Aluminum Briggs and Stratton air filter adapter

[firemanjim]

https://youtu.be/5t_TnmtM0Bk
Short on time at the moment, so I will be direct....
I'm going to start making aluminum air filter adapters for the Briggs pulse jet carburetors. It is a velocity stack design, and will use a 1.3875" ID automotive type air filter.
Please read the video description , and leave comments or suggestions.
I am also working on a new velocity stack filter adapter for the predator 212 engines, in aluminium. I also have my original style adapter, made out of hard, heat resistant plastic. That model uses the larger diameter filters. These will be for sale on my website, as well as eBay. Ordering information will be posted at a later date.
Thanks,
Jimmy

 

[bob58o]

Does the inside mirror the outside?
I, maybe incorrectly, assumed "velocity stack" was associated with a trumpet shape?
I see you said considered by some.

 

[Hellion]

Taken from the 270962 Single Cylinder L-Head manual, the ones you're making should fit the following:

Pulsa-Jet, Fixed Jet – Pilot Jet
Model Series 80200, 82200, 90200, 91200,
92200, 94200, 112200, 130200, 132200,
135200, 136200, 137200

These have an oval flange on the carb opening and take two screws to fasten the factory air filter box.

 

[firemanjim]

Does the inside mirror the outside?
I, maybe incorrectly, assumed "velocity stack" was associated with a trumpet shape?
I see you said considered by some.

Yes , the inside does mirror the outside . The wall thickness is just over .06" .....
I've seen straight pipes as well as tapered pipes used as a velocity stack. As stated, the inside follows the outside, so you have a transition from the larger ID to the smaller ID, with a 3/8" radius at the point of intersect.
This is actually was wanting feedback. The outside has to have the straight section to mount the filter to. The inside COULD be just tapered, but that would decrease the diameter of the inlet. I think this would also decrease the amount of, and SPEED of the airflow, but I'm no genius engineer. Looking at some of the air intakes on sports cars I've owned, some had the same basic stepped shape as I have in the current program. In fact, if you look at the intake just before the mass airflow sensor on a 2002 Z28 camaro, it has more transition angle, shorter, and MAYBE a .045" radii.....
What's yall's opinion? Should I set it up as a poll question?

 

[Hellion]

BUMP.

Failed to see that this was posted in Engines and Clutches.

 

[bob58o]

I have no real helpful input. Lol

I just thought a rounded edge opening (vs square edge opening) would allow air to pour into the v stack easier, with less turbulence?

 

[firemanjim]

Ok, so I drew this out today for the predator 212 engines. If you look at the air entry, the top shows transition as an angle. The bottom shows a radius . I can do it either way. I think either way is about the same, since these are just small cc engines and not highly tuned race engines. I am pretty sure at this scale, it's really just down to aesthetics and preferences. ...
This is drawn to scale and the only dimension missing is the overall length which is 2 1/2 "...... These will be made out of Mylar and aluminum. It might ( or will be ) necessary to shorten the carb studs by a 1/4 " ..... The nuts might need to be screwed on as you are putting it on . The length of the stud from carb face is about 1.25" and that is approximately the same distance in between where nut goes and the bells OD. .... I'll know for sure once I make the first one.
So what do you guys think ? My machine is no longer tied up with a special set up, so I am hoping to machine the first 4 Briggs adapters this week. Work currently keeps fluctuating on a weekly basis, so we will see what happens.
Bob, ..... I could do that too..... that is the whole point of this thread. To get feedback from the people who buy and use these things... what do you guys want ? What do you like and not like ? If you could make your own, what would it look like.... I'm trying to make something that appeals to the average kart enthusiast as well as a weekend racer..... So please , all input is appreciated. .....
Who know,...... maybe I'll be giving one away when it's all said and done. As well as a Predator adaptor. ..... I am known for giving stuff away..... lol

 

[2SlickNick]

Hey Jim, really glad you are back at it...

I can confirm... Jim is a giver. I wear my DiyGk shirt at least once a week( I won it in Jim's Christmas contest).

 

[chancer]

Jim I think those designs look Good. I dont know what else you could do to make them better.
Oh wait.
Unless there is a way to not have to cut the carb bolts shorter. If you were making parts for the general public they would prefer easy "Bolt on" after market parts.

But like you said possibly just put the nuts on as your tightening it down. Just trying to help you with potential customer complaints in the future.

 

[Hellion]

...It is a velocity stack design, and will use a 1.3875" ID automotive type air filter.

I thought the terminal outside diameter for the Briggs design was set to be 1.5" to use similarly sized air filters with a 1.5" or 38 mm ID?

Has this changed or is it a typo/brain fart?

 

[itsid]

fluid dynamics.. again.. I knew I should've listened back then

AAAAnyways, IDK what type of financial momentum a prototype would cause...
but for ~250 bucks you can get a decent 3d printer (with a spool of ABS filament) and print some variations (longer, narrower, steeper angles, shallower angles... you name it)
then all you need is to mount them and test drive...
they won't hold as long of course, but for a testdrive it'll do.

Frankly, I doubt you'd need a Dyno or something to tell which one is the one you'd want to end up with on your engine.
And if it's good for you... it can't be bad for any of us, right?

From what little I remember a shallower angle is not necessarily the better option (drag on the walls reduce speed and it might "feel" like a narrower straight tube in the end)
And sharp edges are not helpfull either (turbulences and such)
45° is maybe a bit steep already (90° reflection)
35° maybe 40 is about as steep as I would guess is reasonable...

But this is far beyond something I could work out in my head...

'sid

 

[Hellion]

...But this is far beyond something I could work out in my head...

Well by all means, break out the pencil, paper and calculator and let's see what you can come up with.

Honestly this is getting interesting and thanks for adding the info you just did.

 

[chancer]

Jimmy
Something you may want to look at. All this is over my head but AGK sells a simple adaptor and they point out a couple features:
"Adaptor has chamferred slots on carb mating surface which mirror the stock design. You will not find this feature in other air filter adaptors. The center bore incorporates a venturi design for more air velocity."
https://www.affordablegokarts.com/m..._Code=A&Product_Code=12350&Category_Code=AFC1

 

[firemanjim]

I thought the terminal outside diameter for the Briggs design was set to be 1.5" to use similarly sized air filters with a 1.5" or 38 mm ID?

Has this changed or is it a typo/brain fart?

The OD on the Briggs is 1.3875"..... The drawing I just posted is for the predator engine. ....


Chancer, I'm gonna look into that " slotted thingy " not found on any other adapters. That's fixing to change.....

 

[chancer]

That is great! I am glad to be of help. I thought maybe I was just rambling again.

 

[Hellion]

Any word on this project?

What are the estimated lead times?

Is the plant down for maintenance?
Vehicle carrier delays, inclement weather delays, recalls, quality holds, parts shortages, worker strikes or other supply chain delays should not factor into the estimated lead time. I understand that.

I think we're behind schedule but I don't know what the schedule is.

...I am glad to be of help. I thought maybe I was just rambling again...

You usually do, but thanks for keeping it on topic for once.

 

[bob58o]

I kinda would want something like this I suppose.

 

[Hellion]

^^ Neat design; you can see how the rolled edge (like you've mentioned all along) would defeat turbulence and at the same time enhance air flow and speed--and the inverted cone in the top of the filter...

That's quite a brilliant design.

bob580 =

 

[chancer]

Any word on this project?

What are the estimated lead times?

Patience Daniel Son!

Rome was no built in a day!

 

[Hellion]

Don't mean to state the obvious but the appearance or cross section would best be described like that of a trumpet bell with perhaps an exaggerated roll on the lip.

Googling "Velocity Stack" nets you all kinds of wonderful images...

I'm curious about the type of "oddball" filter that fits it and how good the seal is... Bob?