the tube narrows)and welded in a new 2.5" flange. Then I then cut out just after the muffler (near where there's an upswing ahead of the rear axle) and sized/bent a new tube to replace it. The upstream end is the other half of a new flange and the downstream welds into where the muffler was cut out.

Net result was a noticeable difference in spool-up time for the turbo, a small economy increase (~1-2 MPG is you don't stomp on it) and a slightly throatier tone to the exhaust at idle. At highway speed, the sound difference is barely noticeable (if at all).

Dan

Squeeto · **Posted:** Mon Apr 11, 2011 5:28 pm

dgeist wrote:

The #4 flange is the one that narrows down to near 2" (more like 2-3/16"). When I say "I", I mean the muffler shop with me standing off to the side. I cut about 1 inch before it (just before where the tube narrows)and welded in a new 2.5" flange. Then I then cut out just after the muffler (near where there's an upswing ahead of the rear axle) and sized/bent a new tube to replace it. The upstream end is the other half of a new flange and the downstream welds into where the muffler was cut out.
Dan

Thanks Dan.
Only question is why did you need to cut downstream of the muffler if you replaced the muffler and pipe anyway?

dgeist · **Posted:** Mon Apr 11, 2011 7:25 pm

Squeeto wrote:

Thanks Dan.
Only question is why did you need to cut downstream of the muffler if you replaced the muffler and pipe anyway?

The bend that takes it up and over the rear axle is DOM or anything, but it's pretty close to 2.5" all the way, so replicating it would make the work a lot harder and more expensive, so I just re-used the section that's not really that bad.

The purist would replicate it all with smoother mandrel bends in stainless, but I'm not that guy nor do I have access to his shop.

Dan

warp2diesel · **Posted:** Mon Apr 11, 2011 7:28 pm

Don't forget the flange on the CAT that bolts up to the muffler, it is the 2 1/8" choke point. Good free flowing muffler and open up the CAT flange and you will have 0.0PSI back pressure with the CAT intact.

Darthyota · **Joined:** Wed Apr 06, 2011 6:12 pm **Posts:** 11

so is the o2 sensor before or after the cat?

SLS · **Posted:** Mon Apr 11, 2011 11:33 pm

Nice photo...................

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