Gearbox/drivetrain noise in 5th and 6th gear

[meccanisti]

Just wondering if this is a ‘characteristic’ or an issue…

I have a very distinctive and reproducible fluttering noise, almost like a heat shield vibrating, but only in 5th or 6th gear (manual) and only between 2250 and 2750rpm when on the throttle. It’s not the same as the drivetrain labouring/diff lash type noise - it’s much quieter.

It’s also not road speed related (if I’m in 5th and change up or down for example, and maintain same speed it goes) and it’s not present in any other gears.

It’s not a major issue, and there is no effect on performance, is this just a characteristic of the drivetrain or something else?

Thanks

 

[Wonza]

The fluttering noise is from the supercharger behind the drivers seat I believe.

 

[meccanisti]

The fluttering noise is from the supercharger behind the drivers seat I believe.

That was my first thought, but I am wondering why it can't be heard in gears 1-4....

 

[Wonza]

That was my first thought, but I am wondering why it can't be heard in gears 1-4....

Maybe because the revs aren’t high. Higher revs equals supercharger spinning faster. Higher the gear, lower the speed is less revs. If you floor it, then you hear the whining noise rather than the fluttering behind your ears.

 

[meccanisti]

Maybe because the revs aren’t high. Higher revs equals supercharger spinning faster. Higher the gear, lower the speed is less revs. If you floor it, then you hear the whining noise rather than the fluttering behind your ears.

That specific RPM (2250-2750) in gears 1, 2, 3 or 4 does not make the same noise...... I'm not sure what you mean here.

I'm not talking about a constant road speed, the noise is at a specific engine speed at partial throttle in gears 5 and 6 only.

 

[d15b7]

This is not Emira specific, but on my turbocharged race Honda Civic (K24/20 with EFR7163) I get a similar flutter/surge at certain rpm’s only in certain gears. I attributed it to different loads in different gears (even though the rpm is the same). For instance, 2000 rpm in 6th (say 55 mph) is a much higher load on the engine than 2000 rpm in third gear (say 35 mph). I have a blow off diverter valve that releases boost during shifts and whatnot, and sometimes at certain rpm’s and loads it’ll flutter some and surge and make noises. It never does it at much higher loads and speeds. I’ve never done anything about it cause it’s a racecar and that sort of driveability problem isn’t really an issue.

I wonder if the Emira is doing something similar (diverter/bypass valve surging/fluttering at that particular rpm/load/speed)

 

[meccanisti]

This is not Emira specific, but on my turbocharged race Honda Civic (K24/20 with EFR7163) I get a similar flutter/surge at certain rpm’s only in certain gears. I attributed it to different loads in different gears (even though the rpm is the same). For instance, 2000 rpm in 6th (say 55 mph) is a much higher load on the engine than 2000 rpm in third gear (say 35 mph). I have a blow off diverter valve that releases boost during shifts and whatnot, and sometimes at certain rpm’s and loads it’ll flutter some and surge and make noises. It never does it at much higher loads and speeds. I’ve never done anything about it cause it’s a racecar and that sort of driveability problem isn’t really an issue.

I wonder if the Emira is doing something similar (diverter/bypass valve surging/fluttering at that particular rpm/load/speed)

Thanks - useful info.

 

[Seneca Emira]

@meccanisti - I'm hearing a similar sound in my Emira. Did this turn out to be normal or was it addressed by your dealer?