Vapor lock questions for the hotter climate guys

[Mark Maras]

4 hours ago, jalexquijano said:

do you think that thermal cloth i wrapped around the metal fuel rail is doing anything to lower the gasoline temperature? Should i remove it? it looks silly and if aint helping with the fuel percolation i might as well remove it.  

 If it looks silly (I agree) and you don't like it, why not remove it before the fuel rail, drive it and share any change you experience with the club members? The fuel rail could come later. Your contribution to solving the problem may prove valuable to others with Zs in warmer temperatures. I, for one, am curious how much change you notice in changing one thing at a time.

[jalexquijano]

okay! i will remove it first and test it to see if there is any change!

[jalexquijano]

Jeff,

Any pictures you can provide me with regarding the routing of the rubber fuel hoses which replace the original metal fuel rail? I want to know the lenght of the hoses, fittings and correct routing.

[Mark Maras]

4 hours ago, jalexquijano said:

 

Any pictures you can provide me with regarding the routing of the rubber fuel hoses which replace the original metal fuel rail? I want to know the lenght of the hoses, fittings and correct routing.

 One thing at a time, remember? A small implement of destruction (side cutters) and ten minutes is all it will take to remove the insulation from the fuel rail. We're all waiting for the results. 

 We'll get to the fuel rail replacement in due time.

[Zed Head]

Saw your post on another forum and thought of something that might make it easier to actually do something.  You can leave the metal fuel rail in place and just disconnect it, running a rubber hose to replace its function.  If it has a positive effect then you can decide whether or not to remove the metal rail.  All you need is some hose and a screwdriver for the hose clamps.  No need to unbolt anything anything, just pull a hose end off and replace it with another hose.

[psdenno]

I was going over back issues of a car club magazine pertaining to another old car I own and came upon this piece of vapor lock advice for cars built in the last century.

"Adding a pint of diesel fuel per 10 gallons of gasoline will raise the boiling point of modern gasoline, helping to prevent vapor lock."

The article went on to say, "In addition, the diesel fuel will help keep the gaskets soft in the carburetor and fuel system.  The engine will not smoke and the diesel will not cause any problems as an additive.  Modern fuel is formulated to vaporize at a lower temperature to help with emissions."

I had never seen that advice before and have no idea if it's valid, urban legend, or voodoo magic.  Anyone have experience or opinions?

Dennis

 

 

[Zed Head]

I've had a similar thought but with regard to detonation.  Another plus would be more energy per unit volume.  Seems like the pros would have had to think of it.  One downside I would guess is that diesel needs high pressures to burn fully, I think.  CR's on diesel engines are much higher than gasoline.  Probably would dirty the plugs a lot faster.  And smell bad.

I'm not sure the idea pans out fully though.  The high vapor pressure components are still in the formulation and they would "distill" or "fractionate" out.  The fuel is a blend of molecules, so all you'd really end up with is a lower concentration of the unwanted molecules, but they'd still bubble and boil.  It might be the same for my detonation argument.  It makes sense from an "averaging out" view, but I don't think that's how the fuel works.

An easy experiment though.  Do you have a name or author for the article?  

[psdenno]

2 hours ago, Zed Head said:

An easy experiment though.  Do you have a name or author for the article?  

Author:  Randy Rundle

His Site:  www.http://fifthaveinternetgarage.com/

Tech tip appeared in Turning Wheels, June 2015.

Dennis

[Mark Maras]

 The consensus of opinion (on line) seems to be that diesel in gas does raise the boiling point and can alleviate vapor lock (according to the "good ol boys). Varying opinions on the negatives but most negs. could be explained by the ratio being used. My question is, could one achieve the same results with 2 cycle oil instead of diesel? The use of two cycle oil mix in a Wankel is what got me thinking about it.

[Zed Head]

Thanks.  I couldn't find the actual reference to using diesel to change vapor pressure but I did find another article that kind of shows he's just a guy like us, pulling together odds and ends and making assumptions.  

http://fifthaveinternetgarage.com/pdf/RefiningModernGasoline.pdf

" Ethanol alcohol attracts water. It picks up moisture throughout the fuel system. In the early gasohol era, this sensitivity to water led to problems because service stations often had water in the bottom of their underground tanks. Officially… the petroleum industry is well aware of these considerations and companies using ethanol have implemented procedures to eliminate moisture in underground storage tanks. It is best to check the fuel you buy to see for sure if there is water in your fuel, especially if you are going to place your antique vehicle in storage for longer than 60 days. The addition of 10% ethanol will typically contribute 2.5 or more octane numbers to the finished blend. The addition of ethanol increases vapor pressure by up to 1.0 psi although refiners may make other alterations to limit vapor pressure to comply with federal regulations. Ethanol is approximately 35% oxygen (which is part of the source of vapor lock when we use modern gasoline in our antique vehicles) so a 10% blend would contain approximately 3.5 weight percent (w%) oxygen that improves combustion properties. Ethanol is often confused with methanol. These two alcohols have distinctly different characteristics. Unlike ethanol, methanol is very toxic. Ethanol provides better water tolerance and better fuel system compatibility and contains less oxygen than methanol. Methanol causes a significant increase in volatility (which is why it is used in race cars and performance applications) while ethanol results in only a slight increase.

[Zed Head]

1 minute ago, Mark Maras said:

 The consensus of opinion (on line) seems to be that diesel in gas does raise the boiling point and can alleviate vapor lock (according to the "good ol boys). Varying opinions on the negatives but most negs. could be explained by the ratio being used. My question is, could one achieve the same results with 2 cycle oil instead of diesel? The use of two cycle oil mix in a Wankel is what got me thinking about it.

Do you have some links, I'm searched out.  

The thing is, when it comes to boiling or vaporizing, the low boiling components go first.  They don't wait for the high boiling components, if more high oilers are added.  There's no averaging down.  Fuel is a blend of vapor pressures.

[Mark Maras]

 

1 hour ago, Zed Head said:

1 hour ago, Zed Head said:

Do you have some links, I'm searched out.  

The thing is, when it comes to boiling or vaporizing, the low boiling components go first.  They don't wait for the high boiling components, if more high oilers are added.  There's no averaging down.  Fuel is a blend of vapor pressures.

 

 

 Most of my searches were at antique auto clubs. Nothing scientific, just a lot of old timers opinions. There was a consensus of opinion about not doing it if your engine has sensors, catalytic converter, etc. In other words, early 70's cars and older.

 Your explanation makes sense. The heated fuel lines and or float bowl become a mini refinery, of sorts.

 Reading the old auto journals from the early 1900's, what fuel to burn in an engine was a heated topic. Gas was expensive and of varying quality. One of the more interesting methods of doctoring poor gas was adding a mix of acetone and water to the gas to up the octane rating and prevent vapor-lock. Reportedly, it worked.

 They also recommended "When testing the boiling point of your petrol, It's advisable to do it outside."