F2000 - USA Skip Barber

[imtoofast]

Hey people! -- wow, I wish I had discovered this phenomenal website earlier!

Im a mechanical engineer who has just begun racing myself. Wasnt born rich and only started racing once i could earn some extra butter . Nonetheless, apparently I have some pretty good natural talent. I just won a full ride for the season and am heading out into my racing career - all the while keeping my engineering job.

Im going to be racing the Skip Barber f2000 nationals in the states and wanted to get some expert help on a few issues im facing.

I just attended a pre season test. I went through all the setup changes in the car and notices a few things that I would like to get some help on.

Firstly, these cars were designed for smaller tires and a lighter gearbox. So by nature, the car is not right. It soft and reacts weirdly to std setup changes. Among the things that I notices was that when I tightened the rear bar, the car gained rear end high speed stability and grip - can someone explain this? I would have presumed softening a bar gives you more grip.

Secondly, these are only 150bhp engines with a top speed of around 130mph. There are 1 inch gaps in the body panels - when the panels dont sit right (old cars) - whats the aero benefit if i tape the gaps? or is there any?

I dive in deeper once I can enough people on this thread

Thanks!

[Jersey Tom]

Those cars, to my knowledge, are intentionally under-sprung to really highlight driver errors (so you can improve yourself).

To your first question, "grip" has a variety of interpretations.. even among pro drivers and certainly among amateurs. Really depends on the situation. Adding bar will make a suspension less independent and mechanically compliant. At a place like Sebring or maybe even parts of Lime Rock, it could make the car a bit skiddish.

Other than that, there are a few possible outcomes. One.. if the car's limit trim is noticeably understeer, adding rear bar will make the balance a bit more neutral, use the tires better, and give you a little extra lateral capacity.

You can also have the situation where even though the limit trim is understeer, a really softly sprung car can feel like an oversteer machine through transients just because the car never really takes a set and you're always chasing it around. In that event, adding rear bar and stiffening up the roll response could certainly make the car feel more "planted," and even if the true limit of the car is the same, it let's the driver take a faster lap.

With regard to gaps in bodywork.. taping them up can't hurt, can it? Do a coast-down test, start at the same speed, 3 runs with them open. Car in neutral. Then, tape em up, do another 3 runs. See if it reduces drag at all.

[xpensive]

Wasnt born rich and only started racing...

So, why bother?

Soory, I just couldn't help that one...welcome to F1T!

[Mystery Steve]

... these are only 150bhp engines with a top speed of around 130mph. There are 1 inch gaps in the body panels - when the panels dont sit right (old cars) - whats the aero benefit if i tape the gaps? or is there any?

If you were on an all out qualifying lap, I would say every incremental improvement helps. But when these cars are running together, the draft/tow effect is so great that I don't think it would matter. In the "New Videos" thread, I posted a 3 part YouTube series of a Skip Barber race. They must have had over 100 passes during a half hour race. It's interesting to watch the drivers compensate for the easy slingshot passes. Not sure what class these cars are, so maybe this doesn't even apply, but it's fun to watch at least.

[imtoofast]

Wow - im amazed at the quick replied. Now I know what to do while at work

Thanks guys!

Jersey tom -> I was at sebring during the test- the modified course (turn 1 and then turn 14-16). Turn 1 is where i noticed the most significant change when i went to a harder rear bar. The rear end just planted itself once i turned in. Actually, i had the fastest apex speed to turn 1 - when i went harder on the rear bar.

You bring up a great point about "grip". When I think about it - I could just be feeling a more stable rear end. And that might give me a perception of increased grip - it help me gain more and more confidence with the rear end into high speed corners resulting in me thinking i was getting more grip. The end result was that I was on average 1-2 mph faster than the top drivers into turn 1.

The section through 14-16. right, left, right. I call it the wishes washy section since a soft car like the skippy tends to not like going through there. Here, I found that lowering the rear tire pressures made the car more stable (weird, since your increasing the rear 'softness'). BUT, i was faster when i went higher (through the section's split time) in pressure - it made the car more twitchy but definitely faster against the clock.

so here's the dilema. Im off to homestead miami for the first race weekend in march. The cars are all tested, and like you mentioned, the baseline setup is for a small bit of understeer. my ideal setup for sebring was a little harder in the rear, a wee bit softer in the front, and a bit more pressure in the tires all around. homestead, is a slippery track - very slippery. all corners are 1st gear. so heavy braking and generally low speed. what would be your best guess in trying to get more 'grip'. I tested for an hr on that track and its almost like indoor karting in terms of grip level.

And yes, skippy - atleast at the national level is all about racecraft and the draft. but it helps to have a car setup well, especially when you want to dive in in the last lap and win.

xpensive - hmmm, good point. but here's something. 4 days in a race car - thats it. apart from video games that is. and i wiped out a field of drivers with 8 yrs of exp and at least 3-4 yrs in the f2000 cars. people saw that, and now i race for free hmmmm.. 9 days in a race car -> im among the top 5 drivers for the national championship.. haven't raced yet, though

[sticky667]

xpensive - hmmm, good point. but here's something. 4 days in a race car - thats it. apart from video games that is. and i wiped out a field of drivers with 8 yrs of exp and at least 3-4 yrs in the f2000 cars. people saw that, and now i race for free hmmmm.. 9 days in a race car -> im among the top 5 drivers for the national championship.. haven't raced yet, though

don't get ahead of yourself there pal. you haven't even raced the first race.

[imtoofast]

sticky -> i completely agree. i was being a lil sarcastic. racing is apparently a whole different game and i know i have a TON to learn.

any advice?

[Jersey Tom]

As a baseline, start with whatever setup you used at Sebring, and work from there.

You have to be able to identify the difference between lateral grip, longitudinal grip, balance, and mechanical compliance (particularly with a 'slippery' track).. and how each is affecting your lap time.

If you have tight corners with long straights, getting power down early is essential. To that end...

1) Trying to brake really late has more potential to hurt than help. If you blow entry, you'll blow mid corner.. if you blow your apex you'll ruin exit.. and if you ruin exit you'll be miserable on the straights. If anything brake a tick early or do whatever you need to, in order to make sure the apex is nailed and you can get in the throttle.

2) Be mindful of the rear bar and focus on how it makes the car feel on exit.

3) Inflation pressure is a really good tuning tool both for grip and balance.

How much testing time will you have in advance of the race? As a start you might focus on Baseline, Baseline +3psi all around, Baseline -3psi all around.. move in the direction that improves speed. If you notice the balance could stand to be improved, you can make small (<1psi) changes. Ie fronts +0.5psi, rears -0.5psi.

Do some short runs, then long. There's a "sweet spot" for air pressure.. where going above or below will make for slower laps. You can aim to hit that sweet spot either early in your run, mid, or late. Either way, you'll probably want to make sure that the car is going to be comfortable, precise, and predictable to drive at the end.. ie when the pressure is ON and the sweat is dripping and it's really easy to make mistakes.

As for the race itself.. patience above all else.