Alpha N Mapping Results

The transmission losses will be less if the run was done in 3rd gear as the overall speed wasn't as fast as it would be in 4th. Also the ration won't be 1:1 more like 1.2:1 making the engine turn over easier. I usually calculate between 18 and 20% losses in 4th gear. BUT, as I said earlier, these chassis dynos which calculate flywheel power are only calculated by figures being put into the computer by the operator to start with. Some people say that it doesn't matter if you get the readings in 3rd or 4th gear, but actually it does. When I map cars I do it in 3rd as the dyno will be even more sensitive to any adjustments you make, but I use 4th for the initial and final power runs as 4th is normally the "straight through" gear. Mind you looking at that graph...202kmh at 7290 rpm isn't 3rd gear, I would have said that was 4th??

The only real way you can "accurately" measure flywheel power is by removing the engine and bolting it to an engine dyno.

Steve...any news from Chris yet about the bolsters?

When Gerry visited me, he did say his Dastek dynos are extremely accurate. He can get readings off his dyno, go to another Dastek dyno elsewhere in the country with different atmospheric temps and get identical readings with the same car.

If we were to upgrade, this dyno would probably be our choice.

UweM3 wrote: 215m3 wrote: Uwe Mine showed a shade under 200 at the wheels. Gerry has said the rwp can depend on many issues: - Yeah agree. And the main issue is what the Dyno operator wants to show to you to make you a happy customer.

Rubbish m8! That may be true in the case of some operators but not with Gerry at Dastek who are not just RR but also create and supply piggy ecus and dynos to various forms around the country. Their rollers are some of the most frequently calibrated I've come across.

Gerry once mapped my car for 6 hours - got only 1.5% gain through their unichip and so removed the chip and charged me nothing.

He's highly respected, ex rally wrx, more knowledegable than most.. rollers do vary but I do know that the conditions used by Dastek are more accurate than most (this results on apparently 'optimistic' figures.. E.g. few dynos cool exhaust as well as intake to replicate driving conditions and has a massive effect. Nuff said.

Col, glad to see the wee beast is nearing conclusion - glad Alpha N working out -  bring her up one night.

SHEPSM3 wrote: I think crank/flywheel figures should be ignored. These are only calculated to certain calculations fed into the computer. The one to look at is the wheel power. As long as nothing has changed, ie same tyre size/wear/pressures, dyno room temperature, gear used (should be the straight through gear - 4th for a 5 speed overdrive box), the wheel power should be the same on whatever dyno you use. Opening myself for a beating The Dyno I use is old, installed in 1985  Its Bosch and does not calculate flywheel power. However, the wheel power IS accurate. I have mapped cars here and just for the sake of getting a flywheel figure I took a couple down to another local chap who has a spanking new Sun dyno. The wheel figures were bang on the same as I had on our dyno. Bosch stopped making dyno's earlier this year. Gerry has also used our dyno, and commented on how good and sensitive it is. Some dynos have software which calculate the power figure and correct it by whatever the room temperature is. The Dastek dyno is "probably" one of the best. Gerry certainly wouldn't make the dyno read figures just to make the customer happy. I certainly wouldn't either. Whats the point in that. If the car only makes 180 bhp after being carefully mapped, thats all its going to give - no matter who maps the car. Perhaps we should consider getting the frictional losses down produced by the transmission, wheel bearings, etc. Different gearbox/diff oils, etc. Maybe a new topic?

Toby and myself had a good chat with Gerry about rear wheel power, flywheel power etc and he was very adamant about the accuracies of his set up.

Ready now for all the arguments starting - my car put down about 218 at the wheels which on my car equated to 246 at the flywheel.  Had less losses than Tobys.  3.64 diff, smaller tyre etc

However, as Toby said, we are interested in how the car performs - not necessarily the *highest* power readings.

We have a fair bit of data on Dastek Dynos now - Toby's late 215, Tobys Track Car, my car, various other M Models and I know that Steve M had his Cecotto run on the Dastek as well.

Very subjective discussion....

I think crank/flywheel figures should be ignored. These are only calculated to certain calculations fed into the computer.

The one to look at is the wheel power. As long as nothing has changed, ie same tyre size/wear/pressures, dyno room temperature, gear used (should be the straight through gear - 4th for a 5 speed overdrive box), the wheel power should be the same on whatever dyno you use. Opening myself for a beating

The Dyno I use is old, installed in 1985  Its Bosch and does not calculate flywheel power. However, the wheel power IS accurate. I have mapped cars here and just for the sake of getting a flywheel figure I took a couple down to another local chap who has a spanking new Sun dyno. The wheel figures were bang on the same as I had on our dyno. Bosch stopped making dyno's earlier this year. Gerry has also used our dyno, and commented on how good and sensitive it is.

Some dynos have software which calculate the power figure and correct it by whatever the room temperature is.

The Dastek dyno is "probably" one of the best. Gerry certainly wouldn't make the dyno read figures just to make the customer happy. I certainly wouldn't either. Whats the point in that. If the car only makes 180 bhp after being carefully mapped, thats all its going to give - no matter who maps the car.

Perhaps we should consider getting the frictional losses down produced by the transmission, wheel bearings, etc. Different gearbox/diff oils, etc. Maybe a new topic?