A3 or S3? Decision points on a pre-owned soon to be tuned A3/S3...

[MRPANDA]

Looking into a new project car.

Will definitely be tuned.

Trying to determine differences between an A3 & S3 given my plans, which include:

Stage 3+ Engine Mods
Upgraded DSG clutchpacks/TCU tune
Upgraded brakes
Aftermarket suspension (sways/springs/shocks)
Aftermarket wheels & tires


Given the changes I plan to make, would a lightly used A3 at approx $28k make sense, or a lightly used S3 at approx $38k?

Aside from nicer seats and a nicer front bumper - is there anything from the S3 that I wouldn't have in the A3 after the planned modifications?

Any other thoughts would be very helpful. I'm leaning towards A3 + $15k in mods - but I'm not sure if there's something I'm overlooking seeing as I don't know this platform well.

[HurrayFive]

Looking into a new project car.

Will definitely be tuned.

Trying to determine differences between an A3 & S3 given my plans, which include:

Stage 3+ Engine Mods
Upgraded DSG clutchpacks/TCU tune
Upgraded brakes
Aftermarket suspension (sways/springs/shocks)
Aftermarket wheels & tires


Given the changes I plan to make, would a lightly used A3 at approx $28k make sense, or a lightly used S3 at approx $38k?

Aside from nicer seats and a nicer front bumper - is there anything from the S3 that I wouldn't have in the A3 after the planned modifications?

Any other thoughts would be very helpful. I'm leaning towards A3 + $15k in mods - but I'm not sure if there's something I'm overlooking seeing as I don't know this platform well.

Lots of info available if you search. If you're planning on going stage 3+, the S3 is the safer bet for longevity.

The most significant difference between the S3/R version of the engine between the A3/GTi version is likely the unique high temperature aluminum-silicon cylinder head. It's supposedly extremely resilient to repeated high temperature stress. On top of that, the S3/R engine has upgraded forged connecting rods, wrist pins, a forged crankshaft, strengthened engine cover, on top of sodium filled exhaust valves, and a number of smaller tweaks.

Folks unfamiliar with the extreme and complex mechanical stresses involved in high output forced induction applications will write those changes off, but there's engineering science behind them at stock power levels, let alone tuned or turbo swapped. There's a reason APR torture tested the stage 3 kit on an S3/R engine. Till date at upwards of 550HP, there have been no reported failures on the stock S3/R engine on any of the forums.

Does that mean the A3/GTi engine can't handle that power? Not at all. The E888 is still an iron block motor, it's stout and reliable. That said, long term longevity at high output - the S3/R version is the more robust motor, end of story. The extra cost more than offsets the cost of doing all of those changes manually, not including any superficial interior/exterior differences.

Short version - the S3 was purpose built and engineered for performance, if that's your goal, start with that.

[Lusky]

afaik to date nobody has been able to provide proof of those differences you listed, with the only thing showing a different part number are the springs. Others here have also stated VW switched to this aluminum version for the MK6 going forward.

When will we ever have confirmation either way?

[HurrayFive]

afaik to date nobody has been able to provide proof of those differences you listed, with the only thing showing a different part number are the springs. Others here have also stated VW switched to this aluminum version for the MK6 going forward.

When will we ever have confirmation either way?

https://www.audiusa.com/content/dam/...a-kit-0115.pdf

From page 9:

"S3 Sedan high-performance engine:

Significant upgrades compared to the already highly agile 2.0T engine and influenced from TFSI
development in racing

Design changes for the new Audi S3 engine:

• Pistons with new bolts and rings
• Reinforced connecting rods
• New mounts transfer the power to the crankshaft
• Gray cast iron crankcase reinforced at the main bearing seats and the main bearing cover
• New cylinder head made from lightweight aluminum-silicon alloy characterized by high strength and temperature resistance
• New exhaust valves, valve seats and springs
• New high-pressure injection valves
• New turbocharger includes a self-adapting plastic seal between the compression wheel and housing, which improves efficiency

"

On top of that, the S3 runs a lower 9.3:1 (compared to 9.6:1 in the A3) compression ratio that's slightly better suited to higher boost applications.

On page 10, it specifically mentions the construction of each model's cylinder head is "Aluminum" and the S3 is "Aluminum-Silicon" - the E888 HAS had an aluminum cylinder head since the MK6. The aluminum-silicon alloy version created for the MK7 R/S3 is unique and designed to tolerate higher thermal stress.

Like I said, end of the day, the E888 is a proven, stout motor thanks to the iron block design - you're just getting an already strengthened version with the S3, if adding power is your ultimate goal, I'm going with the version that's been modified to accommodate the extra power.

[mroberte]

Really depends also on your driving style and if you plan to keep the car for pretty long. Personally I've built enough engines to know that the A3 can handle the stage 3 reliably, however beyond that it's getting to the engines max stress-wise.

If you tune the engine properly and keep the boat in normal ranges, you should be fine than going with the S3 engine.

I've read that the a3 engine provides higher yields than the s3. Might be because of that higher cr.

[Lusky]

Well this should data should end all of the debating on here, nice post! When I made my decision to go with the A3 over the S3 I was unaware of these differences however I was comfortable with going Stage 3+ and the A3 being fine. If power levels beyond do become available and upgrading internals are needed I was already prepared to do it. In Las Vegas we pay a surcharge tax every year to the DMV based on base price of the vehicle. This also played a role in my decision to build an A3 with a base price of 34K versus getting another ZO6 which I have enjoyed in the past but lived in states where it was cheap to register every year. Other vehicles I was looking at were M4, GC SRT8.

[ahfunaki]

https://www.audiusa.com/content/dam/...a-kit-0115.pdf

From page 9:

"S3 Sedan high-performance engine:

Significant upgrades compared to the already highly agile 2.0T engine and influenced from TFSI
development in racing

Design changes for the new Audi S3 engine:

• Pistons with new bolts and rings
• Reinforced connecting rods
• New mounts transfer the power to the crankshaft
• Gray cast iron crankcase reinforced at the main bearing seats and the main bearing cover
• New cylinder head made from lightweight aluminum-silicon alloy characterized by high strength and temperature resistance
• New exhaust valves, valve seats and springs
• New high-pressure injection valves
• New turbocharger includes a self-adapting plastic seal between the compression wheel and housing, which improves efficiency

"

On top of that, the S3 runs a lower 9.3:1 (compared to 9.6:1 in the A3) compression ratio that's slightly better suited to higher boost applications.

On page 10, it specifically mentions the construction of each model's cylinder head is "Aluminum" and the S3 is "Aluminum-Silicon" - the E888 HAS had an aluminum cylinder head since the MK6. The aluminum-silicon alloy version created for the MK7 R/S3 is unique and designed to tolerate higher thermal stress.

Like I said, end of the day, the E888 is a proven, stout motor thanks to the iron block design - you're just getting an already strengthened version with the S3, if adding power is your ultimate goal, I'm going with the version that's been modified to accommodate the extra power.

Thank you for that link!

[MRPANDA]

Appreciate all the info! Sounds like I have some things to contemplate.