High-Performance Airbox

[Steam Driver]

Anyone have any experience with the Fabspeed High-Performance airbox for the 964? Pluses, minuses? I have a minor clearance issue using the 964 intake in my SC. It can be overcome with some creative “squishing” installing the cover but I’m looking at options.

I’m puzzled why this must not be an issue with the 964 but I’m guessing there must have been some redesign in the oil filter console/filler neck areas.

[Bill Verburg]

Originally Posted by Steam Driver

Anyone have any experience with the Fabspeed High-Performance airbox for the 964? Pluses, minuses? I have a minor clearance issue using the 964 intake in my SC. It can be overcome with some creative “squishing” installing the cover but I’m looking at options.

I’m puzzled why this must not be an issue with the 964 but I’m guessing there must have been some redesign in the oil filter console/filler neck areas.

Unless they have something new it's just an air box cover for the stock air filter on the stock air box, it does provide extra room to the side to clear the hinges etc.

[Steam Driver]

Yes, a way to mount the stock filter; that pretty much describes it.

I need the clearance for R&R the stock cover and filter. I could alter the stock 964 cover of course, but I was looking around for other options. A stock cover only on eBay is in the 150-175 range, the Fabspeed item is 271.

With the current arrangement I can squeeze things together but the “snorkel” has to be removed and there is no room to reinstall it either. Something must have been different with the 964 to permit it.

I’m guessing that a change in appearance/being different is its prime benefit. They claim some power increases, but I’ll bet a lot of that is because of no doubt increased intake noise. Noise equals perceived power a lot of times; just ask any Harley rider.

“Harley-Davidson; the world’s most efficient means of converting gasoline to noise without the annoying side effect of horsepower,.”

[Bill Verburg]

Originally Posted by Steam Driver

Yes, a way to mount the stock filter; that pretty much describes it.

I need the clearance for R&R the stock cover and filter. I could alter the stock 964 cover of course, but I was looking around for other options. A stock cover only on eBay is in the 150-175 range, the Fabspeed item is 271.

With the current arrangement I can squeeze things together but the “snorkel” has to be removed and there is no room to reinstall it either. Something must have been different with the 964 to permit it.

I’m guessing that a change in appearance/being different is its prime benefit. They claim some power increases, but I’ll bet a lot of that is because of no doubt increased intake noise. Noise equals perceived power a lot of times; just ask any Harley rider.

“Harley-Davidson; the world’s most efficient means of converting gasoline to noise without the annoying side effect of horsepower,.”

W/ a 3.6 t/p the space to the right of the airbox is very limited, the cheapest way to get clearance is to trim the stock cover down to a minimum. The Cup cars often ran that way.

The snorkel is an attempt to direct cooler air into the air box, it's more effective at lower speeds, at higher speeds the entire area is quite cool due to the very large volume of air going through the engine compartment.

[Peteinjp]

It’s also about controlling noise.

[Steam Driver]

I will probably end up trimming the airbox cover, but the reference to intake air temperature is significant. I’m going to have to think about that because I have some personal experience with the difference it could make.

“Back in the day” I had a 180hp Corvair turbo and I had read about the cold air thing in a Corvair performance book. So I got some dryer hose and ran it from the snout on the air filter up into the plenum area under the air intake grille (second generation Corvair).

I didn’t have a dyno, but I did have a fairly steep hill where I could pass a point at X rpm in 3rd, floor it, and see how fast I was going/rpm gained going by my second point. BIG difference noted so the dryer hose stayed.

Amusing side note. One day I was accelerating and suddenly power dropped way off; enough to throw me forward in the seat. I limped home thinking maybe the turbo had gone south or something, but what I found was something amazing.

Since dryer hose is round and the air cleaner snout is oval I had packed the void areas with shop towels to keep hot air from sneaking in. One of these had gotten sucked into the snout probably shutting off about 95% of the air. It wasn’t just loosely interfering, it was packed in on the element like it had been tamped! Extracting that things went back to normal.

[Bill Verburg]

Originally Posted by Peteinjp

It’s also about controlling noise.

True but w/ a 3.6 t/p properly situated in the bay you have little choice

When the 3.6 is mounted using 964/993 console & crossbar the engine is low enough to fit a stock airbox
964 motor and all accessories in my '76 C3 using 964 console and crossbar, the issue is the exhaust is too low unless custom fabrication is used


w/ a 993 vram mounted the same way the air box fits but the cover needs to be trimmed, stock heater fan does not fit



w/ a 993 nvr mounted the same way the air box and cover fit




But when a 911 3.2 console and 911 crossbar are used, the engine now sits like any other 911 6 and the exhaust is no longer an issue, but the air box cover no longer clears unless it is trimmed to the bar bones, or a cone is used
either of these presents the ame intake noise

[Steam Driver]

Interesting pictures Bill. Here is what my installation looks like.







You will note the snorkel is absent. For some reason or other your installation seems to have a little more clearance on the right side than mine. But I can’t figure out why. The 993 cover appears to be a little shallower, but that may be just an illusion.

The cold air thing is intriguing. As I am currently w/o A/C I’m thinking a duct could fabricated between the old snorkel fitting directly up under the engine air grille. I have significant experience in fiberglass fabrication and could definitely do it. A project for “down the road.”

[tobluforu]

Different maf?

[Bill Verburg]

a 964 intake and associated parts is a bit taller than the 993 version on my car

[josephvman]

I just dremeled out the cover on my 3.2 airbox. Definitely more intake noise but can't definitively say it changed the feel. The car has a M&K sport muffler with cat bypass pipe and a SW Chip, so it's pretty punchy regardless. Definitely makes it easier to change the filter, which is a good thing because this setup requires more frequent changes.

Originally Posted by Bill Verburg

W/ a 3.6 t/p the space to the right of the airbox is very limited, the cheapest way to get clearance is to trim the stock cover down to a minimum. The Cup cars often ran that way.

The snorkel is an attempt to direct cooler air into the air box, it's more effective at lower speeds, at higher speeds the entire area is quite cool due to the very large volume of air going through the engine compartment.

[Steam Driver]

There is no AFM. This project is based on the MS2 which is a Speed Density/MAP based system. We made a tube to replace the AFM and accommodate the oil tank vapor hose. The AF housing mounts in exactly the same location as it did the 964 using the mounting points on the plenum and in the filter housing. So the close clearance issue is baffling to me unless a stock 964 has the same issues. I think that was my real question; why does this issue exist unless it did in the 964.

Sharp eyes may notice the flexible tubing between the intake boot and the tube. There is a front to back misalignment caused by my using, at least for now, the SC TB. The SC TB doesn’t seal the same so there is a 1/4-inch phenolic “adapter plate.” They don’t seal the same; one uses a flat gasket, the other an “O” ring. If everything else works out I may at some point move up to the slightly larger 964 TB and this misalignment will go away. I didn’t go that route to begin with because it may have caused some “tip in” issues off idle and there are enough variables to deal with already.

For now since there is no real need to pull the air filter I will leave it as it is. At some time later I will probably go joesephv’s route.