First Autocross of 2022 (in which a mailbox meets its maker)!

It's been a tough year for our SCCA Region but Brandon came through and found us a venue while the Wickliffe parking lot cures!  As I finished the Winter upgrades, I was very eager to get on a course and see how they improved things.

I learned that,, in a complex system, such as a car,, (yes, those are nested commas.  Engineers can use nested parenthesis so engineers attempting writing can use nested commas!) an improvement in one area can be a detriment to the overall system.  For example, if one spends the Winter upgrading the front suspension it is likely true that the front wheels will have more grip.  Sadly, if no corresponding modifications are made to the rear suspension a slight tendency to oversteer may be experienced! 

For example, I took this corner in my neighborhood at moderate speed but pushed the accelerator a bit much and experienced catastrophic oversteer.  Fortunately, the neighbors were very nice and allowed me to fix the damage.  Ernest drove bulldozers for the US Army in Germany in the 60's, worked with my father-in-law at CF in Richfield (although they never met), and he and Patricia both volunteer at the local prom and church flower sales.  BB is OK although has a rocker panel dent to remind me to take care of physics!  She also has agreed to allow me to continue to pilot her in spite of my transgressions!

Rex Stout wrote "in a universe based on causation, coincidence is always suspect".  However, I coincidentally heard a podcast about the Chevy Corvair and Ralph Nader's hatred of it, which needed unusual attention to avoid catastrophic oversteer.  For example, a higher rear tire pressure than front, which was unheard of at that time.  Therefore, I used 45psi rear and 35 psi front along with 3 of 18 clicks of shock damping on the front versus 12 on the rear, to almost correct this issue at the first autocross.



However neutral handling (not quite but close) does not make for fast laps at the autocross.  Also, a nominal 232hp in a 2100lb car does not make for hot laps.


My ever optimistic evaluation is:
  1. I really don't know what this engine is producing.  It has a custom intake and custom exhaust with no air box and no catalyst, so my stock ignition and injection tuning is certainly wrong.  Maybe I'll find time for a chassis dyno next summer.
  2. My tires are definitely degrading.  They are 4 seasons old and also driven on the street.  I noticed that pebbles don't stick to them anymore like they do on the tires of other autocrosser's who have 1 or 2 year old tires.
  3. Brandon pointed out on a ride-along that I depress the clutch when braking.  I had no idea but confirmed it at this event.  That could be leading to torque interruptions at the tires which do not help a smooth run.
  4. I have no training.  I like to think I am extracting everything from the car but that is likely untrue.  I was able to adjust my cornering so as to maintain 1.1g in all three sweepers by my last run but still, something is lacking.
In optimistic summary, I have set a solid foundation with my modifications:
  1. Native 50/50 weight distribution, with reduced moment of inertia due to the lighter engine/transmission which is lower and further back.
  2. Fully tunable suspension front and rear.
  3. Independent rear suspension with limited slip differential.
  4. Improved roll center front and rear.
  5. 232hp in a 2100lb car.
But I have done no tuning or optimization.  Hopefully, the flexibility I built in will allow me to get competitive!  It's time to do engineering.  I just need access to a proving ground where I can try all my settings cost free!  Hmmm.

In any case, Keep having #funwithcars !  I will too!

Comments

  1. I think the dyno visit is key. I bet you’ll get significant hp gain

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  2. It’s a pretty amazing car. You have gotten a lot of enjoyment out of it. Plus it strikes fear in the hearts of mailboxes everywhere!

    ReplyDelete

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