ITG filters on an MFI 911

[Keith S]

Following on from my requset for info on fitting aftermarket filters to my 2.7 Carrera, here's what I've found. Should also work with any other MFI 2.4 etc.

OK, as ITG is a British company, I was able to 'talk' to them easily by e-mail and fax, explaining the installation problems and was able to e-mail them the pic that was published on the forum which shows an MFI engine with ITG filters.

Their tech guy visited me on our magazine booth at a classic car show at the weekend and delivered what they think is the solution. The problem, as you suggest, is height. The filters they came up with are just 40mm high (internal), 65mm (external). The part number is JC40/40 and you need two of them. To go with these is a pair of blank base plates, part number 9JC40 (two off).

The reason for supplying blank base plates is that their is no 'off the shelf' base plate to fit the Porsche MFI set-up. You need to remove the airbox (and the clips which hold it in place), offer up the base plates and filters until you find the ideal position for them (clearance etc) and then, with a hole saw, cut out the openings for the venturis. To secure the baseplates to the stacks you'll need to drill the original plastic baseplate (which is part of the injector stacks) and bolt the new baseplate to it with, say, four M6 nyloc nuts and bolts.

You will need to remove the long oil breather pipe which connects the oil filler with the original air-box and either run it into a breather catch can or through a K&N-style oil breather filter.

I hope this all makes sense! I'll be covering it in the magazine when done. I've offered the new filters up to the car and it doesn't look like there will be any major problems.

Good luck!
KS

[pwd72s]

Keith, I'm pretty sure I know the car with the ITG filters you wrote about. The car and it's owner. You'll note one thing in the pic. The fuel lines on Tom's car are the RSR flexible lines. Tom said the factory hard lines wouldn't clear. He was able to land one of the last sets of these lines left in the USA and they weren't cheap. Maybe they could be fabricated ? Anyway, don't want to post Tom's e mail, but if you want to e mail me with any questions you might have along with your e mail address, I'll cut & paste, pass it on to Tom. I drool every time I see that car of Tom's...gawd it's nice! Best, Paul

[tobluforu]

Hey keith, If you can, make sure you take pictures of the entire process. I think there are a few people on this board who would like to do this mod. including myself. Will the mfi fuel lines get in the way? Will there be a tight enough seal between new base plate and stacks? Keep us informed.
Thanks

[Keith S]

Originally posted by tobluforu
Hey keith, If you can, make sure you take pictures of the entire process. I think there are a few people on this board who would like to do this mod. including myself. Will the mfi fuel lines get in the way? Will there be a tight enough seal between new base plate and stacks? Keep us informed.
Thanks

I'll be taking pics for use in 911 & Porsche World - I'll let you all know what gives about the fuel lines! regarding a seal, when you remove the stock airbox, there is a rubber seal around ths tcok mlded-in baseplate which should seal just fine against the ITG baseplate. If not, a touch of silicon (I hate the stuff but it does have its uses) should help.

[NYSCAR]

Thanks to Keith for doing the front work on this stuff. I think the thing with the standard setup of the ITG filters like Tom's (although not sure how his car is set up) is the air horns fit inside the filter instead of the filter and baseplate sitting on top of the stack. With the formerly mentioned setup, the filter itself sits over the stack ends and has potential to interfere with items below the top of the stacks (fuel lines, MFI pump, etc)

On a side note, I was wondering if there would be a way to design an open element filter design based off of what we already have with the MFI airbox. The airbox itself uses clamps to secure itself down to a mount on top of the stacks. What if we were to develop a system similar to the ITG/twm induction half-round billet air filters (http://www.twminduction.com/Filter/FilterBilletFrame.html) made to fit snugly on top of the stacks with a lip for the clamps to grab, and fairly stiff cross beam in the back that connects the two sides (necessary because the securing clamps do not go all the way around the stacks, and thus have to be a fairly rigid one piece design). This would require *no* stack modifications, would provide engine lid clearance, that gorgeous intake rip roar, and would totally open up the area in between the stacks just like a seperate air filter setup does. Essentially mimicing the setup of the stock airbox, without the actual airbox. Sound feasable?

Brad

[NYSCAR]

Example:

[pwd72s]

NYSCAR..great idea. Now all we have to do is assure ITG people it would sell? I wonder how large the market is, how many MFI cars left? I'm not good with computers, but to see a pic of Tom's engine, go to Jack Olsens home site, click on his images from last year's R Gruppe gathering in Cambria, California. ITG filters atop MFI stacks...looks "way cool"! Of course, I'll probably stick with stock...it's almost an obligation, sort of like a marriage vow, I guess.

[911pcars]

Not to rain on anybody's parade because I actually like and encourage thinking outside "normal" bounderies, but if you're going to use the factory airbox, why not just use a good replacement filter (foam, paper or otherwise)?

I thought the purpose of the ITG, K&N-type filters was to provide more work space in the engine bay while increasing the filtering area for intake air (besides the "neat" look). I don't think I'd spend $100+ putting replacement filters and adapter housing(s) inside a factory airbox when a $10-$30 filter gives me equivalent service.

I'm not familiar with the ITG setup on the MFI stacks, but It sounds like perhaps a spacer is needed below the baseplate along with some element modifications for hood clearance.

Just my $.02
Sherwood Lee
http://members.rennlist.org/911pcars

[911pcars]

For reference, here is the ITG setup referred to in the above posts:

[NYSCAR]

Hi Sherwood,

I didn't mean the picture I drew to be an exploded view, rather a before and after. No part of the factory airbox would be used except the base that holds the clips that you use to secure the top part. I.e. unclip the airbox, pull it off, put it safely in your closet when your wife is not looking , and take the new proposed filter pair with the connecting bar and clip it onto the base the original airbox sat on. The base of the new filter on eather side would have a lip where the clips could grab. Not sure how you change the element on ITG's half round filters, but the base itself looks to be machined billet aluminum, so you'd make one of these to fit nicely on the base the original air box sat on (with the gasket). Thats the hard part. Think if we got enough pelican requests to buy this setup they'd do a small production run?

Brad

[NYSCAR]

Here's the type i was thinking about, but maybe we could use something else as well. For 3 barrels, no stalks coming down, just a flat baseplate that would clip right in, just like the bottoms of the original MFI air box.

[911pcars]

Nyscar,
Ahhh, sorry for the misinterpretation. Disregard my dissing statement above.

The factory "bathtub" baseplates are X inches high and there isn't a lot of room above it. If an ITG-type filter element is used, I don't think there is enough vertical clearance to have more than a curved top surface exposed to air. In addition, because of the open-at-the-top filter element, I'm not sure how ITG's handle rainwater or even if they recommend using these in less than ideal weather, Some sort of rain hat would be desireable in this case.

Sherwood

[CamB]

Theoretically they are ok in the rain, as the oil impregnation will shed the water. Theoretically.

I am not sure I want some water getting a straight shot at my cylinders though

Oh, and I was told that by someone who should know (it was either ITG or one of their agents).

Cam

[pwd72s]

Sherwood, pretty obvious from your excellent pic of Tom's engine, it HAS BEEN DONE. Good point on rain shields. Never asked Tom about that. But amazing as it sounds, this car has been Tom's daily driver for years, until buying a 914 for that chore earlier this year. Tom lives in Portland, Oregon...pretty similar annual rainfall to London. Don't know if there were moisture problems tho. NYCSCAR's idea may allow for clearance of the hard lines, but don't know if then there would be enough up top. Sure has been a fun discussion, though. And to think, Tom's sweating the details has led to all this! Detail sweating? Note the little black dots on the engine compartment crossbar where the factory engine lid rubber buttons rest. Those are additional rubber bumpers, so the paint isn't rubbed off by the factory pieces. More thoughts...instead of a solid connecting bar, NYSCAR, do you think maybe a connecting tube could be utilized, with the U curve at a downward slope? Perhaps then a fitting could be made that would allow the use of the stock oil breather & overflow drain hoses?

[NYSCAR]

I guess my goal was to design a setup that was easy to remove (can't beat the quick clips), required no modification, and all the benifits of an open system. Unfortunately A) there probably isn't enough demand to warrant such an effort and B) the benefits are mostly minor and aesthetic (cool sound, neat looks, don't have to remove the airbox to fiddle with things normally obscured by the stock airbox). I personally wanted the cool sound

The rain on these filters would be a consideration, but to get *alot* of water into the engine bay on top of the filters would probably require one to drive in reverse at least 30mph in a downpour (not recommended with any air filter setup). A little moisture probably won't hurt, and might help cylinder temps and keep your pistons clean. As far as clearance, not sure if the half round ITG's will work or not, but I figure the air box itself has some height and has no problems with clearance, so I think it might be possible.

Anyway I guess this is all academic unless I start my own machine shop.

Brad

[Paul Thomas]

It is much easier to fit a set of K&N watershields and the rain is a non-issue like it is with the ITG setup. The K&N's already have the holes you just have to bore them to the size of the velocity stack top. The only height problem is under a factory deck lid. They fit just fine under a ducktail or other. I also have mine for sale because i am getting aluminum stacks and will be able to go back to normal K&N's.

[Keith S]

Originally posted by P-THOMAS
It is much easier to fit a set of K&N watershields and the rain is a non-issue like it is with the ITG setup. The K&N's already have the holes you just have to bore them to the size of the velocity stack top. The only height problem is under a factory deck lid. They fit just fine under a ducktail or other. I also have mine for sale because i am getting aluminum stacks and will be able to go back to normal K&N's.

Yes, it's the height issue which is a problem here when retainng the factory original MFI stacks. I have the 'rain hat' K&Ns on my 914/6 and there is no way they would work on the MFI stacks and fit under the decklid. As for rain bein a problem, unless the car is sat for some time out in pouring rain, there will be no problem. The oil and filter material will take care of most of it - unless you park your car outside every night (which I don't expect many Porsche owners do. If necessary, a small rain guard under the deck lid grill over the right-side (rearmost) filter would do the trick without affecting cooling.