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IM mod

335I

Full Member
Joined
Dec 3, 2012
Messages
77
Location
New Mexico
Has anyone done this yet from the Avy side? Debaffling the IM good for a proven 25whp. Seems as the IM necks down to about 55mm right after the 78mm TB which can be opened up from the inside and there is a baffle that is very restrictive further along the IM.
 
Since no one seems to be interested in this mod but you, pm me your cell and ill shoot you some pics
 
On the 2500 intake you have cut open the bottom of the manifold and remove the divider that's in there and then you can open up the opening up to the number two cylinder intake runner and then weld it back up. This is suppose to really help the stock intake flow at better and increase both low and top end. The air has to drop down into the lower plenum and then make a 180 deg. turn come up into the main plenum and then some of the air has to make a 90 deg turn to get the back intake runners.

I have a modified one from Raylar but have not put it on yet because I want to get it powder coated first and I'm also going to plug the so called PCV port in the bottom and weld on a fitting and run the PCV through catch cans with baffles because I believe this is where part of the oil usage on the 8.1L comes from. It's always sucking in the oil mist from the lifter valley, every 8.1L manifold I've looked at is black inside and coated with baked on oil.

I'll take pictures when I finish it and post them, I'm trying to clean the baked on oil from the inside and have most of it off but not all. I've have a parts washed with a citrus based cleaner but that only removed part of it. I've soaked it for a week, tried brake cleaner, kerosene,  pressure washed it and almost every available solvent but can't seem to get all off it off in the parts of the manifold I can't reach with a brush or scraper. I've tried to find a shop with a hot tank but no one uses those around here anymore because of the VOC regs in the area and disposal issues. If you have any ideas let me know.


Take a look at the video from Rayal and you kinda see what to do.



http://www.raylarengineering.com/intake_manifold.html


 
I didn't say I got it from Raylar, I got it from someone who paid for it from them and I got it for a lot less..

Modifying it is pretty simple, not much more that porting work and a little welding. One of the biggest areas is the behind the throttle body where chokes down. Cut that out and clean it up to the #2 runner, remove the floor so the air doesn't have to make the turns, a little match porting to the heads and your good to go...
 
It was not like no one was interested, I just prefer to let you post what you are doing and comment after you finish.


Now a couple of things that tube is from the EGR valve on the 02-03 then in 04 they made it a combined  EGR and Crank case ventilation but not a valve.

But do finish the project and let us know how it comes out, because there maybe only 15 of us active 2500 owners left.
 
WOW... Only 15 2500 owners left... I thought there ware a lot more than that, we are a rare breed...
 
Randy said:
WOW... Only 15 2500 owners left... I thought there ware a lot more than that, we are a rare breed...

Ask one of the folks that sold their 2500 for the HDs way more maintenance.  >:D
 
I think I remember someone starting a 2500 Nation many years ago. I will have to go look. wait... Yep there's one from 2004.. We should update it and have a roll call to find out how many are out there. Hell there's every other kind of nation white, blue, black, lifted, lower, bagged, tagged and a door ding on the left rear fender nation.
 
there's an 8.1 group on Facebook about 200 hundred members 8.1 classifieds! awesome people on there
 
Check this out


http://csr.ebay.com/cse/success.jsf?itemid=261865171247&mode=revise&draftId=430499798901&motors=1
 
I was looking at that too, that's how much I got one from a guy who bought it from Raylar $350. That's cheaper than that other guy who does it for $650 and way cheaper than Raylar... The modification is not hard to do, I have another manifold that I picked up on ebay years ago for $20 and was going modify it and use it, but now I will modify it and sell it..

The hardest part is cleaning the thing, no shops around me have hot tanks any more due to VOC and disposal regs.. I'm also have oil baffle/separators and plugging the internal PCV and going external. That port in the bottom just sucks in oil vapors and coats the inside of the manifold and then gets sucked right into the combustion chamber where it's burned. It's no wonder the 8.1L use oil, that has to be part of it..
 
It sure does I have exactly that way externally, got rid of oil consumption and also switched to 30w oil. Thats pretty cheap 300 bones good for about the same hp as headers but 1/3 of the price...lol.
 
Randy said:
.. that other guy who does it for $650 and way cheaper than Raylar...

What 'other guy?'  I'd like to have this done to my intake manifold but $1K is a lot of money to pay for a modified intake.  Is there someone other than Raylar that performs the same service for $650?  I wish I knew how to weld :(

EDIT: Just followed the eBay link posted by 335I, so I see there's at least one person out there modifying intakes for a fee.  Anybody purchased from that seller?
 
The bottom of the manifold when you cut it open for access is far enough away from the main body so you shouldn't have to worry about warping.

You can cut it open with an air saw, plasma cutter or cut off wheel, what ever you prefer or have available, then cut out the floor and open up the chamber, grind/smooth down the edges, clean up the ports and your done. Then you can weld it up, should be Tig welded. If you can't Tig or don't have the equipment any welding shop could do for probably less than $50.00 depending on how big you cut the access hole, it only needs to be about 4"x 5", maybe bigger if you don't have a plasma cutter..
 

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So you did that one then? that little opening makes it way more difficult, I cut the entire hump off then you have all the room to maneuver around in there
 
 
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