Shifty

Can anybody advise of a good cold air intake modification for a 1990 C4?
Thanks,
Miguel

kgorman

http://www.porsche964.co.uk/technical/airbox_mod.htm

Bill Verburg

911/964/993 are uniquue in the automotive world in that they are air cooled. This is important to keep in mind because that big fan is moving prodigious quantities of air through the engine compartment keeping intake temps down, especially at speed where it is needed.

I would just try to pick up the air from the area immediately under the grill and be happy with that.

Red rooster

Miguel,
I would stay with the standard air box. The 911 motor bay is well known for holding pockets of hot air especially foward of the fan.
The 993 TT has an extended snorkel on the air box to clear the intercooler so cold air is picked up.
A quick Hammer test for intake air temperature will soon persaude you that cut away boxes/cone filters make intake noise and lose power !

All the best

Geoff

dfinnegan

Geoff,

I have a drilled airbox. The car came this way. I can check the intake air temperature, but I don't have an original box to check against. I suppose I could block off the holes in my existing box some how and check that out.

What would you expect the differences in temp to be and how much power loss would you expect per N Degrees F?

I'm a little surprised to hear this, as well, as I had thought that most folks believed that drilling the air box would result in some minor improvement in power due to the freer air flow. No?

Thanks,
Dave

C H

On turbo cars you gain about 10% in power per 10 degrees of cooler air. I would guess that you lose power off the line on a modified intake, but probably gain power when the car is moving lots of air from the outside, since there is more air available and will be cooler than the air in the engine bay.

Drilling the box produces a pretty neat sound and worth drilling the box just for that reason alone.

I really want to fabricate a "snorkle" type box that would press up againt the grill, but there is really no room, especially if you want to keep you A/C.

Dyno figures or at least a gtech numbers would be nice to have to see if there is anything gained, but I would imagaine 1-2 HP at most.

Red rooster

Dave,
The colder the intake air , the greater its density and so more power !!

As a test hook up your Hammer , go to Actual values and IAT . Check how much higher the temperature is than ambient. Go for a drive around and see what happens. One situation is when you pull up at lights for a while. Then the temperature really starts to climb. It will take a few miles of driving to get it back down.
One simple test is to just go for a good drive , pull over , open the motor lid and check with your hand how hot it gets at the back of the motor bay !

This is where a cone filter lives !!!!!!!!!!!!!!!!!!!!!!!!

All the best

Geoff

Shifty

Thanks everyone, I'll stay keep it original for now.
Miguel