Dea_944t

I remember seeing a thread about the power increase (or possibly that the stock air box was restrictive from app. 300HP and upwards) when changing from the stock air box to an open filter when using a MAF but I just can't find it?

I need the stock air box for the vehicle inspection but if the power increase is substantial I'm getting a second setup with an open filter since it's easy to change.

/Dea

marcoturbo

Yes, the stock airbox is restrictive.

I don't have a dyno proof but the car feels and spools faster with a cone filter. When I was using my MAF kit in a stealth mode EGTs were really higher than with the MAF tree (+100 °c gap in 5th gear).

ChrisJ951

From the factory the 944 Turbo was very restrictive with the AFM and the exhaust. The reason being is that in development the 944 turbo was faster than the 930 turbo and Porsche couldn't let that happen so they detuned the car significantly. In 1986 they easily could have had a 280-300hp 944 from the factory.

964-C2

Must be because the afr's changed (?).
Did you have a wideband 02?

Voith

Snorkel from airbox to chasis is the most resistive part of airbox. Thats why 968 turbo S had this version:



You can buy this ETG advanced snorkel, but at 350€ its not cheap.

http://cgi.ebay.de/ws/eBayISAPI.dll?...691358171.html

Steve113

will the stock box really flow anymore with the larger snorkle?

kevincnc

Thanks for posting that Voith. I've been wanting to make one like it for years but it hasn't been worth my time. Even with the airbox opening being the smallest cross section, it sure can't hurt- all the restrictions add up. I have some German family here and in Germany & will try to find out what it would take to get one without the logo. Maybe we could do a group buy if there is enough interest.

teamcrossworks

Kevin,

Looks like what I've been wanting for some time.

Please follow up with this...I would definitely be interested if the price was reasonable.

Thanks.

Scott H

You may get more torque/better spool, but the AFM maxes out (voltage-wise) around 300-320hp.

74goldtarga

This is from Nize on another P-car forum from 2008. Believe this is a dyno tested difference between MAF/MAP and snorkel and stock air box where that was the only change between runs.

"i've compared performance with the stock air box and snorkle versus just a filter attached to the compressor inlet.

the difference is significant, and it's definitely worth removing the stock air box and snorkle if you want maximum turbo performance.

all things being equal, the spoolup is about 200rpm faster without the stock afm/snorkle, but the real difference is after 4500rpm when the air restriction becomes really noticeable. the result is way more area under the curve and a gain of over 36whp.

it's obvious that most of the power and performance gains from a MAF setup is actually coming from removing the stock intake restrictions. if your mods can support it (MAP or MAF), i would highly recommend removing the stock AFM and snorkle for best performance gains."

Paulyy

i was actually just about to copy the same passage and post it.

Ben951S

So an A-Tune, which uses a MAP sensor, would benefit from airbox removal? I just haven't found a good set up to get cold/cooler air into a cone filter vs. hot engine bay air...

teamcrossworks

My ultimate plan was to adapt an M-Tune to the stock air box with some kind of increased cold air intake...think I'm wasting brain cells thinking about it?

I just like the "stock" look.

Voith

http://www.balancemotorsport.co.uk/p...cnumber=108059

Something like this that is not too restrictive would be perfect.

doabarrelroll

I'm surprised the stock air box is that restrictive. I would think that the advantages of a colder intake would outweigh the restriction of air through a slightly narrower passage.