manuel downshift (engine brake) on the new M54 biturbo engine?
#1
Senior Members
Thread Starter
Join Date: May 2004
Location: NY416
Posts: 680
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://5series.net/forums/images/icons/icon1.gif)
The new biturbo M54 engine BMW is offering in the 335i e92 coupe looks very promising, i understand it will be making its way into the new e60 by 07.
I am very interested in this engine but very reluctant to go for the turbo design.
I must drive standard transmisison, my habit is to downshift enabling engine braking (foot off the gas). reducing speed by not touching the brakes.
I have the fear that once I downshift and the rev goes up (past 4K), the turbo will 'kick in'. Thus instead of slowing the car, I am picking up speed.
Can anyone here please advice me on the subject?
Has the 'new turbos' in general overcome this engine braking driving method?
Anyone here planning a test drive on the new M54 on the 335i (e92)?
Or any our our european friends here, can you please take a 6 speed manuel and see how this works?
I am also very concerned with turbo lag, although BMW specifically says its been reduced and refined. How true is it? Not even a tinest of the tinest turbo lag feel? Smooth as silk, glides like butter all the way?
I highly doubt, but will be so glad to be told otherwise.
comments / advice appreciated.
I am very interested in this engine but very reluctant to go for the turbo design.
I must drive standard transmisison, my habit is to downshift enabling engine braking (foot off the gas). reducing speed by not touching the brakes.
I have the fear that once I downshift and the rev goes up (past 4K), the turbo will 'kick in'. Thus instead of slowing the car, I am picking up speed.
Can anyone here please advice me on the subject?
Has the 'new turbos' in general overcome this engine braking driving method?
Anyone here planning a test drive on the new M54 on the 335i (e92)?
Or any our our european friends here, can you please take a 6 speed manuel and see how this works?
I am also very concerned with turbo lag, although BMW specifically says its been reduced and refined. How true is it? Not even a tinest of the tinest turbo lag feel? Smooth as silk, glides like butter all the way?
I highly doubt, but will be so glad to be told otherwise.
comments / advice appreciated.
#2
Contributors
Join Date: Nov 2004
Location: Essex, UK
Posts: 2,325
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://5series.net/forums/images/icons/icon1.gif)
Originally Posted by rollee' post='299865' date='Jun 19 2006, 09:42 PM
I am very interested in this engine but very reluctant to go for the turbo design.
I must drive standard transmisison, my habit is to downshift enabling engine braking (foot off the gas). reducing speed by not touching the brakes.
I have the fear that once I downshift and the rev goes up (past 4K), the turbo will 'kick in'. Thus instead of slowing the car, I am picking up speed.
Can anyone here please advice me on the subject?
Has the 'new turbos' in general overcome this engine braking driving method?
I must drive standard transmisison, my habit is to downshift enabling engine braking (foot off the gas). reducing speed by not touching the brakes.
I have the fear that once I downshift and the rev goes up (past 4K), the turbo will 'kick in'. Thus instead of slowing the car, I am picking up speed.
Can anyone here please advice me on the subject?
Has the 'new turbos' in general overcome this engine braking driving method?
This is how most modern engines work so the turbo's should make no difference...
In regards to lag this engine produces peak torque lower down than diesel engines, so my guess lag will not be an issue, just a constant stream of power/torque from 1,300rpm to 5,000rpm! (Incredible!)
#3
Contributors
![Default](https://5series.net/forums/images/icons/icon1.gif)
First of all, brake pads and rotor replacement are much cheaper than transmission and engine replacement.
Turbo "kicks in" at low RPM ~2000rpm, not somewhere near that 4K rpm. I'm sure BMW engineers know manual transmission drive WILL do engine-braking, so they MUST take this into account.
Regarding "turbo lag", I think it'll be negligible because of the two small turbos. This means that the turbo fan is very light. Think about this a 2.0L would crank out 280hp, roughly with turbo, and BMW I6 w/ turbo cranks out only 300hp. All and all, test drive is a must to figure out if there is any sign of turbo lag at round 2000 rpm. This you don't feel any turbo lag or engine braking issue, this engine will be a gem. I'd rather go for I6 300hp than 360hp V8 which is 150+lbs heavier.
Turbo "kicks in" at low RPM ~2000rpm, not somewhere near that 4K rpm. I'm sure BMW engineers know manual transmission drive WILL do engine-braking, so they MUST take this into account.
Regarding "turbo lag", I think it'll be negligible because of the two small turbos. This means that the turbo fan is very light. Think about this a 2.0L would crank out 280hp, roughly with turbo, and BMW I6 w/ turbo cranks out only 300hp. All and all, test drive is a must to figure out if there is any sign of turbo lag at round 2000 rpm. This you don't feel any turbo lag or engine braking issue, this engine will be a gem. I'd rather go for I6 300hp than 360hp V8 which is 150+lbs heavier.
#5
Contributors
Join Date: Aug 2005
Location: Austin TX
Posts: 6,554
Likes: 0
Received 0 Likes
on
0 Posts
My Ride: 2014 X5 xDrive 5.0 M Package Carbon Black Metallic/2008 M Roadster Imola Red
![Default](https://5series.net/forums/images/icons/icon1.gif)
A turbocharged car will drive essentially the same way as a normally aspirated or surpercharged car under normal driving conditions. I am not sure what the BMW turbo set up will be like, but if the company says that there won't be any, or only a small amount of, turbo lag, then I would believe them. Bad turbo lag need not be present. There are several ways of overcoming this problem. For example, once can use a smallish turbo since a smaller turbo will spool up more quickly than a larger one--and, thus, produce much less lag than the second. On the other side of the coin, the smaller one will produce less HP. But, all things considered, BMW should be able to produce an engine that provides the HP it wants without significant turbo lag. Another way to deal with the lag issue is to use multiple turbos, for example, in a sequential set up--where a smallish turbo gets things started and then hands off to a larger one.
#6
Members
Join Date: Jan 2006
Location: Southern California, USA
Posts: 117
Likes: 0
Received 0 Likes
on
0 Posts
My Ride: 530i, Sport Package, Premium Package, Navigation.
![Default](https://5series.net/forums/images/icons/icon1.gif)
I thought with most turbos that when at light loads, at idle, or under high vacuum, the wastegate is open for exhaust gasses to bypass the turbocharger equating to no boost.
#7
Contributors
Join Date: Aug 2005
Location: Austin TX
Posts: 6,554
Likes: 0
Received 0 Likes
on
0 Posts
My Ride: 2014 X5 xDrive 5.0 M Package Carbon Black Metallic/2008 M Roadster Imola Red
![Default](https://5series.net/forums/images/icons/icon1.gif)
Originally Posted by jchuan8338' post='299916' date='Jun 19 2006, 05:46 PM
I thought with most turbos that when at light loads, at idle, or under high vacuum, the wastegate is open for exhaust gasses to bypass the turbocharger equating to no boost.
#8
Senior Members
Join Date: Jun 2006
Location: Northern NJ
Posts: 630
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://5series.net/forums/images/icons/icon1.gif)
Originally Posted by my530i' post='299879' date='Jun 19 2006, 05:04 PM
First of all, brake pads and rotor replacement are much cheaper than transmission and engine replacement.
Does downshifting really damage the transmission and engine?
#9
Members
Join Date: Feb 2005
Location: Minneapolis, MN
Posts: 138
Likes: 0
Received 0 Likes
on
0 Posts
My Ride: 545i - ordered in January delivered April 21st! Black Sapphire Metallic, Black Dakota Leather, Anthracite Maple.
![Default](https://5series.net/forums/images/icons/icon1.gif)
The engine and tranmission was not made to slow you down - that is what brakes are for and The turbo will not slow the car down at any greater rate than a normal motor.
#10
Contributors
Join Date: Aug 2005
Location: Austin TX
Posts: 6,554
Likes: 0
Received 0 Likes
on
0 Posts
My Ride: 2014 X5 xDrive 5.0 M Package Carbon Black Metallic/2008 M Roadster Imola Red
![Default](https://5series.net/forums/images/icons/icon1.gif)
Originally Posted by Kzang' post='299957' date='Jun 19 2006, 07:34 PM
? I thought everyone used downshifting to reduce speed quickly and eventually come to a stop in a manual.
Does downshifting really damage the transmission and engine?
Does downshifting really damage the transmission and engine?