TTiD loss of performance low down

[carrera]

Yes, I did see that thread

Most aftermarket were £18-30, branded aftermarket £60, but a huge jump to Saab OEM

The part I bought was £30, but with offers & discounts the price came down significantly. If it doesn't last 5 years, then that will be a lesson learnt, but the OEM has only lasted 14 years / 90,000 miles. Compare that to the fact that I have never seen a failed Samco silicon hose. They're pretty resistant to hacksaws.

[carrera]

The bits arrived during the week

There was a bonus clip that could have been used for the intercooler end, but you can see the difference in the quality & engineering of the Mikalor clamps

Fitted it and the performance is back 

While I was underneath I spotted that one of the CV boots had a broken clip, so I refilled the boot & put a clip in place to make the car mobile again.

Then I noticed some other fluid on the cam belt end of the engine. It seems that there's a pinhole failure in the power steering pipe. They seem to be unobtanium so I am attempting to effect a repair

[carrera]

Oh, I seem to have left this dangling.

The steering pipe repair is in another thread, new parts necessary.

I have run the car for a few months now. Absolutely no further problems or error codes.

I have been thinking about the performance of the TTiD and suddenly the penny dropped, having found these power graphs at https://www.automobile-catalog.com/curve/2011/3039035/saab_9-5_2_0t_aero_xwd.html

The torque is limited to 400Nm, this is because the F40 gearbox is limited to a continuous 400 Nm loading (add a 0 onto the 40)

You can see how the torque drops off beyond 2250 rpm, which will be due to a limit on the boost level, I think it's 2.9 bar absolute.

This gives a quite narrow peak torque band, with the engine really running out of puff a bit over 4000 rpm

Compare this to the 2.0 petrol engine where peak torque is restricted to 350Nm and peak power restricted to 220hp. But that torque is available from 2500 rpm to almost 5000. It's also obvious that raising the power limit in the ECU will extend that up to 5500 rpm, So both engines are restricted

I decided to do a 0-60 test in the TTiD yesterday, but instead of using the rev range, I changed up early to use the torque. It knocked 2 seconds off the time & was consistent with the linked performance data. 

In conclusion it is evident that much more performance is readily achievable from both cars as a "stage 1" tune

For the petrol car you can see the inflection point at 2500rpm where the torque limit operates, while for the diesel some more air & fuel via additional boost (unless this is just a fuel restriction) would seem to be the way forward while the torque restriction could simply be lifted to produce 430-450Nm very easily....

The F40 gearboxes are apparently very striong, with wide availability on the used market, so 10% over continuous rating would seem to be reliable as the torque demand in road use is not continuous

As it's being shared in an XWD format, the stresses on each driven wheel should be lower than the 2WD versions too

Thoughts ?

[sgould]

Is the XWD drive train the same as the V6?  If so, torque increase should not be an issue.  Although I'm not sure that the NG9-5 V6 came in a manual form, but the V6 in the NG9-3 has 450Nm, I think.  I'm away from home at the moment and can't check.

[carrera]

I think the Haldex XWD in the 9-5 is pretty much exactly the same as the NG9-3, 450Nm is achievable and of interest if that is the real number for the 9-3

517Nm on the same engine in an Insignia, but with some mods. 220-230 hp instead of 190 would be a rough conversion I think

https://insignia-drivers.uk/forum/insignia-ownership-technical-workshop/engine-drive-train-transmission/362123-a20dtr-biturbo-tuning-guide-260ps-517nm-my-experience-with-dyno-print