Honest question

[jredwine207]

I happened to be in the right place at the right time when I was given the opportunity to buy a 2015 A5 with 158k miles for under $2000. All of the body panels are straight, and the interior is good shape. Mechanically speaking it's pretty obvious the previous owner didn't actually appreciate the car his parents gave him. It's been horribly modified, and doesn't currently run. I'll be honest I bought the car knowing it was going to need some serious TLC. I've been trying to find threads concerning the VAG 2.0T that is extremely common within our cars. I already have a plan of attack for the car, but I am unsure about something and need some guidance. I know someone that has a wrecked S3. To put it simpley how hard would it be to use the engine from the S3 in the A5. I understand that they are different in terms of one being a Haldex transverse engine vrs the longitudinal designs of the A4/A5. Are the blocks the exact same? Will the motor mounts mount properly or would I need to fabricate mounts to make the engine work?

[jredwine207]

My thought was instead of ripping apart the stock engine, tearing it down, and rebuilding that engine. It might be a better idea to use the S3 engine since it has several OEM upgrades, and has nearly 100 more base HP.

[RockJGC]

This is a good question. I'd think the blocks are basically the same, but like you said already---the S3 has everything set up transversely, so I can't imagine it would be an easy swap. Why not just pull the engine out of the A5 and rebuild it for more performance? You could essentially make it very similar to the S3 engine and build it for a K04 (or larger) turbo.

[hahnmgh63]

I know back in the day the Mk1 Audi tt 225bhp engine had mostly forged internals compared to the 180bhp tt and 170~180bhp A4's. I think there was something different about the flywheel end of the crankshaft which prohibited it to be used in the longditudanal setup but don't remember for sure anymore. I think the place I'd ask would be the A4 forums as there is a lot more A4's than A5's out there so a lot more posts/enthusiasts.

[Smac770]

But which S3 engine is this? A CYFB? A CYFB is an EA888 Gen3 power class 3 engine. Even if you sorted the physicals, good luck getting the car electronics to play along. Audi loves to just say "f u, no" to trying to do anything interesting with their junk.