Hey guys, I've been needing to put a filter on my Dellorto 48 for too long. Luckily, the car is far from a daily driver.
When I bought my carb it didn't come with the original filter offered by RB. It came with nothing. So, I have a couple questions...

1. Does anyone have the dimensions of the base plate for the filter? I would like to make one and fit the biggest filter I can on it. I know the "height" will be restricted by the oil filler neck.

2. I have the FB Competition Manual and in there they make an empty airbox leading to a filter at the entrance. Large diameter pipe brings cold air in from the front, essentially like one for a FI car. This is on a Weber downdraft carb.
What could be the effects of building a box like that? Would the air horns still be able to do their job and get enough air?
I will run filter socks as a last resort.

Here is a picture of a box that was offered for Miatas w/ ITBs


Thanks a lot.

 

1. 4 3/8 " x 8 1/4"

2. No matter if its an air box or an air cleaner there must be about 1 1/2" clearance
above the top of the air horns so that they can do the job of smoothing the flow
and making it clean into the carb. Theres no airbox that I can find premade for this.

What you can do is get the ReSpeed radiator plate with the builtin 3" adapter so
you can run a filter infront of the radiator and then pipe it back to a box for the
carb. The box you will need to makeup on your own.

If you had the RB filter assembly, making a box might be easy. Just replace the filter
with some sheet AL bent around and sealed good with a 3" hose out the front side
to go to the cold air intake from in front of the radiator.

Don't run filter socks, they impede the air flow and hurt performance. They look
cool and all but they don't do jack for performance and hurt it.

Hmmm, I think I have the makings for another mod now Anyway, you might be
able to do the same with a third party filter setup for the Dell.

 

I agree that socks sucks lol

 

Old guys think alike

 

Thanks for the replies gentlemen!
I think I will try to go the box route. I have access to some aluminum sheet, so why not?
Also, I've only rarely seen this done.
It's times like this I wish I had the alternator relocated, so I could just run the pipe off the side of the box facing the radiator.
I will probably build the box as large as i can, and then run the intake piping at a diagonal to the radiator shroud and then through with a filter, RE Speed style. I would like it exiting on the drivers side.

Tim I take it that a 3" pipe will deliver enough air? This is the biggest thing I am worried about.

 

You can run the K&N oval filter and it will fit but I think it was after the 2nd time I tried to put it back on, I began to resent it, it came with the car and so I've kept it up until now but it's a complete pain in the *** to get on and off the car, the 4 studs you can see are actually all loose so they can be angled up to slip the filter on and then you have to dance around with it to line up the holes with the cap, the cap also barely fits on and overtime you will do as I did and just begin to crush and deform the filter to the point where it looks like hell and just isn't worth it.

If you do build a box and relocate the alternator I'd love to get ahold of the plans, I had planned to do something similar or just run open top stacks with mesh on them and then use the flexible ducting to direct air from in front of the radiator up to the intake at highway speeds. The car isn't my daily anymore so not too concerned with long term filtration.

 

HERE YOU GO









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I do like those little stack filters Directfreak,
On the K&Ns on the bottom, do you clamp the lip of the velocity stack onto one of the grooves in the urethane base? Or would you push the stack through and clamp onto the body of the stack?
Sorry for my lack of knowledge, I'm still trying to figure all this out

Now, if I could do the box and use the Dellorto on a Lake Cities manifold and relocate the alternator that would be the business! I think Gravity_Fed started a project like that w/ ITBs...

 

these filters suck also. but it will work only if the honey comb metal screens are used. However thats a waste of $$$, so I recommend a trip to the hardware store and purchase a metal screen strainer (be sure to shove it inside the air horns)

 

sorry sir, I'm not old

 

Wacky what do you think of the motorcycle K&Ns? Think they would work out ok?

 

I havent tried motorcycle filters....the problem with the above filters is that the foam or material they use is too restrictive just like the socks. speaking of filters, I installed an aussie made cold air intake for his IDA....although the plenum got 2 inlets (air intake/hoses), the carb was not getting enough air that it made the engine run like ****. Ran better with the K&N filter

 

Hmmm, that is what I am worried about.
I'm running the carb on a 12a large streetport and would like as much Clean Cool air as possible. I want to start driving the thing a little more.

Do you remember the diameter of the two pipes going in?

 

Ahhh, here is a similar design to the competition airbox I was talking about in my first post...
The site says it has a 130mm inlet, so about 5.1 inches.
http://www.efihardware.com/products/...with-IDA-weber



I've also done some more digging and found a thread by dj55b. He pretty much did the same thing that I want to, but there hasn't really been too much progress. I think RE-Speed is taking up a lot of time. I am still waiting anxiously for his supercharger build!
Anyway, here's a link to his post too, for informations sake. There is some good stuff there.
https://www.rx7club.com/1st-generation-specific-1979-1985-18/cold-ram-air-box-fabrication-my-itb-845522/

 

Yeah I was reading on a Cobra kit car forum about them. Some guys were running webers on ford v8s, and were saying that they were pretty restrictive. One guy had dynoed before and after and got like 450 whp with the little individual screen filters and like 505 whp without. Something like that, I'm not totally remembering the numbers spot on.

Pretty restrictive. Granted these are 500hp v8s, so the effect would be less for us. Still the cool airbox seems like a better solution, especially if you could have a cool lexan cover to still let you see the magic inside.

 

i think 3" is enough for a stock or maybe street port 12A, 170-175hp?

the competition book wants 110mm, which is 4" and change for 260hp...

 

http://cbperformance.com/catalog.asp?ProductID=550

http://cbperformance.com/catalog.asp?ProductID=310

This place has alot of stuff and the prices seem really good. I found it last night in the archives.

 

that's a good find

 

Im going to try and make a box next week, Im leaving my current job to start my own auto business. ill make sure to let you guys know how it turns out

 

good luck, i mocked one up out of cardboard, but didn't get any further than that...

 

I use the screen filters on my lake city setup because it is all that will fit between the horns and the frame.

On a dyno I only lost 2hp using the screens. Granted it is a stock port 12a but I don't have heart burn losing 2hp for peace of mind I won't suck a rock into my engine!

 

i run filter socks....

is that bad?

http://www.pipercross.net/competitio...ucts_socks.asp

 

run it without the socks...you may like it. if youre concerned about rocks, get a sink strainer as I mentioned above.

 

its not so much rocks as just dust. lubbock is pretty much a desert. and any time the wind is higher than 15mph the sky turns brown and i try to avoid going outside. walking around campus i literally get sand in my mouth.

i clean my rx8s air filter like once a month.

 

If youre not running the LC sidedraft manifold on your FB, then I will stick with K&N oval filter.