V8 engine question

[BlkS5]

I'll admit, I know nothing about these engines in the S5 but can someone tell me what the difference is between the V8 engine in the S5 and the R8?

Am I wrong in thinking the R8 has a faster motor? Is it not the same block? Why can't an S5 do the same things to it's motor to make it more powerfull?

Is it the cam's, intake, heads? won't those fit on our block?

[beemercer]

Assuming the S5's V8 is similar to the Q7's V8, this Audi Training Manual does a good job explaining the differences. There are a lot of them, for one the RS4/R8 high-rev FSI V8 has a completely different rotating assembly.

http://www.jlosee.com/images/RS4/PDF...ssp.921603.pdf

[JimmyBones]

Yes the R8 has a more powerful engine than the S5 and it is a big difference. The V8 R8 (just like the RS4) makes 420 horsepower as the S5 only makes 340 horsepower. Now the R8 got the high performance 4.2 FSI V8 from the RS4 but they made improvements on it further like a dry sump oil system. The RS4 engine has better flowing heads and valves, cams, higher compression pistons, etc. The RS4 or R8 parts may fit the S5 engine but it would require the engine to be pulled and dismantled to find out.

The RS4 and R8 also have two ECMs to keep up with all the electronics of the engine for the high reving.

[BlkS5]

I figured the extra hp comes from the heads and cams. Both engines are 4.2 liter so knowing that it is very unlikely due to production costs that the main part of the engine is different, one would think you could put RS4 heads and cams on it. The problem would probably be in the tuning since everything is run by comouters now.

How about headers? Does someone make headers for the RS4? If so, I do not see why they would not fit the S5. I was told the platform was the same.

[JimmyBones]

I figured the extra hp comes from the heads and cams. Both engines are 4.2 liter so knowing that it is very unlikely due to production costs that the main part of the engine is different, one would think you could put RS4 heads and cams on it. The problem would probably be in the tuning since everything is run by comouters now.

How about headers? Does someone make headers for the RS4? If so, I do not see why they would not fit the S5. I was told the platform was the same.

JHM makes headers for the B6/B7 S4s and they said that they will decide on making headers for the RS4 and S5 when they get there. Either way the engine will have to be dropped to install headers because it is just that damn tight in the engine compartment so installing headers will either cost a lot or eat up a lot of time depending on how you have them installed.

Also Audi has always had tiny tweaks to the V8s depending on what model they were in so in effect each V8 platform is a little different.

[BlkS5]

Assuming the S5's V8 is similar to the Q7's V8, this Audi Training Manual does a good job explaining the differences. There are a lot of them, for one the RS4/R8 high-rev FSI V8 has a completely different rotating assembly.

http://www.jlosee.com/images/RS4/PDF...ssp.921603.pdf

Thanks for the manual. It seems the Q7 has our engine and it is the same block as the RS4. Looks the the intake manifold has bigger ports on the RS and the other thing I find interesting is the headers on the RS (page 29). Those should bolt right on to our motor. ???? But as Mr Bones pointed out a huuuuuuge pain in the ass to get them on.

Beemercer, could you post one of those for the S5? It would be great to have.