People who seem to be happy with the new F80 M3 / F82 M4 engine direction

[pkimM3r]

Originally Posted by NISFAN

Have you driven a Golf 1.4TFSi with this? In case you haven't it is terrible, not seemless transition at all.

is that from the factory? The Golf 1.4TFSi?? That thing is like the civic nonvtec of the golfs lol.

I will one up you, have you seen this??

[pkimM3r]

Originally Posted by solstice

Someone mentioned that they had talked to an M3 test driver who said something to the extent of the car having a "2nd surge of power". It sounds like some type of sequential setup wether it contains a electrical engine or is one of the mechanical systems.

I wonder if this is just ECU boost control - similar to the 1m and the IS series having an extra 7 seconds of overboost for more torque - just later in the rev band.

[solstice]

Originally Posted by pkim1079

I wonder if this is just ECU boost control - similar to the 1m and the IS series having an extra 7 seconds of overboost for more torque - just later in the rev band.

Good point and likely what it is.

[NISFAN]

Originally Posted by pkim1079

is that from the factory? The Golf 1.4TFSi?? That thing is like the civic nonvtec of the golfs lol.

I will one up you, have you seen this??

I understand that VW have dropped the twin charger concept, replaced by Turbo only.

That looks fun

[pkimM3r]

700hp and weighs 2500lbs.....owner said that there was too much turbo lag and brought a VF supercharger to the builder LOL.

[swamp2]

Originally Posted by Boss330

This presentation has some comparisons on throttle response between a regular turbo and a electrically boosted turbo.

Nice charts. We should have been using these all along to discuss lag - a graph of torque vs. time due to step response on throttle. I've taken the liberty to add a typical NA response in purple and highlighting turbo lag in orange, it's probably more accurate to stick with it as a description simply as the time duration along the x-axis (rather than the highlighted area). Other than an exchange of power for torque this matches my first definition of turbo lag quite closely. However, to give one tiny concession to NISFAN, the case he likes to talk about would not have the NA and turbo torque asymptotes at the same level (and would then be headed right back to saying the NA engine has the lag...).

Also interesting are the double "kinks" in the blue curve which is what the prior poster was referring to in describing the electrical and computer controlled stuff as a bit artificial feeling (not sure if that was the exact term he used), which is indeed apparent in this system and you would feel this for sure and it would be a bit odd.

[NISFAN]

Originally Posted by swamp2

Nice charts. We should have been using these all along to discuss lag - a graph of torque vs. time due to step response on throttle. I've taken the liberty to add a typical NA response in purple and highlighting turbo lag in orange, it's probably more accurate to stick with it as a description simply as the time duration along the x-axis (rather than the highlighted area). Other than an exchange of power for torque this matches my first definition of turbo lag quite closely. However, to give one tiny concession to NISFAN, the case he likes to talk about would not have the NA and turbo torque asymptotes at the same level (and would then be headed right back to saying the NA engine has the lag...).

Also interesting are the double "kinks" in the blue curve which is what the prior poster was referring to in describing the electrical and computer controlled stuff as a bit artificial feeling (not sure if that was the exact term he used), which is indeed apparent in this system and you would feel this for sure and it would be a bit odd.

Swamp, this engine looks like a generator pack diesel. Note the increase in torque, but constant revs (almost). This can only be due to a load that increases with power output, like a generator set.

In any case the torque delay on the un assisted turbo doesn't make any sense. Lag that lasts for 4.5 seconds plus? No chance. More likely due to an uncontrolled wastegate, which starts boost leak very early, or other factors.

If it is indeed a generator set, the turbo system is matched so that at full power, the flow is exactly in the center island of the flow map (maximum efficiency island). In other words a very big turbo for the application. OK for static RPM/Load generators sets, no good for dynamic engines.

I am trying to find some graphs I had of Turbo response at different RPM WOT events. These clearly show high RPM response as being fractions of a second.

[swamp2]

Originally Posted by NISFAN

Swamp, this engine looks like a generator pack diesel. Note the increase in torque, but constant revs (almost). This can only be due to a load that increases with power output, like a generator set.

In any case the torque delay on the un assisted turbo doesn't make any sense. Lag that lasts for 4.5 seconds plus? No chance. More likely due to an uncontrolled wastegate, which starts boost leak very early, or other factors.

These graphs are actually for an off highway 4.4l diesel engines. I do not know what loads were used in the test but indeed they are not constant. Anyway, the point was not at all to provide an actual time duration typical for turbo lag in a modern road going automobile (I'm well aware that 3.5 seconds of lag is not typical in such cars...). The point was to show cleanly and conceptually the differences between different approaches, including an full electric turbo design, and what their transient torque curves will look like. Compress the x axis quite a bit (or equivalently change the scaling) and the comparison would be more technically correct.

I sure hope we can get some sort of similar real world transient torque test from BMW M upon release of the first big "dump" of tech info on the new engine. I'm sure they have some graphs about turbo lag (or lack thereof) but they don't always have the most clear technical marketing. There will be plenty of overuse of the work "dynamic" for sure...