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| Chicken Drumstick Member Since: 17 Aug 2020 Location: Near MK Posts: 707  
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The trouble here is, a dyno, assuming you are meaning a rolling road or chassis dyno rather than an engine dyno. Is a tool and not a measure.
This means figures from one dyno or even the same dyno on a previous session are not generally directly comparable. There are lots of reasons for this. Such as different dynos physically work differently, some use static drag weights while others have varying load. This can give a huge spread of final figure differences. There are different units used such as Imperial and Metric Horse Power. Am I’m unsure how kw is actually achieved as HP is a calculated figured not a measured one. A dyno will measure torque and rpm and use them to calculate HP the dyno is a “brake” device the static or varying load. Hence the B in Brake Horse Power. HP = torque x rpm / 5252 Dynos can then be setup differently too giving the operator quite a lot of control to manipulate the final figures. The figures can be a here and now based on what the vehicle is doing at the time. But these are subject to huge variation as temperature and humidity will play a big factor. Therefore on a cold day you might see significantly better figures. Your altitude can also impact the results. Dynos should have “correction” standards they can use to remove environmental variables. But there are multiple standards and you are relying on the operator to know what they are doing and not abuse the fact that they can heavily influence the figures. Then there is the issue that you are measuring torque at the wheels rather than at the engine. So things like tyre tread and pressure can impact the results. A lot of places then try to calculate drivetrain losses, but in reality it is only a guess and one that again is open to the operator having a lot of control over the figure. I only say all this, as I suspect you will not find any real comparable figures. And if they are higher or lower than your figures it doesn’t mean that they are any more power or not. Obviously on the day if you run vehicles back to back using the same setup you can get a trend of which vehicles make more power. And using the dyno as a tool to see impact of modifications when run back to back. As for the 300Tdi. Land Rover rated the engine at 111bhp. Since the 1980s most manufacture claims have been fairly accurate and reasonable. Although occasionally auto makers get caught out (including Land Rover). On the assumption 111bhp is correct at the engine (all car makers have always rated engine power not at the wheels). The drivetrain losses as a finger in the air guess for a 4wd vehicle with a drive train like the LR it is probably something like 25-33% loss. Meaning wheel power should be in the region of 75-83hp. Tdi engines respond well to simple tuning such as tweaking the pump and adding a big intercooler. Lots of places claim 135-150hp at the engine. But I suspect none of them have proven this really. My hunch is that most of the performance gain is “below the curve”. Ie not drastically changing the Peak values but improving torque and power across the rev range. I would think you’d be doing very very well to see over 135hp Peak with a Tdi. Anyhow to answer more directly. On a dyno day at our local club we have whp figures for Tdi Land Rover’s varying from 30whp thru to 78whp. However the way this dyno worked the claimed engine figures didn’t correlate directly with the wheel figures. Hence why I posted the above. Eg A 300Tdi making 59whp the dyno claimed 130hp at the engine. While another vehicle making 77whp the dyno claimed 124hp at the engine. This was based on coast down measurements and claims of drivetrain losses. |
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30th Jun 2024 8:27am |
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