Had my ’95 M3 3.0 Dyno’d today.

Well done Sean....Here, here!

I wasn't doubting any of Powerstations figures, although I was interested in the wheel power. The reason I was interested in this is that our dyno at work only measures power at the wheels, not flywheel. I usually calculate in approx 22% losses on cars like the M3 if the customer askes what the flywheel figure is. I also stress this to be only a rough figure assuming the losses are 22%. I was however supprised that Simons wheel figure was 223/224bhp, but based this on what I usually use to calculate the flywheel figure.

It seemed strange to me that nearly all E36 M3 3ltrs I have dyno'd in the past make approx 220-225bhp at the wheels in standard trim on our dyno, equating to anything between 282-289bhp at the flywheel, suggesting my losses to be pretty close considering the standard output is 286bhp. (I have heard that this figure can be over optamistic)

But as nearly 29% losses were showing for Simons car, then perhaps I should have been calculating more losses myself? Can you imagine the dissapointment of a customer who I told had 314bhp if he went to another dyno on a shoot out day and only getting 286bhp?? This is why I suggest only between 18 and 25% losses depending on vehicle, tyres used, wheel sizes, diff and gear ratios, etc, etc.

You are also right in that the only "true" flywheel power can only really be trusted in an engine dyno, not a chassis dyno. Although Dastek's chassis dyno I have been realiably informed is pretty damn accurate at calculating the flywheel power.

Powerstation, and Maha the dyno manufacturers will always insist thier dyno's are accurate. So too will everyone else who has a dyno.

Just think of how much quicker Simons car would be if the losses on his car were attended to.

Simon, I guess everyone is entitiled to thier opinions, and this is what the forums are all about - expressing and sharing them. Face it, not everyone is going to agree with everyone else opinions, which can be frustrating - obviously.

Thats all I have to say on this subject.

Jayson, you are right, I have found big increases from BMW's when re-mapping them, although I have not done a 750i, I have done a 540i v8 which made not quite 50bhp more but getting on that way with de-cat exhaust system.

All BMW's generally respond very well to chipping. This is one make I like doing as some results can be very satisfying indeed.

535i sport wrote: [ What I cant understand is how anyone can quote what the losses should be as like Rich said,losses can be altered by things like tyre pressure,tread depth,tyre size and so on.

Yes I agree you cannot quote the specific losses, as this obviously varies per car, but it is the case that their isnt a massive difference between cars of the same type (FWD, RWD etc), so an estimate is used to go from @wheel to @fly.  If your only interetsed in @wheel then you don't have to make anything up.

Just to balance the arugument across the 2 camps, there is an equal counter argument against RR's measuring transmission losses.  What the RR is supposed to be measuring is how much POWER is lost through the transmission right ? well how can it do then when at the time of a coastdown there is no 'power' going through the wheels ? So you are not measureing power loss, more drag.

At the end of the day this type of discussion will go round and round in circles forever, my advice is read more and decide which camp you sit in, and take it from there.  I have found researching this area fascinating to be honest, always nice to know a bit more than your average joe about RRs.

Also another bug bear with Powerstation's RR is that they don't quote torque in lb/ft like most other people

Dont get me wrong, they are a good company per se

B1g Al wrote: There's a fairly accurate sum for it. More often than not dividing the FLYWHEEL power by 1.26 or multiplying the Road wheel power by the 1.26 either way of whatever figure you have this will show to be very accurate. I have been using this sum for ages to determine figures and hasn't let me down.

How can that work for all cars ?

SHEPSM3 wrote: Doesn't seem to work in Simons case, but is pretty close to my calcs. Simon, I am sure if you can get some sort of deal from Powerstation for a "shoot out" day, maybe include some mag, hot dog/burger trailer?? You may get some people to come along? It would be a fun day, and possibly end some doubts?

I doubt it would end any doubts that people have on here.Would probably start another 4-5 page long discussion over who's R/R is right/wrong etc etc !

I did try to get some interest in the R/R day at Powerstation on December 10th that a mate of mine is organising. Its now mainly a Jap day but there is going to be a few different makes there.

Ive heard that Japenese performance magazine are going to be there and there is going to be some really big power Lancer Evo's including one Norris designs Evo with around 850bhp !

It also seems funny to me that Powerstation has a good reputation around the Jap boys and their Dyno has a good reputation for being accurate.

It just makes me wonder if I had posted that my car produced 260bhp on their Dyno whether people on here would be saying that their R/R is well known for under reading. Just a thought !!!

Mine has 178.16 BHP @ 7000 RPM @ R/W's. I calculate it to be approx 223 BHP @ F/W (20% loss)

With 22% loss thats 228.4 BHP @ F/W

With 25% loss (apparant BMW quotation) thats hey presto 237.6 BHP @ F/W

With 27-28% loss (suspect a certain make of dyno calc's) thats 244-247.4 BHP.

Whichever one it is, and I believe my calcs, I am extremely happy with the results considering the blunders my engine has been subjected to. 178.16BHP is accurate and was repeated on our dyno 3 times in a row. Can't wait to dyno it again with the correct 2.5 crank fitted and compression upto spec.  

msportman wrote: What type of RR is it...ie Electo dyno (Magneto arrangement?) 4 wheel drive transmissions will obviously give more losses.

I think Powerstations dyno is a MAHA. I am sure that the retarders are "brakes" like disc's and pad's on a car? Could be wrong on this.

No disrespect intended, but when I've heard about complaints or suspicions about flywheel figures, it usually involves a certain make of Dyno.