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.
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?
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.
Great video! Loved it.
That was a nice video. Loved It.
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. 
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
Thanks for posting......cornering speed vs straight line speed is always the issue. Can the rear wing be adjusted to be less drag?
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.
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?
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.
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.
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!
[canoe service links]
frenchyd said: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.
If you run any type of oil accumulator it needs a check valve with a small hole drilled in it so that it can provide a backup source quickly, but when oil pump pressure recovers it will re-fill slowly rather than starving the motor until it's charged.
When I went from street tires to purple crack on an autocross car I added an accumulator, but not an Accusump. I had a ~2 quart aluminum canister mounted upside down. I had a 12v solenoid valve wired to the "ignition on" power and a bullet style check valve with a .030 hole drilled in the shuttle.
1. When I first installed it and cranked the car, it slowly filled until the captured air pressure equalized with the oil pressure.
2. When I turned the car off, the solenoid valve closed and trapped pressurized oil in the accumulator.
3. While the car was off I added additional oil to bring the level back up to normal. (I could determine the amount stored in the accumulator by the amount I had to add at this point)
4. When I turned the key to the "on" position, the solenoid opened and pre-charged the lubrication circuit. I could tell because the oil pressure light would go off before I cranked the car.
5. When I cranked the car, the accumulator would slowly re-charge via the orifice hole in the check valve. This allows it to act as both a pre-oiler and an accumulator.
ulrickaka said:[canoe service links]
Yeah, if you can smell the kaka in your canoe... you probably need to a better diy wing in your race car.
I love it when canoes bump threads like this, otherwise I wouldn't have seen the awesome video.
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