Any new A/C Center Vent / Bow Tie removal projects completed?

RickM · RickM's Garage

After re-reading Don's excellent write-up I noticed a few others were embarking upon their own designs. Anything new?
I'd love to see pics or alternatives to the harware used and more detail on the procedure to cut an additional hole into the bulkhead for added flow.

nhromyak · nhromyak's Garage

I did this last year. I decided against putting on performance Aire's vent diffuser. It seems to work well.

Good luck.

RickM · RickM's Garage

Bump for the morning crowd...

Joeaksa · 04-18-2003, 09:15 AM

I was lucky enought to find a used Performance Aire kit from a Pelican member and am in the process of installing the under dash vents this weekend. Cannot wait to get somemore airflow in the car...

The underbody condensor is next weeks project...

Joe

greglepore · 04-18-2003, 09:27 AM

Can I get a link to the original thread-tried to search, no avail.

RickM · RickM's Garage

The link is below. I'd still like see the procedure for drilling another hole in the bulkhead/firewall for an additional tube.

No more Bowtie! My center vent kit

greglepore · 04-18-2003, 01:35 PM

Thanks. That solves that. No $100 vents for me!

Steve W · Steve W's Garage

Here's a pic of my Performance Aire vent, you can see it mounted right over the where the bowtie used to be. The second hole is to be made with a 1 1/4" to 1 3/8" holesaw exactly 2 1/8" to the right of the factory tube, measured center to center. When you bore through the first firewall, you need to continue about an inch in and bore through the second wall into the fan's plenum. You then insert a 1 1/4", thin walled plastic tube (preferably black similar in size to the factory one), about 2 or 3" long from the fan plenum into the cabin, using black silicone to seal both ends. The vent diffusers are then placed directly over the tubes. You can get by without the diffusers, as the tubes will dump a lot of cool air at you, but the adjustable diffusers help aim it a little.

Adman · 04-19-2003, 06:21 AM

Steve...Performance Aire told me to make certain I had no electronics producing heat in the passenger foot board. Its directly over the return air inlet to the evaporater. Is that an amp in your foot board? If so...is it having a negative effect?
Matthew

Joeaksa · 04-19-2003, 09:45 AM

Steve,

Did you leave some room behind the amp for the airflow into the evap unit? Also, does your evap unit draw air from inside the tranny tunnel as well? Some have another intake that draw air from two places...

Joe

Steve W · Steve W's Garage

When I installed the Alpine processor, I did not know then that there was the location where the AC intake was. Since it's only about an inch and a half thick and a non heat producing parametric equalizer, I don't think I noticed any negative effect on airflow, nor added any heat. The second airhole though, sure adds a lot of airflow. Performance Aire says the flaw of the 911 AC system is not so much the cooling capacity of the system as much as it is lack of airflow volume. And it is not that the blower is incapable, but that the ducting system is an afterthought and poorly designed. Just adding the second tube ports the blower directly to your waistline, and you will get more air from the two tubes than all the other vents combined. I asked about upgrading my small dash vents to the later style ones, for which they said it adds a small but minor improvement in comparison. I asked them about possibly inserting a larger diameter tube, and they said doing so only made it overdump air and that the 1/ 1/4" tube was best. I still haven't figured out how what they meant by that. If you are the primary passenger of your car, and mainly worry about yourself getting the cooled air, bore the second hole so that when you silicone in the second tube, it will aim more towards your crotch. Then you really won't need the diffusers. Actually this just gave me a thought. For what amounts to a couple of dollars, every 911 owner can perform this mod to his ac system for a dramatic improvement to the ac performance. Only then if he is still not satisfied, he can add the Performance Aire diffusers right over it for about $50 more.

Joe, I wasn't aware that air was also drawn through the shifter tunnel, I don't see where the return air would enter, as it looks like it's all carpeted. I would think your car and mine are similar.

jyl · jyl's Garage

I didn't realize the trick was not only to put a diffuser on the bow-tie hole, but to cut a second hole!

Does the modification reduce the noise of the A/C? Here in the SF Bay, the cooling power of the stock A/C is adequate, but at the height of summer I do have to run the fan on high - a lot of fan and air noise. So, does having more vents mean less noise?

Don Plumley · Don Plumley's Garage

Thanks Rick!

Mine still looks the same and works great:

Joeaksa · 04-19-2003, 09:20 PM

Steve,

It was news to me as well then talked to someone who pulled their unit out of the "smugglers box" and found that it draws air from the pax footwell AND a second intake that goes to the tranny tunnel. I remember on my old 911 that it had a shift cover that was actually a grill type cover and now it all became clear.

I am getting ready to pull my evap unit out and will drill the second hole at that time along with the Performance Aire underdash vents. Just installed them today and they look very nice.

Joe