WRC Testing

[stefanvv]

No, that's impossible. New engines have 20% less capacity, half turbo pressure and smaller restrictor. That itself means their characteristics must look completely different than those of the old engines. Direct injection is of course good but can't completely change the engine characteristics.

Yes, you're probably right about the engine, and I couldn't find any detailed characteristics of the 1.6l WRC engines. But I still think the drivetrain is much better in corner handling and probably makes the whole difference.

[stefanvv]

The only I could find is these specifications (DS3's look much less powerful here than Polo, Polo peak torque looks impressive):
Citroën DS3 WRC - Citroën WRC
Volkswagen Motorsport -*Technical Specifications - Polo R WRC
http://www.crash.net/world+rally/fea...fications.html

[miniwintz]

425 NM of torque at 5000 RPM means that the Polo has ~300 HP at 80% of the max power revs, meaning that there is 20% of the engine range where power is near maximal.
For comparison, Focus WRC's engine was rated for max power (300 bhp) between 4000 - 6500 rpm so yes the range is wider, but Polo's engine has 5% more peak power
But still, those figures are not very meaningful without the associated curves.

I think Polo's 1.6L engine is really close in terms of performance to what was done in the 2.0L era, Citroen and Ford might be a little bit behind (on paper...), but that's just speculation.

[stefanvv]

According to these papers, Loeb must be really good driver

[Mirek]

Guys, don't believe these press numbers. They have nothing to do with reality and Your assumptions will only go wrong way if You judge anything from them. Or do You believe Focus WRC had 20-30 Hp less than ten years older Corolla or Octavia? The torque figures are even more out of reality.

[Barreis]

What is the real hp of 2,0L and 1,6L wrc engines? Somewhere between 330 and 390hp I guess...

[miniwintz]

The restrictor limits the maximum theoretical output of WRC cars engines.
With the 34mm restrictor of 2.0L engines, theoretical limit was around 330 hp IIRC, a bit less with the new 33mm one, but engine efficiency is also increased with the newer engines so it might be similar all in all.

Anyway, on a side note, Mirek you are absolutely right that those press numbers are most likely full of sh**
According to Citroën, max torque on their DS3 engine is 350 NM at 3,250 and max power is 300 hp at 6,000 RPM. That doesn't make sense since 350 NM, even at 6000 RPM, wouldn't be sufficient to produce 300 hp And inversely 300 hp at 6000 RPM means 356 NM of torque which is higher than "the maximum torque" of 350 NM announced.

Either one of the figures is false, or both, most likely
Btw now that I think about it that also stands for the (unofficial) figures of the Focus' engine specs, 550 NM of torque at 4000 RPM means 330 hp which is higher than the announced max power output of 300 hp... All in all it's hard to judge without real dyno tests, which we will never see I am afraid

[Mirek]

Octavia WRC in 2002 had 320 Hp and 600 Nm. The best Fabia WRC in 2006 had some 340 Hp at 4500-5500 rpm and 640 Nm at 2500 rpm if I remember. That was with in that time already obsolete 20V engine. In that time Focus WRC had already 750 Nm if my information is correct (with similar peak power but in much larger rpm range). Latest 2.0 cars must have been over 800 Nm in my opinion and the power between 350 and 400 Hp.

[OldF]

I agree with Mirek about the difference of old and new WRC cars torque / power curves.

Race Engine Technology - Dec/Jan 2012 (posted originally by makinen_fan)

At the same time, a mandatory 8500 rpm maximum engine speed has not had any real impact since, because of the effect of the restrictor, the current engine operates primarily within the 5750 - 7250 rpm range.

The high-torque 2.0 litre engine was very close to its maximum power output all the way from 4000 to 7000 rpm. It thus had a spread of useful power twice that of today’s engines. Of course, the previous-generation WRC engine was an “oddball” thanks to the exploitation of extremely high boost.

Arnfield says, “We could make those massive torque numbers with the 2.0 litre engine whereas now, with the limit on manifold pressure, we are more in line with more normal competition engines – our torque curve is a more conventional shape.”

[miniwintz]

I highly doubt WRC engines could produce 350 or even 400 hp with a 34mm restrictor in the turbocharger. With 33% engine efficiency the theoretical upper limit is 335 hp

Avoiding the details of the calculation and assuming standard pressure and temp with a 34 mm restrictor the max mass flow is about 0.22 kg/s; let’s say A/F = 14 hence 0.22 / 14 = 15.7 10–3 kg/s fuel.
Energy per unit mass of fuel (the heating value) is about 47-48 MJ, and the engine efficiency is usually about 32-33%, hence as first order approximation we can reasonably hope to extract something in the order of 15.7 * 48 * 0.33 = 248 kW, make it 250 kW = 335 hp.
Based on that calculation and given that very likely max power isn’t the main concern in the application, I would say that probably best engines are between 320 and 330 hp.

WRC engines - Forum - F1technical.net

Now with the 33mm restrictor, it's very likely that the max output is not far away from 300 hp