The sound of turbo E30's redlining...?

[Garageaholic]

I hear an rpm "stuttering" right before every shift on any bmw turbo "youtube" clip I watch. it sounds like redlining bounce.

Is this stuttering the engine hitting redline prematurely? Is that even good for a turbo engine? It sounds like shit actually IMHO.

[Erick]

I've been in 3 turbocharged m20s and none of them have done that in person. And I havent noticed that in any videos either.

[Garageaholic]

Ok, i'll give you an example.....

http://www.youtube.com/watch?v=c0o5Cz-n4mA

watch from like 2:07 on and you will see what i'm talking about. Is this normal? I mean. I will soon have a turbo car and I dont know that if i drive it like like this that I will have a working car for long.

Do you notice the redline bouncing?

[PeaveyBassist]

Is it just a really hard revlimiter? i.e. ignition and fuel?

Will

[Mastrcruse]

I hear the redline bouncing. I have no clue but just a suggestion. Have a camera in the car and set the camera up just like you had it, down the street. Compare the videos and see if you are actually hitting the limiter. I know it sounds stupid but could you be hitting the redline and not paying attention to it while driving? I have hit the revlimiter 1 time and it was when I wasn't paying attention.

[Erick]

I dont hear anything, the only "sputtering" I hear is the compressor surge from the turbo. That's when the pressure that the blow off valve doesnt release goes back and hits the compressor wheel, forcing the turbo to spin backwards.... a lot of compressor surge is bad (like having no BOV), however all turbo cars have some sort of compressor surge.

It doesnt happen at redline, it happens when the throttle body closes. It happens especially if you slowly lift off the gas, keeping the BOV from fully opening.

[Mastrcruse]

So could he get rid of most of it with a bigger BOV?

[Erick]

Maybe some, but not all. Sounds like he has a huge turbo in there.

[cplagz]

he's got an external gate with screamer pipe by the sounds of it ... thats the "harsh" sound you can hear, but IRL it's beautiful :D

[JasonC]

It sounds like he is hitting the revlimiter. And is having alot of compressure surge like rwdrift said. I'm getting almost the same sound from my charger, but it's leaning out really bad and popping like that cause of my fuel pressure problem.

[Teaguer]

In the driving scenes he is most definitely bumping the rev limiter .

And WTF is up with those E34 ft turn signals ?

[mitch500]

I dont hear anything, the only "sputtering" I hear is the compressor surge from the turbo. That's when the pressure that the blow off valve doesnt release goes back and hits the compressor wheel, forcing the turbo to spin backwards.... a lot of compressor surge is bad (like having no BOV), however all turbo cars have some sort of compressor surge.

It doesnt happen at redline, it happens when the throttle body closes. It happens especially if you slowly lift off the gas, keeping the BOV from fully opening.

watch towards the end of the film, its when hes accelerating.

[mops]

I'm pretty sure that the sound in question is

1) fuel cut rev limiter (nice bouncing of the redline effect - throttle fully open)
2) compressor surge as the throttle closes (too small bov, or incorrently setup, large turbo, it is bad for turbo

[325is_e30]

i know exactly what you're talking about. its just the rev limiter bouncing. when you have a car spining tire like that, sometimes it hard to shift fast enough

[MR 325]

He also has the r3vlimiter set at a low 5800.