Dome LMP Discussion

[ep16]

Originally Posted by alexkiller8

judd doesn't update their lmp engines from years, what could you expect in a pair of months?

I forgot that part yeah, i'm try to be optimistic, failing dismally tho

[The Badger]

Originally Posted by ep16

Got a horrible feeling the engines won't go 24 hours tho...or anything close to that unfortunately.

I reckon they will do 24 hours , but now at the rate we are hoping for . Big let down this year I feel .

[gwyllion]

Originally Posted by knighty

I think this may be a historical issue whereby the V8 Judd engine was designed as an LMP2 engine at a certain power level and crankshaft operating speed range for that particular LMP2 dricve cycle, but when the ACO stepped these LMP2 engines up to the LMP1 class it appears to have played hell for Judd, first for the 5.5 V10, aparrently the crank torsional vibrations were so bad they resorted to the older 5.0 Engine in the grandfathering situation........now I suspect as the V8 is more powerful in the LMP1 scenario it has shifted the crankshaft operating speed into an regieme whereby its torsionally vibrating very badly, to hear that they have resorted to mounting the engine on isolator blocks is not good to hear, but I guess needs must and all that.......saying that this is pretty much the route that Dyson and Deltawing have taken whereby the engine is not really fully or semi-stressed like a traditional LMP engine installation........Judd should be able to install a crankshaft torsional damper on the nose of the crank of on the intermediate drive gear between the crankshaft and the cam drives and solve the problem.........realistically this is the same problem that blighted the Ford-Cosworth DFV in 1967, it can easily be retro-fixed if they get the right bits to bolt on, lets hope thay can fix it, best it happens now rather than in the 3rd may test or the race

I think that your theory that the Judd V8 is forced to run at a higher power level and more revs than it was originally designed for, does not hold.

When the Judd DB 3.4 V8 was introduced in 2008 as an LMP2 engine, it ran with a 42.9 mm air restrictor. As an LMP1 engine, it now has to run with a 43.3 mm air restrictor. That is a difference of less than 2% in restrictor area.

[The Badger]

Originally Posted by WMUCarGuy

S101.5 I believe.

Yep , your right . My mistake .

That S101 was a lovely machine too

[chernaudi]

But how much development has the engine had--in LMP2 it hasn't had to run against the current spec Acura/HPD V8s or Toyota'a TMG badged V8, let alone the Audi or Pug diesel engines.

And it's also odd that the engine had decent reliability last year if I remember correctly.

But it goes back to what Baretzky said about the R10's engine--getting at least 95% of the power is the easy part. The extra last couple of percentage points and having the engine be reliable is the challenging part. It could be something as simple as engine mapping issues focusing on high revs. I'm betting that the extra few hundred RPM they have to turn to crank up the wick might be causing some of the reliability issues this year, and could be causing the problems that Pescarolo and Dome have had with the S102.

Of course, this could be solved or at least remedied by using a crossplane crank like the original Honda/HPD 2.65T V8 Indy Car engine, but with those small engines, the rotational inertia of the crossplane crank will sap a lot of power, as the engine might not have the torque to spin the heavier crank as fast as far as acceleration and deceleration of the moving mass.

[gwyllion]

Originally Posted by chernaudi

But how much development has the engine had--in LMP2 it hasn't had to run against the current spec Acura/HPD V8s or Toyota'a TMG badged V8, let alone the Audi or Pug diesel engines.

In LMP2 the Judd V8 had to compete at Le Mans against the Porsche RS Spyder (2008-2009) and the Acura ARX-01 (2010).

[chernaudi]

There's a big difference, and that's time and class change. In ACO rules racing, the Porsche and Acura engines were rachteted down compared to the ALMS spec engines due to different air restrictors and the ALMS cars were lighter.

In the ALMS, I don't think that the Judd V8 would've been competitive against the RS Spyder and the ARX-01, certainly not much more than what they're facing today.

And because of larger air restrictors and above all else evolution, the TMG and HPD V8s are probably making more power than the Porsche and the original HPD V8s. It seems that even though it's a newish engine (at least compared to the GV series), it seems that time and the factory funded engines haven't been kind to the DB and it's derivatives.

HPD/Honda and Toyota/TMG are big, racing oriented companies, while Judd is a very small company relatively speaking. That alone doesn't account for this, but Judd also has a lot of customers (LMP2 teams and Lotus), and one has to wonder if that's lead to the LMP1 engine not getting the attention it needs in terms of updates.

[knighty]

Originally Posted by gwyllion

I think that your theory that the Judd V8 is forced to run at a higher power level and more revs than it was originally designed for, does not hold.

When the Judd DB 3.4 V8 was introduced in 2008 as an LMP2 engine, it ran with a 42.9 mm air restrictor. As an LMP1 engine, it now has to run with a 43.3 mm air restrictor. That is a difference of less than 2% in restrictor area.

alright, alright, its just an educated theory, certainly "something" has changed, another theory could be the introduction of E85 fuel......do they run on E85??.....failing that it may be E10??.......either way this would have the effect of potentially contamination the oil via dilution, which would thin the oil and perhaps be more relevant top the crankshaft main bearing failure.

but certainly they are saying the engine is vibrating, perhaps they are just not used to it, comparativley speaking the 72 degree Judd 5.5 V10 was pretty smooth running.......but the flat plane crank V8's have had a terrible side-to side shaking moment since day one, the V8 Nissan IES 4.0 motor was another culprit.

[gwyllion]

In http://www.lemans.org/en/races/24h/u...uick_6956.html Minassian reveals that the Dome is running with low drag aero in order to prepare for Le Mans.

Are you satisfied with the first two days?
"Our philosophy also applies to the car. Yesterday, it was in 'Le Mans' configuration, with a very low aerodynamic force. We are pleased to see that it will be quick. We will continue working in this direction because Le Mans is a high speed circuit. The seconds gained on the straight could not be found elsewhere ... It is also free time! However, we must remain vigilant not to go overboard and make the car undriveable. That's what we wanted to do yesterday."

Are you saying that the Dome S102.5 Judd will be fast on the straights?
"Here we reach 290 km/h, where the Audi does 300. At Le Mans, I think we can reach 320 km/h."

...

Back to Spa-Francorchamps. What do you anticipate for the race?
"Tomorrow, we return to the settings best suited to this circuit. I think we will be able to keep pace with the Lola-Toyota, even though it will not be easy."

[alexkiller8]

dome s102 has been built to run at le mans, i never saw that car in a not-LM aero configuration. A little bit optimistic for him to think that the car can have the same pace of the lola-toyota that run almost 3 seconds faster.

[Gingers4Justice]

It's still dissapointingly slow. But then again, was it ever realistic to expect this car to be as fast as the fastest petrol, even?

[Simmi]

Originally Posted by Gingers4Justice

It's still dissapointingly slow. But then again, was it ever realistic to expect this car to be as fast as the fastest petrol, even?

Fastest petrol maybe. Some people on the forum thought it could take pole at LM. I'm just hoping they can get through the full six hours and learn some more about the car.

[The Badger]

Are you allowed a special qualy engine now ?

Pole ..... no chance for Henri .

[TF110]

I think they'll be as fast as Rebellion at least come LeMans. More knowledge of the car can't hurt.

[ep16]

Originally Posted by TF110

I think they'll be as fast as Rebellion at least come LeMans. More knowledge of the car can't hurt.

Niether would a stronger engine...but you play the cards you are dealt with and we can be very confident that Pescarolo will get the maximum out of those cards. How much those cards equate to remains to be seen tough.

[gwyllion]

Originally Posted by Gingers4Justice

It's still dissapointingly slow. But then again, was it ever realistic to expect this car to be as fast as the fastest petrol, even?

At the moment Dome is the fastest petrol LMP1 in the race

[alexkiller8]

maybe the not so hight track temperature helps them a bit, is really strange that rebellion lola have difficulties to have that incredible fast pace that they had during qualifying.

[gwyllion]

Originally Posted by gwyllion

In http://www.lemans.org/en/races/24h/u...uick_6956.html Minassian reveals that the Dome is running with low drag aero in order to prepare for Le Mans.

The top speeds really show that the Dome was running less drag than the other petrol cars: http://fiawec.alkamelsystems.com/Res...Speed_Race.PDF

• Audi #4: 302.5 km/h
• Audi #3: 300 km/h
• Audi #1: 299.2 km/h
• Audi #2: 296.7 km/h
• Dome #17: 290.3 km/h
• HPD #22: 289.5 km/h
• Rebellion #12: 280.5 km/h
• Rebellion #13: 279.1 km/h
• HPD #21: 279.1 km/h
• Oak #15: 277.6 km/h

[Pandamasque]

I'm rather surprised to see both e-trons being behind ultras on top speed. They weigh the same, seemed to have similar if not identical aero package, yet pack more power.

[Articus]

I think the e-Trons were running more front downforce to deal with the increased front tire wear from the hybrid drivetrain later in theire stints.

[gwyllion]

The 500 kJ energy of the hybrid system is used way before the car reaches its top speed. The front drive shafts on the e-tron quattro increase drag.

[Japanese Samurai]

Dome's race report says that the aero parts of high downforce spec for Spa was only an attachment of under panel.
http://www.dome.co.jp/news/news/dt_116.html

[gwyllion]

Originally Posted by gwyllion

http://endurance-info.com/version2/a...nce-10336.html has a short report of todays test at the Bugatti circuit.

In order to solve the vibration issues, the Judd V8 is installed on silent blocks.

They had hoped to do some running on a dry track, but Minassian had to stop to car because of an oil warning light. The cause of this warning turned out to be a failure of a crankshaft bearing, which meant the end of the test session.

According to http://www.ouest-france.fr/sport/une...73452_actu.Htm Judd has identified the issue that cause the engine failure: a piston touched the head gasket. This has presumably been fixed on the new engine that Pescarolo got for Spa.

[Articus]

Originally Posted by gwyllion

The 500 kJ energy of the hybrid system is used way before the car reaches its top speed. The front drive shafts on the e-tron quattro increase drag.

this makes sense.

[gwyllion]

Some more comments on the Judd V8 by Bourdais:

“The first goal is to show in qualifying what the Dome is capable of,” he said. “We don’t have the money to run a full endurance simulation, and the Judd V8 is not as reliable as their V10. Everything loosens, undoes itself and breaks. The thing is revving at 11,000 rpm, and it’s tough…it’s not easy on the car. Everything was great with the car with the V10, but the V8 is a little bit different story. It just interacts with the chassis differently. We don’t really have big targets, but we want to show what the car can do, and then take it as long as we can in the race…”

source: http://auto-racing.speedtv.com/artic...-bourdais//P2/