Interesting day on the dyno - Alfa Romeo Bulletin Board & Forums
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post #1 of 6 (permalink) Old 05-02-2017, 10:33 AM Thread Starter
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Interesting day on the dyno

Rather than drive the GTV6 500+ miles to Al Mitchell's I took the GTV6 to Carolina Chassis Dyno in Lexington SC - about 45 minutes away. It is a Mustang Dyno.
The first run made 204 HP at the wheels at about 5400 rpm. It was running lean but only made it up to 206 when we added fuel. We then moved the max ignition advance from 32 to 33 and it made 212 HP and another degree (34 total) got us to 214 HP at 6000 rpm. Max torque was 207 ft-lb at 5300. The runs were in 3rd gear. Using the rule of thumb 15% transmission loss gives 252 HP and 243 ft-lb at the flywheel.
The starter quit after the penultimate run and we waited a little while for it to cool down but it only worked when I tapped it with a hammer and long socket extension. Then it refused to start again after the last run and it tried to start when we pushed it but it would not catch and I called for a tow. When the tow truck arrived I turned on the ignition and noticed that the fuel pressure was high (I have an electronic gauge). I loosened a clamp to vent the pressure, turned the key and it fired up so I drove it home. The car had a misfire up to about 5000 rpm when it was on the dyno and it acted up all the way home and the tachometer quit. I have some troubleshooting to do on the ignition system but it seems to be a good sign that it is fine at WOT above 5000 rpm!
You can see on the charts that the dyno was struggling to control the motor below 5000 rpm but it is clear that the power curve is flat from about 5400 to 6800. The junk at 6800 is the rev limiter cutting in.
The RW torque at 3500 appears to be about 170 which corresponds well with what we saw at Al's before we broke the driveshaft.
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Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke

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post #2 of 6 (permalink) Old 05-02-2017, 02:46 PM Thread Starter
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Here is the Megasquirt data log for the final run. The AFR is well controlled and just bit lean at the very top.

The motor is a 164L with S pistons and was built by Giuseppe Lore. The heads and GTV6 runners are unmodified and the plenum was cleaned up and the volume increased by Richard Jemison. It has Richard's street cams and a modified Greg Gordon cold air intake. Exhaust is CSC headers into a single 2.5" pipe and a Borla straight through muffler. Ignition is Crane Hi-6. The Megasquirt controller was built by Al Mitchell who also supplied a set of matched fuel injectors and other necessary parts. It returned 22 mpg for the 500 mile trip to Al's which was mostly cruising at 75 - 80 mph. I am pleased with how it performs. I will probably set the rev limit to 6500 as there is no point in stressing it beyond that.
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Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #3 of 6 (permalink) Old 05-02-2017, 02:54 PM
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Great update Ed!! Glad things are coming around!


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John (JP) Perry

1972 Montreal - done!
1982 GTV6 - making it a track car!
1991 164B - sold 8/2013
1989 Milano Verde - sold 11/2012
1986 Spider Quad - sold 1/2012
1991 164L - sold 11/2011 and regret selling it
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post #4 of 6 (permalink) Old 05-02-2017, 07:31 PM Thread Starter
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Quote:
Great update Ed!! Glad things are coming around!
You are welcome to drive it anytime. It has the motor that I bought from Erik. You may have helped load it into my wife's Highlander.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #5 of 6 (permalink) Old 05-03-2017, 03:59 AM
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I did. Wow...I forgot about that motor. Once my GTV6 gets back on road, I will arrange to come down. Thanks for invite!


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John (JP) Perry

1972 Montreal - done!
1982 GTV6 - making it a track car!
1991 164B - sold 8/2013
1989 Milano Verde - sold 11/2012
1986 Spider Quad - sold 1/2012
1991 164L - sold 11/2011 and regret selling it
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post #6 of 6 (permalink) Old 11-26-2017, 02:31 PM Thread Starter
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I posted in the Megasquirt thread about removing the Crane Hi-6 CD ignition and how much better the car runs now. Today I tested the Crane ignition on the bench with the CD type ignition coil that was also in the GTV6. The only good news is that it makes enormous sparks. The rev limiter does not work - I did not notice that because I use a fuel rev limiter in Megasquirt. The power/diagnostic LED does not illuminate - I did not notice that because I could not see it under the parcel shelf. The tach signal is garbage which explains the tach reading low. Maybe I can use the Crane to light my gas grill! One of my many complaints about CD ignition is that they are complex and have failure modes that hard to understand. Your car acts up and you think "maybe it is the CD ignition" but short of tearing it out there is no way to know.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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