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Discussion Starter #1
Here's a thread I know will generate some controversy. Over the weekend I did my TB porting. As I had all the parts out, I started looking at them and the engineering side of my brain clicked in.

So here's the thought process. The TB actually has an opening of much less than 3". I guess that's why that last 90º elbow actually narrows down to that. Most people would argue that's a bad thing.

So here's the engineering talk. If I remember my second year fluid dynamics correct, the air velocity will actually increase as it passes through that "nasty" elbow - a good thing - hmmm. With the L Intake, we get 3" of air slamming into the TB. One third of the air actually just hits the wall of the TB. That's bound to create turbulance and back pressure - a bad thing - hmmm.

I hate it when I think too much!

Opinions anyone?

[ February 11, 2002: Message edited by: Rick W ]
 

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So i guess K&N had it right........ ha.
 

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I believe you are correct about the difference in diameters increasing the velocity of the air. I am not so sure about the bend. I seem to recall bends in pipes causing losses. Also, the roughness of the pipe also effects the airflow certain ways (laminar / turbulent).
 

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i'm not doubting that these theories are correct, but then how do you account for the faster 1/4 ET and subseuquent estimated horsepower? :p
 

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Discussion Starter #5
I don't believe the "nasty" OEM 90º elbow is any rougher than the nitrile 90º elbow in the L Intake on the inside.

I also believe the L Intake improves performance over the OEM crap. My bet on the worst part of the OEM intake is the big boxy type elbow where the PCV tube attaches.

Did Stephen Lister do any experiments hooking up his intake to the last 90º elbow? My theory is that with the OEM elbow the airflow would be more laminar AND at a higher velocity.

Don't get me wrong. This is NOT a K&N advertisment. I see no advantage with the conical filter or paying their price. By mod'ing the OEM airbox, you're providing more than enough air to fill a 3" tube while still protecting the intake air from engine heat and Mother Nature's moisture. I also like the idea of creating something with my own hands (there goes my eng'g side again).

I think I'm talking myself into mod'ing the L Intake to use the OEM elbow and see how things work. I figure the most that needs to be changed is the length of the 3.5" piece aluminum piece and it's coresponding PVC heat shield.

Comments welcome.

[ February 11, 2002: Message edited by: Rick W ]
 

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I have to think before I speak on this topic(yes,this is going to be a hefty controvercy)Every month I vote JoeKD for IOM(and will until he wins) simply for the fact that he DID build the L-intake and looks awesome-it took a ton of initiative and faith to build it on a whim(and I say 'whim' as understated as I can) Bacause I don't have the time or patience(or skill for that matter) I didn't construct the ListerDesigned Intake- I simply waited until a well reputed company made one for our cars-NOTHING WRONG WITH THAT RIGHT?! Now since K&N made an OffRoad Kit(simply too new to go through Cali emissions) AND someone else had the balls and initiative to install it before I did and heard that they(MoparPerformance) was actually pleased(leave out the 'may even outperform the L-intake blah blah blah')-hence the controversy...I heard the OEM last piece may be the most restrictive part-yeah-I looked at it as i was installing my own K&N Intake last Tuesday night-I agree that it narrows just before it hits the TB-but it's supposed to-Like the post before me I agree that the 3" nitrile elbow that the L-intake uses would make the air plow into the lower part of the TB and basically get dragged into where it was supposed to go-with the OEM piece(plenum?)it it narrows exactly how it is supposed to...

Now...let the games begin!
(hope I can hold my clout better than MoparPerformance)(without writing a novel)
 

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All of the above may well be true! However, what about at WOT when the reworked TB and "butterfly" are no longer making a restriction? Hmmmmm You would certainly think that DC engineers would have taken everything into account. Me thinks they did and came up with a middle of the road position, as most carmakers do, when weighing performance against MPG, sound factors, etc
 

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Discussion Starter #8
No matter how much you mod your TB the plain simple truth is that it's opening will never be larger than the outlet of that last OEM elbow (is plenum the proper name?).

If it's done right, that "restriction" is a good thing - it's called the "venturi effect".

My concern with the nitrile elbow is what happens to all that air that can't physically enter the TB. Does it just swirl around near the entrance of the TB disrupting the normal flow of the air?
 

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No, your theroy has one simple flaw, it would only apply to a pressurized intake. The TB will only take what it can. The stock intake TB connector is restrictive and thus the TB has only so much air.

The stock intake also slows down the air velocity due to its unsmooth design

If you remove a TB, and connect the 90 degree L_intake Elbow, you will see that its not as you say. The airflow will follow the outside of the 90 degree elbow and thus creates a direct shot into the TB which the stock intake messes up due to its flatspot.

Connect the two parts, the stock connector anr the 90 degree one nad you will see that its actually less condusive to what your saying.

I spent months on many designs and tests.
There was no gain at all as long as the stock TB connector stayed there. Adding a K&N cone to the stock intake did nothing(dyno proven). The only thing that helped was replacing that part. I would have gladly used the stock TB connector becuse it would have saved a lot of fabrications.

Even a 68MM TB does nothing with the stock intake tube.

Also the Stock airbox, with 2 2" holes in its bottom flowed just as well as a K&N cone filter.

I also tested 4" 3.5" 2.75" and 2.5 inch intakes, the 3" was the design that provided the best gains.

The best idea I have heard, is someone sugessed puting the 90 degree elbow off my intake design on the K&N Intake, I suspect that combination would rock!!


Peace, trying to help here.
 

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Discussion Starter #10
Thanks for more insight into your design. It's actually refreshing to have a civil debate for a change. Thats what this site is all about - an exchange of ideas.
 

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ROCK ON........
 

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Just out of curiosity...what would you guys say if I could engineer a ram air hood with a ram air intake? I'm thinking something like the NASCAR TREP. Not some over grown hood scoop. Those belong on 60's muscle cars. ;)
 

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I would say that I would be VERY interested if it made my car look sweet and drive fast!!!

BTW make sure the hood looks like the one in imaging (that is sweet)
 
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