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Discussion Starter #1
I have my doubts on improvements of a larger sized intake pipe. First off, the size of the AFM doesn't increase, so you can't really get more air through there. I have also read that the farther away from the intake valve you are, the less the size of the air chambers matter (something to do with air velocity and bursts...I don't fully understand it but a competent guy who understands engines better than me explained it to me). So my question is, why upgrade the intake pipe at all? Does anyone have any dyno sheets which show a power improvement? I can understand getting rid of the stock airbox and replacing that with a cone filter though. And if its all just for looks, then I FULLY understand. Anyways, just thinking out loud.
 

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the size and smoothness of the pipe's inside makes a lot of difference in the amount of turbulence in the intake stream. This correlates to the correct atomization of fuel, and also the velocity of intake air. The size of pipe used changes air pressure as well. I'll do a dyno with just the pipe and stock air box to show the diff. more info later...
 

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Yes, there is some hp gains on a metal intake pipe. My 85 was the test car for the Rabid Chimp intake pipe & we did dyno test this (he paid for the dyno). We did the first test w/ the original plastic piping, then we installed the prototype pipe. In some places we saw about a 3hp gain.

Dyno results were posted 2 years ago on the Yahoo list, but I can't remember where the link is now.
 

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Does anyone have any dyno results with just swapping the stock air box and filter with an open element filter?
 

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Discussion Starter #5
Chris, was that with the stock airbox?
 

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A 3 inch intake pipe will probably gain 2 or 3 HP as Chris says the dyno showed. That sounds about right. Another reason to put in the steel intake pipe is just to get rid of all the 20 year old plastic and rubber intake piping that can crack and create intake leaks.
A K&N cone filter should gain about 5 or 6 HP.
The throttle body and the AFM have almost identical cross sectional areas. (Do you think that is just by coincidence?)
I did some work on porting a spare AFM I had, and was able to remove several imperfections and obstructions to increase the cross sectional area by about 5%. I expected about a 5 to 10% improvement in flow due to less obstructions. However, I sold it to someone who desperately needed it and don't know if it made any gains. I'll have to try another one and test it on my 83. Maybe I can do some quarter mile runs with stock one, then do some more runs the same day with ported one and see if my MPH improve.
By the way, MPH is much more consistent from run to run and a better yardstick to measure improvements with. Quarter mile times can be very inconsistent due to differences in launches.
 

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Sam,

No, it was not. At the time (2 years ago), I was still running the HKS Super Power Flow mushroom filter. HKS got installed around ~97 or 98.

I need to put the HKS mushroom back on temporarily. The K&N is getting pretty filthy & is due for a cleaning.
 

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Putting a larger AFM would of course help but making the inside of the intake pipe smoother will create less turbulance (notice the ridges on the original plastic pipe). Price wise I would think the best way to go is ditch the airbox and get a K&N and follow that up by a aftermarket intake pipe.
 

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TOYMAN321 said:
Putting a larger AFM would of course help but making the inside of the intake pipe smoother will create less turbulance (notice the ridges on the original plastic pipe). Price wise I would think the best way to go is ditch the airbox and get a K&N and follow that up by a aftermarket intake pipe.
Yes, and then install the whole shibang on a 6MGE to bring the air velocity back up to speed with the larger diameter pipe. :wink:
 

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Of course the best solution is to get rid of the AFM all together and replace it with a 3"-3.5" MAF, then port the throttle body as much as you can get away with 8)
 
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