Hey a curious question to all of you Audi owners that have the 4.2L engines... The 2009 Audi R8 comes with the 4.2L V8 and puts out 420 engine horsepower, and with some Audi's such as mine (2000 Audi A6 4.2L Quattro) put out 300 engine horsepower... I'm just wondering how with the same bore and no type of forced induction they pull out THAT much more power! If anyone has any ideas or knows I am VERY curious! lol Thanks!!!

 

2000 Audi A6 4.2L Quattro

Standard Engine 4.2L 300 hp V8
Horsepower 300 @ 6200 RPM
Torque (lb-ft) 295 @ 3000 RPM


2009 Audi R8 4.2L

Base Number of Cylinders: 8
Base Engine Size: 4.2 liters
Base Engine Type: V8
Horsepower: 420 hp
Max Horsepower: 7800 rpm
Torque: 317 ft-lbs.
Max Torque: 4500 rpm
Drive Type: AWD
Turning Circle: 38.7 ft.



hmmmm....

 

the new 4.2 has FSI technology and wat not you know
better internals and parts

its not the same engine

 

Exact same block, but a whole different beast. There is no way of getting that kinda power out of your engine until the 4.2L supercharger is developed by PES for you engine.

 

But still differant internals such as cams and compression ratios and things of that nature are not going to make a 120HP differance. I just don't understand how the bore can be the same and no type of forced induction and they pull that much horsepower! lol I mean I could see them pulling an extra 50HP maybe we a light weight crank, differant cams, compression ratio and tuning... but 120HP? Maybe its just me but that seems extreme cause they can't have to big a cam in there because the car would sound like a lopeing beast! lol Just my imput could totally be wrong but I don't know the whole thing just seems real extreme...

 

Comparing the 8 year old 4.2 from the A6 to the current 4.2 in the R8 is misguided. A better comparison is the current 4.2 in the A6 to the current 4.2 in the R8. Both current 4.2 engines have a bore of 3.33, which is slightly different than the bore in the old 4.2 engine from 2000. Both current engines have a stroke of 3.65, which is also slightly different than the stroke in the old 4.2 from 2000. Both current 4.2 engines have a compression of 12.5:1, which is different than the old 4.2 from 2000. Both of the current 4.2 engines are running an FSI fuel system, which is different than the old 4.2 from 2000. Both of the current 4.2 engines have a timing chain, which is different from the old 4.2. Both of the current 4.2 engines have 4 valves per cylinder, while the old 4.2 had 5 valves per cylinder. While both of the current 4.2 engines are the same exact size in cubic centimeters, the old 4.2 is slightly different. As a result, while the current 4.2 engines are somewhat similar, the old 4.2 is a clearly a different engine.

A comparison of the HP on the current 4.2s has the A6 at 350HP @ 6800 and the R8 with 420HP @ 7800. The torque comparions has the A6 with 325 lbs @ 3500 and the R8 with 317 lbs @ 4500-6000. As for a partial explanation on the diffrent power levels in the current 4.2s, the R8 has a cast iron block instead of the aluminum block found in the A6, and the R8 has a Dry sump oil system. In addition, there are certain programming differences.

 

also look at the peak RPM. Redline is a lot higher where the car is going to make its top end HP. Notice the torque specs are not much different because the stroke is the same as your car. Better software, and electronics play a large part into these numbers also.