Health check at mrc 309bhp vac issues and decoke

[lengster1]

Most out there are only making 360-370 and that's not much for the weight,they need to be in good order and fettled to be a real high performance motor.

[lengster1]

180 isn't bad but avants are faster

[MikeFish]

180 isn't bad but avants are faster

But the dogs in the back won't like it!

[Jamiestanton]

Ha ha yeh and the ladders on the roof may blow off

[Graze]

So my stock RS did 201.9kw or about 275 PS (if I got the conversion right)

I'm told that's pretty normal. Car has done 53,000km

Was planning on getting it carbon cleaned around the 60,000 km mark

These numbers are nothing like what I'm reading in this thread, should I do the carbon clean sooner?

Graze

[MikeFish]

So my stock RS did 201.9kw or about 275 PS (if I got the conversion right)

I'm told that's pretty normal. Car has done 53,000km

Was planning on getting it carbon cleaned around the 60,000 km mark

These numbers are nothing like what I'm reading in this thread, should I do the carbon clean sooner?

Graze

275PS is way too low. I assume your 'RS' is a B7 RS4? Your problem is not carbon, I'd save your money and get somebody to look at your engine. Most likely a vacuum problem with power that low.

[adsgreen]

I'm sure people have said that if the manifold flaps are well and truly stuck either due to carbon or vacuum then you'll get at most around 270-290ps.
But this will trip a mil light instantly...

[billq]

So my stock RS did 201.9kw or about 275 PS (if I got the conversion right)

I'm told that's pretty normal. Car has done 53,000km

Was planning on getting it carbon cleaned around the 60,000 km mark

These numbers are nothing like what I'm reading in this thread, should I do the carbon clean sooner?

Graze

275PS is way too low. I assume your 'RS' is a B7 RS4? Your problem is not carbon, I'd save your money and get somebody to look at your engine. Most likely a vacuum problem with power that low.

I think that is about right Graze. We measure power at the wheels where as these guys measure power at the flywheel (between you and me, it sounds like a bit of guess work as the engine isn't removed)

[ArthurPE]

graphs for wheel power, very accurate, all these guys do is independent dyno testing, some for type rating (DIN/ISO/TUV/EEC) for manufacturers
http://rototest-research.eu/popup/perfo ... artsID=769
car had 17000 miles on it, so it had dirty valves

http://rototest-research.eu/popup/perfo ... artsID=281
car had 600 miles, so was clean

clean 349 HP
dirty 333 HP
4.5% loss, but not all is due the deposits, I estimate tire wear had a lot to do with it

a car making 275 at the wheels has a lot more issues than carbon

[Graze]

Arthur

car runs well and pulls hard (although I haven't driven another B7 RS4)

what should i be looking for if you think it has other things wrong with it?

Graze

[billq]

If those dyno charts a accurate, it appears they are only losing 15-20% through drive train loss.
Everything I have ever seen indicates awd cars lose roughly 30%.

[ArthurPE]

If those dyno charts a accurate, it appears they are only losing 15-20% through drive train loss.
Everything I have ever seen indicates awd cars lose roughly 30%.

they are accurate, that's all these guys do is dyno, not tune or anything else, just dyno
what have you 'seen''?
rated 420
making 340 (use ~ average)

losses = (420-340)/420 ~20%
which is what would be expected and is quite high
most 2wd lose 10-15%

no way is it losing 30% or 125 HP
the most I've seen on a dyno that actually measures losses is ~100HP (car had other issues) which is only 24% or so
30% is only possible with the brakes applied

[ArthurPE]

Arthur

car runs well and pulls hard (although I haven't driven another B7 RS4)

what should i be looking for if you think it has other things wrong with it?

Graze

do some 3k to 8k 3rd gear runs, maybe 3 to 5 of them
post the results

[Graze]

Will try And find somewhere to do them without losing my licence - not easy around Brisbane

Graze

[adsgreen]

Arthur

car runs well and pulls hard (although I haven't driven another B7 RS4)

what should i be looking for if you think it has other things wrong with it?

Graze

Vacuum system the obvious place to start.

I do think that a fair bit of the problems are resolved during cleaning when the silly 10p one way vacuum valve is changed.