Mike Frye

Leslie,

Those pics are a little grainy, I'll wait until you scan them in next week if that's OK. You can just e-mail them if you like. I'm at m.r.frye at comcast.net

Tony,

If you're going back soon, let me know because I need to do the same.

hacker-pschorr

Seeing another L-Jet car running lean on boost I can only assume we are having the same issue.

I'm not 100% sure it's fuel related as much as it might be ignition. I have a video lying around here showing my tailpipe at full boost. It's a red cone of fire forming like the tail end of a jet, that is not the sign of a lean mixture yet the A/F said it was. This is unburnt fuel igniting when it reaches the outside air at the tailpipe.
I connect the dyno wide band to a bung just after the Y collector; I do not use tail sniffers.

I know there has been a lot of debate about how unburnt fuel shows up on the A/F meter. This proves beyond any doubt the unburnt fuel is not measured at all, showing a lean mixture.

So, is the problem the coil? I doubt it, these are pretty strong (could be wrong, just my guess).
Or maybe the ignition amplifier? If I could get my hands on a MSD 6L I would try it just to see. I have a spare green wire to cut up so I can install the MSD without making any permanent changes to the harness.
Another culprit is the distributor itself. A very common performance upgrade for domestic cars is a distributor with the plug connections spaced further apart. We might be arcing between plugs at high boost causing a bad, weak or missing spark. One easy solution could be to cut away part of the rotor to make it narrower, lowering the chances of this happening.

I like to look at what the factory did. They took the 16V 928 from 240bhp to 310. What did they change? They went with a dual coil with separate amplifiers and a dual distributor spacing out the plug connections.

Leslie 928 S2

Quote:

Originally Posted by Mike Frye

Leslie,

Those pics are a little grainy, I'll wait until you scan them in next week if that's OK. You can just e-mail them....<snip>

Yeah, Mike, they weren't really for you this time. I just threw them up there in case anyone wanted a looksee before next Monday. If I don't get ahold of someone at TT to send the files before next Monday ( ) I'll email you full res versions first thing Monday morning, promise! We can't wait to see your video!

Leslie 928 S2

Ok, finally had a minute to scan Kevin's runs. Here they are....





Mike, I'm mailing full res versions to you right now!!

And I'm still trying to reach one of the clowns at TT about the run files.

Leslie 928 S2

About smoothing....I just remembered that this explanation was given to me by Carl at 928 Motorsports back when we were doing dyno runs on Pandora for him. I received this explanation by email.

Quote:

Originally Posted by Carl @ 928 Motorsports

As to SAE smoothing – that tool on the DynoJet software averages the peaks and valleys to smooth out the jaggedness of the lines. It also tends to round down when it averages. So – if you want your dyno chart to show every possible HP and the highest numbers – set Smoothing to Zero. The lines will be more jaggedy but the HP number will be higher. If you want the chart to have the smoothest lines, set Smoothing to 5, but you will “lose” about 4 HP at the peak because of the averaging.

Hope this helps!

Mike Frye

OK Leslie,

I'll get to work on it tonight and set it up as soon as I get the images. The other ones were over 100mb and I uploaded them to an ftp sight for free download. Will you be able to get files that big or do you want me to burn you a disk?

Leslie 928 S2

Since we're on dial up at home, Mike, we can't really watch videos on the computer.....so it would be extremely appreciated if you could do a disk for us.

Thanks!!

jthwan22

Anymore plan for another dyno day? My car is back in action.

Mike Frye

Very cool,

I think Tony and Kevin are up for a repeat performance soon and I never really got a good run so I'm in too. I have to get a new O2 sensor and put it in first though. I think they're all waiting for me to get my car ready so if I can get it right in the next few weeks I'll start another thread. Stay tuned...

cobalt

I would be interested but I am booked solid for September and have only a few open Oct weekends.

Leslie 928 S2

I put in a call to TT this morning and left a voice mail asking what days they might have available at the end of September and through October. Let you know what I hear!

toofast928

I'm in..........

Leslie 928 S2

Please see the new thread for another dyno day!
New Dyno Day Thread!