Dynochart - need opinions

[ChrisZang]

So, yesterday was my first DE of the season at Thunderhill and it turned out to be a cold day of constant downpour. So after two miserable sessions I threw in the towel.
As I had some time to kill, I went to the local race store on the track and had my car Dyno'ed

Considering the mods I made so far:
cat bypass, Pedro "techno-torque", underdrive pulley, low restrictive exhaust, Softronic chip tuning, I had hoped for a significant increase in HP and Torque

Negatives were: low octane (91) and high humidity

The Dyno rsults had my peak wheel HP at 215 (which should translate into maybe 260 ~ 265 crank HP) and 195 max. torque



So I was hoping for a few opinions or comparable Dyno results

[ckkrause]

Just a thought.... I avoided DE sessions, (early on), then racing in the rain for several years... Finally, in fall/winter 2011, I bit the bullet and stayed out on track in the race car in the first weekend of constant rain. It horrible... I had a death grip on the wheel and was about 40 secs(!!!) off my best times. So the next race weekend I went out in the rain again after reading tons of stuff on line about racing in the wet and got a little better... particularly when I relaxed the death grip... It wasn't until the 3rd wet weekend that I finally stopped trying to "race in the rain" and started to drive by feel and get smooth.... Eventually I got within about 15 sec. of my usual times and even won one of the races as I was one of few who didn't spin.... and it became a different kind of fun.......

Stay with it!

-Chuck

w/respect to the dyno... since you should assume a loss of about 15%, you were probably getting more like 250 hp...

[blue2000s]

I wouldn't get too hung up on numbers from a chassis dyno. They vary alot from dyno to dyno and day to day. The only real use for a chassis dyno is real time tuning and maybe to do a to b comparisons on modifications that you can make within a short amount of time. I'd be surprised though, if your mods netted more than 10 real horsepower.

[Topless]

Looks about par for a 2002 Box S Chris:
Finally: Dyno charts of de-snorked 986S!!! - 6speedonline.com Forums

I wouldn't get too worked up though. As others have said, high humidity and dyno runs do vary a lot from day to day.

[ChrisZang]

Bonus question:

Do I get it right that my "sweet spot" for shifting up should be between 5.5k and 6k RPM?

[fivepointnine]

no, you want to run the engine higher, that way when you hit the next gear you are in the power band

[Topless]

Originally Posted by ChrisZang

Bonus question:

Do I get it right that my "sweet spot" for shifting up should be between 5.5k and 6k RPM?

Based on your torque curve I would use a shift point of 6K. Torque begins to fall off after that. Run to redline only when you need to extend a gear and avoid a shift approaching a corner. YMMV

[blue2000s]

Please explain what you mean by "sweet spot". For maximum acceleration, the best place to shift is at or near red line. It maximizes the torque delivered to the rear wheels. This can get to be a very heated discussion, by the way.

[ChrisZang]

With sweet spot I mean what gets me the fastest laptimes

So if I remember the old saying "Horsepower sells cars but Torque wins races" where in the Dyno-chart should I look?

[amschnellsten]

As said earlier dyno results are only helpful for comparison. Your numbers are not bad though.

[Topless]

Originally Posted by ChrisZang

With sweet spot I mean what gets me the fastest laptimes

So if I remember the old saying "Horsepower sells cars but Torque wins races" where in the Dyno-chart should I look?

Ignore the dyno chart. While blue2000s is absolutely correct from a theoretical standpoint, it gets more complicated on a race track. For fastest laps you must prioritize:

1. Maximum momentum through the corners
2. Maximum grip (wheel spin and drifting sideways is slow)
3. Maximum acceleration on the straights
4. Minimum input (every time you shift, brake, or turn the wheel the car loses momentum and slows down)

Often this means carrying a higher gear through a corner to maintain momentum and reduce driver input as long as you can stay above 4k rpm. On long straights with unlimited traction, always shift at redline for 4th, 5th gears.

[Ghostrider 310]

Picking the cleanest line should be on the list too.

[Topless]

Originally Posted by Ghostrider 310

Picking the cleanest line should be on the list too.

Of course. The cleanest line is the one that makes those other 4 things possible.