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Flat Bottom with Diffuser questions


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I am planning to add a diffuser to my Brunton Stalker similar to what xcarguy created. Also I was planning to add additional under body panels to my car to make it as flat as possible.

 

In the pictures below I plan to add aluminum or carbon fiber panels (the rear splitter would also have rakes like xcarguy).

 

Any thing I should think about before embarking on this project?

 

For example, I wondered why the drive shaft wasn't already covered by aluminum? I plan to cover it but seemed like the opening may be there for a reason.

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You need to be careful to not obstruct too much airflow through the engine compartment and around the transmission, otherwise you will get overheating problems.

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I did this on my Westfield a number of years ago....a splitter at the front, filled in around the sump in the engine bay, stock flat floor pan, and then a diffuser out the rear.

 

Many will say that it's a waste of time given that a Seven is shaped like a brick and I completely disagree. To me it means that there's some big low hanging fruit and the flat bottom was easiest to pick. I get MUCH less lift at speed, it's quieter, and it doesn't feel like you've hit the brakes when you drop the throttle at speed. It works. Why wouldn't it?

 

It's worth the time - go for it.

 

dave

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I did this on my Westfield a number of years ago....a splitter at the front, filled in around the sump in the engine bay, stock flat floor pan, and then a diffuser out the rear.

dave

 

So did you vent the sides of your engine compartment? On my Westfield, the tunnel seems to be where all the air from the radiator ends up.

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So did you vent the sides of your engine compartment? On my Westfield, the tunnel seems to be where all the air from the radiator ends up.

 

Are you asking if I added vents? No....I didn't cut in any additional vents.

 

I wondered about the airflow after it passed through the radiator so I did some string tests so i could see the way the air was moving. I suspect that much of the air that came in through the rad (as well as the openings inboard of the front wheels) went out the bottom of the engine compartment. This would of course raise the air pressure under the car and help create both lift and drag.

 

When I closed off the underside of the car it changed the way the air flowed through the engine compartment. I now have air coming out the side openings inboard of the front wheels (on a Westie these are very big). I also have air coming out the vents at the top rear of the engine cover. These smaller triangular vents actually pulled air in before enclosing the underside of the engine compartment and now air rushes out of them. This would seem to be an indication that I used to have a low pressure area in the engine compartment largely caused by the open bottom and now I have a high pressure area that pushes air out the sides and top.

 

Does that make sense?

 

dave

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I refitted a panel directly behind the nose cone on my Locost. It has been laying around in the garage for years I had just not got around to putting it back on. The car went from running very cool to instant overheating, about 4 laps at VIR and I was at critical temps. There is a lot of air coming thru the nosecone it has to go somewhere. I tried to upload a picture, but it did not work.

 

Graham

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I refitted a panel directly behind the nose cone on my Locost. It has been laying around in the garage for years I had just not got around to putting it back on. The car went from running very cool to instant overheating, about 4 laps at VIR and I was at critical temps. There is a lot of air coming thru the nosecone it has to go somewhere. I tried to upload a picture, but it did not work.

 

Graham

 

Most Stalkers run with open sides on the engine bay; plenty of room for air to escape.

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