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Is250 Torque Curve


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Has anyone seen a torque curve on the IS250? I was wondering what the ideal shift points are, and though I am starting to get a better feel of the car as I start to push it, it would be easier to see the reality from the charts, rather than just pushing the gas pedal and relying on butt measurements.

TIA

larry

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  • 6 months later...
Has anyone seen a torque curve on the IS250? I was wondering what the ideal shift points are, and though I am starting to get a better feel of the car as I start to push it, it would be easier to see the reality from the charts, rather than just pushing the gas pedal and relying on butt measurements.

TIA

larry

Please see the one from the Japan Lexus website

Japan engine data (in metric units, just read the diagram ignore the Japanese characters)

It seems to have more than 90% of torque from 2000 to 5000, so you can shift anywhere in that region.

Are you driving a manual? The engine is so quiet that it provides little audio clue for shifting! :unsure:

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It seems to have more than 90% of torque from 2000 to 5000, so you can shift anywhere in that region.

I was quite surprised to see how flat the torque curve actually was...as well as how linear the power curve was. May as well maximize HP and shift at 6,400 RPM (don't forget to take into account the short delay if you have an automatic in manual mode!).

But converting measuring units always confuse me. I'm used to seeing the torque & HP curves always cross at 5,252 RPM's.

One of the online conversion calculators I used showed 158kW = 212 HP. 260nM = 192 ft-lbs. It's interesting that the US site shows only 204 HP and 185 ft-lbs. Perhaps its different fuel standards in Japan?

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It seems to have more than 90% of torque from 2000 to 5000, so you can shift anywhere in that region.

I was quite surprised to see how flat the torque curve actually was...as well as how linear the power curve was. May as well maximize HP and shift at 6,400 RPM (don't forget to take into account the short delay if you have an automatic in manual mode!).

But converting measuring units always confuse me. I'm used to seeing the torque & HP curves always cross at 5,252 RPM's.

One of the online conversion calculators I used showed 158kW = 212 HP. 260nM = 192 ft-lbs. It's interesting that the US site shows only 204 HP and 185 ft-lbs. Perhaps its different fuel standards in Japan?

I think Lexus are quoting the 204 bhp as a general figure globally, but the actual individual power output will vary depending on quite a few factors e.g. temperature/humidityfuel octane. Would like to get mine dyno'd to see what it's pushing out at the hubs with the Joe Z/free flow filter and the Tanabe system. Also looking to increase power with a single Rotrex supercharger...but early days yet....and no I can't just buy a 350 :cries:

Could always wait for the IS-F release in the UK :ph34r:

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But converting measuring units always confuse me. I'm used to seeing the torque & HP curves always cross at 5,252 RPM's.

One of the online conversion calculators I used showed 158kW = 212 HP. 260nM = 192 ft-lbs. It's interesting that the US site shows only 204 HP and 185 ft-lbs. Perhaps its different fuel standards in Japan?

Where the "cross" appeared depends on how you draw the graph, torque and power actually have two different verticle axises (y-scale).

You conversion is correct. The Japanese page is measuring raw engine output (measured at the flywheel without the transmission) with JIS specifications (without alternator, hydraulic pump [cf. Lexus 2nd gen IS uses electric steering assitance], air conditioning etc attached; with a higher atmospheric pressure and lower air temperature than the SEA method). The commonly reported net bhp (brake horse power or "dyno") method is by measuring the torque at the driving wheels (rear in this case) with the actual car so as to estimate the engine output (compensated for the power needed to drive the wheels with the gearbox in neutral). Apparently, the IS250 is having a equipment (alternator, hydraulic pump, airconditioning etc) lost of about 4.8% (seems quite efficient). Moreover, noting that the IS250 engine has a compression ratio above 12, it's power is likely to be sensitive to atmospheric pressure and temperature.

Whatever the methods of measuring, such curves always assume a maximum torque situation (i.e. maximum load on the engine). In real use other than in drag racing (or in those aftermarket upgrading kit demonstrations), maximum torque is nearly never invoked. Consequently, those curves are not indicative of the actual power. Especially with the direct fuel injection system of the IS250, the on-board engine management computer will inject less fuel than what the stoichiometric ratio required (stratified combusion mode) at low loading to enhance economy, so you do not always get the same torque at the same revs.

Anyway, my actual experience with driving the IS250 is that it can pull quite strongly from 1800 onwards with a heavy right foot and enough money to pay the oil companies.::wacko:

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