Deceleration HP ???

[dynoman14]

Is anybody out there measuring this on their engine dyno or chassis dyno? I will post a couple links to a post on Speed if any body wants to take a look.

http://speedtalk.com/forum/viewtopic.php?f=1&t=31298&p=372332#p372332

[ford396]

I have never measured engine deceleration #s, but I have checked driveline rotational horsepower. I realize it is not the same thing, but would it be measured the same way, only leaving the drive line engaged instead of neutral?

[stockcar5]

a fun read..

http://speedtalk.com/forum/viewtopic.php?f=1&t=31276

[Chico]

interesting very interesting

[dynoman14]

Ford,
What you are checking is coast down HP of the drive train if you are just throwing the trans in neutral and letting the dyno drum coast down. You can check for bad universal joints and transmission bearings if you know what to look for and have data smoothing turned off.

Deceleration HP is the HP the car generates just as it would on the track, accelerate up to 7500rpms, decelerate back down to 3500 and then stab it down again. For every track and driver it can be different but you can get a good idea with a decent recall tach or a Mychron system in the car.

Most systems won't accomodate data gathering in the decel mode but can be programmed by the right folks. I have been running mine that way since I started testing battery back-up and KERS type systems for PAD in the 90's.

It is also hard to get accurate data with only one mag p/u on the inertia wheel as the data is not really coming in fast enough for you to evaluate and form acceleration and instantaneous acceleration curves without extrapolation or data smoothing.

If you have a pretty smart Kart guy around and access to some of the old Gold stuff you can actually get dyno numbers off the car while running. It is a little more complicated with the new systems but can be done with the GPS and acceleration numbers ( although side forces and jitter are a big issue in gathering data in dirt cars ).

If you are pretty sharp you can also measure stagger HP loss, spool HP loss, gleason losses, lockers losses and just about anything else you can dream up. You can also measure the losses thru different QC gears and the results of those tests would blow your mind.

Believe it or don't my customers have been happy with the results as I have done work for Panoz, Tex, Jerico, Tiger, Factory 9, Motive Gear, DPI, Benson, Senneker and many others. Still have a couple pretty good projects going now but will have to wait til later to discuss them.

One of my first tests on a locker system in a dirt car was 11 years ago and the guy that runs the stuff is still pretty dominant with it today. It has branched out to a couple other competitors since and if look real close you will see which wheels are ratcheting, you can really see it at night. Many people think it is traction control but good traction control is neither visible or audible and does not involve the wheels but engine management.

There are a couple CUP teams that have found some secrets in Programming and others still struggling to figure it out. You can hear it in Qualifying if you are at the track and sitting close to corner exit.