Quote:
Originally Posted by t5frankie
whats with the jump on the bandwagon slagging hlm off again?, i have seen plenty of bog standard motors on the rollers there hitting the manufacturers figures bang on or very near to, just cos hamish dont kiss everyones arse he gets a slagging off lol, and i respect him for being like that he tells you how it is. and also it seems vpc is a much friendlier forum than here. How did the op get a bhp reading if his car is an auto from a dyno?
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Not getting involved with any dyno operator or forum bashing here. I haven't posted on here for ages but followed the link from my usual haunt.
Frankie - the OP got a BHP figure because MAHA measure tyre drag. I don't know whether this is because transmission drag is very low by comparison - anybody have a suggestion? I notice that on some dynos they coast in neutral with no transmission drag and other others just dip the clutch and leave it in gear. I suspect tyre drag is higher than transmission drag but thats just a hunch - it will certainly be quite high on a twin roller set up like a MAHA. All other dynos measure something as drag too - your results at MAHA and HLM are both valid if taken in context and Bens post should help explain the differences. They should both arrive at the same flywheel figure even if the wheel figures are wildly different - again refer to Bens post as it makes clear why wheel figures are not the holy grail. HLM use a very large roller with less rolling resistance than twin smaller rollers so tyre drag WILL be different.
Comparing WHP figures between any dynos is fundamentally flawed unless the dyno is identical and all other conditions are identical. Neither MAHA or HLM is wrong and for tuning purposes where you might check for power changes after a new modification either is reliable - stick with one dyno and keep anything that may effect drag constant eg. tyre type and tyre pressure.
MAHA have a good reputation with car manufacturers because their fly figures compare well with engine dyno results - to rubbish them in light of the above and Bens post is misleading. I acknowledge that HLMs dyno yields accurate fly figures too so no bias intended.