Rasping noise on redline upshifts

[Liam22]

Looking for a best-guess diagnosis on this before I pull the clutch out...

2007 Coupe (manual). The drivetrain is generally super smooth and without strange noises... apart from redline upshifts. No problem at 6500rpm, I talking right up there at 6800-7000. During the upshift, there is a strange rasping noise (that's the best way I can describe it). It's like someone blowing a high-pitched raspberry. Goes away as soon as the clutch is re-engaged so I'm thinking it's clutch/transmission related as opposed to engine.

Is this a known thing? My plan is to replace clutch and flywheel, but not until I've done a few track days.

 

[ben g]

Has it had a Blackbox mod done? Only reason I ask is because a few people have posted videos of the sound from their modified Blackbox and it does sound like the exhaust blows a raspberry when the revs come down, after being revved up.

 

[Liam22]

Good point. It has had a mid section delete, but the back box is standard AFAIK.

 

[Smartbear]

Good point. It has had a mid section delete, but the back box is standard AFAIK.

I think You’ve just answered your own question :wink:
Rob

 

[Liam22]

I'll try to confirm this by revving it to the redline at idle. Not something I like doing to an unloaded engine but it will remove the transmission from the equation...

 

[RKM]

Don't!

 

[Flyingfifer]

This is how mine sounds with the DLV mod :wub:

[youtube]uKN3g9q9SbY[/youtube]

 

[Liam22]

Don't!

It's going racing. If it can't handle a quick run to the red line I'd sooner know now

All I hear in the video is popping on the overrun. That's not what I've got. What does DLV stand for?

 

[Flyingfifer]

DuckLakeView its the username of the guy that does the mod

 

[R60BBA]

I'll try to confirm this by revving it to the redline at idle. Not something I like doing to an unloaded engine but it will remove the transmission from the equation...

If the engine is warm, there is nothing wrong with redlining an engine in neutral on occasion.

Hope you find the answer.

 

[Smartbear]

Don't!

It's going racing. If it can't handle a quick run to the red line I'd sooner know now

All I hear in the video is popping on the overrun. That's not what I've got. What does DLV stand for?

What racing are you doing with it? :?
Rob

 

[Liam22]

What racing are you doing with it? :?
Rob

I've been doing 750MC Roadsports for the last few years in class C with a Mazda RX8. The initial plan for the Z4C is to do the same again in class B (240bhp/ton limit). That might be hard to achieve in terms of weight loss, in which case the MSVT SuperCup is another option (225bhp/ton limit).

Both are 45 minute "mini endurance" format, with a mandatory 1-2 minute pit stop.

 

[R60BBA]

What racing are you doing with it? :?
Rob

The initial plan for the Z4C is to do the same again in class B (240bhp/ton limit). That might be hard to achieve in terms of weight loss, in which case the MSVT SuperCup is another option (225bhp/ton limit).

Z4C has 261bhp from factory.

Although my 30,000 miler dyno’ed at 248.

How does that work then?

 

[synthedup]

What racing are you doing with it? :?
Rob

The initial plan for the Z4C is to do the same again in class B (240bhp/ton limit). That might be hard to achieve in terms of weight loss, in which case the MSVT SuperCup is another option (225bhp/ton limit).

Z4C has 261bhp from factory.

Although my 30,000 miler dyno’ed at 248.

How does that work then?

Its bhp per ton

 

[R60BBA]

The initial plan for the Z4C is to do the same again in class B (240bhp/ton limit). That might be hard to achieve in terms of weight loss, in which case the MSVT SuperCup is another option (225bhp/ton limit).

Z4C has 261bhp from factory.

Although my 30,000 miler dyno’ed at 248.

How does that work then?

Its bhp per ton

Ahh I see!

My bad!