DodgeIntrepid.Net Forums banner

1 - 20 of 69 Posts

·
Registered
Joined
·
47 Posts
Discussion Starter · #1 ·
The 'air restrictor' that I have seen many on this board remove is not an air restrictor. It is a turbulence reducer. The most restrictive part of the intake system, from a fluid dynamics standpoint, is the corrugated tube connecting the airbox to the throttle body. The rest of the system, while posessed of some tight turns and bends, has a smooth interior giving little resistance to laminar airflow. The corrugated section is a relatively necessary evil as it couples a moving device (engine) to a non-moving device (airbox) requiring some give and take in the connection. Dodge solved this by using a corrugated slightly flexible tube to connect the two. The engineers realized the airflow disruption this would cause, however, so they put a venturi cone at the beginning of the corrugated section. This venturi smoothly directs the airflow to the center of the tube, away from all of the ridges which break up laminar airflow. It's a tradeoff in that it has less area to flow air through than the large corrugated tube, but it's better designed. The same principle applies in exhaust systems-a well designed mandrel bent small exhaust system will flow more air than a poorly designed crimp-bent exhaust system. The 'roar' that you may hear when the 'restrictor' is removed is in fact your nice airflow becoming turbulent just before it goes into your engine, and turbulence is bad.
whodat
 

·
Registered
Joined
·
973 Posts
whodat - not trying to start a big argument, BUT - if these cone things were soooo good then why did they drop the whole idea?
 

·
Registered
Joined
·
47 Posts
Discussion Starter · #4 ·
I honestly don't know. My Intrepid is a 94, so that is as far as my experience with this particular model go. Perhaps they decided that the extra performance it got wasn't worth the extra money each venturi costs?
whodat
 

·
Registered
Joined
·
47 Posts
Discussion Starter · #6 · (Edited)
I lose because I don't know the real answer, or because you don't understand the scale of economics in the auto industry? How many intrepids are produced annually? Edit: Here you go- http://www.daimlerchrysler.com/index_e.htm?/news/top/2000/t01004_e.htm
Multiply that number by your $2

"Never argue with a fool, people watching may not be able to tell the difference."

whodat

Other Edit: It's spelled 'lose' not 'loose'
 

·
Registered
Joined
·
1,122 Posts
Well considering the fact that the part doesn't cost anywhere near $2 for that many of them. I would bet that it is under $1 for the volume of parts that they must produce. Plastic parts are the cheapest thing going. The tools to injection mold them are even, relatively speaking, cheap and when you are making so many other plastic parts of the same material, the material cost is next to nothing. That makes this part a REALLY inexpensive adder. However, it is an added cost to the overall vehicle. That is a perfectly viable reason for discontinuing them. Mostlikely, they found that it was just another thing they could cut off to save money and canned it.

This isn't just a cone. It is a nozzle-diffuser to be exact and can be considered a venturi, which actually accelerates the fluid (be it air or whatever) as it passes through it. This was mainly put in there for the exact purpose that whodat brought up as well as being a silencer. As we all have observed, the engine gets louder when you remove the 'cone'.
 

·
Registered
Joined
·
1,461 Posts
I haven't studied that far into physics yet...

Bottom line, remove it or keep it? (for performance not noise)

(only people who know what these guy's are talking about reply to my question, no opinions please, and no one saying how they felt better performance)
 

·
Registered
Joined
·
59 Posts
Yipeeee

Whodat, while I can appreciate your genious-caliber knowledge of etymology and your dextrous typing ability (obviously far surperior to mine), I suggest that you admit your minimal grasp of economics.

You should not be multiplying the $2 by the volume of the entire intrepid fleet, but rather, you should pose these questions:
Does the extra piece provide a service for which most consumers would be grateful?
If you were purchasing a new car, and the sales rep. asked you, "Sir, would like us to install a highly sophisticated "venturi cone" which will increase performance while reducing engine noise? The cost is $2"
Would you say, " NO, i need those two dollars so I can get a Big Mac on the way home"?


By the way, from looking at the cone after taking it out, I would say that it reduces the effectiveness of the natural vacuum created by movement of air through the engine.
 

·
Registered
Joined
·
59 Posts
I think the intrepid , through the years has gone through transition periods. Economists at dodge are continuously evaluating te target market to which the Intrepid line is aimed. Orrigionally, it was a more "family-oriented" sedan, and since that target market would quickly sacrifice performance for a quieter ride, they installed the cone. But the Intrepid's market share is changing (evidence: the R/T model & the 5.7 coming in'04) to cater to those who desire street speed that comftorably seats five. This crowd places more emphasis on performance and less on sound. In fact, some even enjoy the sound of unrestricted airflow.
By the way, whodat, I respect your knowledge of aeronautics, and I am not challenging your knowledge in that area
 

·
Registered
Joined
·
47 Posts
Discussion Starter · #12 · (Edited)
Re: Yipeeee

NextLevelIntrepidMXB2 said:
Whodat, while I can appreciate your genious-caliber knowledge of etymology and your dextrous typing ability (obviously far surperior to mine), I suggest that you admit your minimal grasp of economics.

You should not be multiplying the $2 by the volume of the entire intrepid fleet, but rather, you should pose these questions:
Does the extra piece provide a service for which most consumers would be grateful?
If you were purchasing a new car, and the sales rep. asked you, "Sir, would like us to install a highly sophisticated "venturi cone" which will increase performance while reducing engine noise? The cost is $2"
Would you say, " NO, i need those two dollars so I can get a Big Mac on the way home"?


By the way, from looking at the cone after taking it out, I would say that it reduces the effectiveness of the natural vacuum created by movement of air through the engine.
First of all, it's 'superior' not 'surperior'. And your question to the consumer would be good, but that's not who they're asking. The question is not for the consumers 'Would you be willing to pay $2 extra for this?' The question is to the bean counters at DC "Can we take this out without the consumer noticing, and still charge them the same price? Let's see, at around 10,000 intrepids a month, that's 120,000 intrepids a year, times $2, if nobody notices we save $240,000 a year."

whodat

BTW, thanks Anthony.
 

·
Registered
Joined
·
2,427 Posts
i don't see what the argument is concerning taking out the restrictor. they were installed from 93 to 97 on both the 3.3 and the 3.5 engine.
 

·
Registered
Joined
·
169 Posts
OK, I'm not a genius in physics, but I do know from experience. I removed my restrictor and the engine became alot louder above 3000 rpm. Do you think Chrysler installed these to smoothen out the the air flow of the intake? HELL NO. They did it because the target buyers (namely families) dont want a loud car (which is already loud to begin with thankfully to bad noise insulation for road noise). Other automakers do this, BMW and Chevy have put these on their cars. I removed the restrictors from several cars. And they became alot louder. Did Chrysler install the resonator behind the existing muffer to make the car perform better? No, they did it because the 3.5L engine is louder than the 3.3L and needed to quiet for all the families to ride in. If Chrysler wanted to smooth out the air flow why did they make a 3" pipe go into a 1.5" funnel. Sounds like "restriction" to me.
 

·
Registered
Joined
·
47 Posts
Discussion Starter · #15 · (Edited)
brun064 said:
OK, I'm not a genius in physics, but I do know from experience. I removed my restrictor and the engine became alot louder above 3000 rpm. Do you think Chrysler installed these to smoothen out the the air flow of the intake? HELL NO. They did it because the target buyers (namely families) dont want a loud car (which is already loud to begin with thankfully to bad noise insulation for road noise).
What causes the noise? Smooth airflow, or turbulence? If the air flows nice and smoothly, what would be there to cause the noise? Nothing. If you give the airflow a bunch of ridges to push against, and to disrupt the smooth airflow it will make noise.

brun064 said:

If Chrysler wanted to smooth out the air flow why did they make a 3" pipe go into a 1.5" funnel. Sounds like "restriction" to me.
Can you drive faster on a smooth, freshly paved narrow road or a wide bumpy dirt road? The design is often more important than overall physical dimensions, particularly when talking about fluid dynamics.

whodat
Edit; As for the road noise, in my car I found the two biggest sources of noise to be the tires and the door seals. I replaced the stock goodyear (touring tires on a performance sedan!) with yokohama AVS dB, ultra-high-performance all-season tires, designed specifically for extremely low noise (hence the dB in the name). That reduced the noise level tremendously. Next the door seals-in my vehicle the door seals were one-piece units which are press-fit over a ridge around the doorframe. After a number of years they shrunk slightly and pulled away from the corners at the upper edges of the door, allowing a lot of airflow. I pulled the door sill plate and stretched the rubber out there to gain the extra length needed to reseat the rest properly, and put the sill plate back on to hold the stretch. Much quieter now.
 

·
Registered
Joined
·
104 Posts
VERY interesting discussion!
But you better be careful, whodat. Next thing you'll try to tell everyone is those tornado thingys are junk. But don't do that til I crawl under my desk!
 

·
Registered
Joined
·
169 Posts
I replaced my peice going from my air box to my intake with a peice pf PVC. It made no difference in sound. The engine noise is well louder than that of air passing over plastic ridges. Why would the engine get louder if I removed the restrictor? Because more air flow is getting into the engine. Who cares really? The fact is that if you take out the restrictor your car will go faster.
 

·
Registered
Joined
·
104 Posts
Interesting observation on the sound, brun.
As for the going faster, did you do before and after 1/4 mile time trials. Mine certainly "feels" better with the K&N and the silencer/restrictor thingy removed, but I did not do any quantitative comparisons, so it could be just a placebo affect.

BTW, Cool website!

-steve
 

·
Registered
Joined
·
2,427 Posts
i don't think there's any difference in performance from removing the restrictor. the difference you probably feel is most likely the K&N air filter, not because it's giving you more HP, but because it's making your throttle response a lot better. the K&N and restrictor removal maybe gives like .5hp at the very most.
 

·
Registered
Joined
·
29 Posts
restrictor

Not to start any arguments....but Whodat has a good point as far as "restrictor" is concerned. The airflow going through the intake is not slowed down by the plastic piece within it. Its actually accelerated to compensate for the reduction in diameter, simple fluid dynamics. However, I do not know the reason why dodge does not include the venturi with the second gen., but the second generation engine as far more efficient than the first. No need for useless technology.
 
1 - 20 of 69 Posts
Top