levigarrett76

I have had the AFE bladerunner on my 07' for over a year now...installed the GDP ont he 06 yesterday. There is definitely a seat of the pants difference...especially with the manual tranny in my 07'.


I got to thinking about the neckdown restriction in the stock intake horn..do you all think this has something to do with the EPA.. Maybe helping to spool up the turbo faster with stock fueling to help prevent pre boost smoke?

I know the 98.5-02's had a very similar intake...but without the restriction...this is the only sense i can make of Cummins putting that restriction in there?

What do you all think???

CTD NUT

Adding any additional restriction downstream from the compressor will only hurt compressor flow....not increase it. The more free flowing the intake plumbing is, the faster the potential spool up times. Emissions requirements usually require faster spool up, not slower.

levigarrett76

im just trying to make sense of why cummins put that restriction in the intake horn ...when it did not used to be there on the 98-02 motors.

CTD NUT

I have not clue. I would spend too long trying to make sense of that one....it almost appears as if the engineers were trying to keep the intake horn as low as possible for possible hood clearance reasons....which makes no sense in the Dodge application since there is generous hood clearance in that location....perhaps the horn was a carry over from another 5.9 application and they were not interested in designing another different horn for the Dodge application? That logic is doubtful but I can't think of another reason why it is the the way it is.

levigarrett76

i just look at the 2nd gen 24v valve horn and the 3rd gen horn next to each other and they HAD to have put that restriction bump in there for some reason!

...The only sense i can make of the factory doing things to decrease effiecency on these trucks always seems to lead back to the epa...for example the cam profile that produces the "in cylinder EGR".

MikeyB

Ease of manufacturing. Look where the bolt holes are. They figured it was good enough.

MikeyB

levigarrett76

why did they go from the 2nd gen design though?

stroker101

new management/engineers? almost like where i work. we'll do something for years then all of a sudden we get some new engineers and we're changing things that has worked in the past.

maybe they wanted to keep the 4 mounting bolts uniform in length? who knows. but it didn't make sense to chock the horn down

CTD NUT

Haha....never thought of that. I can hear the engineer now: "Hey, lets retool this casting and save .02 by using shorter bolts. And now we have one less item on our bill of materials because all the bolts are the same length. I saved the company $500 this year by doing that."

levigarrett76

i would like to think better of cummins than that!!!...unless this is a dodge part?

CTD NUT

It is a Cummins part. Every company no matter how good its rep is will have at least one non-sensical jabbering engineer...I think it must be a prerequisite or something.

levigarrett76

I know we deal with it building Longhorn Steakhouses all the time, im dealing with is right now as a matter a fact, haha

Pearce

I know they do it. I've built and installed a custom long arm suspension for both a 1994 Grand Cherokee and a 1998. And it was clear all the little things they trimmed out when we got to hacking things up. shorter bolts, thinner metal, etc. Minor things but different, .02 here .02 there

chipmonk

that does make sense, because trucks with less restrictive horns and manifolds will make less psi than those with restrictive stock ones.

CTD NUT

Yup, but they flow higher. Pressure = the resistance to flow.