Audi S4 vs RS4 Tuning Comparison Question

[rharris]

Yes, please post. If you can't post, then please e-mail to rnharris at bellsouth dot net.

[BlackShadow]

Thanks for your very informative piece Golich. I would also be very interested in the article. My E-mail is: isamson@bloomberg.net if you can't the thing posted.

[ajsl]

Golich, just upload it to some web space and post a link to it here If you need some web space drop me a line on AJSL <at> Digitalphage.com

[DaveP]

Or drop us a PM, and we'll get it put on here....

[Nikolaos]

I have modified my S4 ´00 sedan into an RS4 in all ways, including engine.

There are so many parts in the engine, which are different. Actually, nothing is same and the cost of doing all those mods is huge. My engine is running right now 470 MTM reliable PS.

Because I did all those modifications step by step I can say that after replacing the cylinder heads and complete RS4 intake the running of the engine completely changed. Before, when I had K04, RS4 IC, oil cooler, injectors, fuel pump, fuel regulator etc, it was still an S4 engine with power at the mid revs. But when you replace cylinder heads and all the rest then it becomes a high rev RS4 engine.

Probably the only pure RS4 sedan worldwide!

Nikolaos

[s4orce]

I was thinking about future tuning for my S4, and can't seem to understand the following:

It seems that if you remap an RS4 and stick a full Milltech on it, you get 460 bhp.

It you take an S4 and remap it with KO4 turbos, RS4 injectors, MAF a full Milltech etc, you don't get 460 bhp. In fact you seem to get a bit below or a bit above 400bhp, depending on which tuner you think is more credible.

In the second example haven't you basically converted an S4 to an RS4? Therefore, why the difference in tuned power?

Good question. Essentially, ( for a bit of change ) you can take the S4 to RS4 levels and higher. As others have stated it is pretty expensive. I did just that after I bought the O.CT stage 6 kit for the S4. It didn't quite deliver on the performance scale I was seeking ( not to mention I was not shipped the actual O.CT turbos but normal K04's instead , but that's a whole other story ). Most of these stage 2 or 3 kits do not include the necessary hardware and tuning to take the S4 to newer heights. I was making ( supposedly ) about 425HP and about 580nm torque with the O.CT kit. I then decided to add some additional RS4 parts which differ GREATLY from the S4, namely new heads ( I added 2.8 heads ) RS4 Intake mani, RS4 throttle Body and Fuel rail and added Sportec Intake AND Exhaust cams ( Many folks simply use just the RS4 INTAKE cam and leave the Exhaust cams alone). I also swapped out the turbos and had a set of Hybrid K04's made here in the states that uses the compressor wheel off the RS6 turbo. Added some custom Sportec tuning for 91 and 100 octane and the results were awesome compared to my O.CT stage 6 kit. On 100 octane I am running @ 410-425hp AT the wheels. the Dyno I was tuned on reads higher for elevation ( plus it was a Hub Dyno ) and there I was at 497 WHP on 100 octane. The shop compared my run to stock 996 turbo and overlaid it on my 100 octane run and it was simply amazing.

So the trick is, add better breathing and more fuel with some custom tuning and you can beat most any off the shelf RS4 tuning program.

[Golich]

Dave sent PM

Rharris, Black shadow email and attachments sent.

[BlackShadow]

Yeah, come on, send it on, pretty please. I'm still waiting.

[AFAP18]

S4fource


Where did you get the hybrid turbos? I am wondering if it would work for me.

W.O.T

[S4RS4]

Interesting stuff here! I have a genuine RS4 complete engine in a '98 S4 running on the S4 ECU but with custom programme. I am having some problems getting expected power. Currently running 1.6 bar boost with no CAT's and full APR downpipes and exhaust and it makes 415bhp and 430lbs torque but there is a huge dip in the torque curve at 3000rpm - just where you need it and I should be seeing 460bhp. One question came up after much head scratching - is the variable cam timing different for the Rs4 to the S4? Anybody know the answer to this???

[Nordschleife]

Interesting stuff here! I have a genuine RS4 complete engine in a '98 S4 running on the S4 ECU but with custom programme. I am having some problems getting expected power. Currently running 1.6 bar boost with no CAT's and full APR downpipes and exhaust and it makes 415bhp and 430lbs torque but there is a huge dip in the torque curve at 3000rpm - just where you need it and I should be seeing 460bhp. One question came up after much head scratching - is the variable cam timing different for the Rs4 to the S4? Anybody know the answer to this???

Ditch APR and talk directly to MTM in Germany, otherwise waste a great deal of time.
R+C
PS why would you spend the serious money to buy a complete RS4 engine and run it with a S4 ECU? No US tuner knows diddly squat about the RS4 engine! If you buy the engine, the ECU is cheap!

[DaveP]

"The Power Of the RS4" is now available in the downloads section....thanks to Golich!

[BlackShadow]

Nice one. I shall have a read and, hopefully, increase my knowledge.

[S4RS4]

Interesting stuff here! I have a genuine RS4 complete engine in a '98 S4 running on the S4 ECU but with custom programme. I am having some problems getting expected power. Currently running 1.6 bar boost with no CAT's and full APR downpipes and exhaust and it makes 415bhp and 430lbs torque but there is a huge dip in the torque curve at 3000rpm - just where you need it and I should be seeing 460bhp. One question came up after much head scratching - is the variable cam timing different for the Rs4 to the S4? Anybody know the answer to this???

Ditch APR and talk directly to MTM in Germany, otherwise waste a great deal of time.
R+C
PS why would you spend the serious money to buy a complete RS4 engine and run it with a S4 ECU? No US tuner knows diddly squat about the RS4 engine! If you buy the engine, the ECU is cheap!

APR are having nothing to do with this. I just have their downpipes & exhaust. Also, I am not in the US but in the UK where reputable tuners have lokked at this car. Because it is an early S4, the RS4 ECU cannot be used without re-wiring major parts of the car. I have the engine loom from the RS4 but it will not plug into my car's wiring. If it were a later S4, it would just plug in. I know early S4's that produce 450bhp + so there is nothing wrong with the ECU processor's ability to make the horsepower. We just wern't sure if there was a variable cam timing difference. Anyway, it goes in for more mapping soon.

[Golich]

I'm pretty ceratin the CAMs are different and given the significant difference in the RPM response from my previous S4 to my RS4 I'd be supprised if the variable valve timig wasn't different.