Dealership to Dyno: Our FR-S gets measured

[Arsenal Autosport]

We picked up our Asphalt Grey FR-S today from Alan Jay Toyota/Scion in Sebring, Florida earlier today. It's a manual with the BeSpoke radio and what I really found surprising was how great this color is, especially in bright sunlight. There is some orange peel that I noticed on the rear decklid, but overall the car is really pretty. After getting over the joy of picking up the new toy, I made my first stop of the day at our friend's shop: Titan Motorsports. They have an AWD Dynojet and our goal was to get a baseline idea of the power numbers and curve.

I'll leave my first driving impressions for another thread, because this is about the baseline pulls we made today (but MAN is this car fun!).

We did 4 pulls, the first 3 were fairly close together and today was a hot day in Orlando, all three pulls were between 160.8 and 161.1whp. We decided to let her rest for a few minutes and turned the fans on high to cool everything down so that there was as little heatsoak as possible.

On the 4th and final run, the car posted 164.7whp:



Video of the run is coming tomorrow!

I was satisfied with the numbers and I think we have a great baseline to work from. This car at 200whp, with a little less weight and some suspension upgrades is going to be a little rocketship...

Follow us on Facebook, Instagram and here on FT86club to see how we build up our FR-S to make a great platform even better. We have parts in development and will be offering them for sale very soon. The car goes on track next weekend for the first time. Pictures and video to follow.

-Jon

[Pseud0logik]

So either the car is over-rated or it has 17%-18% drivetrain loss.

I'd like to see more baseline numbers after 500+ miles and an oil change.

[Arsenal Autosport]

And here's the video:

[ame="http://www.youtube.com/watch?v=KVJJfDp0c1w"]2013 Scion FR-S Dyno - Stock, 164.7 RWHP - YouTube[/ame]


-Jon

[Prava]

I know the specs say that the car is 200whp at 7000rpm... But I don't entirely understand how a dyno works entirely. Is it a 3rd gear pull to a certain rpm/mph? Can somebody explain it simply? And also, simply why its not pulling towards the 200whp zone rather than 164.7whp?

[powertrip]

Originally Posted by Prava

I know the specs say that the car is 200whp at 7000rpm... But I don't entirely understand how a dyno works entirely. Is it a 3rd gear pull to a certain rpm/mph? Can somebody explain it simply? And also, simply why its not pulling towards the 200whp zone rather than 164.7whp?

You use the gear that equates most closely to a 1:1 ratio on the torque multiplier (gearing). The reason it pulls less than stated Crank HP is due to parasitic loss in the drivetrain. Pulleys, transmission, wheels, etc leech power from the motor on the way to the rear wheels.

[Draco-REX]

Originally Posted by Pseud0logik

So either the car is over-rated or it has 17%-18% drivetrain loss.

I'd like to see more baseline numbers after 500+ miles and an oil change.

17%-18% driveline loss is appropriate for FR car with manual transmission and an independent rear. In fact, it might be a little high, but that could be a dyno variance. Solid rear axle cars with manual transmissions are in the 12%-15% range. An independent rear or auto will bump that another 2%-5% each.

It's when you start looking at AWD that the numbers really jump since you're nearly doubling the driveline. Subarus will see as much as 26% driveline loss.

Originally Posted by Prava

I know the specs say that the car is 200whp at 7000rpm... But I don't entirely understand how a dyno works entirely. Is it a 3rd gear pull to a certain rpm/mph? Can somebody explain it simply? And also, simply why its not pulling towards the 200whp zone rather than 164.7whp?

The specs aren't whp (wheel horsepower), they are bhp (brake horsepower) which is measured at the crank with a dyno called an engine brake.

It takes power to turn everything connected to the engine, so the more you have connected (transmission, driveshaft, differential, half shafts, and wheels) the more driveline loss you'll see. So whp is a better measurement of the real power seen when driving the car, but bhp sells cars because it's a higher number.

[civicdrivr]

Do you have an AFR readout from that run?

[Arsenal Autosport]

Originally Posted by civicdrivr

Do you have an AFR readout from that run?

No AFR reading on this run since we weren't doing any tuning. That will likely come soon though.

[Matt Andrews]

i assume you couldn't find a tach signal to add that to the graph? thanks for posting. will be curious to see how others do as we get baseline data as well...

[Spaceywilly]

91 or 93 octane?

[Arsenal Autosport]

Originally Posted by Matt Andrews

i assume you couldn't find a tach signal to add that to the graph? thanks for posting. will be curious to see how others do as we get baseline data as well...

I'm not sure why he printed it with Speed instead of RPM. I only noticed that after I left. The 1/4 tank that the dealer put in had just run down to nearly empty. This run was made on a nearly full tank of 93.

[tonystewart]

Great Baseline, thank you!

[Tradewind]

Sounds like the correct power figure, actually very high for a 2.0 Subaru engine. Well done for getting this power from it

Would like to see a power run on a Dyno Dynamics or Mainline dyno ......... anyone?

[Ryephile]

Originally Posted by Pseud0logik

So either the car is over-rated or it has 17%-18% drivetrain loss.

I'd like to see more baseline numbers after 500+ miles and an oil change.

This dyno looks to be on-par with everyone elses baseline dyno on low-mileage cars. You can reasonably expect a few more HP in a couple thousand miles, but nothing to write home about.

Originally Posted by Prava

I know the specs say that the car is 200whp at 7000rpm... But I don't entirely understand how a dyno works entirely. Is it a 3rd gear pull to a certain rpm/mph? Can somebody explain it simply? And also, simply why its not pulling towards the 200whp zone rather than 164.7whp?

Just a correction: OEM's advertise engine power in crank horsepower, typically done to SAE J1349 [or J2723]. However, OEM's also typically bias their advertising lower than actual in anticipation of a certain engine-build tolerance range at the factory. This is intended to ensure even poorly broken-in engines with on-edge tolerances will make advertised power. OEM's can also bias the advertised number to play games with other brands.

Wheel or hub horsepower measured on a chassis dyno is subject to drivetrain losses and will of course read lower. Getting hung up on the actual number isn't relevant; chassis dynos are best used as comparative tools where you're making back-to-back changes on the same car on the same dyno.

If you want a "real" number, remove your engine from the car and put it in an engine dyno cell and run it according to the SAE methods.