Overheating problem after changing bumper

[mcsmarte]

A couple of weeks ago I finally got my replacement bumper for my 99 C2 installed. It is a 997 GT3 replica bumper for the 996 that doesn't need the headlight conversion, only bumper changed. Also installed a GT2 wing on the back - which I guess lets less air in compared to the standard wing.

This past weekend I took it to the track and besides having lots of fun I experienced the temperature needle went all the way to the red after 20 minutes full throttle, and this happened twice that day. I never thought this thing to the end, but the air vents in the GT3 bumper are much bigger and so I thought that at least there would be enough air coming in. And there is a lot of air coming in, but the problem is that the radiator air ducts don't align very well with the bumper intakes and the scooping effect that they have with the regular bumper is now a lot less. The air comes in, but goes around the radiator on the outside and actually pushes on the inside plastic fender.

I have been wondering about 4 options.

1. Installing new radiator air ducts from the 997 GT3, but will they fit? 997.575.321.02 and 997.575.322.02. ~$300

2. Install a center radiator to add extra cooling, but I guess I would need the air ducts from a 997 GT3 then as well? $600-700

3. Removing the radiator air ducts altogether and somehow insulate the inside of the front better forcing ALL air coming in to exit through the radiators? $50-100

4. Installing a ram air scoop on the wing to increase the airflow into the engine compartment and air filter ~$300 painted

Doing 1 and 4 would be my preference, not sure that an extra radiator would give me that much more. Doing number 3 might be easier, but I have doubts myself about the outcome

How much does the air flow in the rear actually matter? I would guess that it is a lot less than the water cooling, but probably still a good thing?

The car looks a lot better than standard I think, but without proper cooling it might not last as long as a regular 996

Anybody with some good advice or experience on this matter?

Thanks

Danny

[1999Porsche911]

Air is going to take the path of least resistance and if you do not have the bumper openings properly sealed with the ducts or other method, little air is going to pass through radiators. I would install the proper ducts as well as run the fans on high to draw more air into the radiators.

Air flow to the engine compartment is also important. The more flow you have, the cooler your car will run and the cooler your intake temperatures will be, giving you more power. You can manually turn on the engine compartment fan to assist in increasing the airflow.

[phillipj]

1999Porsche911,

How do you manually turn on the engine compartment fan?

Thanks!

[1999Porsche911]

1999Porsche911,

How do you manually turn on the engine compartment fan?

Thanks!

Radiator Fan and Engine Compartment Fan Switch Mod

The 3.4 996 runs extremely hot when driving around town in temperatures higher than 75 degrees. This mod is a way to reduce coolant temps back to a safer level, helping to reduce oil temps and improving performance.

The mod consists of installing a switch that will allow you to turn on the high speed radiator fans at any time, while maintaining the automatic operation of the fans. We do the same for the engine compartment fan.

Radiator Fans

Connect a wire to the ground (Pin #85) of the 2 high speed fan relays located on the relay carrier located in the driver’s side foot well. The relays are #20 and #22. Feed this wire to where your switch will be located. Connect the wire to one side of the switch. Connect another wire from the other contact on the switch and then connect the other end of this wire to a chassis ground point.

With key on, this switch will now immediately turn on both radiator fans providing maximum cooling. When you turn the key off, the fans will continue to run for about 5 seconds until the relay shuts down. Your fan operation remains normal when the switch is off.

Engine Compartment Fan

Connect a wire to the ground of the relay located in the relay carrier behind the passenger seat, driver’s side. Relay #8. . Feed this wire to where your switch will be located. I simply fed the wire along the driver’s side of the car and under the door sill. Connect the wire to one side of the switch. Connect another wire from the other contact on the switch and connect the other end of this wire to a chassis ground point.

With key on, this switch will now immediately turn on the fan drawing air into the engine compartment. When you turn the key off, the fan will continue to run for about 5 seconds until the relay shuts down. Your fan operation remains normal when the switch is off. This mod helps keep the engine compartment much cooler when driving around town and is particularly beneficial to any engine that draws its intake air from inside the engine compartment, such as the EVO SC.

If you are adventurous, you can automate the operation of these switches so they will switch off at a specific speed, or operate when vacuum is present only, etc. You can choose any style switch you want and even use Porsche switches. I simply used 2 toggle switches that I installed in the batwing,

Jim

[phillipj]

Jim,

Thank you! I have never tried any electrical work. Sounds simple but a little intimidating This sounds like a really good idea especially in the summer here in L.A. So is the switch visable in the batwing?

Thanks again! great info :clapping:

Phillip

[txhokie4life]

Jim,

Thank you! I have never tried any electrical work. Sounds simple but a little intimidating This sounds like a really good idea especially in the summer here in L.A. So is the switch visable in the batwing?

Thanks again! great info :clapping:

Phillip

You have full control over the fans with a Duramatic as well.

You could then even monitor the exact engine and oil temperatures.

m

[phillipj]

You mean with the Duremetric I could set the fans to come on full time?

[Loren]

You mean with the Duremetric I could set the fans to come on full time?

No, can not be done with any tool - you would have to hard wire them to a switch.

In that case you are taking control away from the DME.

[1999Porsche911]

Speaking of the Durametric software, I was told it does not show ignotion timing. Is that true?