Pug WRC puts out 580lb-ft of torque.

[Rodan]

I was shocked when I heard that. Nicky Grist made that comment on last nights day 2 coverage. How impressive is that considering the 2ltr power plant?

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[johnfelstead]

what is impresive is that they get that much torque with a 34mm turbo restrictor. That isnt a HUGE amount for an unrestricted 2 litre turbo engine, not bad though.

They will all be in the range of 500lb/ft upwards, even the Skoda! Club Level Escort Cosworths are over 450Lb/ft.

[driggity]

Originally posted by johnfelstead
They will all be in the range of 500lb/ft upwards, even the Skoda! Club Level Escort Cosworths are over 450Lb/ft.

From the way Nicky was talking it sounded like the other WRC cars are down between 70 and 100 lb/ft compared to the Pugs. He seemed to think that this was the major reason for their dominance this year.

[johnfelstead]

not a chance they are that far ahead. 20-30lb/ft is feasable if they found something very special. I would expect the Subaru/Mitsubishi and Ford engine to be pretty close, Skoda and Hyundai less so.

[jmott]

Originally posted by Rodan
I was shocked when I heard that. Nicky Grist made that comment on last nights day 2 coverage. How impressive is that considering the 2ltr power plant?

dont f1 cars put out about that much without a turbo and 2 liters or less?

[grimlock]

Originally posted by jmott



dont f1 cars put out about that much without a turbo and 2 liters or less?

No. Given that a modern 3-liter V10 F1 engine has a HP peak of somewhere around 850 and a redline of ~18000 RPM, the equation tells us that it's making somewhere in the vicinity of 250 lb/ft at 18000. That's going to be off somewhat because we don't know what the curves look like, but it's probably in the neighborhood.

F1 engines and WRC engines are almost complete opposites. WRC engines have restricted horsepower because of the turbo inlet restrictor. F1 engines have restricted torque because their displacement and number of cylinders is fixed.

Ross N.

P.S. Mr. Felstead will be along directly to point a spotlight at whatever I said wrong, so just wait for him.

[johnfelstead]

thats about right Grimlock.

F1 engines broke the 19,000 rpm limit this year!

The only way to increase power with a limited capacity and being Normaly Aspirated after you have optimised cam design, head flow etc is to increase the RPM.

The higher you take the RPM the more apart the power/torque figures get.

WRC engines dont rev much above 7000rpm and do their best work in the 3500-6000rpm range, the really late spec wrc engines are running very high compresion, our own club spec GroupA engine is running 9.4:1 compresion, which goes against what is traditional for a turbo engine, but you have to run this to cope with a restricted turbo inlet. Without the restrictor our engine would produce about the same torque but over 500BHP, with teh restrictor we run 330BHP so you use the torque in the lower rev range.

[EJ20K]

John I though that WRC engines made around 310 HP, probably alot of torque but HP was limited because of the air restrictor ..... are you 100% sure about you guys getting 320HP on you rally car using the 34mm air restrictor ?????

[Midwayman]

Additionally I heard that the US pro-rally car is making more power than the WRC cars. (From restrictor differances I understand)

[dwx]

They can put out more horsepower than the WRC cars since they run a 40mm restrictor in open class. Most of the cars aren't as well developed as a WRC car (for obvious cost reasons). When Subaru brought over a WRC car last year to run a few events, it wasn't even close.

[MGXsport]

Can they play with the restrictor as in the way it is shaped?

Chris

[EJ20K]

Originally posted by Midwayman
Additionally I heard that the US pro-rally car is making more power than the WRC cars. (From restrictor differances I understand)

yep ..... but not even near the same torque levels

[ChrisW]

Originally posted by johnfelstead
what is impresive is that they get that much torque with a 34mm turbo restrictor. That isnt a HUGE amount for an unrestricted 2 litre turbo engine, not bad though.

They will all be in the range of 500lb/ft upwards, even the Skoda! Club Level Escort Cosworths are over 450Lb/ft.

from what nicky grist was saying, he said that the restrictor actually helped generate more torgue and wasn't limiting the overall engine performance that much.

[johnfelstead]

yep, positive we have 330BHP. You should be able to get over 400BHP from a 40mm restrictor. The FIA mandated 300BHP as a limit, thats why you see 300BHP listed in the car specs, the reality is slightly diferent.

What Nicky would have meant was that they concentrate on engine torque more than power when working with a restricted turbo engine so that area of engine development has improved. If they took the restrictors off these engines, trust me, they would be well over 600BHP with diferent cams and turbos and maps. Restricting the turbo isnt helping produce torque, it's just moved development in that field forward.

I just wish one day they scrap the current setup and go for mid engined, NA V6 2.5 litre screemers, now that would look/sound awesome!

[EJ20K]

Originally posted by johnfelstead
yep, positive we have 330BHP. You should be able to get over 400BHP from a 40mm restrictor. The FIA mandated 300BHP as a limit, thats why you see 300BHP listed in the car specs, the reality is slightly diferent.

What Nicky would have meant was that they concentrate on engine torque more than power when working with a restricted turbo engine so that area of engine development has improved. If they took the restrictors off these engines, trust me, they would be well over 600BHP with diferent cams and turbos and maps. Restricting the turbo isnt helping produce torque, it's just moved development in that field forward.

I just wish one day they scrap the current setup and go for mid engined, NA V6 2.5 litre screemers, now that would look/sound awesome!

John,

So how much power (HP's) are the top team WRC engines making ? with the FIA grp. A 34mm air restrictor

[johnfelstead]

Its going to be pretty much what we have as the airflow rate is the limiting factor to power, thats why restrictors work. These engines have a very flat torque curve around 3000rpm to 5000rpm then it starts to tail off. You have to drive them diferently to an unrestricted engine, if you rev the nuts off them you get nowhere fast.

[EJ20K]

thanx John, now I got a better idea.
So a WRC engine should be around:

330 flywheel HP
65 kgm.f Torque

usable powerband between 3000 - 6000 rpm, but at what boost levels do they get this sort of power ????? (promise this is the last question )

[johnfelstead]

the WRC engines are not built in the same way as a traditional turbo engine. Normally, as you up the boost/power you lower the compresion ratio. With a restricted turbo engine you do the complete oposite, you up the compresion ratio to make it less reliant on turbo boost. Also the boost curves are totally diferent, you control the boost to be very high in the 2500-5000rpm range and then you make it reduce as the revs increase to stop the turbo going supersonic as the airflow increases.

To do all this requires very acurate waste gate control, the latest spec WRC engines have gone back to external waste gates and use very acurate airflow valves to control this wastegate. Our own setup still has an inbuilt wastegate and we use a couple of fuel injectors, uses as air valves to control the waste gate actuator. You basically pulse these to provide the airflow required, it's very acurate. We are running about 2.5 BAR (36psi) boost in the lower revs and letting this tail off as the revs rise.

I dont know the boost levels the current spec WRC engines are producing, but our own engine spec is what was used in the last Escort WRC's that Msport ran so its going to be fairly close to the mark, we just dont run it so on the edge. Incedently we have to run special high octane FIA spec fuel, normal super unleaded would melt it. (we have a second map for running it on 98RON as a get out of the **** mode). Our own engine is 9.4:1 CR, i would think the current spec engines are higher than this.

[XT6Wagon]

Restrictors limit HP not torque. So to maximize accleration you have to make the AVG HP across the powerband as close to that Max HP as possible. This means that if 300 is the theoretical limit of the restrictor, then you need to have 300HP from as low an RPM as possible then on upto redline. Since HP=torqueXrpm/5250 this means the torque at 300HP and 3K rpm will be quite high.

[Jewbaru]

I heard the Subaru WRC car runs ~45psi down low like John mentioned, then trails off to 9psi at redline.

[97itr153]

Originally posted by johnfelstead
These engines have a very flat torque curve around 3000rpm to 5000rpm then it starts to tail off.

Actually, WRC car torque curves are downward sloping in the 3000 to 5000 rpm range. Let's look at the Peugeot WRC car for example.

300 bhp
580 lbs/ft

5252*300/580 = 2717 rpm

This means that peak torque MUST arrive at NO HIGHER than 2717 rpms. In order for this car as fast as possible, the torque must drop in proportion to the increase in rpm. What you end up with then is a FLAT POWER CURVE. This means that the driver can pick any shift point as long as he always stays on the FLAT part of the POWER CURVE.

If this car were to make the same amount of TORQUE at 3000 rpm and 5000 rpm (flat torque curve), then there will be a lot of wasted torque especially around 3000 rpm.

This example is for illustration purposes only and therefore will NOT imitate reality exactly...but you get the idea.

[Carlos Fandango]

I would like to know who crowned johnfelstead as a tuning guru?

and what kind of car is a wrx sti5 type ra v lim? is that like a 22b or something?

[BOY]

Originally posted by Carlos Fandango
I would like to know who crowned johnfelstead as a tuning guru?

and what kind of car is a wrx sti5 type ra v lim? is that like a 22b or something?

Anyway, the same technique is being used in Cobb's conebasher. The compression is still 9 or 9.5:1 and the boost is relatively low. The logic behind the decision was to make grunt for the tight corners of the auto-x where if they relied on boost for power they'd be in lag-land.

[Carlos Fandango]

whats wrong with my post?

I seriously want to know how he got the red writing underneath his name which says tuning guru.

is that such a silly request?

[Jaxx]

yes newbie...
it is

john = rally/racing/engine super guru