Milwaukee Midget

[Milwaukee Midget]

I'm so busted - yeah, I trade beer for parts.

Speaking of parts - this appeared on ebay a short time back.  It's a Formula 3 BMC short stroke crank for the A-series inline engine.

I can't complain about the one I had made up, but shucks, man, this would have been so darned cool.  Probably the rarest of all factory BMC A series race parts -

http://www.ebay.co.uk/itm/BMC-FORMULA-3-CRANKSHAFT-40B-MG-SPRITE-RACE-/120704376673

Why wasn't this for sale last December?!?!?

[Koncretekid]

I have a question about Bill's dyno readout.  I see that the "x" scale is calibrated in mph instead of RPM, but it shouldn't matter.  But what I see is that your torque curve was still building when you ended the run.  Because hp is simply torque multiplied by rpm (and a fudge factor), unless your torque starts dropping at a rate faster than a 45 degree line, you could get more horsepower by increasing rpm.  Oh, I forgot - -that's a Harley.  Maybe your rpm's are maxed out.
Tom

[saltwheels262]

tom,

not sure about the x scale.
there is an rpm  scale on the right side of the readout.

the motor builder did say that power will not increase above 5500 rpm.
also said motor will wear out quicker at higher engine speeds.
rpm limiter is set at 6100. with the gearing I have, runs are completed
about 5460.

hope to see you again , at the races in  '12.

bill

[turborick]

Here are a couple from about 15 years ago of my old Turbo GSXR 1100

[Milwaukee Midget]

Thanks, Rick.  I'm seeing "S=3" on your first printout - is the "S" the "smoothing"?

Anybody got a definition of what that means?

[turborick]

Thanks, Rick.  I'm seeing "S=3" on your first printout - is the "S" the "smoothing"?

Anybody got a definition of what that means?

yes S=3 is smoothing factor 3

I have never seen a dyno graph so full of spikes as yours.
the only time I see spikes on my dyno is when the engine misfires bad or the tach signal is getting corrupted.
listening to your video your engine appears to be misfiring.
10 to 1 is the lower limit on most wide band units so it could be richer even, I would expect your engine to misfire being that rich.

[4-barrel Mike]

I think I'm going to buy myself an early Xmas present: http://www.amazon.com/Dyno-Testing-Tuning-Harold-Bettes/dp/1934709743/ref=sr_1_2?ie=UTF8&qid=1322166407&sr=8-2

OBTW, Harold hasn't been on site since April, anyone know why?

Mike

[Milwaukee Midget]

Thanks, Rick.  I'm seeing "S=3" on your first printout - is the "S" the "smoothing"?

Anybody got a definition of what that means?

yes S=3 is smoothing factor 3

I have never seen a dyno graph so full of spikes as yours.
the only time I see spikes on my dyno is when the engine misfires bad or the tach signal is getting corrupted.
listening to your video your engine appears to be misfiring.
10 to 1 is the lower limit on most wide band units so it could be richer even, I would expect your engine to misfire being that rich.

Hmm . . ., okay, you're hearing misfire.  I'll admit it's struggling to get on the cam, but guess I'm missing what you're hearing.  I'm taking this all in - just want to go faster. 

[Ron Gibson]

Ok, After my ears stop bleeding, stupid question. I know nothing about recording but would it be possible to slow the sound track down and scope it for intensity. Maybe see if a missing cylinder shows on scope.

[Captthundarr]

Chris, Happy Turkeyday. I don't pretend to know much about dyno work but I can read a few printouts. After reviewing the videos again I'm with Rick. There seems to be a lot of misfire then smooths out when it comes on the cam with the occasional pop. At first I couldn't tell if it was the audio on the vid then listened on my desk top with sound system. I' m kind of on the tuning learning curve with you. Would an over rich condition at the carb cause the miss?

[Milwaukee Midget]

Thanks, guys.
 
Ron - I could download the audio track into ProTools, an audio recording program, and probably break it down to each pulse, but given that the recording method was fairly low resolution, the room was very live, with lots of audio reflection, and the microphones were simple, built-in condensers intended for consumer use, I doubt if I could get it to reveal anything of consequence.

Mike - THE Harold Bettes?  As in "huntin' for signs " Harold?

I'll drop him a PM - Hope he's doing well.  He's a sharp mind.

Here's a good link regarding HP loss at the rear wheels - it's in an old forum that Harold used to write on, and gives a pretty concise outline regarding drivetrain loss issues.

http://www.eng-tips.com/viewthread.cfm?qid=116240

Yeah, I'll pick up the book.

A point Mark Wolbrink brought up during the session was he wondered if the drums were loaded correctly.  Any thoughts?

I like to think I'm still capable of checking my ego at the door, and I want to get this right, so I've got to ask myself, is the dyno lying, or are my senses completely off base with this one?

Regarding the mixture - At about 52 seconds into the second video, the car fires up, and there's a little whiff of white smoke on fire up, which clears right away.  If the mixture was rich - 10:1 or better - I should be seeing black smoke.  And as poorly as it idles with 310 degrees of duration, I would expect it to load up the plugs, which are 2 heat ranges colder than stock.  I should also see a lot of black soot in the exhaust pipe.  I wiped out the end of the exhaust pipe with a white paper towel, and pulled out a light dusting of dry, gray soot.

I pulled the plugs after each run.  They were gray/tan, and looked like a textbook picture of what a "normal" plug should look like.

The line on the A/F ratio on the graph is flat as Kansas, which means one of two things - either it was reading a mixture so wrong that it failed to produce anything other than a line representing the limits of its readout capabilities, or it wasn't working at all.  If it was indeed higher than 10:1 A/F, certainly the exhaust and plugs should have indicated that, so my inclination, for the time being, is to suspect that the sniffer was malfunctioning.

Regarding the spikes in the graph.  If indeed, the power output of the engine was as erratic as the line indicates, and the graph is indicating numerous wild swings of 15 hp in a 700 rpm band in 4th gear, wouldn't that rattle the living hades out of the drivetrain?  My foot was planted, I was sitting on an unpadded aluminum seat with my hand on the shifter - about as physically intimate with this thing as I could be with my clothes on.  From the driver's seat, it was smooth and uneventful.  Other than the shifts, I'm not seeing any undue bobbing in the car during the runs.  I would think one would be able to see a 25% swing in horsepower application in the video.

Maybe I don't know what a misfire sounds like - I clearly hear it stumbling before it gets on the cam, but I'm not hearing it once the head starts flowing.  Can someone tell me what I should be listening to?

Again, everyone, thanks for the input - it's been a steep learning curve.

[WhizzbangK.C.]

When I'm troubleshooting something, at my "day" job or at home, and some reading doesn't seem to be making sense, I always perform a "reality check". For example, if it's an electrical problem and getting a wonky reading on my meter, I'll take the same reading with a different meter, to see if they jibe. Or I'll take a reading in the same place on a different vehicle, or take a "known value" reading on one of the parts I keep in my box for such an event.

In the case of your A/F reading, you should call your dyno guy and tell him of your concerns. It would be an easy thing to plug his sensor into another vehicle and take a reading. If it were a stock street vehicle and he gets the same reading, the sensor would be obviously bad. I'd think he'd want to know this.

One would think that a professional operation would have extra sensors on hand, as well as a method to calibrate and verify their readings. Seems necessary to me to provide the basic service with full confidence.

Do not under any circumstances start messing with A/F ratio on the basis of the readings that you have there. Sensors can lie, physical reality has a much harder time doing that. With visual indications that you are not extremely rich, the sensor needs to be verified accurate before you even think about jetting changes. Last year Brian burned a piston due to this exact mistake. Expensive lesson learned. 

[Buickguy3]

   Get a second [or third ] opinion. Take some close-up photos of the plugs and send them to Rick at ERC. He gave us lots of insight on issues that we were having last year. He's helpful and easy to work with. Just a thought.
   Doug 

[38flattie]

Chris, I finally made it home, and was able to watch the video! Man, that thing sounds mean! I sure hope you get everything figured out

[Tman]

Chris, the Eagle is in the nest and all eggs are fine