View Full Version : Time spent at 100% throttle in Autocross/Endurance

04-21-2011, 01:13 PM
If some of you guys would be willing to share the time your vehicle has spent at 100% throttle around Endurance and/or Autocross the past couple of years.

I realize there will be variance so if you would be willing to include the year, MI/CA/VIR, engine, and time, I would appreciate it.


Jay Lawrence
06-01-2011, 06:24 PM
For our F4 turbo with ~70kW and ~100Nm, the range is about 5-15%, heavily dependent on driver. Note that this value includes rev-matching too. I imagine for the single teams the value could be somewhat higher.

06-02-2011, 08:17 PM
With our 36 kW CFR450X we're at full throttle 15-20%.

Edit: Just looked at the logged data for endurance at MIS last month, looks like we were at full throttle about 20% on that course. There was a lot of lap-to-lap and driver-to-driver variation.

Scott Wordley
06-14-2011, 08:01 PM
Between 10-20%, even with massive wings, so still majorly grip limited, and over powered.

nowhere fast
06-15-2011, 03:12 AM
Originally posted by Scott Wordley:
over powered

I disagree. If you spend x% of a lap at 100% throttle then additional power will increase your speed for ~x% of the lap.

That said, the low amount of time spent at 100% throttle suggests that bigger gains in lap time may be available elsewhere.

06-15-2011, 02:27 PM
Scott, is that a car with traction control and full-throttle upshifting, or without?

Jay Lawrence
06-15-2011, 03:57 PM
As a point of interest, our 5-15% full throttle relates to a car with 100Nm at about 7500rpm, where 75% throttle gives something like 97% power, so the 5-15% is a little less meaningful. That is in a car with TC but no full-throttle upshift.

Scott Wordley
06-16-2011, 05:00 PM
Nathan, thats my point, in our view better to spend your resources working on things to improve your speed over 85% of the lap rather than the 15%, which consequently shrinks if you are successful.

The "elsewhere" you are talking about is cornering, braking and combined cornering acceleration. All these modes can be improved with more grip through the generation of downforce.

Thrainer, this is with traction control but no full throttle upshifts.

06-19-2011, 05:15 AM
600RR 240-250kg car on 6" hoosiers.
No traction control. No launch control. Cut spark not working on these runs


Blanchard (Professional Driver) during his fastest autocross.

Blanchard During endurance

Matty (team leader, 2nd fastest driver) during endurance

06-19-2011, 05:24 AM
Originally posted by Scott Wordley:
Nathan, thats my point, in our view better to spend your resources working on things to improve your speed over 85% of the lap rather than the 15%, which consequently shrinks if you are successful. I echo Scott's sentiments.
As much as we used to have guys coming in wanting to work on engine, I used to steer them away from it, as they will do a lot "engineering" on another section of the car, and it's more beneficial for the car as well.

Scott Wordley
06-19-2011, 05:43 PM
Interesting graphs, thanks for sharing that.
I like large amount of power modulation you have in the high throttle openings. Did you achieve that simply through good control of the airflow (throttle size, and or Cam), or via retarding the spark? What size throttle body were you running? Most of our modulation is at low throttle openings, with little difference between 60%-100% which I see as a problem for driveability and something I'd like to improve.

Timmy sure is a freak! Make sure you bring him to the car swap this year so we can all figure out how fast our cars can really go.

Did you guys ever test the fuel usage of your drivers? Would be an interesting comparison.

06-20-2011, 06:50 AM
Throttle is a 20mm dual radius barrel throttle body.
The power modulation is achieved through airflow as the motor has been tuned for peak power/torque at all throttle and rpm points.

What your's tells me is that your throttle body is to big. Once you pass 60% opening on the throttle then you already have as much airflow as the motor can consume. Thus wasting resolution.
My understanding is that you want to aim for fueling to level out around the 90% mark (not much change between 90 and 100%). This tells you your motor can't consume any more air, but you have good resolution/modulation.

Some facts from all our endurance last year.
Blanchard and Johnny (our fastest enduro)
Tim used 46.5% of the fuel (3kg total), for 47.7% of the track time (27min 52sec overall)

Matt and Bowler used 6.6% less fuel than Tim and Johnny, 5.8% more track time.
Matt used 56.8% of the fuel (2.8 kg total) for 47.1% of the time (29 min 29 sec overall)

Overall for both endurance (adding fuel and time together)
Tim - 24.0% fuel for 23.2% of the time
Matt - 27.4% fuel for 24.2% of the time
Johnny - 27.7% of the fuel for 25.4% of the time
Bowler - 20.9% of the fuel for 27.2% of the time

You got to love comprehensive data logging.
You want a copy of our data from the comp on Thursday Scott?