[DaveC113]

Testing went well! I ended up lowering the splitter beforehand as the QR mount bolts are hard to get to. This is the biggest issue with the splitter but I don't think I'll be adjusting height much. The rear QR mounts need to go up about 10mm or so to improve the AOA without the front edge being too low, and I have some room to shape the rear of the splitter or add diffusers. So I think I'll get a bit more DF out of it, but I have to say I'm more than happy with the way the car handled today.

Wing started out at 6 degrees and I tried 10, 6 works best for now.

The car can't be street driven with this splitter so I wanted to leave the stock splitter on it, it's riveted and taped on so not trivial to take on/off. AJ's splitter is functional but honestly without a way to adjust height it's up way higher than ideal. A friend got one for his Mustang and while it looks nice it's mounted way too high with no great way to lower it.

My previous PB at High Plains was 2:00.8. New PB is 1:58.3 and I have a ways to go to learn the car's new abilities at speed. The difference is massive. And this is with Vitour P1s I got last winter, with many track days and about 6 autox events on them. Well into the wear bars and they still have a couple more days until they cord I'd guess.

My Dad went with me and took some pics on track I'll post when I get them. Here's one static pic and a vid of the 1:58

[Baddawg53]

Nice results! Significant drop in times there.

My question is, do you think you were at the limit of the car prior? Was the gain there entirely mechanical? I ask because I feel like a lot of my big increases I get after upgrades are more confidence driven than actual mechanical performance driven. Placebo effect I guess. However I know that I'm definitely not driving the car near the limit.

[DaveC113]

Originally Posted by Baddawg53

Nice results! Significant drop in times there.

My question is, do you think you were at the limit of the car prior? Was the gain there entirely mechanical? I ask because I feel like a lot of my big increases I get after upgrades are more confidence driven than actual mechanical performance driven. Placebo effect I guess. However I know that I'm definitely not driving the car near the limit.

That's a great question. The human/machine interface is one of the most interesting things about cars, bikes, skis, and even audio/video systems.

Before I started participating in autox and track events I raced mt bikes in enduro racing which is a series of stages that are only timed on the downhill portions. Mt biking is all about the rider, but the bike setup is critical in that the bike must do what the rider intends. A fast bike is not the same for everyone.

I think cars are similar, although the car itself has far more impact on times than bikes do in mtb, but the overall concept of setting up the machine to fit the driver's preferences are similar. So a fast car is one that fits the driver's style and does what the driver intends. It's difficult to separate that out from some objective truth about whether the car is actually more capable. I think that truth exists but how much a faster time is an improvement in the car vs making the car more in tune with the driver is going to be difficult to separate out.

I think in many cases the truth is going to be some of each. There's no doubt adding 1000 lbs of DF at speed is going to improve grip. But the confidence I get having the rear end planted around high speed corners, the fact I can now trail brake into the apex to a degree I couldn't w/o aero, the overall stability and precision of adding aero is also a big improvement in driver confidence that allows the driver to get closer to the car's limits more of the time.

tl;dr The car is both much more capable and much more confidence inspiring to drive with aero. So far I'm super happy with the results.

[eimarshall]

Nice work!

For adjusting the height on the QR mounts, you could just put shims/washers under the brackets that mount to the splitter. Move the frame mounts to the highest setting you could possibly want and then just use shims to adjust the final AOA of the splitter.

I also fount that the lateral edges of the OEM "splitter" were lower than the middle. I trimmed the whole OEM splitter 5-10mm to allow for more rear vertical adjustment. You couldn't see it had been trimmed unless you layed on the ground next to the car.

[DaveC113]

Originally Posted by eimarshall

Nice work!

For adjusting the height on the QR mounts, you could just put shims/washers under the brackets that mount to the splitter. Move the frame mounts to the highest setting you could possibly want and then just use shims to adjust the final AOA of the splitter.

I also fount that the lateral edges of the OEM "splitter" were lower than the middle. I trimmed the whole OEM splitter 5-10mm to allow for more rear vertical adjustment. You couldn't see it had been trimmed unless you layed on the ground next to the car.

Shims sounds like a good solution to adjust splitter height, thanks! I was going to adjust the splitter tomorrow, so good timing. I may need longer elevator bolts too, no big deal but we'll see if the hardware store has them. I'm using 4 bolts per mount, but that's likely overkill. I think one on each end would likely be enough. So now I'm thinking I'll adjust the mounts 12mm higher than I planned and use a piece of 12mm ply as a shim. Then if I'm at a rough venue that scrapes too much I can quickly raise it 12mm.

There's also the question of diffusers, where they'd go, and diffusers vs AOA in that a larger AOA might eat into vertical space for a diffuser.

Also how much scraping is considered normal?... At HPR the Ti blocks scraped the ground maybe 6 times a lap, just a short scrape and a tiny bit of wear on the blocks at the end of the day. So seems about right, but probably too low for some autox venues.

Here's a few pics from HPR:

[carguy55]

My first attempt at a DIY splitter. I run mine on track with about 3" ground clearance with a 6" extension using 18" tires. The height is easily adjusted by the support rods since its all chassis mounted. The splitter can be lifted and locked in a raised position for trailer loading etc using AJs lift and lock support rods.