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Windtunnel Test Data - #2 versus #19 - Why such the large difference?


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#2 is the Baseline Test Mule run and #19 is a bone stock 240z. If you look at the front lift of #2, it was approximately 308 lbs while that for #19 was only approximately 207 lbs. The test mule did not achieve that low of a lift value until the BRE spook spoiler was added.

 

Does anyone have any theories as to why there is such a large difference in lift? Is it because the 280z has a larger front opening compared to the 240z?

 

The question was asked before but never answered.

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There were two main differences I recall. The test mule had larger tires and wheels than the stock 240Z, but I'm not certain what the exact sizes were. Probably the main difference was that the test mule didn't have a front bumper on it, just an open grill area. So, there was likely a much larger ball of stagnant air in front of the mule, without the bumper helping to divert air over the car, which increased drag some and front lift a lot.

 

John

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The influence of the front bumper on airflow is an interesting one, there seems to be a trend (in AU anyway) to run competition S30's without one. Thats in classes where very few non standard tweaks are allowed.

 

Eg here is the S30 which won its class in this years Targa Tasmania.

siddins targa 08_thumb.jpg

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Couple reasons that worked for you guys... You have a lower profile than the test mule did, and that lower distance to the ground helped the overall aero overcome the big gaping hole... Fill that hole in and it would do even better...

 

And jt1 is correctabout the other differences... The wheel/tire combo raised the test mule significantly, and as we all know, the underside of an S30 is a bad place to let air hang...

 

Mike

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The influence of the front bumper on airflow is an interesting one, there seems to be a trend (in AU anyway) to run competition S30's without one.

 

Removing weight from the front of the car is always a good thing, and the bunper is as far away from the CG as you can get, so it's even better. In the case of a 280, you're removing quite a bit of weight. However, the optimum solution would be a very lightweight bumper that would help direct air over the car, if the rules allowed it.

 

jt

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