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Volvo B18/B20 air filter upgrade

sspony

Active member
Joined
May 15, 2012
Location
Maryland
Hello All,
Recently completed a small upgrade to the B18 motor in my 65' 122s and thought I would share it on here. For those of you who like to come up with new ideas and custom modifications hopefully this is helpful. I'm not claiming this is the "best way", just simple the way I decided to do it.

We all know the stock replacement air filters that fit the SU carbs in many of our old Volvos can be; expensive, hard to get, ugly, flow poorly and just lack any kind of "cool" factor.

When I purchased my amazon and opened the hood I found two very old, and very dirty, stock air filters. Here's a pic of what I was dealing with:
image.jpg




After pricing the replacements at $75 each, and determining that I didn't like the look of adding a 140 air-box I decided to come up with my own solution.
Design Phase:
image_2_1.jpg




The project began with a trip to the scrap bin at work, hoping to find some 3" aluminum pipe I stumbled across some true "Scrap Treasure"... two pieces of hacked up 4" aluminum round stock. So I changed my design and took it to the drill press and lathe:
image_1_1.jpg



A little while later my adapters we're ready! Did I mention that they double as mini velocity stacks?
image_7.jpg



During the install I realized I would need to obtain some shorter bolts then the stock configuration:
image_1.jpg


Found some great hi-flow reusable air filters from spectre that fit under the hood perfectly.(Spectre p/n: 8161) These are also available in a variety of colors to match other color schemes. Did I mention that they we're only $20/ea :-D

Here's a pic of the finished project:
image_2.jpg


Better looking, better flowing, and cheaper!
 
Those are nice. There are K&N filters that just bolt on though. Maybe not cheaper but they're supposed to last a lifetime after all.

Although the atock air filters are probably not the worst-flowing part of a B18.
 
K&N's are nice, however they are expensive and don't really have much of a looks factor to them.

140 airbox is a great idea with affordable filters but I'm not a fan of the look personally, and the boxes are getting more expensive.

I'll be honest, the biggest motivator for this project was the fact that I just like tinkering and I'm cheap (true t-bricker eh? haha). The filters cost me $20 each, new bolts we're $2 and the aluminum stock was $3. So total I only had $45 into a set of filters. As I said before, mostly just putting it out there for everyone as just another angle to address the filters. I do appreciate the comments and feedback though!
 
K&N filters suck and let tons of dirt through. Use an OE 140 airbox with giant filter? Keeps all dirt out, carbs don't ice up if the tstat works in winter. *shrug*

Not to mention cold air.

Everyone gets a hard on about CAI then they get to pushrod engines and all of a sudden hot air is OK again.
 
from what he has there, a couple silicone couplers and a couple pieces of aluminum IC tubing and BAM cold air intake(s)

Would not be hard at all! The OD of the aluminum adapters is 4". Would there be any significant benefit to running CAI's on this unmodified motor though? Also where we're you thinking you would route them?
 
Would not be hard at all! The OD of the aluminum adapters is 4". Would there be any significant benefit to running CAI's on this unmodified motor though? Also where we're you thinking you would route them?

sure there is, increased air density will give you more hp/tq, I'd think that the easiest place would be to bring the 2 pipes together and run it out the front radiator support... or pipe them through the inner fender...
 
sure there is, increased air density will give you more hp/tq, I'd think that the easiest place would be to bring the 2 pipes together and run it out the front radiator support... or pipe them through the inner fender...

Through the inner fender would be the closest and easiest. But I'd rather not cut holes in my car if it can be avoided. I'll look around the radiator support this evening and see if there's any potential there.
 
A CAI on something with such an open engine bay as an Amazon will not make as much of a difference compared to a more modern car. There is a lot of air moving around there when at speed. What difference there is may be made null by the restriction of additional plumbing. More importantly you may lose some of the nice intake noise of the carb mounted filters.

Screw the guessing, I might just mount a temp sensor on one of my air filters and see what the difference is from ambient. Stay tuned.
 
My MAT sensor is mounted in the bay where the end of the djet manifold and cone filter meet. I need to See what it says, but I'm sure it's well above ambient temp at normal op temp. If I move my plumbing to the other side if the radiator I'd probably see temps fall to ambient or pretty close to it.
 
After thought... These were originally set up with mech fans, and withe the fan going, it probably is closer to ambient than what I have (my e-fan comes in at 190) so my numbers will be a bit skewed.
 
I swapped my djet air canister for a cone. On the 71 (not sure about older) there is a hole in the core support that the factory air box has a hose running through. Some tubing could be run through it and the air filter placed in front of the radiator. I would bet some of the older cars have the same hole since the carb air box had a hose run through the core support.

DSC03312.jpg
 
A CAI on something with such an open engine bay as an Amazon will not make as much of a difference compared to a more modern car. There is a lot of air moving around there when at speed. What difference there is may be made null by the restriction of additional plumbing. More importantly you may lose some of the nice intake noise of the carb mounted filters.

Screw the guessing, I might just mount a temp sensor on one of my air filters and see what the difference is from ambient. Stay tuned.

This sounds awesome! Be sure to post your findings!

Same to you Chris, I'm curious to see what the differences are.
 
I swapped my djet air canister for a cone. On the 71 (not sure about older) there is a hole in the core support that the factory air box has a hose running through. Some tubing could be run through it and the air filter placed in front of the radiator. I would bet some of the older cars have the same hole since the carb air box had a hose run through the core support.

DSC03312.jpg

the 122 didn't get either of those style filter boxes (that I have ever seen) just retro-fits. It's easy enough to cut a hole in the rad support (might have to relocate the coolant tank, or mount a filter box to the fender and drill a bunch of holes in it to let the air in from outside of the engine bay.

There is also a 122 out there that is running DCOE webers that has the air piped in from where the heater pulls from the cowl vent. Apple Farmer Racing
engine_l.jpg
 
The most critical part here is what is the difference between the engine bay temp at normal operation and the ambient temp. Following that, we'll have to look at how much that temp difference could potentially benefit the engines performance.
 
I wouldnt worry too much about it unless you start hearing any pinging when summer comes... but for giggles, I'll get engine bay temps and ambient temps posted up tomorrow...

BTW, howd that Crane Ignition install work out?
 
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