2008 WRC Engine Specs

Garrett · Jul 7, 2008

caveguru said:
they could always be comparing it to the street car's torque at some rather low (pre street boost) RPM like 2,500. If they get down to where the street car only makes 150 tq, then its partly due to their faster boost build that they can get 2.5x. At 4k, it may be more like 1.5-2x.

Frank

Exactly, Rally cars need instant throttle response and low-end ballz. Thus, their engines are tweaked to have large amounts of low-end torque.

You can do this easily with a turbocharged engine and it's "power" can remain the same because the same amount of work can be done over the entire rev-band, but down low it can trade of rotational speed for greater force.

This can be done with engineering in longer crank-throw, but smaller dia pistons, etc Then add in efficiencies found in blue-printed quickly scrolling turbos and there you are. Rally cars have soooo much low-end torque, their first gear is really tall for an AWD car.

I really wish they would make the flat-4 boxer engine more undersquare, specially with fuel prices on the rise.

Btw, 700nm of torque is about 520ft-lb

-Garrett

Spaceman · Jul 7, 2008

The link I provided had more technical data on the car:

Bore: 92mm
Stroke: 75 mm
Power: 300 bhp @ 5500 RPM
Torque: 650 Nm @ 3000 RPM
Turbo: IHI with 34 mm restrictor and Subaru anti-lag system.

WRXGuyInUSA · Jul 7, 2008

Forget this techo mumbo-jumbo...

I WANNA DRIVE THE DAMN THING!!! :lol:

mattjk · Jul 7, 2008

yup, hard to believe but if you take a 600hp and 600fttq car and choke the exhaust, hp will go down and torque will stay about the same. i've seen this happen on old supras where the stock mufflers collapse on itself. dynos show up as 300fttq and about 170hp, instead of 300hp.

Digitalfiend · Jul 8, 2008

mattjk said:
yup, hard to believe but if you take a 600hp and 600fttq car and choke the exhaust, hp will go down and torque will stay about the same. i've seen this happen on old supras where the stock mufflers collapse on itself. dynos show up as 300fttq and about 170hp, instead of 300hp.

Don't you mean the reverse? Therefore, horsepower stays the same but torque drops? There is no way for a dyno plot to show a decline in horsepower while the torque stays the same since horsepower is a function of torque and RPM. Since RPM always increases, if the torque stays the same, the horsepower will always rise.

Digitalfiend · Jul 8, 2008

Spaceman said:
The link I provided had more technical data on the car:

Bore: 92mm
Stroke: 75 mm
Power: 300 bhp @ 5500 RPM
Torque: 650 Nm @ 3000 RPM
Turbo: IHI with 34 mm restrictor and Subaru anti-lag system.

Ah, that's better and somewhat surprising actually. Granted, having over 440lb-ft @ 3000rpm probably doesn't suck, but I thought it would be more. The anti-lag, tranny, and lightweight certainly make up for it though. :lol:

BobaSti · Jul 8, 2008

rally cars use something called anti- lag, basically the car is at full boost from 1 rpm.

thekiffer · Jul 8, 2008

Nobody has mentioned differential gearing. You can get a lot of torque from lower gears. I am sure this is also true on the Tranny too.

speedball3 · Jul 8, 2008

thekiffer said:
Nobody has mentioned differential gearing. You can get a lot of torque from lower gears. I am sure this is also true on the Tranny too.

Maybe I'm missing something... torque from differentials and transmission? Isn't the engine the only thing producing power? Granted, all the speed and that insane 3.5 0-60 on gravel time is a factor of both engine and transmission/differentials...but the gearing shouldn't ADD torque. If anything, gearing takes away delivered power.

WRXGuyInUSA · Jul 8, 2008

Digitalfiend said:
Don't you mean the reverse? Therefore, horsepower stays the same but torque drops? There is no way for a dyno plot to show a decline in horsepower while the torque stays the same since horsepower is a function of torque and RPM. Since RPM always increases, if the torque stays the same, the horsepower will always rise.

No, I think he's right.

The amount of airflow at lower RPM's is substantially less than at a high RPM. You will still be able to make big torque down low, but as it attempts to increase airflow, it won't allow it... making the HP figure drop dramatically...

thekiffer · Jul 8, 2008

speedball3 said:
Maybe I'm missing something... torque from differentials and transmission? Isn't the engine the only thing producing power? Granted, all the speed and that insane 3.5 0-60 on gravel time is a factor of both engine and transmission/differentials...but the gearing shouldn't ADD torque. If anything, gearing takes away delivered power.

I am no math guy but gears create torque hig gears ie. 3:11-2:89 often times are used in NASCar versus 4:11 in Drag racing.

Example: My jeep has 5:15 gears. The smaller the engine the lower the gearing that you need to create big torque. Problem still is that if your transmission combinatio doesn't have a range of gearing combinations you can pull a house but you can't drive over 55 on the highway.

I have seen 4cylinders in Rockcrawling with gear ratio's of 200:1 and trust me they have torque

Gears are how pulling works. Think of a hand winch. You generate the initially energy on a hand winch but you could not actually pull a boat onto a trailor. The gears help your torque the boat onto the trailer.

As stated I don't know the math or the physics behind it but I am sure somebody on here does.

Digitalfiend · Jul 8, 2008

thekiffer explained it well. Gearing is relatively simple. It is a torque multiplier and is why each higher gear feels "weaker" and yields less acceleration overall than the previous gear. Some of the early STi owners did the 4.11 final drive swap which yields faster acceleration over the 3.9 FD (although it also requires more frequent shifting

).

Gearing is also another reason why the STI is so fast from a stop. 300lb-ft can only go so far and is certainly not going to move 3300lbs to 30mph in 1.2 seconds at a 1:1 gearing.

Digitalfiend · Jul 8, 2008

WRXGuyInUSA said:
No, I think he's right.

The amount of airflow at lower RPM's is substantially less than at a high RPM. You will still be able to make big torque down low, but as it attempts to increase airflow, it won't allow it... making the HP figure drop dramatically...

I was referring to the statement that the torque stays the same as the horsepower drops:

mattjk said:
yup, hard to believe but if you take a 600hp and 600fttq car and choke the exhaust, hp will go down and torque will stay about the same.

I assumed he was talking about the torque curve. Now perhaps he meant peak torque will stay the same, which is true. A restrictor won't allow enough air for the engine to maintain the torque at the higher RPMs, so it will plummet dramatically and, eventually, cause horsepower to drop. If that is what he meant, then OK.

It just sounded like he meant the torque would stay the same as the RPMs increased but the horsepower would drop, which is impossible. :lol:

Jesse · Jul 8, 2008

freakin crazy...

WRXGuyInUSA · Jul 8, 2008

Digitalfiend said:
I was referring to the statement that the torque stays the same as the horsepower drops:

I assumed he was talking about the torque curve. Now perhaps he meant peak torque will stay the same, which is true. A restrictor won't allow enough air for the engine to maintain the torque at the higher RPMs, so it will plummet dramatically and, eventually, cause horsepower to drop. If that is what he meant, then OK.

It just sounded like he meant the torque would stay the same as the RPMs increased but the horsepower would drop, which is impossible. :lol:

I'm in full agreement there! :lol:

2008 WRC Engine Specs

Garrett

Spaceman

WRXGuyInUSA

mattjk

Digitalfiend

Digitalfiend

BobaSti

thekiffer

speedball3

WRXGuyInUSA

thekiffer

Digitalfiend

Digitalfiend

Jesse

WRXGuyInUSA

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