Turbo lag on a 2011 X5 35d

[Penguin]

Originally Posted by JCL

I think there is a risk that all types of perceived lag are being collectively labelled 'turbo lag' in this thread.

MY experience in test driving various BMW models over the years has been that the main contributor to BMW "lag" is the automatic transmissions.

I owned a 1965 Corvair with a factory turbo and if you wanted to see turbo lag, that was a perfect example, due to the 60's turbo technology, aggravated significantly by the long piping required due to the engine layout:



That's the turbo on the right, the air cleaner on the left, and a side-draft marine application carburetor in-between. The chrome pipe coming out of the turbocharger feeds the intake charge to the two heads on opposite sides, and there was similar piping under the engine to get the exhaust from both sides up to the turbocharger.

[Richard in NC]

Even in the 80's was real turbo lag. I had 2 Daytona Turbos. Imagine being at 2000 RPMs and punching it. Wait for it, wait for it, cross 2500 RPM and bang, off it goes. Nothing at all below 2500. Even punching it above 2500 took about 1-2 full seconds before full boost. My Z4 35i is worlds ahead of that with decent power by 1800 RPM and maybe 1/2 second to full boost at worst. Most N/A cars don't have that response down low. It's only a lag compared to the best cars. My '02 M5 could rock your head back and forth in sync with punching the throttle from 2000 RPM up.

Of course the X5 weighs 1500 lbs heavier and has the extra weight to get moving. Plus I definitely had auto transmission lag in my '08 550i. DS or manual mode cured that. I'd suspect the Diesel still with the 6sp auto would be the same.

[JCL]

Originally Posted by Penguin

MY experience in test driving various BMW models over the years has been that the main contributor to BMW "lag" is the automatic transmissions.

I owned a 1965 Corvair with a factory turbo and if you wanted to see turbo lag, that was a perfect example, due to the 60's turbo technology, aggravated significantly by the long piping required due to the engine layout:



That's the turbo on the right, the air cleaner on the left, and a side-draft marine application carburetor in-between. The chrome pipe coming out of the turbocharger feeds the intake charge to the two heads on opposite sides, and there was similar piping under the engine to get the exhaust from both sides up to the turbocharger.

Neat powertrain. Never worked on one of those.

Agree with Richard that it wasn't much better by the eighties. Early '80s Pontiac Trans Am (2nd generation body style) went to a small GM V8 with a turbo, as all the large V8s were cut. Throttle lag was similar to a ship with an engine room telegraph.