Horsepower meter on Bugatti - how does this work?

[Porsche-O-Phile]

Anyone know? I know they put "torque meters" on turbine driven aircraft but I think this is the first time I've seen an on-board dyno for horsepower. At least I'm assuming that's what the gauge on the left is.

Anyone know how this thing would work? Can I get one on my 911?

[Jim Sims]

Measure torque on the output shaft and combine with RPM to compute power.
Torque usually measured with a electrical strain gage array mounted on the output shaft. Power and data link to strain gage on rotating shafts is usually wireless but older units used brushes and slip rings. I believe both inductive and capacitive coupling has been used for the wireless connection. Mechanical energy harvesting can now be used to power the gages and run the data collection and transmission - now being done on rotating helicopter components. One might mount such a system in a 911 on the 915 input shaft as it passes through the final drive housing.

[Red88Carrera]

There are a few factory vehicles that offer an onboard torque meter. I believe the Chevy SSR pickup is one of them. Torque and HP are not a direct conversion. You need to know rpm(tach) and a few other things. Here is one way to calculate HP if you know the torque.
http://roadstarclinic.com/content/view/103/118/

[jmshepard]

back in the old days on turbine helicopters (hueys, OH-58, OH-6, AH-1), the torque gauge used oil pressure to drive two spring loaded plates in opposition to each other. It was in essence a very finely calibrated oil pressure instrument and measured torque as a function of the engine oil pump.

[Won]

I thought it was just a glorified turbo boost gauge.

[Noah930]

Originally Posted by Porsche-O-Phile

Anyone know how this thing would work? Can I get one on my 911?

Uh, you might wanna get someone to recalibrate that meter if you intend to stick it in your '74.

[GH85Carrera]

Originally Posted by Noah930

Uh, you might wanna get someone to recalibrate that meter if you intend to stick it in your '74.

Yea maybe a max of 300 would be optimistic.

[Wayne 962]

F = ma. We know m (mass) and a (acceleration).

Power (KW or HP) is force over time. Force is related to torque via the length of the torque arm. We know time. Therefore, computing HP or KW would be pretty easy, if you know the mass, acceleration, and time period.

This is how those accelerometer HP meters work - you have to punch in the weight of the car, and then it measures the acceleration, which can then give a pretty good estimate of the horsepower...

-Wayne

[snbush67]

I haven't seen any confirmations of this, but this car stereo is supposed to measure horsepower

G-Analyzer: This unit is equipped with a sensor that measures the forces of gravity on the vehicle. This sensor enables the receiver to calculate G-forces during acceleration, braking, and cornering. The G-Analyzer has a stop watch that can be automatically started when forward or reverse G-forces are detected. The G-Analyzer also has a horsepower analysis tool that measures your vehicle's horsepower and displays a graph with max power. Setup and calibration for acceleration and braking must be performed before using the G-Analyzer.

Note: Features like the horsepower analysis tool should not be used on public roads.

http://www.crutchfield.com/S-ybnf6eClF6n/App/Product/Item/Main.aspx?g=278650&tab=detailed_info&i=113KDCX890

[Paul K]

FWIW, Bentleys have what is basically a power reserve gauge. That would be interesting on a 911...

Cheers,

Paul.

[Porsche-O-Phile]

Originally Posted by Noah930

Uh, you might wanna get someone to recalibrate that meter if you intend to stick it in your '74.

Tppht. Hater.

I'd just get a few "type R" stickers and a gigantic wing, some mismatched body panels, a faux carbon fiber hood and a fart can exhaust, then I could easily make 1,001 horsepower, right?

[burgermeister]

They know RPM, fuel flow, and air flow so they can run the engine. Dyno testing they had to do for engine development surely got them a thermal efficiency map, which they probably added to the ignition, fuel, and cam timing (and whatever else they have in their engine) maps. Then looking up the HP electronically should be pretty simple.

[rick-l]

So does it measure torque at the crankshaft and how? It is not too impressive if all it does is measure acceleration and take a guess at the mass to derive HP.

The owner at Bentley of St Louis started the car up for us and I glanced at it and never saw it move. I was more interested in watching the car jump up and down and the two huge aircraft control surface type spoilers ext/retract.

[beepbeep]

Ahh...measuring torque would be spectaculary complex solution to non-existing problem.

I'm quite certain Bugatti "power-meter" is proportional to air mass inhaled by engine. Knowing air mass from AMM (and compensating for ignition timing, if you are picky) would give you power.

The nice part is that you have all inputs allready there. Only thing you need to do is do a dyno pull and make lookup table for air mass vs. HP and then let the stepper motor in indicator display it.

SAAB had ordinary boost meter replaced by gauge that actually displayed air mass but reverted to fake boost gauge (actually a stepper motor controlled by ECU) as customers liked it that way.

HP meter is IMHO utterly needless device probably installed there to make car "special".

[rick-l]

Another interesting aspect of this car is the tires are supposed to be changed every 5000 miles. They are metric size and apparently are $5000 a set.

The wheels are only good for 15,000 miles and I think I remember hearing $25,000 (although $75,000 sticks in my mind).

[Superman]

It sounds like you need to read through your owner's manual, Jeff.

[carnutzzz]

My guess is that it's simply calculated from RPM.

I'll check my Veyron when I get home. That is- unless Penelope Cruz borrowed it to run to the grocery store to surprise me with dinner again. It's always some new lingerie she just bought and a variation on chicken.

Life gets so routine.

Just kidding babe- see you at 6!

[nameisbauer]

Originally Posted by rick-l

Another interesting aspect of this car is the tires are supposed to be changed every 5000 miles.

Unless you are running at full tilt, then they will only last 15 min, but thats ok because you run out of fuel in 12 min as a safeguard.

[gtc]

A set of tires that only last 63 miles? That's pretty ridiculous tread life, especially when you realize they're costing you $5.55 a second.
But then if you can afford a Veyron, why would you care?

[Gogar]

"Captain Slow" explains "why" pretty well here:

http://www.youtube.com/watch?v=dsYKVoFkvHQ