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Just got back from the dyno- updated with dyno chart

Discussion pertaining to positive pressure E28s.
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turbodan
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Joined: Jan 09, 2007 10:19 PM

Just got back from the dyno- updated with dyno chart

Post by turbodan »

This time it did 290 HP and 350 ft-lbs of torque at the wheels, uncorrected. It was a balmy 90 degrees in the shop, 25 inches of mercury, 16 percent humidity. I'll check out the datalogs to see what the IATs were, but I bet it'd do an honest 300 RWHP on a cooler day. The AFR's were good on the first pull until around 5k rpm where they began to drop. They got into the high 10's by 6500. So I got that fixed up and it brought the torque curve up dramatically. I'll post that chart as soon as I can get a picture of it. Its hella flat. Its still making around 270 RWHP by 6500.

Image
Last edited by turbodan on Dec 21, 2008 10:50 PM, edited 2 times in total.
Jeremy
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Post by Jeremy »

Not bad for home built and tuned mostly by the seat of your pants. :up:

Looking forward to seeing the graph.

Jeremy
turbodan
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Post by turbodan »

My AFR's definitely sucked on the first pull. Down into the 10's by 6500. Peak power and torque were unaffected, but it was killing the top end.

I had been suspicious of the VE table in MS, as it seemed to run best with more and more fuel all the way up to redline. After a few pulls it looks identical to the torque curve. So its pretty accurate. I would have never figured that out with the butt dyno.

I'm really thinking it'll do 12's. It felt good before, but its got so much more top end with the dyno tune. I'll have to play with the ignition timing. I could even get a little more out...
Martin in BellevueWA
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Post by Martin in BellevueWA »

Good to know the AFR's are safe.
turbodan
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Post by turbodan »

Image

Alright. I dont have a camera or a scanner, so I laid the chart over the screen on my laptop and traced it out. It came out really good. The scales are SAE corrected in the chart, so dont pay too much attention to that.
Wildstoats
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Post by Wildstoats »

What kind of dyno where you on?
Jeremy
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Post by Jeremy »

Kinda weird that there's no "torque plateau" in the mid-range. It spikes up, then just steadily falls off. Does the m20 do that same thing stock? I don't think I've ever seen a dyno curve from that motor.

Also, I guess the numbers on the graph are "brake" numbers? Any idea what factor they used for driveline loss?

Jeremy
turbodan
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Post by turbodan »

Those are SAE corrected numbers at the wheels at sea level on the graph. The altitude correction doesnt really apply for turbo cars tuned for the elevation, so its more like crank hp. The factor was 1.23, as it shows on the left side of the chart. 1.2 is the standard factor for 5500 feet, then another 3 percent for the temperature. I would have traced the uncorrected chart if I knew the scales were different. In any case, the curves are the same regardless of any correction factor.

With the factor of 1.03, that bumps the uncorrected #'s to 298 and 360. So I can say it does an honest 300 RWHP.

The dyno was a 1200hp 200 mph Dynojet. Thats all I know about it. It was the same dyno I made an uncorrected 230hp/266tq on earlier this year with 60 degree ambient air temps. It went up a good 70 hp and 100 foot pounds of torque since then, and with a huge improvement in the top end power. I'll see if I can get scans of the uncorrected rear wheel sheet and the sheet with the new dyno over the plot from the old dyno for tomorrow.

The torque peak has something to do with the way the motor builds boost. Its not a steady 15 or 16 psi. There are spikes and dips. I think thats just the way it is with the internal wastegate and check valve style MBC.
T_C_D
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Post by T_C_D »

That's a great result. Car obviously runs very well.
Shawn D.
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Post by Shawn D. »

Great job, Turbodan!
turbodan
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Post by turbodan »

Thanks guys. Hopefully it'll stay together making that kind of power. I think I'm happy with where its at. 350+ foot pounds seems like an awful lot of torque. The way I drive it doesnt help either.

With that powerband, I'm hoping it'll dip into the 12's, and it should be trapping at least 110. Thats a good place to be.

Here are the actual charts:
This is one of the first pulls, as it came in off the street on the butt dyno and ninja skill tune. I though it was dipping into the 10's on the very first pull, so perhaps this was the second or third:
Image

This is the fourth pull, after some major adjustments using the dyno wideband:
Image

This is the tuned run on an uncorrected scale:
Image

And this is this weekends run laid over the chart from earlier this year, when I ran the GT2560R .64, stock injection and RRFPR:
Image

The runs earlier this year were with 60 degree ambient temps, and this weekend it was over 90, as you can see on the scans. Add another 10 hp and ft-lbs for temperature difference...
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