136 replies to this topic

[Shi]

Looks like what I wrote was indeed the idea, but I forgot the problem of exhaust valves overheating when you retard the timing so much and keep injecting: http://scarbsf1.word...le-engine-maps/

But that could indeed be a reason why Red Bull can gain so much speed in Q3 compared to other times, perhaps they only use the super map for the 1 or 2 laps in Q3 to protect the exhaust valves?

Also, it seems to be 10% air at the intake, and in the past Renault kept the intake fully open (while not injecting fuel) on overrun to cool the exhaust valves, which is why the ban could not be implemented in Spain, as the Renault engine had not been proven reliable with intake closed to 10%: http://www.jamesalle...-was-suspended/

[Dr. Jimmmah!]

Just a guess, but I think to build in true traction control, the ECU needs to be able to monitor wheel rotation speeds. If you eliminate the possibility of that then you've eliminated intelligent traction control.

TC is wheel slip based, requiring wheel rotation speed and vehicle speed.

[Shi]

TC is wheel slip based, requiring wheel rotation speed and vehicle speed.

For vehicle speed, is it typically derived from the wheel speeds of the undriven wheels, or perhaps with accelerometers+gyros? Thinking about that, what do they do with 4WD cars?

[Dr. Jimmmah!]

For vehicle speed, is it typically derived from the wheel speeds of the undriven wheels, or perhaps with accelerometers+gyros? Thinking about that, what do they do with 4WD cars?

I'm not sure. F1 cars use optical measurements, but they ain't cheap. Certainly not cheap enough to throw on your run of the mill Subaru.

[yonson]

There are many forms of traction control, you can monitor either wheel speed or drive shaft speed vs a known engine RPM or simply rear wheel speed vs. front wheel speed or GPS speed etc... the teams know how fast the engine should accelerate, if you accelerate faster than that you have wheelspin and can compensate etc... there are tons of options/ways to do it.

I'm not sure how they are doing the blown diffuser, in order for the airflow to be effective they need a lot of it, which would use a lot of fuel unless they are running the mixture really lean and retarding the timing a lot. I'll check with some guys I know and see if I can find out some more info on it.

[Nacho]

For vehicle speed, is it typically derived from the wheel speeds of the undriven wheels, or perhaps with accelerometers+gyros? Thinking about that, what do they do with 4WD cars?

AFAIK, it's typically based off acceleration tables. If the acceleration of the wheel speed is outside realistic parameters, the computer determines the wheels are slipping instead of putting power down.

[kngrsll]

this thread is awesome... that crazy mclaren exhaust is cool as shit

[Dr. Jimmmah!]

Very simple solution the FIA came up with to 'ban' the blown diffusers. Let them blow all the exhaust they want on the overrun or under braking for reliability reasons (a la Renault, using overrun gas to cool exhaust valves), but the new rule will mandate that the exhaust must point up (as they did the years before blown diffusers became popular).

That way nobody can argue that they NEED a blown diffuser-type system under braking for reliability reasons.

[Redliner]

Very simple solution the FIA came up with to 'ban' the blown diffusers. Let them blow all the exhaust they want on the overrun or under braking for reliability reasons (a la Renault, using overrun gas to cool exhaust valves), but the new rule will mandate that the exhaust must point up (as they did the years before blown diffusers became popular).

That way nobody can argue that they NEED a blown diffuser-type system under braking for reliability reasons.

...which won't apply until 2012. They'll still allow 10% for Silverstone on.

[tibby]

It's as simple as having an Anti-Lag system for a naturally aspirated car. Which is pretty much what someone was explaining. Exhaust Valve opens...super retarded timing allows the combustion to happen when the exhaust valve is open and all the force goes out the exhaust. Been on rally cars for years to keep the turbo spinning when off throttle.

[Redliner]

[DrDickAction]