This past Saturday was a full day. Got up in the morning to prep the car for an evening of drag racing, then we were off to a dyno day.

Cheryl dyno'd her car first. Her car is an 07 6MT Sedan, bone stock. It got some attention. A bunch of people were asking what we thought it would put down, and my guess was 265, based on other dynojet plots I've seen around the web.

This was the first HR for this dyno, and consequently, the first time the guys had had to strap down one of the new sedans. Fortunately it wasn't a problem, unlike when I had my 05 dyno'd at Z1 back in March.

I had the guy do the first two pulls in 4th gear, and the 3rd pull in 5th gear. For the 07 guys wondering why, the first gen sedans had a speed limiter of ~145mph, which meant that a pull in 5th gear would not go to redline.

The first pull netted 264.72/224.90. The second pull was almost exactly the same: 264.75/225.97. We're talking a difference of 3 tenths of 1 horsepower at peak. When the two plots are overlaid, they are nearly identical. Those are the two most consistent pulls I have ever witnessed.

The last pull, in 5th gear, yielded 267.21/232.67. So right around what I was expecting. After that pull, the owner was kind enough to entertain us with a few extra pulls for observation purposes. The next pull was again performed in 4th gear, just so we could see how far off the tach was. In my car, the tach is off by about 100rpms at redline in first, 200 in 2nd, almost 350 in 4rd, and almost 400rpms off at the top of 4th. We didn't measure the variance in any of the other gears, but it appears that the tach is still optimistic, right at 400rpms again. The tach registered between 7900 and 8k rpms before he encountered the fuel cut, and the measured roller speed of the dyno was almost an exact 7500.

After that, we tried to find the speed limiter. Unlike my car, it turns out that Cheryl's 07 can take 5th all the way to fuel cut. Then we tried 6th, and it topped out at a speedo-indicated 160mph, which was right at 155mph on the rollers.

One thing I noticed was how rich Cheryl's ecu is running. When my car was stock and dyno'd in the heat, my car ran rich, but nowhere close to this. At the beginning of the run, the a/fs were just under 12:1. They quickly leaned marginally, to just above 12:1. But they started declining at about 3300rpms, richening to 11.5:1 at 4500rpms. After that, they were stable until 7k, when the ecu just dumped gobs of fuel, enough that the a/fs were under 10:1 and eventually reached a flat 10:1 at redline.

I have no idea what the future holds in regards to tuning, but there is a lot of power left on the table based on a/fs alone. The a/f's are so rich that for a novice like myself it appears the car is ready for boost from the factory.

I have attached two images to this post. The first post includes the plots of Cheryl's first two runs. Notice how consistent the new motor is. The second image plots her best run. Look closely at the a/f's.

More info and a contrast to my car to follow.

 

Now on to my car. When we arrived, one of my friends(owns one of the local shops) was there, and he asked me what I thought I would run. He remembered that my best was somewhere around 265, and I confirmed that he was correct. He told me not to expect those numbers that day due to the heat. He said several cars were down on power. I just smiled, and said "we'll see." From then on, he kept poking fun at me saying I wasn't going to do better than 245.

So after Cheryl's car was done, I pulled up my car and they strapped it down. I did my typical procedure of 4th, 4th, and 5th. The first pull got me 259. The second 261. Then the third gave me 266.40/248.87. So much for 245

What can I say, I know my car. My a/fs weren't as steady as when it was tuned back in March, but much more steady than stock. I've removed my stillen airbox, but it hasn't seemed to have affected my tune very much at all.

The conditions were awful. Temps in the garage were between 95 and 98 degrees for all of the runs(for both Cheryl and myself), and the pressure was dropping. The baro was only 28.81. So the correction factor was an incredible 1.06.

That proves one thing about correction factors on dynojets. Compared to my last dyno in March where the correction factor was 1.00, the plots were almost identical.

So let's compare the power of the two cars: at peak, my car made .8hp less than Cheryl's car. At peak, my car made 16ft/lbs more torque to the wheels than Cheryl's car. But that only tells part of the story. When the two plots are overlaid, one can see where the differences lie.

From 2500 to 2750rpms, my car is a dog, making between 10 and 12tq less to the wheels. From that point there is a surge(you can feel it when you drive), and the two plots cross at 2900. At 3500, may car benefits from a 12tq lead; at 4k, it's 30 ft/lbs. From there my car's advantage slowly declines. At 5k rpms, it's back down to 13 ft/lbs. At 5600rpms, it's 15 ft/lbs.

The major difference in the two cars lies in the power delivery after 5500rpms. At 5500, my car is making 96.9% of peak horsepower. Cheryl's car, on the other hand, is only making 89.5%. From 5500 to 6300, my car only picks up about 10hp. Cheryl's car picks up twice that, eventually peaking at 267 at 6900 rpms.

I have attached 4 images. The first is my best pull of the day. The second is an overlay of Cheryl's best pull versus my best pull. The third shows how my best run back in march, with a correction factor of 1.00 plots versus my best pull from Saturday, with a correction factor of 1.06. The last image shows the same two runs, except this time they are uncorrected. I find it interesting that the heat, humidity, and low pressure cost me 12 to 15 ft/lbs of torque over the entire range, in raw uncorrected hp.

 

Now it's time for some videos of the dyno day. Please forgive the video. I'm still a complete video novice, and as a result, much of the video is shaky, or has one of my fingers partially blocking the view.

This first video is a quickie of Cheryl's car before the first pull. Nothing major here:

The second clip is of Cheryl's first pull, fourth gear:

The third clip is of Cheryl's second pull, fourth gear:

The next clip is of Cheryl's 3rd pull, 5th gear:

Next is a video of the tach as we hit the fuel cut in 4th gear in Cheryl's car:

Next is a clip of my first pull in first gear. I'm too close for all my pulls, so the exhaust drowns out the audio a bit:

Second pull, 4th gear:

Last pull, 5th gear:

This last video is of the car that was on the dyno before Cheryl's car. It's not an action shot, just a walk around. It's a gorgeous red 240. It's tig488's new ride. I wouldn't mind getting rid of my sedan for something like this:

 

man seems like FI is the only way to go to keep up

with the g37 along the corner i feel outdated

 

awesome info and sweet vids!! VERY interesting results! i have a utec/mrev2/stillen box as well with the crawford plenum on my 6mt...when i rolled on the dyno after a 3 hour drive temps where in 95-100 range also and ~20 pulls later i had 250hp and 260 torque. (baselined at 240) ..weird its about the exact opposite of ur results!? i DEF need to open things up a bit more with some headers, etc...

did u guys "test" yours cars on the street?

 

You are the man Trey Great write up and vids!!! Very cool to see u and ur wife out for a dyno day in 2 G's with impressive results.

 

great rite up trey...

Im a lil bit of a novice with this stuff myself. I see that you ran a 13.6 with your car which is really great, congrats btw. Just curious though, being that yours and cheryls cars are putting down such similar numbers on the dyno, advantages and disadvatages varying through the powerband, my thoughts of pulling a 13.6 - 13.8 range with my 07 S 6mt arent that far feched are they.

I honestly thought i could do it seeing that an X did a 13.9....but alot of people dont seem to think so, and besides that i seen some other post of people doing around 14 flat.

Im not saying its going to easy but i think with the rite factors on my side (temp, humidity, launch, shifts etc) i think those numbers really are within reach. What do you think?

 

very cool and interesting observation. thank you for that data!

this would go a loooong way to explaining the poor mileage our cars get for this class. it also implies that- unlike most other modern vehicles- ours are actually likely to benefit from a "computer upgrade". A little leaner across the board under WOT would be nice, say 12.5:1. At partial throttle, even more lean is acceptable- around 13.5 or so. we would get more power and more mileage.

I wonder if nissan is preparing for bad fuel?

 

Thanks for sharing. In comparing your results to the HR we dynoed here, there is probably another 7-8whp available, if it were not for that nasty rich dip at the end.

 

you can't reliably compare two different dynos, especially when you're talking about a ~3% difference (I'm guessing variance from dyno to dyno could easily be beyond 3%, so you are not talking about statistical relevance here).

 

Very interesting data. Thanks for sharing. I too wonder why the 07 is running so rich. Wouldn't this foul up the engine a lot sooner than normal?

 

Thanks, Trey for sharing the vids/dyno charts for the 07 MT, I have been unable to find much info for the 07. Interesting about the rich A/F at high revs. Perhaps tuned rich to keep lower EGT temps @ high rev/help improve reliability.

 

def intersting

 

im a little a clueless when it comes to a/f ratios and all that stuff. Am i wrong or are people saying that by leaning the car out a little bit it will actually improve performance?

 

Very good post. Thanks for taking the time & the effort to do this. I wish someone would do a similar comparison (a modded non revup with a stock HR) with the 280hp motor.