Peugeot 908 secret=Ferrari F1's J-Damper

[chernaudi]

I read Marshall Pruett's Le Mans analyisis about why Peugeot lost Le Mans, and he made a refernece to the 908's seemingly ultra-stiff suspension giving them trouble in the rain and on bumpier sections of the track at Le Mans. It's well known that Peugeot driver Marc Gene is the lead test driver for Ferrari's F1 team, and it seems that Gene may've spill some secrets about Ferrari's F1 challengers' suspension to Peugeot. Also, Paulo Cantone also worked for the Ligier(aka Prost post 1996) F1 team.

What I'm trying to get at is that the Pug's ultra-stiff suspension set up probably has links to modern F1 car suspensions, namely Ferrari's J damper system. Granted, at Mulsanne Mike's site, the rear suspension looks coventional(aside from the T-bar/Watts linkage-type device on the top of the gearbox), but with the front suspension buried in the front of the monocoque, one can't really see what's going on aside from the uprights, pushrods, and torsion bars. And with the way that everything is packed in the nose of the 908, could Peugeot be hiding something they don't want others to see, let alone copy or replicate.

Of course, if Pug has drawn inspiration from the Ferrari J damper, it's probably not a 100% copy(the 908 probably uses conventional shocks, instead of Ferrari F1 cars' rotory dampers), but it does seem that they've been able to replicate the functioning as far as how the suspension acts.

So my questions are is just the suspension setup the key to Pug's success in the LMS so far, and could the stiff suspension be there to mask that the 908's tub might not be as stiff as we think it is(Cantone's efforts at Courage weren't known for their chassis rigidity, and the 908's monocoque has two huge holes in each side of it for the doors per ACO/FIA/IMSA rules), and if the suspension set up is the villan of the piece, why doesn't Audi stiffen up their suspension settings?

[MulsanneMike]

Originally Posted by chernaudi

I read Marshall Pruett's Le Mans analyisis about why Peugeot lost Le Mans, and he made a refernece to the 908's seemingly ultra-stiff suspension giving them trouble in the rain and on bumpier sections of the track at Le Mans. It's well known that Peugeot driver Marc Gene is the lead test driver for Ferrari's F1 team, and it seems that Gene may've spill some secrets about Ferrari's F1 challengers' suspension to Peugeot. Also, Paulo Cantone also worked for the Ligier(aka Prost post 1996) F1 team.

What I'm trying to get at is that the Pug's ultra-stiff suspension set up probably has links to modern F1 car suspensions, namely Ferrari's J damper system. Granted, at Mulsanne Mike's site, the rear suspension looks coventional(aside from the T-bar/Watts linkage-type device on the top of the gearbox), but with the front suspension buried in the front of the monocoque, one can't really see what's going on aside from the uprights, pushrods, and torsion bars. And with the way that everything is packed in the nose of the 908, could Peugeot be hiding something they don't want others to see, let alone copy or replicate.

Of course, if Pug has drawn inspiration from the Ferrari J damper, it's probably not a 100% copy(the 908 probably uses conventional shocks, instead of Ferrari F1 cars' rotory dampers), but it does seem that they've been able to replicate the functioning as far as how the suspension acts.

So my questions are is just the suspension setup the key to Pug's success in the LMS so far, and could the stiff suspension be there to mask that the 908's tub might not be as stiff as we think it is(Cantone's efforts at Courage weren't known for their chassis rigidity, and the 908's monocoque has two huge holes in each side of it for the doors per ACO/FIA/IMSA rules), and if the suspension set up is the villan of the piece, why doesn't Audi stiffen up their suspension settings?

Couple of things:

Wouldn't matter how stiff your suspension was if you had a flexing tub. And there's little reason (much less proof) to think the 908's tub is flexible. If anything, a coupe tub has more potential stiffness than a open top tub inspite of the door openings. And the "openings" are that in name really, I doubt they have much impact on stiffness.

A suspension's relative "stiffness" is meerly a tool to contol the underfloor's relationship to the ground, in and of itself it doesn't make a car faster. So Audi won't necessarily find performance by making their platform "stiffer". And the harder the suspension settings, the less mechanical grip there tends to be.

If anything, I'd go out on a limb and say, if we agree the 908 tends to generally run a stiffer setup than the Audi (and short of knowing spring rates we're just guessing and going on what a TV commentator threw out there) than you can point to a much more ride height ciritcal aero platform hence the need for a more rigid relationship to the ground. And again, if we agree that the R10 runs softer, we can argue that the Audi's aero performance is more docile (and frankly, therefore, potentially better) than the 908.

[AU N EGL]

would not a stiff tub / chassie and softer suppension keep the tires on the pavement more?

[chernaudi]

Originally Posted by MulsanneMike

Couple of things:

Wouldn't matter how stiff your suspension was if you had a flexing tub. And there's little reason (much less proof) to think the 908's tub is flexible. If anything, a coupe tub has more potential stiffness than a open top tub inspite of the door openings. And the "openings" are that in name really, I doubt they have much impact on stiffness.

A suspension's relative "stiffness" is meerly a tool to contol the underfloor's relationship to the ground, in and of itself it doesn't make a car faster. So Audi won't necessarily find performance by making their platform "stiffer". And the harder the suspension settings, the less mechanical grip there tends to be.

If anything, I'd go out on a limb and say, if we agree the 908 tends to generally run a stiffer setup than the Audi (and short of knowing spring rates we're just guessing and going on what a TV commentator threw out there) than you can point to a much more ride height ciritcal aero platform hence the need for a more rigid relationship to the ground. And again, if we agree that the R10 runs softer, we can argue that the Audi's aero performance is more docile (and frankly, therefore, potentially better) than the 908.

Well if the Pug has to run a stiffer suspension to maximize their areo package, wouldn't it show up in their peformance? I've seen footage from Spa and Le Mans of the 908, and at Spa, it seemed like the 908 porposed quite a bit over the bumps there, and it seemed at Le Mans(even in the dry) that the 908 was a handful to drive-it was constantly kicking loose out of the Mulsanne Chicanes and out of Arnage, and almost seemed to have haphazard handling over the curbs and such. Such characteristics seem to point towards running a fairly stiff suspension set up. That, and the fact that the 908 was burning it's rain tires off unless the track was thoughly awash.

I mean, the Pug might be fast, but it can't possibly be easy to drive under most conditions with that stiff suspension. So is the 908's advantage basically down to just being a new car, or is it down to one or two tricks as far as aero or suspension/chassis set up?

[cmk]

One would have to say that the issue in Cantone's flexing Courages was less the former and more the latter. I wager that the Peugeot tub is nice and stiff. The issues of the suspension itself I will leave to those who actually engineer chassis.

[ss_collins]

Well without getting too far into it I believe that the 908's were fitted with inerters ("J-dampers") at Le Mans. They are not a Ferrari thing either rather a McLaren / Cambridge university invention.

The Renault/McLaren espionage affair last year let a lot of the technical data out into the open.

[chernaudi]

Originally Posted by ss_collins

Well without getting too far into it I believe that the 908's were fitted with inerters ("J-dampers") at Le Mans. They are not a Ferrari thing either rather a McLaren / Cambridge university invention.

The Renault/McLaren espionage affair last year let a lot of the technical data out into the open.

So you're the one who actually came up with the Peugeot J damper deal that Marshall mentioned.

I do have a couple of questions Sam-what did Peugeot think that they could gain by using the inerter shocks/J dampers, and are they, at least in part, responsible for the 908's peformance gains against the R10(at least in dry weather)?

[chernaudi]

In case one needs to know what a J damper is, look at post 3 here: http://www.speedtv.com/forums/viewthread/225951/

It seems to be a way to get around F1's ban of the old mass damper, as the weight is part of the suspension in the J damper, it gets around the original mass damper ban.

I don't know if this is accurate, but the rear suspension packaging on the 908 seems to lear towards the use of some type of J damper(of course, none of us have seen the full front end suspension assembly of the 908, but undoubtedly if they use inertia shocks on the rear, they have to be up front).

[FIRE]

http://www.grandprix.com/ns/ns20669.html

[chernaudi]

If the J-damper is supposed to increase grip and enhance handling, why did Peugeot have problems at Le Mans in slow corners, in the rain, and over bumps? Did Peugeot get it wrong at Le Mans, or is there something inherently wrong with the J-damper system on sportscars under certian conditions?

[minimangler]

Originally Posted by chernaudi

If the J-damper is supposed to increase grip and enhance handling, why did Peugeot have problems at Le Mans in slow corners, in the rain, and over bumps? Did Peugeot get it wrong at Le Mans, or is there something inherently wrong with the J-damper system on sportscars under certian conditions?

Peugeot got a lot of things wrong at le mans.. i wouldn't be surprised if this is one of them.

[zac510]

Slightly OT, I've read the magazine articles, but one thing I am yet to understand is whether the flywheel on the inerter is on a freewheel (ie a bicycle freewheel) or whether it is affixed to this plunger.

As a tunable device I can't see how it would be less advantageous on a sportscar - it's mostly subjected to all of the same forces as an open-wheeler.

[ger80]

Have a look on this one, even if it used "encrypted" language
WIPO

[zac510]

My brain just melted..!

[ger80]

Originally Posted by zac510

My brain just melted..!

Why? Thats patent writting - claim much / tell nothing

[Tim the Grey]

Zac, cut a spiral gear into a shaft.
Place a flywheel with a matching gear spiral over said shaft.
Attatch one end of the shaft to the moving bit of the suspension.

TADA...

At least, that's what I see described?

[zac510]

Yes like a helix into the shaft.. I think I understand it 99% I am just lost on the detail that eventually the shaft is going to want to return to its original position (through its linear motion). Once the wheel goes into rebound then when the shaft is returning, will it then be forced to decelerate the flywheel and then accelerate it again in the opposite roration direction?
Or if it is non-fixed, like on a flywheel or a ratchet, the flywheel could absorb energy on the bump but then not on the rebound.

I think I understand the concept just fine, I'm probably just getting caught on details that aren't really significant to someone after a basic understanding!

[zac510]

I just re-read the RCE article and it seems that the device is definitely fixed to the shaft.

[knighty]

while you are talking about Peugeots secrets, heres a nice juicy one for you.......the latest issue of race engine magazine has managed to find out that Peugeot are running steel pistons.........this is what allows Peugeot to really crank up the power for qualifying, the reason being a steel piston is more fatigue resistant and generally stronger than its equivalent alloy piston, as used in the Audi R10.......therefore this allows a serious rise in cylinder pressure handling capability, which is achieced by injecting more fuel, lower charge temps, more air etc......which relults in an increase in torque and therefore a significant power increase.

Steel pistons for common-rail diesel engines are currently being marketed by all the big automotive piston suppliers, its not new technology, but I think its the first time in a race-diesel.......big trucks have been using them for about 10-20 years

Ulrich Bartesky has said Audi will never use steel pistons as its "not road relevant technology".......personally I think he is a clever bloke, but he is talking out of his back side on this particular point.......as the Peugeot engine is the better of the two by far.

[Aslak Vind]

Interesting news knighty!

However, the R10 engine is the more lean of the two, sporting a better fueleconomy?

[knighty]

Originally Posted by Aslak Vind

Interesting news knighty!

However, the R10 engine is the more lean of the two, sporting a better fueleconomy?

yeah, I know!.....at this years leMans, I think it was 12 laps for the Pug, then 13 laps for the Audi........if the race stayed dry the pugs would have won for sure, so although the Pug drinks a bit more, its worth having.........all their dry LMS race wins seem to confirm this.

I think its only a matter of time before Audi go the steel piston route too, then you will also see thier fuel economy drop by the same amount.......Audi will only take an ass kicking for so long, then they will just have to go steel pistons route too........they just got lucky with the weather at LeMans.

[chernaudi]

But having steel pistons doesn't have anything to do with the 908's alleged cornering abilities-besides Mahle/Cosworth makes the pistons for both Audi and Peugeot, just like how both engines use the exact same Garrett turbochargers, Dow particle filters/cat converters and Bosch common rail injectors. That's where the J damper comes in as far as the handling-maybe the new Audi(the R15 coupe, or an open car that might be known as the R10 Evo in the same vein as the current RS Spyder-whatever the new Audi LMP will be called) will use the J damper, and maybe be able to utilize it better than Peugeot.

And does anyone think that the 908's straight line speed advantage is simply due to the Pug being a coupe?

[knighty]

Originally Posted by chernaudi

But having steel pistons doesn't have anything to do with the 908's alleged cornering abilities?

do you really think!........I thought pistons were related to cornering speed ......

I was posting about steel pistons as its generally related to one of pugs secret technologies which contributes to its overall performance, but I agree its not the one single factor that makes the car faster.......as they say "a lot of little ones makes one big one"........much like the J-damper

regarding pistons......cosworth racing do not make gallery cooled diesel pistons, or any form of diesel piston to my knowledge........yes cosworth make gasoline race pistons.......Mahle (who now own the old cosworth technology mob) make alloy or steel pistons take your pick, it would be quite feasable for them to supply audi alloy and Pug steel, it all depends on which route the manufacturer wishes to go and pay for.......the fact is Pugeot run steel pistons, Audi run alloy pistons, and its a major difference.......this may not relate to a faster top speed (personally I think it does), but it will deffinatley relate to how quick the car acellerates to this top speed, hence an overall quicker car.

[zac510]

They both must be putting some crazy coatings on them. Any news about that knighty?

[chernaudi]

Originally Posted by knighty

do you really think!........I thought pistons were related to cornering speed ......

I was posting about steel pistons as its generally related to one of pugs secret technologies which contributes to its overall performance, but I agree its not the one single factor that makes the car faster.......as they say "a lot of little ones makes one big one"........much like the J-damper

regarding pistons......cosworth racing do not make gallery cooled diesel pistons, or any form of diesel piston to my knowledge........yes cosworth make gasoline race pistons.......Mahle (who now own the old cosworth technology mob) make alloy or steel pistons take your pick, it would be quite feasable for them to supply audi alloy and Pug steel, it all depends on which route the manufacturer wishes to go and pay for.......the fact is Pugeot run steel pistons, Audi run alloy pistons, and its a major difference.......this may not relate to a faster top speed (personally I think it does), but it will deffinatley relate to how quick the car acellerates to this top speed, hence an overall quicker car.

Well why is it that the R10s have been able to get the jump on the 908s at the start of several races? I think the Pugs have more top end power, but don't have the low end grunt the R10 has. Or maybe Audi's drivers are just better at getting good starts.