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Discussion Starter · #1 ·
Ron (seattleFSB), for those of us too lazy to go outside and remove and measure... what size/type of hose did you use for the intake tube? Hump/straight/reducer?
I used the excellent products from www.siliconeintakes.com. I could disassemble my entire Air Intake Tube and walk you through step by step, but it is really self-explanatory.



First off, I used my existing K&N Air Tube for my MAF Upgrade as it was clean & simple and already had the correct connections to the Throttle body.





I started by cutting off the K&N Air Tube approximately 2" from the relocated Valve Cover Breather tube to ensure I would have enough tube to clamp on an adapter. The cut end was cleaned up to remove any burrs. The old Valve Cover Breather Tube connected to the OEM Air Box and the new K&N Breather Tube connects directly in the Air Tube about 1/3 from the filter.





I then started at K&N Air Tube and worked towards the Pro-M MAF Sensor by using the Silicone Intakes 4.0" to 3.5" reducer, a 3.5" SS Joiner and then a 3.5" to 3.0" reducer. I tried to use all SS T-Bolt Clamps, but I misjudged the Outside Diameter and some were barely too small. The 4.0" and the 3.5" fit, but the 3.5" on the support bracket and the 3.0" on the MAF Sensor were too small. And yes, the 3.5" was too large to move to the MAF Sensor.





I considered using a single 4.0" to 3.0" reducer but each reducer is exactly 3" in length and a reduction of 3" would have pulled the Air Filter in too much to fit behind the heat shield.





I also ordered 2.25" Silicone Straight Couplers for the connections to the 56mm BBK Throttle Body, but found the flanges were larger than I anticipated and I would actually require 2.5" Silicone Straight Couplers. These also come in 3" lengths and in my mock-up I identified that they would have to be shortened about an inch to minimize the change in angle of the entire Air Tube/MAF/Filter. I also mistakenly decided to use SS 2.25" Worm Gear Clamps, (as there is not enough room for the T-Bar Clamps), and again found that they were too small and actually require SS 3.0" Worm Gear Clamps.





Cutting a Straight Silicone Coupler for length is easy. Measure from the end and make at least 4 marks around the Silicone Coupler. Wrap tape on the marks and cut with a sharp blade.





In summary, the whole project is "eazy peezy". Using slightly larger Worm Gear Clamps is easier as you can cut them to length if required, but the SS T-Bar Clamps are cool indeed. Remember to measure the full outside diameter of your connections and adapter length is critical for proper alignment.



Old...




New!!!
 

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'92 Custom w/ '95 MAF 5.0 M/T, 33's, 4.10 LSD
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I then started at K&N Air Tube and worked towards the Pro-M MAF Sensor by using the Silicone Intakes 4.0" to 3.5" reducer, a 3.5" SS Joiner and then a 3.5" to 3.0" reducer.

I considered using a single 4.0" to 3.0" reducer...
All my searches for MAF couplers and K&N air tubes bring me back to this thread...

Is 3.0" the appropriate size for the MAF side of the coupler? Mine seems like it would be 3.25", with 3" requiring a lot of stretching to fit.

I'm further confused by the Bronco/F-series MAF adapters on eBay showing it as 3.5". That's what my K&N tube measures at the tip, which would make sense to be sized that way, but 3.5" would be very loose on the MAF.

I can buy a 3.5" to 3.25" reducer/coupler, if that is indeed the correct size, but I need to do a mock-up on the truck first to make sure that'll fit without cutting the tube down like you had to.

Edit: My actual measurement was 3.2", but 3.25" seemed like the logical extrapolation. Looking at it again, the I.D. of my MAF is exactly 3.0", so I'm thinking the real O.D. figure is 3-1/8" or something peculiar like that.

Edit 2: I suppose the 3.5" for the MAF adapters makes sense, since they would have to be a common [over-]size for fitting aftermarket cone filters.
 

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Thanks, that confirms my measurements. Silicone vacuum-type hose stretches like you say, but I've never known the big couplers with nylon plys to stretch much if any. Your links are to that type, though, so I assume that's what you used...

With as tight of a fit as it must have been, I can't imagine you needed a clamp on the MAF end?
 

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Discussion Starter · #7 ·
I clamped it. Silicone Intakes has very nice T-Bolt Clamps.

Go to the Silicone Intakes link below, navigate to Silicone Reducers and click on any item. Scroll down and you will see a detailed dimension chart that will probably answer any questions you may have.

SiliconeIntakes.com
 

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I clamped it. Silicone Intakes has very nice T-Bolt Clamps.
Yes, I know you clamped it. I said it doesn't seem like you would have needed to, stretching a 3" I.D. over a ~3.2" O.D.

Go to the Silicone Intakes link below, navigate to Silicone Reducers and click on any item. Scroll down and you will see a detailed dimension chart that will probably answer any questions you may have.
1) I've looked at their pages. That's why I commented that you used the nylon ply type, based on your links, despite my experience they don't stretch like that.

2) Those charts just list I.D. and O.D., from what I saw. What questions would that answer? If they had a min/max range for matching coupler I.D., that would be a different matter.
 

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Also have similar setup. Though I started with the speed density knn kit and I also cut it back a bit, not much though if I remember right, I used this coupler.
https://www.summitracing.com/parts/knn-08050
I am also running a pro-m 75mm maf. The filter now has an outerwares on it
 

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Also have similar setup. Though I started with the speed density knn kit and I also cut it back a bit, not much though if I remember right, I used this coupler.
https://www.summitracing.com/parts/knn-08050
I am also running a pro-m 75mm maf. The filter now has an outerwares on it
75mm is the same as stock (a whisker under 3") I.D., isn't it? If so, I would assume the housing has a similar O.D. It certainly doesn't look any thinker on Pro-M's website. That coupler you linked is 3.5" at the small end, which I would expect to be too loose to clamp down without buckling.

I got a response from one eBay seller I inquired with, saying that their 3.5" to 3.0" coupler would not stretch to fit over the ~3.2" MAF. Of the sizes I've found, 3.25" is still the one that makes the most sense. Whether it can clamp down enough is the big question, but I'm puzzled by there being so little information on the topic, consistent or otherwise, as you'd think it would have been addressed by anyone putting a coupler on these MAFs over the past 23 years. Surely, the stock ones have worn out for some people.

p.s. I see you did something similar to what I've got in mind, using the snorkel to pull fresh air into the custom box.
 

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I have no idea what stock is, never put truck together with a stock MAF meter.
Fit good on my application, no weirdness with a normal worm clamp, no buckling. But the pro-m meter flares out towards the middle. I may have the coupler actually on that part, I do not remember. The stock ones I think are straight in that respect so potential not fit as well
 

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Discussion Starter · #13 ·
CBG, you got me looking closely at my Pro-M Meter. 3.5" on the Filter side and 75mm (2.95276") on the Intake Side. My cone filter side goes to a 3.5" flexible rubber and the 3" Silicone Reducer goes to just shy of 3" due to a taper.

Many meters are straight tubes but this is a 75mm Bullet.

 

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That flare you guys have could well be the reason bigger I.D. couplers fit.

I was looking for some big clamps today in the garage, seeing if I had what I need or if I should order some to go with a coupler once I settle on the size, only to remember I had a hardware coupler set aside I had planned on using on one of the cars. It has a soft rubber sleeve under corrugated aluminum and is labeled as 3" on both sides, but it was able to just squeeze over the 3.5" K&N end and clamped down easily on the 3.2" or whatever MAF end.



It's part #PNH-33 and says UPC 3" No-Hub. I picked it up new at Re-Store, a used/reclaimed building supplies place, for a couple bucks and don't know how hard it would be to find elsewhere, but that's another option to throw out there. The aluminum probably doesn't like that much flex from the reduction, so it may not be a long-term solution.

Also, it was a pretty darn tight fit hooking everything up. I had to remove the three bolts holding the airbox down, which gave me just enough room to get the dual tubes on the throttle body. Then I could position the airbox and bolt it back in. I suspect that a proper silicon reducer will be a bit longer than the hardware coupler, so I may end up having to trim the K&N tube a bit.
 
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