Omega Owners Forum - Is there an optimum rpm for t/c efficiency?

Boatboy

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Is there an optimum rpm for t/c efficiency?
20. Jan 2011 at 21:29

I ask because lately I have been trying really hard around town but still can't get out of the mid to high teens as far as mpg goes, so I'm wondering if keeping below 2k rpm is not letting the torque converter grip enough to be efficient.

Put it another way, would harder acceleration save me money Thumbs Up!

Taking that out of the equation, and bearing in mind that plugs, air filter and timing were all done this time last year (by daz) what are the most likely culprits for poor economy?

Steve

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aaronjb

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Re: Is there an optimum rpm for t/c efficiency?
Reply #1 - 20. Jan 2011 at 21:53

I don't baby it around town and get ~19mpg over a tank of fuel (calculated, not the onboard computer which reckons ~22mpg)

Boatboy wrote on 20. Jan 2011 at 21:29:

what are the most likely culprits for poor economy?

I was wondering about this myself; I know on other cars it's common for the coolant temperature sensor to mis-read low which ends up with the ECU forever thinking the car is cold and putting a rich mixture in.. I'm presuming the Omega is the same with two temperature sensors, one for the ECU and one for the dash - I really must get mine on a diagnostic computer and check the ECUs idea of temperature.

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Andy H Omega Knight Offline Posts: 1833 Cornwall Gender: Drives: 03 2.6 Elite Auto	Re: Is there an optimum rpm for t/c efficiency? Reply #2 - 20. Jan 2011 at 21:56 If your motoring is restricted to driving up and down Honeywell hill then you are doing well to get mid teens The Omega is a heavy car. Mine does well for motorway cruising (perhaps 28 mpg) but drops quickly round town and short journeys (especially in cold weather)
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Boatboy

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Re: Is there an optimum rpm for t/c efficiency?
Reply #3 - 20. Jan 2011 at 22:27

Andy H wrote on 20. Jan 2011 at 21:56:

If your motoring is restricted to driving up and down Honeywell hill then you are doing well to get mid teens Grin

The Omega is a heavy car. Mine does well for motorway cruising (perhaps 28 mpg) but drops quickly round town and short journeys (especially in cold weather)

Haha. Holywell hill is no place for a car now. The congestions too bad and there's little parking near the pubs.

What gets me is a lot of people on here quote significantly better mpg and they can't all live in the fens and tailgate cattle lorries everywhere.

If I was that worried I wouldn't have a v6, but I prefer not to throw money away more than I have to. Do enough of that sailing. I wish I could justify lpg, but on a beat up 12 year old gls with 160k on the clock thats lucky to do 6k a year it just don't add up.

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Tony H Omega Baron Offline Posts: 4164 liverpool Gender: Drives: 2.5 ELITE	Re: Is there an optimum rpm for t/c efficiency? Reply #4 - 20. Jan 2011 at 23:11 Town driving really nails the Omega MPG as said a heavy car not really suited to town stop start driving.
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Kevin Wood

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Re: Is there an optimum rpm for t/c efficiency?
Reply #5 - 20. Jan 2011 at 23:44

The torque converter doesn't "grip" in the same way that a clutch does. If that were the case it would be inefficient. It is more like a constantly variable gear ratio based on engine RPM, over a limited range.

If it were that inefficient there would be a lot of heat coming from the transmission cooler!

The answer is to stay above 45 MPH where it's locked up!

.. but failing that, IMHO, read the road ahead, anticipate holdups before you arrive and get off the loud pedal early.. and don't brake unless you absolutely have to. Grin

Kevin

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chrisgixer Omega King Offline Black ones are faster. Posts: 14570 Wokingham Gender: Drives: "Omega Black" 3.2 Elite. Thanks to Joshwyatt.	Re: Is there an optimum rpm for t/c efficiency? Reply #6 - 21. Jan 2011 at 01:31 Accelerate sensibly then let it roll. ....and make sure the multi rams are working. But sounds like they are, expect about 14 mpg around town if inactive on a 2.5 (ime )
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Boatboy Junior Member Offline Posts: 220 St Albans Gender: Drives: 1999 2.5 GLS estate	Re: Is there an optimum rpm for t/c efficiency? Reply #7 - 21. Jan 2011 at 14:27 Kevin Wood wrote on 20. Jan 2011 at 23:44: .. but failing that, IMHO, read the road ahead, anticipate holdups before you arrive and get off the loud pedal early.. and don't brake unless you absolutely have to. I do all that - most of the time Maybe other peoples towns are not the same as mine. Steve
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78bex Newbie Offline Posts: 14 Gender: Drives: 2.2 cd	Re: Is there an optimum rpm for t/c efficiency? Reply #8 - 22. Jan 2011 at 01:35 My 2.2 petrol is returning 19.6 mpg on a 8 mile stop/start commute with all the lecky bits full on. For what it`s worth, I drove a 2010 mondeo 2.0 x sport petrol for 4 days over exactly the same journey and ir retuned 18.7 mpg. Not forgetting the Mondeo is lower emissions of course. load of bo**ck$.
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Vamps

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Re: Is there an optimum rpm for t/c efficiency?
Reply #9 - 22. Jan 2011 at 01:48

78bex wrote on 22. Jan 2011 at 01:35:

My 2.2 petrol is returning 19.6 mpg on a 8 mile stop/start commute with all the lecky bits full on.For what it`s worth, I drove a 2010 mondeo 2.0 x sport petrol for 4 days over exactly the same journey and ir retuned 18.7 mpg. Not forgetting the Mondeo is lower emissions of course.
load of bo**ck$.

Now that's bad... Shocked

My commute is 12 miles each way and for work I run around the town, 20 to 30 miles a day. Averaging 25 to 27 mpg without the sand bags which pulled the mpg down by 3 mpg or there abouts, can get well into the 30's on a steady run..... Thumbs Up!

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