rolling road torque figure
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rolling road torque figure
looking for a bit of information please. had a rolling road day on saturday with a jap car club. my figures came back at 376 bhp and 333lb /ft. now i had a road map last august showing 369bhp and 415 lb/ft (2.5 sti remapped) so obviously i was a bit worried by the low torque. but on checking it looks like the 4wd cars had lower torque than i thought they would have i.e a r33 gtr running 424bhp with 303lb/ft? so was wondering when they get a torque reading does the car have to be left in gear or in neutral on the rundown? sorry for long post but just wanted to know. cheers mike
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A Subaru 2.5 engine will generally run more torque than bhp. My 2.5 car made 473 bhp and 480lbft of torque but my 2 litre car made 440bhp and 380lbft of torque.
As long as it drives fine on the road would not worry about what a RR says as there is so many variables that can affect the power reading.
banny
As long as it drives fine on the road would not worry about what a RR says as there is so many variables that can affect the power reading.
banny
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A Subaru 2.5 engine will generally run more torque than bhp. My 2.5 car made 473 bhp and 480lbft of torque but my 2 litre car made 440bhp and 380lbft of torque.
As long as it drives fine on the road would not worry about what a RR says as there is so many variables that can affect the power reading.
banny
As long as it drives fine on the road would not worry about what a RR says as there is so many variables that can affect the power reading.
banny
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If not, IIRC he assumes 22% losses, so presumably peak power and torque at the wheels will simply be 22% less than the figures quoted on the graph, which is flywheel power?
Ns04
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the 396/415 figure was the original road set up that bob printed off for me. the 376/333 figure was from the rolling road with 296 at the wheels. it just seemed to me that all the 4wd cars had low torque figures. one of the guys had a classic with a 2.5 bottom end that put out 392 bhp but only 310lb/ft of torque. i just thought it wold be higher
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Post the graph...if the torque and BHP lines don't cross at 5252rpm (when plotted on the same scale). Something isn't right.
Seeing bhp is calculated from torque. Mathematically, To achive a 100lb/ft difference with the same BHP would require a very different power delivery of the engine or a conversion/compensation calculation. I'd go for the latter.
The person doing 392bhp and 310lb/ft sounds very odd, which backs that up.
(IIRC - If I recall correctly)
Seeing bhp is calculated from torque. Mathematically, To achive a 100lb/ft difference with the same BHP would require a very different power delivery of the engine or a conversion/compensation calculation. I'd go for the latter.
The person doing 392bhp and 310lb/ft sounds very odd, which backs that up.
(IIRC - If I recall correctly)
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Post the graph...if the torque and BHP lines don't cross at 5252rpm (when plotted on the same scale). Something isn't right.
Seeing bhp is calculated from torque. Mathematically, To achive a 100lb/ft difference with the same BHP would require a very different power delivery of the engine or a conversion/compensation calculation. I'd go for the latter.
The person doing 392bhp and 310lb/ft sounds very odd, which backs that up.
(IIRC - If I recall correctly)
Seeing bhp is calculated from torque. Mathematically, To achive a 100lb/ft difference with the same BHP would require a very different power delivery of the engine or a conversion/compensation calculation. I'd go for the latter.
The person doing 392bhp and 310lb/ft sounds very odd, which backs that up.
(IIRC - If I recall correctly)
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trying to get hold of bob to find out what boost its set at to be honest, and i dont have a gauge. the car has had exhaust,fuel pump, plugs and sti panel filter and of course remap
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Has anyone suggested that the OP may have unintentionally mixed Ft.Lbs and NM? Remember as well, that brake horse power and torque (however expressed) are two sides of the same coin, as oppsed to two completely seperate things.
I cribbed this from a page that explained it clearly:
1. POWER is dependent on TORQUE and RPM.
2. TORQUE and RPM are the MEASURED quantities of engine output.
3. POWER is CALCULATED from torque and RPM, by the following equation:
HP = Torque x RPM ÷ 5252
I wonder if this has helped.....
Simon
I cribbed this from a page that explained it clearly:
1. POWER is dependent on TORQUE and RPM.
2. TORQUE and RPM are the MEASURED quantities of engine output.
3. POWER is CALCULATED from torque and RPM, by the following equation:
HP = Torque x RPM ÷ 5252
I wonder if this has helped.....
Simon
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Well spotted simon - especially seeing 415Nm = 305lb/ft. So that leaves a more plausible 28 lb/ft to be accounted for
(1 lb/ft= 1.35581795Nm )
(1 lb/ft= 1.35581795Nm )
Last edited by Shark Man; 08 April 2008 at 12:20 PM.
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well just spoke to bob and he reckons the rolling road graph is right. he says boost comes on later on a rolling road so will not get same figure for road map and rolling road for torque and its at the wheels..............i think