During the September 2015 Silver State ORR I ran a few "tests" to see if I could reasonable move up to the 180 mph class, but I found the car had problems dissipating heat at sustained higher speeds (over 195 MPH). At the end of the race most of the water had boiled out of the intercooler reservoir.

In April, before the last NORC Open Road Race in May, Bill and I removed the passenger side headlight to allow more air flow to the intercooler heat exchanger (radiator) mounted in the fender.



Well at the end of the race, even though I averaged 2.2 MPH faster (172.4 vs 170.2) and hit 209 MPH, there was still most of the water left in the intercooler reservoir. I still had heat issues when making the 10 mile run in the Speed Trap straight, but it was controlled a lot better then before.

This summer I decided to remove the headlight from the driver's side and add a larger heat exchanger in that fender. With Bill's help I removed the headlight, but because of the ABS parts hanging in the fender area, I couldn't mount the larger radiator, so I went with an additional smaller unit.



I added a vent at the top of the fender, similar to the one I added to the passenger side, and mounted the new unit above the old one. But since this one won't have the air ducting and shroud as the old unit, I added an 8" fan in front.



I added more photos and info on my web site ( http://928.jorj7.com/intercooler/#Update_3 ).

Since the car is still occasionally driven on the streets, Bill and I had installed HID driving lights in April to help with nighttime visibility. I also tried LED bulbs in the fog lights, but they didn't perform as well as the existing fog light bulbs. With the removal of the last headlight I decided to install HID projector headlights. Porken and a few others have done this modification, but there are not kits available for the 928, let alone a low cost one for an occasional use vehicle. So I decided to try my own installation of one of the cheap universal HID projector kits currently on the market. They usually require you to use and modify the existing headlight housing, but I would have to build my own mountings and enclosures.

Here's what I came up with:



Not a factory look, but should be good enough for my application, especially since the total cost was around $150. They would probably perform a little better if they were mounted higher up, but I want to keep the wind resistance as low as possible, I made them to mount flush with the body.

Here's a comparison of Low Beams, old driver's side and new passenger side headlights:



High Beams comparison:



And one more of just the new Low Beams:



I added more photos and info on my web site ( http://928.jorj7.com/HID-Lights/ ), with a lot more photos in the Project Photo Gallery ( http://928.jorj7.com/HID-Lights/HID-Lights/ ).

Lastly, to try and get more heat out of the engine compartment, I added an additional vent in the hood behind the passenger's side radiator:



Next up is tuning before the September SSCC event.

__________________
George
90 S4 Grand Prix White (Murf #5)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com

 

Are those, residential air duct covers?

 

Yes, with the edges cut off so they will mount flush. They seemed to be the only thing I could find in the dimensions I need. They aren't the optimum shape but they work better then just having bare slots.


__________________
George
90 S4 Grand Prix White (Murf #5)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com

 

I like it, well done!

 

Hi George,

If any air flow can get under that cover plate on the lights modification you may create one hell of whistle at some speeds! If you could fit a perspex plate flush over the total aperture that would be brilliant.

As this 928 is now an out and out race car function has to take precedence over form if you are going to get all that additional heat out from under the bonnet- no mean task.

As always do keep your fans [friends] informed as to how you are getting on.

Rgds

Fred

 

did you keep the little lever, so you can adjust the airflow direction?

 

Hi Fred,

I had to look up what perspex was, we call it plexiglass. I used a polycarbonate plate to cover the opening. It's suppose to be a little stronger and more shatter proof. I guess it doesn't show up well in the photo. Here is another angle:



I cut it to shape, then bevelled the edges. Once I know that everything is working well and don't need to do any further adjustments, I probably use silicone caulking to seal the edges better.
__________________
George
90 S4 Grand Prix White (Murf #5)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com

 

That would have been nice for when it rains... but I used the register intake vents that don't come with a closing shutter, so I didn't have that option. They are less expensive though.


__________________
George
90 S4 Grand Prix White (Murf #5)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com

 

[QUOTE=jorj7;13548008]Yes, with the edges cut off so they will mount flush. They seemed to be the only thing I could find in the dimensions I need. They aren't the optimum shape but they work better then just having bare slots.



Being data driven...is there data that says these work as venturi vents at all?

A naca duct is NOT hard to buy and install...

 

Wow, I really like that.

 

[QUOTE=Speedtoys;13548467]Just look at the shape, they have to create a low pressure if the air goes up.

 

From what I know, typically Naca ducts are good for getting air in from a moving air flow, but I'm trying to get air out from a partially closed off area into a lower pressure air zone. The shape of the vent vanes will effect how well they perform at moving the air out and causing less turbulence in the air flowing over the car surface. I can't find the source right now (which is really frustrating since I researched this last year when I put in the first set of these vents), but from what I remember a rounded shape that protrudes into the air flow is better then a straight angular shape or just a flush opening. There are specifically designed vents for cars that have the optimum shape to allow air to flow out of entrapped areas, but I could not find any in the sizes I wanted at a cost that worked for me. Obviously if I had the source material it would be more convincing to you. Maybe someone else can help find it for you.

__________________
George
90 S4 Grand Prix White (Murf #5)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com

 

George--

A NACA duct is equally useful getting a relatively non-turbulent air exit. Don't discount the possibility, as it will allow much better airflow too.

 

George,

What you need on the bonnet and wings to get air to flow out is an aperture that does not have "line of sight" permitting direct flow entry- what you have fitted should achieve this and the air flow over those vents will indeed create a venturi effect which is what you need to happen. The kit you are using may not be the most efficient but if you look at factory cars that have such like the Jaguar XKR of a decade ago your efforts look very similar. What one should not do is place them in areas of high localised pressure like at the base of the windscreen.

Given you are develpoing power levels around twice [?] that of a stock 928, you need to get rid of twice as much heat, presumably in equal proportions in both exhaust and the engine bay, something the car was not originally designed for. If you look at the belly pan this does the same thing but over a much larger area than those top surface vents so whether the additional flow gained is significant is the interesting bit- presumably experience will tell.

Probably not relevant but given the speeds you are travelling at the forces in play are much greater than on a stock 928 and aerodynamics are going to be critical given you are travelling at 50 mph more than a 747 takes off at. The belly pan [as I understand ] creates a ground effect as it sucks the car to the ground and the faster you go the more ground effect is developed so presumably you need to be careful you do not rip the belly pan off [assuming you run with one]. On the other hand presumably you have to consider what the impact is of sucking air out of the engine bay via the topside of the car at those speeds [i.e. will it have any impact on the overall equilibrium of lift forces]. I can visualise the issues but I do not know the answers - I do remember what happened to Mark Webber at Le Mans going down the Mulsanne straight- he went airborne! When watching your wonderful videos of the last event I perceived that when you were going flat out the car seemed [not at all surprisingly] to be "floating" somewhat

I know Carl did some wind tunnel testing on his 928 - presumably he wanted to know how his car was going to react at similarly high speeds at Bonneville. No idea if you have the support of any aeronautical engineer but maybe it is something to consider if you have not done so already but given your approach of building up bit by bit you wil probably have a very good idea of how close to the limit you are [assuming such exists].

Best wishes

Fred

 

do you run any "antifreeze" in the intercooler system? I do, if anything to help with corrosion. I have heard mine bubbling in the past also, so it helps with the boil off also..