Bobbeh Posted August 16, 2005 Share Posted August 16, 2005 Which RRs? If anything I find RR's cant judge higher power cars accurately due to wheel slip, I remember Paul Whiffin having issues due to his car spinning on the rollers. What kinda figure did you get Terry? Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted August 16, 2005 Share Posted August 16, 2005 PTS in Luton had mine as 512 and Leons as 630 when I in my final hybrid phase and he was with HKS twins. My tranny losses were 17%, his 22. G-Force in Aylesbury seem to cope with the power ok Quote Link to comment Share on other sites More sharing options...
Bobbeh Posted August 16, 2005 Share Posted August 16, 2005 Pauls was tested at G-Force.. ever had your cars dyno'd there and if so what was the outcome Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted August 16, 2005 Share Posted August 16, 2005 No mate, I am so "off" RR and dynos you wouldnt believe it. Most put out varying figures, which make any true comparison meaningless. As long as she goes OK then I am happy. Quote Link to comment Share on other sites More sharing options...
Bobbeh Posted August 16, 2005 Share Posted August 16, 2005 I think you should get it done at either Thor or G-Force for the purposes of this discussion The problem with your previous car is we had no 1/4 mile times to compare, I know Leon got an 11.0 time with his when he ran it at TOTB with the HKS twins... so 630 at the wheels? may not be toooo far out. Anyone have his terminals for this time? Maybe we should organise a club dyno day at G-Force again for some updated information. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted August 16, 2005 Share Posted August 16, 2005 I think you should get it done at either Thor or G-Force for the purposes of this discussion Maybe we should organise a club dyno day at G-Force again for some updated information. LOL and I think you should go single for the purpose of discussion... Knock yourself out and organise a day:thumbs: Quote Link to comment Share on other sites More sharing options...
Pete Posted August 16, 2005 Share Posted August 16, 2005 I've never given much thought to BHP figures on a RR. At the end of the day a rolling road is a tool to tune a car up through the rev range before you go out and try it in the real world and fettle it. If using the same road then you'll be able to compare results of your efforts. Like Terry says - as long as the car is performing well then that's all that matters. Quote Link to comment Share on other sites More sharing options...
Bobbeh Posted August 16, 2005 Share Posted August 16, 2005 Im seriously considering it but theres just one little thing on my license thats holiding me back right now Winter is always a good time for a RR day. It would be nice to get some of these single turbo motors down all on the same dyno for a real comparison on a decent dyno Quote Link to comment Share on other sites More sharing options...
Anh Posted August 16, 2005 Share Posted August 16, 2005 Differential, propshaft and tires are in the chain when measuring torque on a RR. How else could it be done? (there were no hub dynos back then) I don't understand how people buy the theory that a 400bhp car needs 100bhp (or more!) to overcome friction inside the gearbox, shafts and tyres. It is so far off reality that it amazes me... Where does the author in that book explicitly say total loss from flywheel to the driven wheels is 4%? You quote him saying manual transmission loses 4%, which is a reasonable estimate. The tires account for most of the losses you see between flywheel horsepower to driven wheel horsepower. Also, trap speed is only a rough indicator to the value of the power bands (different power bands through different gears) at the driven wheels over weight and drag. Quote Link to comment Share on other sites More sharing options...
Ian C Posted August 16, 2005 Share Posted August 16, 2005 I've never given much thought to BHP figures on a RR. At the end of the day a rolling road is a tool to tune a car up through the rev range before you go out and try it in the real world and fettle it. If using the same road then you'll be able to compare results of your efforts. Like Terry says - as long as the car is performing well then that's all that matters. Some people don't believe in hiding behind drivability though i think I've said all along that I'm happy with my car, how it drives, how gosh darn fast it is and that it held together for TOTB quite happily. The dyno was the icing on the cake really and I'm chuffed with it. I like the discussion that's going on around this dyno business especially as people are actually using proper engineering calcs to work things out. And especially as these calcs are close to what I got The SCA dyno measured 580 at the wheels, and there wasn't any wheelspin problems. Digsy worked out what the 5000-5500rpm 'flat spot' in my dyno chart actually was - a tuning effect caused by the cams and the intake runner lengths, netting me extra torque and power up high and skewing the graph somewhat I'll stick with the 8% for now. No-one can accuse me of artificially inflating the crank power figures then I refuse to believe it's more than the low 600's. Because then I'll start worrying lol -Ian Quote Link to comment Share on other sites More sharing options...
JohnA Posted August 17, 2005 Author Share Posted August 17, 2005 Where does the author in that book explicitly say total loss from flywheel to the driven wheels is 4%? the author is Hugh McInnes and he ended up estimating horsepower based on accelerometer readings (for known vehicle weight etc) instead of measuring horsepower on RRs that apparently were as full of 'fluff' back then as they are now. I tend to do the same, that's why I posted this, I found it funny, that's all. The book is not particularly good overall, but it does have 2-3 spots where it tackles issues lost in the mists of time (80s onwards ) Also, trap speed is only a rough indicator to the value of the power bands (different power bands through different gears) at the driven wheels over weight and drag. There are good calculators for bhp from trap speed. Not as inaccurate as one might think at first. Accelerometer calibrated for your type of car is even more accurate, and repeatable too. Quote Link to comment Share on other sites More sharing options...
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