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Modifying Air Cleaner Setup

Just a thought but if you are running larger than stock tires, did you swap to the appropriate speedo gear?
If not, your mileage is waaaay off. You getting much better than you think.
I have the correct gear ... Plus 1 from the previous 32s that I ran, and another in preparation for 35s.
 
iodmko.jpg


The results are two things noticed right away.
Quicker throttle response.
and quicker reacting IATs, both up and down.
Once rolling the temps were 7-12 deg lower then the stock little opening.

I hope this will positively effect the MPG... but not betting on it.
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Just came back from a 2 hour drive, So much more throttle response and quicker to go. Especially on the Hwy. If you have 15 mins make the opening larger. it feel like it's breathing easier.
I'm having trouble figuring out that pic ...
 
I'm having trouble figuring out that pic ...
He cut a giant hole in the front of his air box so it is now pulling air from a bigger area instead of the little hole at the front of most air boxes.
 
Up front, just to the right and below the radiator cap.
 
There is a way to test your air delivery system for restrictions. It invloves the use of a vacuum gauge. The better the quality of the gauge the better your results as you will be looking for values in the less than 5"Hg range. Ideal is atmospheric pressure, no vacuum is the goal...

1. With the air tube disconnected form the TB, measure the residual vacuum in the manifold at WOT. This is your baseline value. BTW, it the manifold shows any residual, your TB is either way dirty or undersized...
2. Install the air tube and with the filter out of the housing, read the residual vacuum in the tube. Should be less than the reference. No restriction.
3. Install filter and measure the residual. Should be less than the reference. No restriction.

If the system is clear until the filter is installed, replace the filter with a new one and remeasure. If there still is residual, open the front ot the box until the residual is gone. Any opening greater than this is for naught. No advantage past atmospheric pressure in the delivery at WOT.

By isolating each segment of the system, it is, IMO, easier to identify the restriction.

The test prodeedure is not my opinion and was obtained from: http://www.fbthrottlebodies.com/ via telehone conversation.

By running this test on my rig, it was determined my TB was undersized. By a ton. My delivery system, on the other hand appears to be fine. Will have to retest once the 68mm TB is in place.
 
He cut a giant hole in the front of his air box so it is now pulling air from a bigger area instead of the little hole at the front of most air boxes.

Correct!
And just about an hour ago I opened it up even more, the front plane is now completely open. Yes it's even more responsive and lower IAT, another 10-15 deg.
 
Correct!
And just about an hour ago I opened it up even more, the front plane is now completely open. Yes it's even more responsive and lower IAT, another 10-15 deg.
Any info on mileage change?

Also, a warning: Be careful driving your rig in any kind of water with the air box opened up like that. It's begging to suck water in.
 
Any info on mileage change?

Also, a warning: Be careful driving your rig in any kind of water with the air box opened up like that. It's begging to suck water in.

yup, 1.5-2mpg better... I think.
further testing ahead.

As for the warning, It's the opposite. The larger opening slows the air there for reducing the suction of items/water. My test: placed my hand in front of the stock little opening and it would pull my hand, now I can feel the air but not pulling my hand towards the opening. Sure the opening is larger, but with the bottom being flush the water that might get sucked in will drain back out. And I'd really have to stuff the nose of the XJ into some seriously deep water for it to get any large amounts past the filter. I did drive around in the heavy down pour yesterday and I checked the filter after and it was dry.
I feel completely safe for normal driving and mild off road. Mud and water crossings would be another another matter that anyone with the stock box should would about.
 
No matter what the air intake mod, as long as it lowers the Intake Air Temp, that is good. If it can do it with less restriction, better. And if it can do it with some degree of water protection, even better. That would be my goals. More power and economy will follow.
 
Cooler air and less restriction is better.

I would be concerned about the increased front opening allowing in large amounts of water, during water crossings, possibly hydrolocking the engine. On this forum, I have read many examples about this happening with stock air cleaners. A lot of water can come around the headlights, straight into the air cleaner's intake.
IMO, protecting the engine, in a off-road vehicle, is more important than increasing the power output by a few percentage points.
Something to think about.
 
IMO, protecting the engine, in a off-road vehicle, is more important than increasing the power output by a few percentage points.
Something to think about.
I agree But I have no plans on crossing water deeper then a foot.... It's still my DD and I can't take a chance with it.
IF and when I get to that point of off roading then I'll be getting to a snorkel ;)
 
I agree But I have no plans on crossing water deeper then a foot.... It's still my DD and I can't take a chance with it.
IF and when I get to that point of off roading then I'll be getting to a snorkel ;)

Well, only if you promise to stay away from water but remember, it is a Jeep and they love stream crossings.
Mine is a DD too and its been headlight deep several times. Good to be prepare for the unexpected.
 
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