Turbo lag in M3 vs M5

[RealStig]

I have done the search before anyone asks and couldn't find anything concrete. I'd love someone like swamp or Boss to explain this. Basically I'm wondering if there is anything different between the M3 and M5 in terms of turbo design and how it impacts the turbo lag. Will the M3's engine be better optimized and feel less lag? From the sounds of it, M3 has more advanced turbo than M5, that being said, when I drove the M5, there was absolutely no lag to me. I just didn't feel it. With that in mind, if M3 is going to be better, that's just amazing.

[ybbiz34]

Originally Posted by RealStig

I have done the search before anyone asks and couldn't find anything concrete. I'd love someone like swamp or Boss to explain this. Basically I'm wondering if there is anything different between the M3 and M5 in terms of turbo design and how it impacts the turbo lag. Will the M3's engine be better optimized and feel less lag? From the sounds of it, M3 has more advanced turbo than M5, that being said, when I drove the M5, there was absolutely no lag to me. I just didn't feel it. With that in mind, if M3 is going to be better, that's just amazing.

Have you ever driven either the N54 or N55-equipped 335i?

Not trying to make a direct comparison to the F80/F82 but just curious.

[tdizzle]

I'd guess it would be comparable to the m5 if not better where response is concerned. I also didn't see noticeable lag in the m5.

[Tonymiabmw]

Originally Posted by tdizzle

I'd guess it would be comparable to the m5 if not better where response is concerned. I also didn't see noticeable lag in the m5.

Omg people are way over analyzing this I've driving all the M cars and all I have to say M3 is alway jewel of all the M cars.

[catpat8000]

Originally Posted by RealStig

Will the M3's engine be better optimized and feel less lag? From the sounds of it, M3 has more advanced turbo than M5, that being said, when I drove the M5, there was absolutely no lag to me. I just didn't feel it. With that in mind, if M3 is going to be better, that's just amazing.

Are you talking about the E60 M5? I agree, that M5 has absolutely no turbo lag

But if you are talking about the F10 M5, it has lots of lag. Very noticable lag.

Put it in manual mode, get it to 3000 rpm, accelerating slowly, then punch it.
It pulls, then it pulls harder, then it pulls even harder, and then it pulls even harder. That's turbo lag.

[/// M sa]

Oh I don't know, maybe when the M3/4 is available to drive then we can compare??

[hwelvaar]

Boss, Thanks for informative post

[RealStig]

Boss,

Exactly what I was looking for, very informative. Thank you!

[dhoggm3]

Information > opinion. Thanks!

[CanAutM3]

As usual, great post. Very well summarized

I would just like to bring the following precision:

Originally Posted by Boss330

Why not twin scroll turbo?

Because it doesn't have enough cylinders for a twin scroll twin turbo application

A twin scroll can be used on a single turbo 6 cylinder application such as the N55 with three cylinders feeding each scroll.

It is most likely what you implied, I just wanted to make it clear

[mkoesel]

Very informative post, Boss. I don't remember reading about the CCM discussed in the context of firing order and crank design, so that was enlightening. I also did not realize that the anti-lag measures found in the S55 were in fact not new and already employed by the S63tu and 1M's N54.

Thinking about the OP's question regarding lag, I don't know if I've ever seen an in depth comparison between the S63tu and the N63tu. This would seem to be the best way to qualify what kind of improvement the CCM brings and how perceptible it is. Even better if it's the Alpina version which is tuned to nearly the same power as the S63tu. Also I wonder if the N63tu uses the Valvetronic anti-lag trick too?

Regarding the S55, I think some of us expected either three twin scrolls or two triple scrolls. I certainly thought it was a good possibility. I suspect the added weight and complexity proved to be unnecessary for the power target and power delivery as you said. But I wonder if we'll see a setup like that on a future BMW I6.

[Pavit]

Boss for president!

Good read, thanks much for sharing with us

[Boss330]

Originally Posted by CanAutM3

As usual, great post. Very well summarized

I would just like to bring the following precision:



A twin scroll can be used on a single turbo 6 cylinder application such as the N55 with three cylinders feeding each scroll.

It is most likely what you implied, I just wanted to make it clear

Thanks

I thought about including the N55 twin scroll setup, but had other engagements so had to run.

And as you said; The N55 uses not a pair of cylinders for each scroll/channel, but actually uses 3 cylinders for each scroll/channel in the turbo. Cyl 1-3 feeds one scroll and cyl 4-6 feeds the other scroll/channel.

[Boss330]

Thanks for the kind words everyone

[Boss330]

Originally Posted by mkoesel

Very informative post, Boss. I don't remember reading about the CCM discussed in the context of firing order and crank design, so that was enlightening. I also did not realize that the anti-lag measures found in the S55 were in fact not new and already employed by the S63tu and 1M's N54.

Thinking about the OP's question regarding lag, I don't know if I've ever seen an in depth comparison between the S63tu and the N63tu. This would seem to be the best way to qualify what kind of improvement the CCM brings and how perceptible it is. Even better if it's the Alpina version which is tuned to nearly the same power as the S63tu. Also I wonder if the N63tu uses the Valvetronic anti-lag trick too?

Regarding the S55, I think some of us expected either three twin scrolls or two triple scrolls. I certainly thought it was a good possibility. I suspect the added weight and complexity proved to be unnecessary for the power target and power delivery as you said. But I wonder if we'll see a setup like that on a future BMW I6.

I remember reading Solstice having driven the Alpina B7 and complained it was laggy. That was the Alpina with the N63Tu (valvetronic).

The N63Tu still employs std exhaust manifolds with no cross bank tubing and also single scroll turbos.

Here is a test review from C&D:

While slower on the clock than the Audi, the BMW also felt more lethargic, thanks in part to lagging throttle tip-in. "Throttle in the BMW is frustrating," said Scott Evans. "Laggy at tip-in and unresponsive in Comfort; better in Sport, but that dead zone at tip-in is still there."

Read more: http://www.motortrend.com/roadtests/...#ixzz2tPPVoWt1

This is the BMW technical training manual for the N63Tu:

http://prodcds.bmwuniversity.com/lib...U%20Engine.pdf

A picture showing the std exhaust manifolds and single scroll turbo:

[mkoesel]

Originally Posted by Boss330

I remember reading Solstice having driven the Alpina B7 and complained it was laggy. That was the Alpina with the N63Tu (valvetronic).

I seem to remember that too now that you mention it. I wonder if he's driven an M5 to compare. Others have complained about lag in that car as well. It would be interesting to drive an M5 and B7 back to back (since we don't get the B5 in the US) to see how the two compare.

The N63Tu still employs std exhaust manifolds with no cross bank tubing and also single scroll turbos.

Exactly. That's why I figured it would make a good comparison.

[RealStig]

I drove an M5 and I can say that there is no lag that I could notice. I owned a 335 and the N55 had far more lag, it was very noticeable.

[solstice]

Originally Posted by mkoesel

It would be interesting to drive an M5 and B7 back to back (since we don't get the B5 in the US) to see how the two compare.

The track day I drove the B7 also included the M5 and M6s. No contest compared to the B7, the S63TU is 1000% better in terms of lag. Even the N63TU is better than the B7. The B7 pulls like a train when it gets going but the lag on off throttle is terrible. I had a passenger in the car during one stint with the B7 and we both laughed at it. I pushed the throttle at the apex and we looked at each other and counted 1.2.3 wooooosh. It's that bad. But then, it's likely not an issue for the driving style of people who actually buy these cars. The S63TU sure has plenty lag compared to for example the S65 but it's not bad for a turbo car, not bad at all.

[mkoesel]

Good info solstice, thanks. So the message is that BMW's anti-lag measures are definitely no joke. Hopefully the S55 is much closer to the S63tu in terms of lag than say a 335i or a B3, which I imagine it will be.

[Needsdecaf]

Originally Posted by RealStig

I drove an M5 and I can say that there is no lag that I could notice. I owned a 335 and the N55 had far more lag, it was very noticeable.

This does not speak well for your driving analytical skills. The lag is very noticeable.

[chicagofan00]

Originally Posted by Needsdecaf

This does not speak well for your driving analytical skills. The lag is very noticeable.

[Boss330]

Originally Posted by Needsdecaf

This does not speak well for your driving analytical skills. The lag is very noticeable.

Originally Posted by chicagofan00

Remember that the S63Tu behaves different in Normal mode vs Sports mode. It has a version of the "pre tensioned" turbos we will get in the S55, but that is only active in Sports mode (as it's detrimental to fuel consumption).


On a different note, it seems RealStig is in good company when talking about the behaviour/response of the S63Tu... Perhaps you should let Chris Harris know he has poor "driving analytical skills"