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boxedfox
boxedfox Reader
8/18/19 8:50 p.m.

A few weeks ago I finally got a chance to test out the DIY wing and splitter that we had installed on our SCCA STU prepared Honda Prelude racecar. So I figured we should use the opportunity to do a little laptime comparison to see how much faster (or slower) the aero kit made our car.

Here are the results in video form. Hope this helps some of you out there who are looking to do something similar.

 

sleepyhead the buffalo
sleepyhead the buffalo Mod Squad
8/19/19 8:21 a.m.

In reply to boxedfox :

so, there was a 4mph difference due to drag (121 vs 117mph)... what was the corner exit speed, and what was the distance dow the straight to hit those speeds?

boxedfox
boxedfox Reader
8/19/19 7:08 p.m.

In reply to sleepyhead the buffalo :

Distance between corner exit and the start of the braking zone to turn 1 is approx 0.289 mi (or approx 1526 ft) according to the GPS.

In the aero-less car the corner exit speed coming onto the main straight was 98.6 mph.

In the aero-equipped car, the corner exit speed coming onto the main straight was 97.4 mph.

Robbie
Robbie UltimaDork
8/31/19 8:19 p.m.

Great video! Loved it.

Cupulate
Cupulate New Spammer
10/12/19 5:06 a.m.

That was a nice video. Loved It. 

Marcus_NineLivesRacing
Marcus_NineLivesRacing New Reader
10/14/19 10:44 a.m.

Great video! Very surprising the engine had oil starvation at 1.1Gs, though I know almost nothing about H-series.

There are other foils(like a 9LR wáng) that have MUCH lower drag than that 3D foil. wink It can even retain the same down-force or even more depending on what 3D foil it is.  This could lead to very minimal down-sides to the aero package. #shamelessplug 

jungle
jungle New Reader
1/9/20 12:45 p.m.

Thanks for posting......cornering speed vs straight line speed is always the issue.  Can the rear wing be adjusted to be less drag?

boxedfox
boxedfox Reader
1/9/20 1:06 p.m.

In reply to jungle :

Yes it can. The budget uprights I used have a fair bit of adjustability. That said, these 3D profile wings are cambered pretty aggressively, so even if you set it to 0 degrees of angle of attack, it will still generate a good bit of downforce as well as a noticeable amount of drag. If drag was a big concern, I would look for a flatter, simpler wing profile to start off with.

Rodan
Rodan Dork
1/11/20 9:05 a.m.

Great video!  Thanks for posting that.

Is the wing position dictated by your class ruleset?  I would think moving it rearward would help it's effectiveness/efficiency?

Also, what were the lap time deltas no aero/ with aero?

boxedfox
boxedfox Reader
1/11/20 6:51 p.m.

In reply to Rodan :

Yes it is. I'm not allowed to mount the wing any further than the rearmost edge of the rear bumper, and the highest part of the wing can't be higher than the roof at its tallest point. If I could, I would hang the wing off the back of the car, mount it slightly higher, and run it at 0 degrees AoA.

When the motor was healthy, having the aero on was worth around 1.7 seconds a lap faster per lap around NJMP Thunderbolt. The car got slower over the course of Sunday, but that was more due to the repeated oil starvation slowly wiping out the bearings from the bottom end of the engine.

frenchyd
frenchyd PowerDork
1/11/20 7:12 p.m.

In reply to boxedfox :

Most engines will starve of oil in high G cornering and braking. Hot oil is extremely thin. Thinner than water. Add some cornering or braking forces and it wil flow up the side or up into the front of the motor away from the pickup .   Doesn't take many revolutions    without oil to start wiping out bearings. 
Jaguar experienced it  in 1953 with their first D types even with the tiny 5 inch wide tires used back then. .  And by the time they got to the grid they were all dry sumped.  
Accusump delays it a few moments feeding from a oil reserve  but as soon as that reserve is  used up the stock oil pump  is sucking air, not only does it have to refill all the bearings but also the reserve before pressure can start to build up. 
A true dry sump sucks all the oil from the pan and puts it in a tank that tends to be tall and narrow  with the bottom shaped like a funnel. That ensures  there is always a head of oil to feed the oil pump.  
 

Rodan
Rodan Dork
1/12/20 8:09 a.m.

In reply to boxedfox :

OK, that's how most rulesets work with wings, it looked farther forward in the video... probably just the angles.

1.7 sec is a significant improvement... especially with losing 4mph on the straight!

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