Before I Port my Z I will prove it on a 4 cylinder first

[sblake01]

The magic porting method is with wirewheels

I think I get it! It's like 'jive' from the movie 'Airplane'. Cold got to be! You know? Shiiiiiiit.

[Willoughby Z]

Eh. Yo knock yourself a pro slick, gray matter live performas down now take TCB'in man.

[sblake01]

Hey, you know what they say... See a broad, to get that booty ack?

Lay ‘er down and slack ‘em yak ‘em!

[FastWoman]

Well, despite any particular person's BS content, I think there's something to learn from almost everyone. To wit:

Time how long it takes to fill a large garbage bag from your exhaust pipe

say at idle.

My worked engine at say ~850 to 900 rpm can do it in 5-6 seconds

I used my other stocker at similar speeds and it took 11-12 seconds.

So at low rpm does it mean I have an increased flow by 100% roughly???

I had never considered a garbage bag test. Interesting. I remember participating in an exercise physiology experiment once. (I was in the control group! ) Our exhaled air was collected in a garbage bag. Its volume and and gas composition were measured.

Now on a car, exhaust rate would be a measure of running efficiency. The more exhaust the car blows in order to maintain the engine at a given RPM, the less efficient the engine is. For instance, if you severely lean out an engine, and then adjust the throttle open enough to restore the RPM to the prior level, you'll be blowing quite a lot of air through the system. The exhaust will blow rather hard. The same would be true with the engine running with the proper mix, but under load, with the throttle cracked to compensate for the RPM sag.

I suspect the OP's "worked" engine is running either leanly or inefficiently, compared to the stock motor. (Sorry!) However, this is still an interesting test for operating efficiency, particularly with regard to adjusting fuel/air ratio. These would be the properties, with the engine at a fixed RPM and not under load:

extreme lean: Hard-blowing, randomly puffing exhaust, spitting condensation. Quick bag-fill times. Low engine vacuum. Incomplete combustion, with unburnt hydrocarbons (soot, gassy smell) in the exhaust. Sooty plugs.

somewhat lean: Hard-blowing exhaust, spitting condensation. Quick bag-fill times. Low engine vacuum. Clean-smelling exhaust. White, chalky looking plugs, with possible electrode erosion.

correct: Longest bag-fill time, highest engine vacuum. Clean, mocha plugs.

somewhat rich: gassy smelling exhaust. Relatively long bag-fill time. High engine vacuum. Sooty plugs and sludgy engine.

extreme rich: Gassy smelling exhaust, with black smoke. Shortened bag-fill time. Low engine vacuum. Extremely sooty plugs and engine sludge.

That said, I think the bag-time test would not be as accurate, sensitive, user-friendly, or useful as a vacuum gauge, the two being essentially redundant for determining the correct AFR.

Edited February 11, 2011 by FastWoman

[sblake01]

I thiink he's been breathing the contents of those bags......I would just use my Gunson Gastester

[Willoughby Z]

FastWoman:

I learned something from your post on theory.

sblake01:

Bags would be cheaper...

[sblake01]

I'd say that in the time I've owned that, it has paid for itself.

[Z train]

Hey, you know what they say... See a broad, to get that booty ack?

Lay ‘er down and slack ‘em yak ‘em!

I didn't know you were bi-lingual!

Edited February 11, 2011 by Z train