Pros and Cons of NA v. Turbo Engine?
05-29-2003, 08:14 PM
#2
Re: Pros and Cons of NA v. Turbo Engine?
NA advantage: higher reliability. Less parts, less heat. Smoother engines (no turbo lag & kick).
Turbo advantage: easier to get more horsepower for cheap. Fun! :-)
Turbo advantage: easier to get more horsepower for cheap. Fun! :-)
05-29-2003, 09:23 PM
#3
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Re: Pros and Cons of NA v. Turbo Engine?
You can visit the A6 board and read about turbos replacements, blown plumbing components and other misc. failures on the 2.7Ts vs the 4.2V8. Which have been flawless, I know as I have a 4.2 with 37K miles.
No question- you can get tons of power out of a smaller engine with a turbos) and associated modifications.
However, there is simply no substitute for torque genereated from a larger volume V8 amd the overall reliability that comes with it.
I beleive (read somewhere) that Audi was dropping the V6 turbo due to emission standards it can't meet going forward and the amount of warranty repair they require.
No question- you can get tons of power out of a smaller engine with a turbos) and associated modifications.
However, there is simply no substitute for torque genereated from a larger volume V8 amd the overall reliability that comes with it.
I beleive (read somewhere) that Audi was dropping the V6 turbo due to emission standards it can't meet going forward and the amount of warranty repair they require.
05-29-2003, 10:04 PM
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driveability
I concurr with the last two posts. But I'll add that the subtlety behind turbo lag is that it creates poor driveability. Your engine's response to your throttle usage varies; turbo lag is inconsistent. The amount of time it takes depends on numerous factors.
The result is that you jerk your passengers around w/out meaning to, and you end up going faster than you meant to. Audi does a very good job of making their turbos as predictable as possible, but it's still not that good. It's good enough that your passengers won't think you're an unsmooth driver just because of it. But there will still be plenty of times when you thought you were going to get the power, and didn't.
There's another problem besides lag, which doesnt have a name AFAIK. In a given press of the accelerator, all of those variables sometimes work out in such a way that you never get full power. 1 in 10 or so sprints ends up maxing out at 90%.
Once you start chipping/tuning your car, predictability is out the window. The car will sit at 80 lb-ft of torque for somewhere between 0.25 and 1.5 secs, and then *WHAM* jump from that to 300+ lb-ft in 0.1 sec. This is really tricky. It's the diff btw 45 and 70 mph in 3rd gear, which around town is the difference between $100 and losing your license.
The result is that you jerk your passengers around w/out meaning to, and you end up going faster than you meant to. Audi does a very good job of making their turbos as predictable as possible, but it's still not that good. It's good enough that your passengers won't think you're an unsmooth driver just because of it. But there will still be plenty of times when you thought you were going to get the power, and didn't.
There's another problem besides lag, which doesnt have a name AFAIK. In a given press of the accelerator, all of those variables sometimes work out in such a way that you never get full power. 1 in 10 or so sprints ends up maxing out at 90%.
Once you start chipping/tuning your car, predictability is out the window. The car will sit at 80 lb-ft of torque for somewhere between 0.25 and 1.5 secs, and then *WHAM* jump from that to 300+ lb-ft in 0.1 sec. This is really tricky. It's the diff btw 45 and 70 mph in 3rd gear, which around town is the difference between $100 and losing your license.
05-30-2003, 05:03 AM
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Re: Pros and Cons of NA v. Turbo Engine?
don't forget noise vibration and harshness (NVH). cars with bigger displacement engines tend to be quieter and smoother than smaller turbo charged motors.
05-30-2003, 05:24 AM
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No question that the NA should be more reliable,
but I would take issue with comments that the 2.7T engine feels jerky, laggy or somehow non-linear.
If there is a boost leak or other plumbing related problem, than the 2.7T will act cranky. But a well tuned, even well-chipped 2.7T is a magnificent powerplant. It feels like a V-8 and produces gobs of low-end torque. I haven't seen the torque curve for the 4.2 yet, but I would bet it is not as flat or broad as the 2.7T. People who ride in my chipped B5 S4 are blown away by the low-end torque and linear acceleration.
Having said all that, I *am* in the market for a B6 S4, mainly because of the better chassis and unbelievably sweet exhaust note, which a V6 just cannot duplicate.
Ed
If there is a boost leak or other plumbing related problem, than the 2.7T will act cranky. But a well tuned, even well-chipped 2.7T is a magnificent powerplant. It feels like a V-8 and produces gobs of low-end torque. I haven't seen the torque curve for the 4.2 yet, but I would bet it is not as flat or broad as the 2.7T. People who ride in my chipped B5 S4 are blown away by the low-end torque and linear acceleration.
Having said all that, I *am* in the market for a B6 S4, mainly because of the better chassis and unbelievably sweet exhaust note, which a V6 just cannot duplicate.
Ed
