Tuesday, August 21, 2012

Controlling the launch

The Focus WRC 02 car I drove in 2003 and 2004 did not have the same comprehensive launch control system as the 04 car I drove in 2005. In fact, I never used it on the '02 car. I could press a green button on the steering wheel which revved the engine at the optimal rpm and boost for the start. I still had to operate the clutch, which is the tricky part.

I found gravel is the easiest surface to start on. Rev the engine rather high and dump the clutch. Piece of cake. Tarmac demands more control, you have to feed the clutch gently. Finding the right balance between not burning the clutch and not stalling is the key. Starting on ice and snow is the trickiest. How to do if you are sitting, for example, on the start line of a Swedish stage, on fresh ice and snow? You can't rev it up and dump the clutch. You'll just find yourself wheelspinning, going nowhere... Feeding it tarmac style won't do it quite either. The secret is to get the car to roll a little bit forward, being careful not to stall, and then dump the clutch gently. Sometimes you'll see drivers dump the clutch brutally on icy stage starts. They can do that when there has been many cars starting on the same place and the ground is dug up to the gravel.

 '02 Focus WRC
In 2004 Rally Monte Carlo the Ford head engineer chatted with me just after shakedown. He said he had been sitting on the start line and timed my start against Markko Märtin's. We had exactly the same time and he said that was a good start. We had coldish tires on damp tarmac and the start led up the hill perhaps a hundred meters until a sharp right, out of the town of Sospel. Markko  was using launch on his '03 spec car, I wasn't. I had a good start there but it wasn't always the case, in fact many times I was unhappy with my starts. From the '03 spec car onwards and including the '04 spec I drove in 2005, launches became a breeze. Here's why:


No matter what, it is always perfect. The result of a very expensive high tech transmission.

Here's what happens in the car:

Once I arrive at the stage start the marshal calls me to the start line if it's free. At this point, on gravel or snow, if I see ruts I'll settle the car in them. That's where grip is best for the launch, unless I think they're too deep for the car. This happens a lot if you run way down the order or on the second pass, at which point the start line often looks like a potato field anyway. 

Once I am nested in, I give a last tightening on my belts, check if all the stuff I need is on, etc. 

I then ask my codriver to read the first 3 or 4 corners out loud so I can visualize my stage beginning and let it flow onwards.

When 10 seconds remain I hit the "STAGE" button which you learned about in my previous post: RSI : Water injection.

Immediately after I push the clutch pedal and engage 1st gear.....clank.

I pull the handbrake, at this point the engine revs up automatically to the optimal amount of rpm preset in the program.

I let go the clutch pedal and the car holds in place...Did I mention the car is equipped with a  hydraulically controlled clutch?

I push the throttle to maximum but the revs remain as before...the boost kicks in.

5,4,3,2,1... I let go the handbrake and the car goes, like magic, every time. A perfect start.

All I have to do then is shift into 2nd gear and drive the stage normally.

If for some reason the computer detects a malfunction during the launch sequence a warning message flashes on the display. All I have to do in that case is keep control over the clutch and launch manually.

'04 Focus WRC
I might have mentionned it before but that magic clutch also kicks in automatically when you spin out, just to keep that engine running for ya. It's there just in case you don't get the reflex to push the pedal in time... A good time saver considering the engine can be a bit long to restart when very hot just after an in-stage stall.

Monday, August 20, 2012

An ARB question

from OldF:

"...Not knowing what you are going to write about, one issue I can’t recall you have been writing about is the anti-roll bars. I know they’re stiffer on tarmac rallies (as the whole suspension set-up) compared to gravel rallies but what is the relationship to other suspension set-ups (spring stiffness, dampers settings etc.)?

Is the suspension set-up chosen for a tarmac or gravel rally and the anti-roll bars stiffness by the suspension set-up or are they chosen independently (slow and twisty tarmac / gravel rallies compared to fast tarmac / gravel rallies or any combination of these)?

I’ve read some book that by the choose of a stiffness of an anti-roll bar, you can make a choose if the car is more under steered or over steered."

Hi OldF,

I hope I understand your question correctly. By the time I got to drive the '04 car there was obviously all the set-ups already determined by Markko and Francois which were in my opinion the best you could have for that car given what they had to work with. To my knowledge we did not modify the ARB's (anti roll bars) during the rallies for slow/fast conditions unless it rained, then we changed the whole setup. The thing the team played around the most with was damper specs and settings. I believe there was a different damper spec for every event or almost.

ARB's, on the other hand were generally always the same for given surfaces.  Sometimes a driver would go one step up or down on front or rear to tweak the car balance. Springs were the same philosophy, generally always the same for a given surface...maybe 2 or 3N up or down for tweaking. Cyprus had the same springs as Finland or sweden...!

Diff maps were the other thing everybody played around with ALL the time.

"I’ve read some book that by the choose of a stiffness of an anti-roll bar, you can make a choose if the car is more under steered or over steered."

Sure, for example I often ran very soft ARB's on the car to improve the grip on the rear. The reason for this is I always liked to drive a car "from the rear" if you know what I mean...? The rear ARB's was so thin on my car that it broke on occasions.  The difference is very subtle, and in my experience it's especially the case on tarmac. I had a case in Catalunya, on a long stage that we ran for the second time, where I could not find a good flow and rythm...something was off and the time was slow. I was confused and thinking really hard what was wrong on the road section...the car felt ok! Then when I rotated the tires I noticed the rear ARB link was hanging down, broken. In my experience the ARB is extremely important for the car balance but the changes it makes are very subtle to feel. It's not like if you change springs...

In my opinion this car was what the french call "une auto pointue" which in my definition book meant that the car was hard to set-up efficiently, because it was difficult to feel the subtle but important differences. Sometimes the only way to know was to look at the clock but please don't get me wrong, the team knew how to setup the car in the best ways. I was extremely happy with my suspension setups.

I hope this answers your question.

Sunday, August 19, 2012

RSI: Water injection

Did you know that the Ford Focus WRC cars I drove had a water tank sitting behind the seat? It was filled with distilled water. Do you know what it was for? Two purposes really. A few seconds before the stage start, I switched a button on, called: STAGE. This button turned all the funky stuff on. It turned the "valves" on (diffs), the ALS on (anti lag system), the stage engine map on with max power and hence water injection. 

If you have ever heard of water injection then you will know that when the engine map is switched into stage mode, water gets sprayed in a very fine cloud, in the air/fuel mixture.


After air passes the turbocharger, it obviously gets compressed but subsequently also heated up quite a bit. 


In turbocharged engines the air and fuel mixture that enters the cylinders can sometimes explode before the spark plug ignites, usually because of extreme temperatures. It can also be due to too low octane fuels but we always used high quality fuel so bar that one. Too much ignition advance or too much turbo boost are obvious other reasons. This early detonation is called engine knock or pinging. I heard this phenomenon once in 1998 when one of the Toyota Team Sweden Celica Group A cars drove by me on the Swedish Rally. It sounds like a very high pitch rattle. This effect is extremely destructive to the engine. To avoid pinging, water is injected along with the fuel and air in the cylinders. This provides additional air cooling and therefore denser air, adding power.


The inter-cooler is there to cool the air down before it reaches the inlet manifold and if I remember correctly the injection happens directly at the entry of the inter-cooler. I may be off on this so if anyone has the knowledge please comment!

In any case water injection is a system which has been used in engines for a long time and as early as for military aircraft prior to WWII.

Back to our WRC Focus, water was also used to cool the inter-cooler radiator . There were a number of sprays which dumped water onto the outside of the radiator when the cooling fluid temperature was exceedingly high.

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