Vapor lock questions for the hotter climate guys

[doradox]

Uhhh... No.

There exists a temperature (shown on the phase diagram I linked to earlier as Tcr) called the "critical temperature". The critical temperature of a substance is the temperature at and above which vapor of that substance cannot be liquefied, no matter how much pressure is applied. In other words, above Tcr, there can be vapor only. No liquid, and certainly no solid. (Haha! Ignoring superheating, of course.)

I was thinking about this and something didn't seem quite right. If a liquid held at a constant volume is heated past the critical point how would the "gas" that now exists be any different than the liquid. Apparently it isn't.

http://en.wikipedia.org/wiki/Phase_%28matter%29

"At the critical point, the liquid and gas become indistinguishable. Above the critical point, there are no longer separate liquid and gas phases: there is only a generic fluid phase referred to as a supercritical fluid. "

So a gas can be compressed to at least a state which is not a gas anymore.

Steve

[Captain Obvious]

I was thinking about this and something didn't seem quite right. If a liquid held at a constant volume is heated past the critical point how would the "gas" that now exists be any different than the liquid.

So a gas can be compressed to at least a state which is not a gas anymore.

Haha! Did you look at the list of references for that page and the ones similar? It looks like someone is bucking for a good thesis grade. A lot of the references cited are less than five years old and lots of them are clearly research!

This is my favorite... Number 25:

Ye, Xiang-Rong; Lin, YH and Wai, CM (2003). "Supercritical fluid fabrication of metal nanowires and nanorods templated by multiwalled carbon nanotubes". Advanced Materials 15 (4): 316–319. doi:10.1002/adma.200390077.

Now there's a citation I can trust!

As a matter of fact, I was just messing with some metal nanowires and nanorods templated by multiwalled carbon nanotubes yesterday in the shop.

Seriously though, good catch. Research continues and concepts are refined. Haha! Back when I was in school, we got by just fine with only three phases. Seems they weren't teaching this at your school either, huh?

[Captain Obvious]

Do you really think a high frequency damper would do anything to improve fuel delivery at RPMS over 1000 to 1500? On a 6 cyl your lines see 3000 PPM or 50 pps at 1000 RPM.

It really doesn't matter, but I don't get your math...

I do this:

Assuming batch fired injectors on a four stroke engine...

At 1000 rev/min there are 500 injections/min

500 injections/min = 8.3 injections/sec

Do I think a high frequency damper might be able to do something to quiet 8.3 pulses per second?

Yes.

Back to the VL.

On your VL issues, it sounds to me (the non-expert on such matters) that you're doing everything right except for the removal of the pusher pump.

[FastWoman]

Common we can get this thread to 100 posts!

100!

[5thhorsemann]

It really doesn't matter, but I don't get your math...

I do this:

Assuming batch fired injectors on a four stroke engine...

At 1000 rev/min there are 500 injections/min

500 injections/min = 8.3 injections/sec

Do I think a high frequency damper might be able to do something to quiet 8.3 pulses per second?

Yes.

On your VL issues, it sounds to me (the non-expert on such matters) that you're doing everything right except for the removal of the pusher pump.

6 injectors firing every second rev @ 1000 rpm = 3000 injection pulses.

[Zed Head]

The 280Z EFI system fires once per revolution according to the FSM.

Edit - Deleted my short story, since it was barely relevant.

Edited August 1, 2011 by Zed Head

[5thhorsemann]

I guess I am speaking out of my field here, I was thinking direct port injection, which 280Z's are not. So perhaps a damper or "hammer arester" would have some stabelizing effect afterall.

[cygnusx1]

Heat is the real enemy though.

[5thhorsemann]

Ive got plenty of time to get the parts together on this fix, just got a call from my doc, had the Xrays read and determined I have 4 broken ribs and 2 bruised in my left back. I put the car in the garage yesterday and had to get help to get out of it. Looks like at least 6 weeks before I'll be able to drive it without the use of an engine lift to remove my dead a$$ from the drivers seat. Sigh.............

[Captain Obvious]

Ive got plenty of time to get the parts together on this fix, just got a call from my doc, had the Xrays read and determined I have 4 broken ribs and 2 bruised in my left back.

Dang Dude. That sounds like no fun at all. I hope you heal quickly!

Since you've got nothing better to do right now than think about the vapor lock problems...

There's a pdf document titled "1973 240z 1974 260z Fuel System Modification Plus" over at xenon that talks some about (Datsun's definition of) vapor lock. Probably nothing you haven't seen already, but if you haven't read that one yet, it's an interesting read.

Also, what year is your car? I remember that you're running round tops, but I don't remember you mentioning a year.

Speedy recovery!!

[FastWoman]

Yeah, ouch!! I guess the manual steering doesn't help the situation either.

Here's hoping you heal quickly and well. In the meantime, you can drive your Z vicariously through all of us!

[5thhorsemann]

It's a 73 with all the 72 intake stuff. I have the 73 recall manual for the VL mods, but aside from the pusher pump I've done all the recommended mod's. I won't have to worry about VL as it will be nice and cool by the time I can drive it again, thanks for the well wishes.