Van

Of course the splitter looks cool... But does it actually work? I mean, work as a splitter to create more down force on the car?

I can answer that question! The answer is YES!

As some of you may know, I'm becoming a data acquisition junkie. I've installed ride height sensors on my car - to some degree, to specifically test Patrick's splitter.

Below is the data (let me know if you have any questions!):



And, of course, a big thank you to CPR for developing a unique product.

Chris White

Montecello? I'll be there on the 30th...
Nice data aquisition - what set up are you using for ride height?

PorscheDoc

I noticed a HUGE improvement coming over alpha zero at heartland park with the splitter. Alpha is after a long straight,you crest a hill then come downhill into a hard right hand turn. Before I would be very light throttle going over the hill (about 115mph), then had to wait for the car to get settled on the other side before I could hit the brakes quickly and turn (and there isn't a whole lot of room to get set up and slowed down). That second or two waiting for the car to settle with the turn coming at you fast is a little frightening. Now I come over the hill full throttle, the car is settled the entire time, tap the brakes on the other side and turn hard. I put a lot of distance on people over alpha and through turn 1 now. I hope there is a way he can continue to make them, as I think everyone should have one.

Van

Monticello's great fun - the last track event I did was there with CVR. (I didn't reset the track name when I did these data runs...)

I have potentiometers on the sway bars. A home-grown, custom solution - but it seems to work!

Wormhole

Hey Van, nice work. Any data on something like a GT splitter for comparison?

Van

Send me a GT splitter, and I'll do a comparison!

Duke

Very cool. I'd like to see that data in combination with GPS track overlay of 2 identical laps with/withou.
So how did the splitter affect lap times?

333pg333

Nice work Van but I'm a little perplexed. Seems to be a massive speed mph difference in parts. Are you saying that this not only increased downforce but also drag? Was this done on the same day?

Van

This was done on a road near my house... not on a track.

Same road, different day - the ONLY thing that changed was the splitter. Everything else (even the tank of gas) was the same.

Because this is just on a piece of road, there are no lap times. The speed is just what I felt was prudent - I was shooting for about 80 (kinda forgot on that first run where I went up to 100...) What's cool to see is that in the 2nd part of the chart, with the splitter, it made more down force at 45 than I made at 60 without the splitter.

Duke

A relevant question - what spring rates do you run?
I suspect pretty high?

fastmover

You got it 333pg333, anytime you increase front or rear downforce or even wide fenders or fender flares, you are creating more drag on the vehicle and mph will be affected.



Semper fi

Van

I run a 450 lb/in spring in the front. That gives me a wheel rate of about 370 per side - which would be 740 lbs/inch total for the front.

At rest, my front ride height sensor reads about 2.68 volts. You'll see that the blue line is pretty consistently above that - which means the front of the car is actually making lift. The red line is much closer to that baseline - the downforce of the splitter is counteracting the lift.

From my measurements, when the front of the car moves up or down by 0.1", the voltage changes 0.02 volts.

On the speed graph, where the 2 lines cross each other, is about 85. At this point, the front ride height with the splitter is about 0.5" lower. This means there's an extra 370 lbs of force pushing down - I think that's considerable.

DanR

WOW, that seems a lot! Especially on the front, have you noticed and imbalance effect due to adding front downforce without impacting the rear? Wondering if the rear is prone to any oversteer tendencies??? (relative tendencies that is)

got any pics of the car post install

Van

Dan, I only got it on a few days ago - and just drive it around town. So it's too early to know how it "feels". But I have a hunch it should be complemented with a better rear wing...

Of course the car is now all torn apart for a new water pump and belts...

Some pictures are here: https://rennlist.com/forums/944-turb...r-pics-19.html

333pg333

Sorry for sounding obvious, I should have been more specific but I find that the speed differential is too much simply to be put down to drag. I ran this splitter too and didn't notice so much of a change in top speed at the track. In hindsight there was a bit though. Maybe 10-15 kmh slower, but that could have easily been due to a slow corner entry speed onto the straight due to crap tyres.

EDIT: I now realise that the speed was indiscriminate and not the object of measurement.
I wonder what results you'd get with a true splitter rather than this which I would describe as a hybrid
splitter / air dam ?