SCCA Solo C Street Discussion

[Wepeel]

I've had a few runs where having a passenger has been my fastest run. This was when by BRZ was stock and was kind of loose in autocross. I never thought it was "too loose", I could drive it no problem. But having the passenger stabilized it and allowed more confident/sooner throttle application, without inducing push on throttle, and sooner throttle application is a large contributor to being faster.

I know some of the fastest autocrossers in the country would consider running with more fuel if the rear end needs stabilized and other adjustments are limited. It's not ideal, but in the end, the car that will let you drive it how you want to drive it will result in a confident proactive drive rather than a reactive defensive drive, and should be faster. Obviously driving style makes a huge difference.

[raul]

Originally Posted by 7thgear

Actually, I want the data. And I wish someone had the data, then I'd shut up. But all I'm reading is "don't do it, it's stupid" but no one saying "I tried it, it didn't work"


Because the only known case of someone close to me doing it (on a track, in a stock mustang) actually went faster when he put his spare tire back in. But that was one case, and a spare in a mustang is probably 40 pounds tops, and no known experiments since then. So I dunno.

This is all useless speculation because there are too many variables to consider to call it an experiment. You need the following:

2 identical cars, and I mean IDENTICAL, down to all wear items and fuel level.
A driver who is incredibly consistent.

If you find that, you've got yourself an experiment.

But what if the alignment has to be optimized for the added weight? Tire pressures adjusted. Ride height changed, etc. By the time you optimize all that, you don't have an experiment anymore. You've heat cycled tires, used up gas, fatigued the driver, conditions have changed. What if the setup change is also faster in the car without the weight? There's a reason no one's done it. It's because anyone doing this long enough knows there's a 99% chance it's going to be a fruitless experiment. There's enough physics knowledge and evidence from other experiments to support that adding weight is 99.9% of the time, worse. You're better off relocating weight than adding it. You're better off setting the car up to behave in a way that lets you drive it at 100%, and still be faster in a straight line due to lower weight. The experiment would not have a worthwhile reward because you're only making the car easier to drive, not actually faster, when in contrast, you can do both without compromising.

[Biggins]

Are we forgetting that C-Street is for your stock car with the basic allowed mods and tires? I'll play with pressures and shocks, and if someone beats me, they beat me. There's nothing more i can do to the car, so I'll just keep driving.

[mrazny]

If you're actually asking if it's to the letter allowed, then no. Loose items must be secured. There's no allowance to add additional structures for securing anything. Passengers and Drivers are required to be helmeted and Seat-Belted. someone laying down in the back is not seat belted.

Whether you're gonna get protested? Depends on the guys you run with, whether they care, whether they know to protest, or whether they feel like dealing with protesting *you*.

Run with a passenger laying down in the backseat? now you're also risking pissing off the Solo Safety Steward who *can* boot you. No need for formal protests at all.

Can a passenger be sitting upright in the back seat? in a Twin, yes. In an old car without seat belts in the rear? no. Also, at a local yes, at an actual tour no.


whether this whole thing makes sense in theory, in practice, or matters, dunno. It would be very hard to quantify results. But you're supposed to have fun, if this makes you have more fun, go for it. Within the rules. Maybe just start with running more gas, easy peasy. Or running with the spare in.

[bimmer635csi]

Just some info I found in the 2014 rulebook:

Originally Posted by 2014 SCCA Rulebook

13.2 BODYWORK

F. Spare tires, tools and jacks may be removed.

So it doesn't say you have to leave it in, nor does it say you have to take it out.

P.S. The 2015 draft rules became available today also. I got some reading to do.

[AustinTX]

I'd like to thank 7thgear for the entertaining discussion. He sure knows how to bring out the best in people with his lively argumen<cough> discussions. I'm personally dragging around plenty of ballast myself, but it's mostly due to being a beer nerd

[7thgear]

Originally Posted by Arigh

You are fundamentally limited here by something pretty simple: F=ma

actually, I'm fundamentally limited by grip

[7thgear]

Originally Posted by AustinTX

I'd like to thank 7thgear for the entertaining discussion. He sure knows how to bring out the best in people with his lively argumen<cough> discussions. I'm personally dragging around plenty of ballast myself, but it's mostly due to being a beer nerd

"if you're not pissing someone off, you're doing it wrong"

[7thgear]

Originally Posted by Arigh

Actually I agree with your entire premise, grip is the limiting factor. And if you add more static downforce, it increases grip!

Please melt a few hundred pounds of lead into your trunk, it can only improve the handling.

I can sense the sarcasm but the truth is that it WILL improve handling.

the car won't be FASTER, but it will feel nicer to drive.


if you don't sense an improved feeling of balance when you have friends in the back seat or suitcases in the trunk then I really can't tell you anything more than that is actually the case.

[DylanFRS]

Originally Posted by 7thgear

I can sense the sarcasm but the truth is that it WILL improve handling.

Wow... Beyond any doubt you KNOW that it will improve handling? In what way? Max g-forces? Max transitional stability? Optimal yaw rate? Statements like that with nothing to actually back them up really grind people's gears in this thread. This isn't the stance side of the forum.

You want to get "theoretical", let's see the theoretical numbers behind your statement that increasing weight in the rear will improve handling.

[7thgear]

Originally Posted by DylanFRS

Wow... Beyond any doubt you KNOW that it will improve handling? In what way? Max g-forces? Max transitional stability? Optimal yaw rate? Statements like that with nothing to actually back them up really grind people's gears in this thread. This isn't the stance side of the forum.

when someone says handling to me, it is the ease with which to maneuver a car.


max g forces are max g forces, I never said anything about improving skidpad numbers.


acceleration is acceleration, I never said anything about improving rates of acceleration


optimal yaw rate and transitional stability, if I'm thinking of what you're thinking then yes, a few lead plates along the floorboard behind the driver but before the axle given our current weight distribution should improve those two.




just got heard back from a friend in SM, who had to add 100lb worth of penalty weight to his trunk mid season after going up to a 315 tire. He said that he did feel that the car would "settle better in the rear" but that it might have been in his head. But the fact that it was in his head already speaks for itself.

[raul]

Originally Posted by 7thgear

I can sense the sarcasm but the truth is that it WILL improve handling.

Your problem solving approach is not logical. Fact is, adding the weight, while it might help the car "feel" better, or handle better in certain situations such as a sustained corner, it is not going to be the optimal solution. If you have adjustments available to you such as ride height or tire pressure changes, you don't add weight to solve a problem otherwise solved without adding it. Play with rake and tire pressures to change the balance of the car to get it to handle how YOU want.

Presumably, if you're thinking about adding weight in the rear, it's because your car is too loose. Instead of adding weight in the rear to increase grip, how about reducing grip in the front by adding a pound or two of air? You can induce a balanced "feel" while cornering without adding the weight. Adding the weight in the rear will also increase the pendulum effect the car has while going through a slalom, and while it might have higher sustained cornering grip, it will be, arguably, harder to drive AND slower through a slalom. Your theory of adding weight falls flat because it is not inclusive of situations like slaloms. Predictability is what you want, and there's no reason to add weight to achieve it. If your car is loose, you can even play with toe settings in the rear to make it easier to drive.

[raul]

Originally Posted by 7thgear

if you don't sense an improved feeling of balance when you have friends in the back seat or suitcases in the trunk then I really can't tell you anything more than that is actually the case.

It's terrible. The weight moves around. And having 1 friend in the back also does not help. The car turns left better than it does right, making it more difficult to drive due to it not being predictable.

[vroom4]

I'm selling my full prep CS setup for 1100 in wilmigton nc if anyone is near.