i would have to agree you dont start a thread with a companies name and then state you have no problem with them, if that was the case why mention their name in the first place :?Gerry H wrote:cng1 wrote:Just a quick few words of caution. The chaps at APT are really good guys but do not under any circumstances view the numbers that come of their rollers with any significance or use them for comparison with anything else.
.To me, that sounds somewhat contradictory. Maybe you'd have received a warmer response if you'd left APT's name out of your opening post as it merely served as a distraction to the point you're trying to make and the subsequent discussion.cng1 wrote:
I have no beef with APT at all, they are really nice chaps with a great facility who do superb work.
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Pro's & Cons of Dyno's
Matt Black Wrapped 2009 GTR with litchfield stage 4.25 
Not another datalogger from the Fens...........haven't you guys got anything better to do? 
I do not know whether this is a really daft question/statement but is fourth gear 1:1 in every car? How about if the car has six gears as opposed to five? Don't some cars run different gearing? I know my Golf has far shorter gearing than the Sierra.
I do not know whether this is a really daft question/statement but is fourth gear 1:1 in every car? How about if the car has six gears as opposed to five? Don't some cars run different gearing? I know my Golf has far shorter gearing than the Sierra.
Pretty sure 4th is 1:1 in the SR20, VG30 and RB25 boxes. Feck knows for other manufacturers though. I've always been amazed by the videos showing the yanks on the dyno in top gear. I actually saw a Ferrari on the dyno in 6th doing a power run not long ago 
For the sakes of a RR day to compare various members cars what differnce does it make, you are all tested in the same circumstances. IMO I would rather be on the APT DD rollers than another local RR that is widely over exagerated in the flywheel figures 
For the sakes of a RR day to compare various members cars what differnce does it make, you are all tested in the same circumstances. IMO I would rather be on the APT DD rollers than another local RR that is widely over exagerated in the flywheel figures Most cars with more 5 gears have 1:1 on 4th, the majority of cars with 6 gears have 1:1 in 5th. Very few boxes have the same ratios as another box and many boxes may have as many as 4 different gearsets depending which model they're fitted to and that's before we get into aftermarket gearsets and race boxes. There are no hard and fast rules so some care is required to use the correct gear. It's all too easy to do half a dozen similar cars in a session and on one forget to use 5th rather than 4th because it has a 6spd box and then that owner gets to brag in the bar because his car apparently has a bunch more power than the rest.
My car generally has to be mapped in top (taking benefit of the reduction by the gearbox) in order to get traction. This is despite having sticky track tyres, 100KG of me sitting in the passenger seat, 4 sacks of sand on the boot and strapping both over the front wheels and back from the cage to tiedown points behind the car. More lard-arsed cars generally have no such problems so can run in 4th with far less strapping and no extra ballast.
My car generally has to be mapped in top (taking benefit of the reduction by the gearbox) in order to get traction. This is despite having sticky track tyres, 100KG of me sitting in the passenger seat, 4 sacks of sand on the boot and strapping both over the front wheels and back from the cage to tiedown points behind the car. More lard-arsed cars generally have no such problems so can run in 4th with far less strapping and no extra ballast.
What ever type of dyno people use or whoever they use the figures obtained are always subjective, after all they are opererated by humans. The important factors are confidence and consistancy. If you're confident in the work they do then use them, if not don't. Whoever you use and what ever system they use if you stick with them then your figures will be consistant. As our car does not have an ecu or other electronic bits and bobs we use a dyno to gauge where the car is and what improvements we have made. The real measurement is taken by the drivers arse 
For me the whole point of a dyno shoot out is a bit of fun with some friends, our car has been dyno'd at 2 different facilities but I only take notice of the figures from my usual centre. If we manage to get the work done on the car in time we will be going to APT for the shoot out, not because we need to know what it's producing but to meet somemore guys from the club and let them see and hear the car.
Whether you use data logging or as we do, a stop watch and video footage of every lap of every track day, surely we should all share one common factor. That is we do what we do because we have a love of fast cars.
For me the whole point of a dyno shoot out is a bit of fun with some friends, our car has been dyno'd at 2 different facilities but I only take notice of the figures from my usual centre. If we manage to get the work done on the car in time we will be going to APT for the shoot out, not because we need to know what it's producing but to meet somemore guys from the club and let them see and hear the car.
Whether you use data logging or as we do, a stop watch and video footage of every lap of every track day, surely we should all share one common factor. That is we do what we do because we have a love of fast cars.
Interesting read.
My own view for what its worth is you should go to a dyno operator who has no vested interest in the car for a reliable reading.
being in the business and having had arguments on this subject many times I know that so many variables can effect the final reading---tyre pressures--camber--foot on the brake--entering "made up transmission losses-- not having the fans working correctly
then theres the argument over hub dynos and wheel dynos.......... we could go on
In the end if the car drives well and the AFR ratios are ok who gives a toss........
example is a guy had a lexus IS200 with enormous HKS Turbo made 420 hp..........well good.............look at the graph and and up until 5000 rpm a N/A IS200 gave more power the final 1450 rpm made the gee gees
begs the question what use would that be as a daily driver ..or a track day car...............
Car then blew up 10 minutes later but thats another story
What do they say.............its torque that wins races...........
My own view for what its worth is you should go to a dyno operator who has no vested interest in the car for a reliable reading.
being in the business and having had arguments on this subject many times I know that so many variables can effect the final reading---tyre pressures--camber--foot on the brake--entering "made up transmission losses-- not having the fans working correctly
then theres the argument over hub dynos and wheel dynos.......... we could go on
In the end if the car drives well and the AFR ratios are ok who gives a toss........
example is a guy had a lexus IS200 with enormous HKS Turbo made 420 hp..........well good.............look at the graph and and up until 5000 rpm a N/A IS200 gave more power the final 1450 rpm made the gee gees
begs the question what use would that be as a daily driver ..or a track day car...............
Car then blew up 10 minutes later but thats another story
What do they say.............its torque that wins races...........
TOM's Lexus IS350 compressor 375 bhp 165 mph on GPS & still pulling (autobahn)- Toyota Aristo V300 Vertex (sold) - Toyota MR2 Roadster - Toyota Soarer 2.5 TT
Since this topic has sprung back into life I was talking to a couple of chaps from Dyno-dynamics who were in the country recently.
They were at pains to note the differences between shoot out mode and the proper dyno modes. In shoot-out mode the dyno applies a set of compensations that were calculated by testing a few different types of cars that were to hand in Oz; a few RWD, a few FWD, a few 4WD etc and they took the average of each type. When the operator chooses your gearbox type and driveline in the shoot-out setup he is in fact picking one of the compensation curves - if your car differs vastly from the exemplar then accuracy will be severely compromised. In their view if you had a shoot-out between a single-seater and a Monaro whilst both would use the same dyno settings the shootout comparisons would be completely invalid.
In Dyno mode the dyno-dynamics can be configured to do a traditional coastdown test or what they recommend is that you drive it down under load and you just let the rollers brake against the load to take the engine all the way back down to just above idle speed. This latter mode is the most accurate that you can get as the tyres are fully deformed and the driveline loaded up but you still get a difference on the way down versus the way up due to the heat building up. The other problem with running down the rev range under load is that you can only reliably do it at full throttle - anywhere else and you have to keep your foot at precisely the same throttle position all the time which in reality doesn't happen.
They were at pains to note the differences between shoot out mode and the proper dyno modes. In shoot-out mode the dyno applies a set of compensations that were calculated by testing a few different types of cars that were to hand in Oz; a few RWD, a few FWD, a few 4WD etc and they took the average of each type. When the operator chooses your gearbox type and driveline in the shoot-out setup he is in fact picking one of the compensation curves - if your car differs vastly from the exemplar then accuracy will be severely compromised. In their view if you had a shoot-out between a single-seater and a Monaro whilst both would use the same dyno settings the shootout comparisons would be completely invalid.
In Dyno mode the dyno-dynamics can be configured to do a traditional coastdown test or what they recommend is that you drive it down under load and you just let the rollers brake against the load to take the engine all the way back down to just above idle speed. This latter mode is the most accurate that you can get as the tyres are fully deformed and the driveline loaded up but you still get a difference on the way down versus the way up due to the heat building up. The other problem with running down the rev range under load is that you can only reliably do it at full throttle - anywhere else and you have to keep your foot at precisely the same throttle position all the time which in reality doesn't happen.
I think you mean expect not except
I would expect accurate results in dyno mode but not necessarily in shootout mode which is what the evidence currently seems to indicate may be the case.
Which reminds me Gary, have you still got your old 2WD portable unit. Last time we talked I recall you saying that you wanted shot of it, if that's still the case drop me an email.
I would expect accurate results in dyno mode but not necessarily in shootout mode which is what the evidence currently seems to indicate may be the case.
Which reminds me Gary, have you still got your old 2WD portable unit. Last time we talked I recall you saying that you wanted shot of it, if that's still the case drop me an email.