Inlet Duct PMD

[Tem]

Precision, in the repeatability sense, is all that's required to measure improvement from a before measurement.  All that is really important is the difference in the measurements - before vs after.

And since US/UK have different gear ratios anyway, you couldn't compare against the other measurements anyway  s;) s;)

[Anonymous]

Just a thought on this (and it's what I'll be doing next weekend!), but one very accurate way of doing a PMD could go as such:

1.  Get a video camera.
2.  Video the rev counter/speedo.
3.  Leave it running while you do your tests, and give a verbal commentary.
4.  Take said footage, and edit it on a PC using any basic video editing software (hell, Windows Movie Maker will do).
5.  Now, when you play back the clip, all you've got to do is to manually fast forward the clip to the instant the needle goes where you want it to (whether it's 62mph, or 6500RPM, or whatever) and look at the time displayed. There are loads of free players out there that will let you measure the footage in hundreths of a second.


Granted, it's a bit convoluted, but it's essentially a simple way of removing that human error involved when pushing the 'stop' button on your stopwatch.

Or am I missing the blatently obvious here?

[Anonymous]

Granted, it's a bit convoluted, but it's essentially a simple way of removing that human error involved when pushing the 'stop' button on your stopwatch.

Or am I missing the blatently obvious here?

... no, you're on track, Ekona.  Some folks, who don't trust their stopwatch finger (or are challenged by walking & chewing bubble gum at the same time    s:D s:D   ) have used GTech's to record their PmD measurements.  ... whatever floats yer boat.

A bigger problem, in general, is the lack of scientific approach ... too many neglect to take measurements (PmD or dyno or 1/4 mile) before they do their modifications ... casting doubt on the actual benefit of whatever modification.

[Tem]

1.  Get a video camera.

Or am I missing the blatently obvious here?

You're missing the point, that this is a poor man's dyno. Meant to be the easiest job on the world and done with stuff that everyone has. It's not the most accurate way to measure, but it is accessible to everyone. Video camera automatically makes this something else  s;) s;)

[Anonymous]

1.  Get a video camera.

Or am I missing the blatently obvious here?

You're missing the point, that this is a poor man's dyno. Meant to be the easiest job on the world and done with stuff that everyone has.

  s:shock: :shock: s:shock:    You mean not everyone has a video camera?!


It's like I'm living in the Third World or something...    s:wink: :wink: s:wink:    s:lol: :lol: s:lol:

[Anonymous]

You're missing the point, that this is a poor man's dyno. Meant to be the easiest job on the world and done with stuff that everyone has. It's not the most accurate way to measure, but it is accessible to everyone.

Good point, Tem.  The tendency to want to find expensive ways to do simple things always amazes me.

For instance, I ran into the same tendency with the "clothes-dryer CAI" idea.  I discovered and offered a way to add 3-4 whp for <$5.  Instead of embracing it, it seems that folks want a purple or pink aluminum tube with a cone air filter, exposed to the heat of the engine bay!!!   Is this so they can impress friends, when they pop the hood? ... even if it doesn't work ... and makes the car slower?

Go figure ...    s:P s:P

[Anonymous]

I know everyone doesn't have one, and I haven't got one (yet), but would it be accurate to measure vehicle speed via an OBD-II data logger?

I'm having a look into getting a circuit board made up (if friends are willing  s;) s;)  ) and then connecting it to my PDA and either writing / hijacking some open source software, or even using my laptop.

I would have thought that this would give an accurate way of logging as the data should be able to tell you how long it was between 0mph, and 60 or 62mph. Again, only really useful for before and after modifications or pub talk  s:) s:)

If I ever get round to sorting it out, I'd be quite happy for people to borrow it on short term loan or trial it on meets and things. Only a thought and still not got the OBD thing off the ground as I'm looking for a really cheap way of building/buying the box that will convert to RS232.