Rasping noise on redline upshifts

Liam22 · Post by **Liam22** » Thu Feb 14, 2019 12:34 pm

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 · Post by **ben g** » Thu Feb 14, 2019 12:41 pm

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 · Post by **Liam22** » Thu Feb 14, 2019 1:20 pm

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

Smartbear · Post by **Smartbear** » Thu Feb 14, 2019 2:43 pm

Liam22 wrote: ↑Thu Feb 14, 2019 1:20 pm 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

Rob

Liam22 · Post by **Liam22** » Thu Feb 14, 2019 3:32 pm

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 · Post by **RKM** » Fri Feb 15, 2019 7:35 pm

Don't!

Flyingfifer · Post by **Flyingfifer** » Fri Feb 15, 2019 8:34 pm

This is how mine sounds with the DLV mod

Liam22 · Post by **Liam22** » Fri Feb 15, 2019 9:43 pm

RKM wrote: ↑Fri Feb 15, 2019 7:35 pmDon'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 · Post by **Flyingfifer** » Sun Feb 17, 2019 8:33 pm

DuckLakeView its the username of the guy that does the mod

R60BBA · Post by **R60BBA** » Sun Feb 17, 2019 11:09 pm

Liam22 wrote: ↑Thu Feb 14, 2019 3:32 pm 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 · Post by **Smartbear** » Sun Feb 17, 2019 11:12 pm

Liam22 wrote: ↑Fri Feb 15, 2019 9:43 pm
RKM wrote: ↑Fri Feb 15, 2019 7:35 pmDon'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 · Post by **Liam22** » Mon Feb 18, 2019 11:36 am

Smartbear wrote: ↑Sun Feb 17, 2019 11:12 pm 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 · Post by **R60BBA** » Mon Feb 18, 2019 1:17 pm

Liam22 wrote: ↑Mon Feb 18, 2019 11:36 am
Smartbear wrote: ↑Sun Feb 17, 2019 11:12 pm 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 · Post by **synthedup** » Mon Feb 18, 2019 1:45 pm

R60BBA wrote: ↑Mon Feb 18, 2019 1:17 pm
Liam22 wrote: ↑Mon Feb 18, 2019 11:36 am
Smartbear wrote: ↑Sun Feb 17, 2019 11:12 pm 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 · Post by **R60BBA** » Mon Feb 18, 2019 6:03 pm

synthedup wrote: ↑Mon Feb 18, 2019 1:45 pm
R60BBA wrote: ↑Mon Feb 18, 2019 1:17 pm
Liam22 wrote: ↑Mon Feb 18, 2019 11:36 am 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!

Z4-forum.com

Z4-forum.com