Performance : Pull in 6th gear

[p27549]

I have a C2 Cab non vario ram and am not too sure on the performance of the car.
The car will pull nicely in 5th up to the red line but once 6th is selected the car does not seems to accelerate as well, In fact it seems to stop accelerating.
Has anyone had a chance to open their 993 up through the gears including 6th. Does the car pull well in 6th from 5000RPM or is it sluggish. I was expecting the car to pull in 6th as if you were changing from 4th to 5th.
Not sure if i have an issue with low power. The car is standard and has covered 55k miles.

Of course not done on the road .....

Cheers

 

[Mark Elder]

ha! - yeah, it's fine, I test this everyday as I commute to work![]

Where can you possibly test this except on a very long straight? - I guess a long airport runway would be fine.

Did not notice any issues at the 9m dyno day (Colin accelerated all the cars up in 6th to the red line). If you have a power fault it might not show up in 5th on the open road, but perhaps does show in 6th because of extra wind resistance?

Perhaps worth getting an OBD readout or getting a dyno run opportunity somewhere.

 

[p27549]

Tried getting an OBD download on Saturday but the garages software would not communicate with the car. Not sure if he had the right Porsche software installed. I think a dyno maybe the way to go as i think the car should pull in 6th like it does in 5th.

 

[angry]

From below 5000rpm they are a little flat,but mine pulls happily round to 165mph no prob.(In Germany obviously)
Sounds like you may have a small problem somewhere.
Dan

 

[p27549]

Please can you give me some more on the resonance flap. How can i check it and where is it.
Thanks
TIM
PCGB member

 

[p27549]

The cars appears to come on cam, more power around the 4000 to 5000rpm mark. Is this an indication of the resonance flap opening or just the engine coming onto Cam.
Thanks

 

[Porker993]

It's not very scientific, I know, but mine pulls like a train in fifth up to 130 mph. Acceleration in sixth is then a little more gentle, as wind resistance starts to take over.

Low down grunt in sixth is still quite strong, if you're caught in the wrong gear, around 80-100.

I generally use fourth/fifth for accelerating and sixth for cruising.

All the above in Germany, obviously.

 

[pse_SC]

All the above in Germany, obviously.

Yeah,right.[]

 

[Mark Elder]

ORIGINAL: p27549

Please can you give me some more on the resonance flap. How can i check it and where is it.
Thanks
TIM
PCGB member

Tim,
The resonance flap is inside the intake manifold and adjusts at different engine speeds to change the size of the inlet manifold area to help the air resonate at a frequency that matches valve opening frequency (and therefore you get a stronger blast of air into the cylinder when the valve is open).

If the flap is not adjusting at correct engine speeds you will not get the designed power output.

You would be missing the power in any gear - but you might not notice in lower gears (unless you were familiar with another 993) because it's only in top where the wind resistance really starts to compete with the engine!

 

[p27549]

Thanks Mark, i will take a look, is there a quick test that can confirm operation like with ignition on it motors through its full range? Can you hear it with engine off.?

 

[RichardLW]

I know that this is a bit O/T but my gt3 pulls in 6th like the 993 pulled in 4th and 5th and, frankly, it is a bit of a worry from a licence perspective. At 30mph, you feel you could just open the door and step out it feels so slow.

 

[Mark Elder]

ORIGINAL: p27549

Thanks Mark, i will take a look, is there a quick test that can confirm operation like with ignition on it motors through its full range? Can you hear it with engine off.?

Hi, not that I'm aware of - I think only way to know is perhaps with an OBD diagnostic kit (or a dyno - but even then you are only guessing about cause).

But, thinking about this more, I believe that the default (not working) position of the resonance flap is actually the best position for the high end of the rev range. So when it's not working the loss of power is in the 4-5k rpm range (others may correct me...?)

I think your loss of power is at the top end of the rev range? I think you need to find someone near by with a working OBD reader.

 

[tertius]

For what its worth I've run my non-vario 993 at VMax a few times so have definitely tested acceleration in 6th - if the car is running as it should it is markedly less than in 5th, however, it should still be accelerating.

When I first ran at VMax it seemed rather lacking and the top speed was below what I was hoping, so I had it checked out with a leakdown test - I was losing a huge amount through one cylinder (70% loss) and quite bad on a couple of others. One top end rebuild later et voila!

 

[Mark Elder]

ORIGINAL: tertius

I was losing a huge amount through one cylinder (70% loss) and quite bad on a couple of others. One top end rebuild later et voila!

At approx how many miles on the clock?

 

[tertius]

ORIGINAL: Mark Elder

ORIGINAL: tertius

I was losing a huge amount through one cylinder (70% loss) and quite bad on a couple of others. One top end rebuild later et voila!

At approx how many miles on the clock?

Around 140k kms (its LHD), so ~85k miles.