While testing an 03 Dodge Cummins 555 HO all stock except for a Banks 4" exhaust we learned that the Defueling was active during our dyno testing and reduced power below average numbers.

How we learned this, Our intention was to grab a base line run then test the Van Aaken C3 Pressure box installed but in off position, then in level 1 then in level 2.

To our surprise the Truck produced a much flatter torque curve with the Van Aaken plugged in but turned off indicating that just the addition of a 4" free flowing exhaust is enough to cause higher boost then defueling.

The Van Aaken does Boost fooling even in the off position so the computer could not see the higher boost produced by the exhaust system.

So without boost fooling you are actually loosing power with a High flow exhaust due to defueling.

The Dyno plot below shows the difference in torque and Hp before and after the Van Aaken C3 install.

 

Ted, thats a great observation, but what do you mean by "before and after the VA C3 install"?

Do you mean Installed and turned on? or Installed and used as a boost fooler in the off position? You made a distinction earlier in the post.

Unless I'm reading the plots wrong, the best plot/numbers from your test mule with the Banks 4" don't look appreciably better than a typical stock '03 HO with factory exhaust that I've seen or read about. Box or no Box. At the Fall Brawl, my totally stock HO was a mid-pack HO at 252/466.

If you consider the defueling event commencing at 2050 rpm the numbers are much worse than pure stock.


Or are you making a subtle statement that refutes the claims made by all the exhaust manufacturers that a higher flow exhaust will yield an increase in horsepower? And that to fully realize their potential, you need to run a boost fooler?

Is my truck making less horsepower & torque with my cool looking and sounding stainless steel 4" exhaust? - Gosh I hope not. What am I reading wrong here? What was the status of the VA box during each of the posted runs?

 

Ted,
Very informative! That is a very dramatic step function at 2100 rpm. Did you happen to record how much boost you actually gained with just the 4" exhaust over the stock 3.5" exhaust? In a stock setup, I would be very surprised to see a large enough difference for the computer to really sense an over-boost condition. Were you able to repeat this condition more than once? Thanks again for posting the data.

The Boss Hog
(Very interesting . . . . . )

 

Bulabula,
There's only one way to know for sure . . . .

The Boss Hog
(Let us know the result . . . . )

 

Akkkkk!

 

I know, I know..... After I posted earlier I was wondering if Kaufman's could do it this weekend rather than waiting for the Fall Brawl or something.

 

on stand by....more info please. post away

 

What I am simply stating here is that the 03-04 computers are more sensitive and will pick up on even the slightest gain in boost and cut fuel to control it.

The Van Aaken C3 does boost fooling plugged in regardless of switch position, Hence the power gains above 2000 rpm.

4" exhaust does and will make more power and be more efficient as long as the computer doesn't see the extra boost it produces.

These findings are repeatable time and time agian.

Here is the Dyno graph with the box in off, level 1 and level 2

 

So basically with the 03-04 computers, if we don't have a boost fooling box we won't recognize any gains from an aftermarket exhaust besides lower EGTs? If that's the case, we shouldn't see any gains from an intake either, right?

If this is right, how do all these aftermarket exhaust companies (and intake companies for that matter) state HP & torque gains on our specific vehicles if that isn't the case?

Let me know if my understanding of these post is wrong.

 

You nailed it!
It takes a guy like me to tell the truth about adertised power gains, most are theoretical or based on earlier version of the same truck.

Alot of times they are UP TOO numbers and not telling the whole story.

In other words they can and will make more power under the right conditions like fooling the computer.

 

Well, I have to say that this kind of upsets me (not at you Ted). People like me spend good money to buy an aftermarket exhaust, intake, etc. knowing that we'll get lower EGTs and thinking that we'll see a little benefit in HP & torque and then come to find out that isn't the case. Since I didn't plan on chipping my truck, I could have saved $500-600 and been in the same place I am now except I'd have a quieter truck

 

As I said a simple boost fooler would correct the problem or in your case where you are not going to spend for a box you can take a turn or 2 out of your wastegate and get out of defueling all together for free.

Then you WILL realize the advertised benifits of Air filter and exhaust.

 

I've read about this wastegate before in regards to people closing it completely, but I'm not sure what the wastegate or its purpose is. Since I'm relatively new with diesels, where is the wastegate on my truck (I have an 04 automatic) and all I have to do is turn it one or two times? Are there any negatives with doing this? Will the one or two turns close it completely and is there any benefit with closing it slightly vs. completely.

 

Hello Chadrock, wastegates are really a whole nother subject and if it aint broke don't fix it.

The wastegates job is to control PEAK boost ONLY it spends most of its life in the closed position, then in the odd event the turbo produces enough boost to overcome the spring inside the wastegate actuator which is preloaded to a specific pressure then the wastegate opens and controls PEAK BOOST Of course there are other factors that play into this somewhat explained above but we are getting off topic here.

 

Ted,

I'll start a new thread and any info there would be appreciated.