My car is totally stock when it comes to performance... I dyno'ed it when I first got it, with less than 1000 miles on the odo... It peaked at 252 HP and 230 Torque... This was on Dec 29, 2006...

So, in order to test the myth of whether or not a car gets "more powerful" after a few thousand miles of "break-in", I decided to re-dyno the car... The car had just over 6900 miles when it was dynoed for the second time...

The result? Well, I'd say it's mixed... The weather conditions were the same both times, and the dyno was the same...

The first time I dyno'ed the car, all 3 runs were done identically.

Less than 1000 miles, Dec 29, 2006 dyno #1:
Runs 1-3, ECT Power, A/C On -
Run 1: 248.77 HP / 223.34 Torque
Run 2: 251.96 HP / 230.02 Torque
Run 3: 250.20 HP / 230.06 Torque

6900 miles, June 15, 2007 dyno #2:
Run 1 - ECT Power, A/C On - Identical to 1st dyno run
Run 1: 251.50 HP / 218.11 Torque

Run 2 - ECT Snow, A/C Off - To see if snow mode helps and if turning the A/C off makes a difference
Run 2: 257.75 HP / 233.07 Torque

Run 3 - ECT Snow, A/C On - To see if snow mode or A/C off caused the better dyno numbers for the second run
Run 3: 252.99 / Torque 227.63

So, it appears that turning the A/C off helped about 5 horsepower...

It also appears that snow mode did not help at all...

Finally, it appears that there was no increase in power from the first time I dyno'ed to the 2nd time if you compare when the A/C was on both times...

I welcome any discussion or thoughts on this...


Picture from the 2nd dyno day:

 

Crazy.... Well it looks like we can scratch that one. I had never heard it before anyway, all I was told was that your gas mileage would inprove after break in.

 

I never thought that power changes before or after break-in.

However, other factors can change power output, mostly being the "health" of the engine through proper maintenance.

 

Thanks for posting, great info. Did you note the temperature, humidity and barometric pressure on each of the two days you tested and apply a correction factor? Or does the dyno software automatically take this into account? Those factors all affect air density, and in turn the amount of power the engine is making.

 

I am not at all surprised. These aren't Chevrolets with flat tappets and a 280 grit cylinder wall finish.

 

Weather (temp and humidity) was basically the same both times... It's an indoor dyno as well...

 

It was a lot colder last year.

 

It was around 60 something degrees this past time... I seem to remember the temperature in December being around the same (Christmas day was like 75 degrees and sunny)

Anyway, the dyno is indoors with a huge fan (3-4 foot) blowing at the open hood of the car... So I don't think there was much difference...

 

The Key to a successful Dyno, is making sure that every power draining accessory device is Turned OFF.....

Jz

 

Looks like you gained ~3 bhp on average. This could be due to atmospheric variables. The only way to be a little more certain would be to do another dyno in the future to see if there is a trend.

I do think cars get stronger as they break in and before they start to wear out. If you look at the long term tests in the car rags, the cars are usually a tick or two faster in the acceleration runs. (I don't recall ever seeing one go slower.) There are many variables such as switching to a better tire but I'm also sure that the clutches are also used/abused... evening things out.

I also think this is why many see a slight gain after they put a mod on. It's probably more than several K miles since their previous dyno and the 4-5 bhp could be the result of break-in v. the mod or a combination.

 

Basically the same? Or exactly? The condition of the dyno also plays a role in this. There's too many variables IMO.

 

Good food for thought. It would be interesting to try to extrapolate those numbers to the flywheel hp of 306. Seems that were other posts that postulated that maybe Lexus was understating true hp levels. Seem to recall ~20% loss between flywheel and rearwheel. If this factor is accurate then your dyno numbers equate to Lexus' 306 hp. Informed comments?

 

Thanks for busting this myth.

 

It's really hard to say... I've seen big differences between dynos... The dyno that I tested my Lexus on is pretty new, and the dyno owner said that his dyno gives lower numbers than all the other dynos in the area... So if I went to a different dyno place the numbers may come out 5-10hp higher... But, given that his is new, and seems to be quite accurate, I agree that it looks like the Lexus 306hp rating is accurate, and not over or under rated by much...

 

You need to get your charts with SAE correction turned on and make sure the smoothing factor is the same for both sets of runs. This will eliminate the weather variables. From what you have posted, we can't say either way how the car has responded with a few thousand miles put on her. Something else that may help is to get the runs overlapped from both dyno sessions. You may have gains in the power band, but not at peak numbers. See if you can get the shop to load the runs on a memory stick and load the files into Winpep you will have a more accurate representation.

If your car is still stock with 15,000 miles or more you may want to dyno again down the road. I don't think driving 5900 miles will yield any real measurable change in the engine power. Too many variables when measuring such small changes in power.