rs4 fsi in a8 fsi vehicle
05-27-2018, 10:37 AM
#1
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rs4 fsi in a8 fsi vehicle
I know i'll be eaten alive on the forum but would love to hear from people on a tech standpoint. After doing some reading from audi's study guide, wouldn't it be possible to turn my 08 fsi a8 into a "rs8"? It looks possible but i did see that the high rev motor has 2 oil coolers. I also see that the teeth on the gears for cams and crank have a 5 less. Lastly, the wieght on the crank for vibration. Just wanted to see what people thought about it. I was thinking about the rs4 super charger kit and would love to make my audi 1of 1.
05-27-2018, 11:04 AM
#2
AudiWorld Wiseguy
I guess you could as it’d physically fit without too much trouble. However I think the real challenge will be the electronics. The RS4 version of the 4.2 FSI motor and it’s consequent ECU was never designed to be hooked up to an automatic transmission. So if you could get the A8’s electronics to accept the RS4 ECU, you then somehow have to make it work with an automatic transmission which it was never designed for.
And then, even if by some amazing miracle you were able to get it all to work together, you’ll still be well down on power and torque over what a factory S8 or W12 comes with, not to mention it no doubt also being a lot cheaper and less hassle to just buy one of these in the first place.
If you want the challenge to create an “RS8”, then I’d suggest you put the (considerable) effort into retrofitting a Bentley Bi-turbo W12, or the biturbo V10 from a Euro RS6.
And then, even if by some amazing miracle you were able to get it all to work together, you’ll still be well down on power and torque over what a factory S8 or W12 comes with, not to mention it no doubt also being a lot cheaper and less hassle to just buy one of these in the first place.
If you want the challenge to create an “RS8”, then I’d suggest you put the (considerable) effort into retrofitting a Bentley Bi-turbo W12, or the biturbo V10 from a Euro RS6.
05-27-2018, 12:20 PM
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Thank you for your response. I did look into the other motors but will not fit with all the piping for turbos. I don't want to replace the transmission due to its strength. I did think about the power aspect, and is why if a swap like this could be done i would go with upgrades for the rs4 motor to come close. If i really wanted s8 power id just sell my 8 for it. I really just like the thought of a 1 off a8... or should i say a8 "plus".
05-27-2018, 12:28 PM
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https://www.goapr.com/products/stage3plus_b7_rs4.html
This was the kit i was looking to use for the power aspect. 628hp at crank is pretty close to s8... just saying 😁
This was the kit i was looking to use for the power aspect. 628hp at crank is pretty close to s8... just saying 😁
05-27-2018, 01:32 PM
#5
AudiWorld Super User
Being unique is over rated! 
What really matters is that the car does what you want it to. If you can get better or equal performance just buying something Audi has already built, why not do that? A few tunes are available for the D4 S8 that are quite cheap and very effective, not that its necessary on the under rated 4.0 motor they have. And you could have it with no muss, no fuss, and with improved features over the D3. Not to mention it would probably be cheaper than the conversion you're talking about.
What really matters is that the car does what you want it to. If you can get better or equal performance just buying something Audi has already built, why not do that? A few tunes are available for the D4 S8 that are quite cheap and very effective, not that its necessary on the under rated 4.0 motor they have. And you could have it with no muss, no fuss, and with improved features over the D3. Not to mention it would probably be cheaper than the conversion you're talking about.
05-27-2018, 02:42 PM
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Thank you jack for your input! The big thing to me is that i honestly love the d3. I have looked at d4's and LOVE the enhancements but not the car. The d3 to me has the look that holds the crown for the a8 platform. Now lets be for real, if unique was overrated we'd all drive a s class lol. To be honest, this is no 2 month project in my eyes and would really mean putting her down for sometime and dont plan on doing that for another 2 years easy 😊
05-28-2018, 08:27 AM
#7
AudiWorld Wiseguy
Why don’t you just upgrade the internals and exhaust system of your existing motor to RS4 specs, or beyond? Then apply a custom tune to your existing ECU to run it and you’re away. You could probably get 450+hp without too much trouble, and a screaming 8k rpm redline.
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