"Robert Harris" 
Fangle  27 Oct 1998
- Propane Intercooler.
- The original idea is simple.  A propane converter drops the propane gas from 
  tank pressure to a low value and then the second stage drops it from a 
  couple of PSI to carb pressure.  A "sponge" is used to absorb a lot of 
  propane and release it at startup.  Flow out of the regulator is by engine 
  demand.  Think High to low, low to -1.5 hg at mixer.  Normally a big shot 
  into second stage and dribble at manifold.  End description of standard 
  converter. 
- Since the water is well above propane boiling, it carries heat into the 
  process so that the first stage doesn't "freeze".  All that is needed is the 
  circulating water bring heat faster to the converter than it can use it. The 
  only way a converter "freezes" is when the heat exchanger is plugged. 
- So what I suggested was that instead of absorbing heat from the cooling 
  system to vaporize the propane, why not plumb an air conditioning condenser 
  coil or similar high pressure coil into the plenum above the intake runners 
  and run the second stage propane through it. Use the +150 heat difference -
  43F Propane BP) from incoming air to vaporize the propane. 
- Since the heating needed is proportional to the load of the engine, and the 
  air flow is proportional to load, it **** should **** work.  At least 
  interesting enough to really look closely at how to hack up a converter and 
  use the latent heat of vaporization to do something useful. 
- As an aftercooler for a turbo, there is absolutely enough flow and heat to 
  make it work. 
- Oh - I forgot.  Doing it this way gets all of the benefits of liquid propane 
  injection ( There is only one - the latent heat of vaporization ) with all 
  the simplicity of vapor mixing.  Completely standard vapor propane 
  technology is used. 

dave.williams@chaos.lrk.ar.us (Dave Williams)
Fangle  24 Nov 1998
- We've been discussing the propane intercooler idea, using the intake air to 
  replace the coolant-heated propane vaporizer.  Assuming we can keep the 
  propane intercooler from coating itself with ice and freezing up like my 
  window air conditioner likes to do, it would work okay. 
- But we don't need a vaporizer if we're just using propane as an octane 
  booster or WOT bi-fuel "additive".  I don't see any reason why we couldn't 
  just use a nitrous solenoid and vent liquid propane in right behind the MAF 
  or just above a carb.  We'd still get maximum charge cooling with no worries 
  about icing. 
- Consider a car running on closed loop at cruise.  Most EFI systems go back 
  to speed-density at WOT.  Some don't.  With those, adding propane would 
  richen the mixture, and the ECU would pull fuel out to try to drop the mix 
  back to stoich.  We wouldn't want that.  Rather than dicking around with the 
  software, it would be easy to add another circuit off the WOT switch that 
  would activate the propane solenoid.  The extra circuit would be a voltage 
  source and a variable resistor with a switching arrangement so the ECU would 
  see the voltage from the circuit instead of the O2 sensor; turn the knob to 
  fake the O2 signal, either "okay we're stoich" or "we're bad lean, dump all 
  the fuel you got". 

bob@bobthecomputerguy.com (Robert Harris)
Fangle  25 Nov 1998
- Then of course if all you want is a hard hit of 112 octane and some super 
  cold at near WOT, we can steal freely from David Vizards book on Nitrous.  
  Use a second tank of pressurized gas to keep the first one at a constant 
  known pressure. 
- For LPG this is falling off a log stupid easy.  Using a Fork Lift tank - 
  about the same size as a barby tank, you will notice it has both a liquid 
  and a vapor valve or port that could be valved.  It also has a safety blow 
  off valve set for about 289 psi (really bad memory today - cold got me down 
  and I might miss going to the Mission for T-day since nobody loves me ....  
  whine sniffle moan) 
- Plumb a tank of CO2 or N2 to the vapor side of the tank.  Use a standard gas 
  regulator to maintain a pressure somewhere below blow off and just above 
  what the tank will develop on a hot day.  Use a nitrous gas cutoff so that 
  you can turn the gas on or off just before being needed. 
- Plumb the liquid propane from the liquid valve after a safety cutoff valve 
  straight to the NOS spray bar mounted under the carb/tbi Maf or whatever.  
  Now when you kick the solenoid on, you get a fixed constant pressure amount 
  of propane flowing thru a known size nozzle.  Use 2 solenoids jetted in a 2 
  to 1 flow relationship and you have four steps. 
- Simple, easy.  Since the charging CO2 pressure is significantly below blow 
  off pressure, there is no danger of rupturing even standard barby tanks much 
  less fork lift tanks. 
- Would you like fries with that order Dave?

bob@bobthecomputerguy.com (Robert Harris)
Fangle  25 Nov 1998
- The problem with liquid propane injection is simple - pressure.  It varies 
  from very - a few PSI around -43 to several hundred psi during the summer. 
  The tank pressure solely depend on temperature. 
- Next is that any pressure drop along the system is going to start localized 
  cooling and "freezing".  Lastly, the point of injection will have to be 
  somewhere hot and violent as the expanding propane makes a lot of cold and 
  ice from the water vapor.  When you close the solenoid, the remaining fuel 
  in the line WILL boil ( PB -43F) and the vapor will purge the line back to 
  the tank, 
- All that said, next idea is to use a pump to bring it up to a known 
  pressure. Fine idea, basis of all factory liquid fangles.  Cept now you have 
  to recirculate the heated unused engine compartment propane thru a very high 
  pressure  (1500 PSI rated for safety ) pump, a separate cooler to reduce the 
  output temperature and inject any surplus back into the tank. 
- And you think MTBE is gas sucks and causes variance from tank to tank, think 
  about LPG.  It varies heavily from time of year and location and scruples 
  from 50/50 butane or more to 95% propane.   And you tend to get more butane 
  earlier in the tank load than later as it is heavier and boils at a much 
  higher temperature.  The puddle of propane you see when venting a tank is 
  actually butane. 
- All that said, if you have a WOT O2 sensor, simply opening a valve and 
  dumping can add fuel and some latent heat of evaporative cooling.  However 
  the resulting mixture will be heterogenous and you will trade the 
  power/detonation/smoothness increase of homogeneous mixtures for the lessor 
  benefit of charge cooling.  How much do you say? 
- Quoting Jay Storers book on propane fuel conversions
  "Earlier we noted there was about 34% less btu content in propane ( when 
  compared to pump gasoline ), and we should therefore expect a 34% drop in 
  efficiency and power when converting to propane. However, we know from 
  experience that a real life engine only loses 5 to 15% when it is converted 
  to propane  (all else being equal; the difference is largely due to the 
  highly homogenized intake mixture produced by a gaseous fuel system). 
- My proposal was simply to try to finger out a way to recover the heat of 
  vaporization without complicated defecation pumps and without losing the 
  benefit of homogeneous burning. 
- Droplet burning is what happens with a diesel or un vaporized gasoline 
  components.  It burns locally stoic, boiling off vapor until it either runs 
  out of air or fuel. 
- Heterogenous burning - think toilet bowl with streaks of blue stuff of 
  varying intensity through out it.  All vaporized, but regions from below the 
  lean limit of flammability to regions too rich to burn.  Better than 
  droplet. Increasing turbulence and temperature move this closer to 
  homogeneous 
- Homogenous.  Every fuel molecule is evenly distributed to air molecules. 
  Burns almost wavelike - long smooth pressure cycle. 
- From what I'm able to dig out from the research (careful - I be on thin ice) 
  is that in a homogeneous mixture such as put out by an LPG or CNG mixer, 
  that the only reason for velocity is charge filling of the cylinder and 
  turbulence from swirl etc has little if any positive effect on combustion.  
  You can't do much to improve perfection, and a homogeneous mixture is 
  already there. 
- Storer also reports that single plane manifolds on V-8's can be taken down 
  to the lean stop of a Vapor mixer and still run happily. 
- Blending some liquid fuel with propane vapor however does have some 
  advantages done right.  First, remember that there is no charge or cylinder 
  cooling from a vapor fuel engine.  This means that as the load increases, 
  the metal runs increasingly hotter - even if the charge temp is kept cool.  
  This liquid vaporization accounts for a significant amount of heat transfer 
  on liquids. 
- Introducing some liquid such a fuel or water that is carried into the 
  cylinder and evaporated there can recover a substantial portion of the lost 
  cooling. If it is a fuel, it helps mix the resulting vapor, which from the 
  liquid will still be heterogenous.  The faster the engine is running and the 
  higher the load, the more liquid fuel it can tolerate. 
- But but but Bob - gasoline is so much lower in octane than propane!  Yes and 
  no.  Its very interesting to look at effective octane curves vs temp and 
  pressure.  Two substances may have the same octane at test conditions, but 
  radically different characteristics at elevated temp and pressure.  Propane 
  loses it effective octane very rapidly above a certain temp and pressure and 
  gasoline loses less.  The additional cooling of the gasoline vaporizing 
  moves the propane back up the octane scale and recovers much of the 
  temperature/pressure induced octane loss - resulting in a higher octane 
  overall mixture - even though gasolines is significantly lower. 
- Consider now that the propane portion of the mix is running down near its 
  lean limit - say 30 to 1 ( For discussion purposes only !!! ).  This means 
  there is 50 % surplus oxygen in the mixture.  If we mixed the appropriate 
  amount of gasoline, we could more than double the btu energy of that charge. 
- And now for the magic and Ginzo Knives.  Since the charge air after the 
  mixer and before the fuel injector is already a homogeneous mix above the 
  lean limit, there is NO "streaks" of uncombustibldy lean mixture - whether 
  the gasoline vaporizes or not.  Since the liquid fuel accounts for only 50% 
  of the total fuel charge, the amount of the total charge that can be pig 
  rich and uncombustable is severely reduced.  Since half the fuel has twice 
  the cylinder heat to pick up, it's far more likely at any given rpm/load to 
  be vaporized. 
- There is no reason the second fuel has to be gasoline.  If you were 
  seriously insane, you might use an alcohol/nitro blend to knock you out of 
  your socks with foot in and casper milque toast foot out.  How evil is up to 
  you. 

dave.williams@chaos.lrk.ar.us (Dave Williams)
Fangle  25 Nov 1998
- -> Plumb a tank of CO2 or N2 to the vapor side of the tank.  Use a
  -> standard gas regulator to maintain a pressure somewhere below blow
  -> off and just above what the tank will develop on a hot day.  Use a
  -> nitrous gas cutoff so that you can turn the gas on or off just before
  -> being needed.
- Why not just leave the propane tank pressurized?  It will be at that 
  pressure on a hot day anyway. 
- I have enough room to mount two or three of the "disposable" size cylinders 
  under the fender, between the wheelwell and passenger side door.  Since the 
  car is a hatchback there's no trunk, and the thermostat on the console reads 
  140F or better on a nice sunny summer day. 

dave.williams@chaos.lrk.ar.us (Dave Williams)
Fangle  26 Nov 1998
- -> Lastly, the point of injection will have to be somewhere hot and violent 
  ->as the expanding propane makes a lot of cold and ice from the water vapor. 
- How much water is in propane?
- Spraying behind the MAF ought to be okay.  There's plenty of air flow. For 
  starting... hmm, another forest-and-trees solution.  I was going to simply 
  vent propane into the airbox, but I already have the EGR plumbing to each 
  intake stack; no reason I can't tee into the EGR line and use the propane 
  for starting pressure and also to dump directly to each cylinder.  Duh. 
- Unless there's a LOT of water it isn't going to matter; starting flow will 
  be very low, and at WOT there's going to be plenty of heat and turbulence in 
  the intake. 

dave.williams@chaos.lrk.ar.us (Dave Williams)
Fangle  26 Nov 1998
- -> The problem with liquid propane injection is simple - pressure.  It
  -> varies from very - a few PSI around -43 to several hundred psi during
  -> the summer. The tank pressure solely depend on temperature.
- I keep forgetting that propane insists on changing state throughout normal 
  weather temperature changes.  However, this "Robert Harris" guy seems to 
  have figured out a simple way around it, so nyaah, nyaah!  
- -> And you think MTBE is gas sucks and causes variance from tank to
  -> tank, think about LPG.  It varies heavily from time of year and
  -> location and scruples from 50 50 butane or more to 95 % propane.
- I know that.  It seems to be the major reason few people try to build 
  engines optimized for propane - a tank of mostly-butane would be the 
  equivalent of a tank of 'bad gas'.  However, as an enrichment, I'm not too 
  worried about it.  It would be nice of there was a way to determine the mix 
  inside the tank, though. 
- -> All that said, if you have a WOT O2 sensor, simply opening a valve
  -> and dumping can add fuel and some latent heat of evaporative cooling.
  -> However the resulting mixture will be heterogenous and you will trade the
  -> power/detonation/smoothness increase of homogeneous mixtures for the
  -> lesser benefit of charge cooling.
- Yes.  Unlike your RV, I can't *carry* enough propane in a sports car to make 
  it further than the end of the street.  We're not even talking barbecue 
  tank, here - we're talking propane torch bottles.  Enrichment is all I can 
  do.  And even then, I probably won't be able to carry enough to make a whole 
  session at a track event, where I'll be running WOT much of the time. 
- The other use for propane is for starting - I forsee some minor problems 
  with my air-assisted injector design, which a dollop of propane while 
  cranking could fix.  Sure, I could carry a big on-board compressor, but it 
  would be easier to provide the pressure with propane, and I need a rich 
  mixture for starting and idle anyway. 
- A 100% propane vehicle is not in my future - even if I could afford 
  $1.85/gal (last week's price from getting my propane heater tank refilled) I 
  couldn't put up with the severely limited refuelling options in my area.  
  And putting a big propane tank in the back yard isn't the answer, either.  
  As a booster fuel... that's a whole different marching band. 

dave.williams@chaos.lrk.ar.us (Dave Williams)
Fangle  26 Nov 1998
- -> Uh, just for your information, some one on the 5.0 list just
  -> mentioned that in Australia they are running LPG powered cars with LPG 
  -> and Nitrous mixed in the same cylinder. Thus nitrous 100% of the time.
- Hm.  Other than the hassle, there doesn't seem to be anything wrong with 
  that. 
- One potential problem with using nitrous oxide to pressurize the propane 
  tank is: when you run out of propane, you're going from rich to lean at WOT.  
  Yow! 
- Which has lower density, propane or nitrous?  Would you pull from the top or 
  bottom of the tank? 
- Back in the old days, a simple $2 can of R-12 would have made all this very 
  simple... 

bob@bobthecomputerguy.com (Robert Harris)
Fangle  16 Mar 1999
- Re-reading Hugh MacInnes Turbo Charges reminded me of another simple thing 
  that can increase power.   Seems that Mack Trucks bled off some boost air to 
  spin a fan that increased the air flow across the intercooler.
- Dah - what a stupid idea.  Imagine increasing the air flow cooling the 
  charge air on a square law principle with increasing boost pressure.  Never 
  work -don't need cool air anyway. 
- Now back to your regularly scheduled fangling whilst I think about propane
  intercooling system for my RV and Plenumed IR and other misc heresy.

dave.williams@chaos.lrk.ar.us (Dave Williams)
fanglers  12 Jan 2000
- -> effort, but the LPG treatment is kewl. Wouldn't it also be possible
  -> to use LPG and NOS in the place of an intercooler on a blown engine?
- Gee, Greg, you missed the Propane Intercooler when it came around last year, 
  or was it year before last? 
- We don't always talk about important social issues, you know.  Every now and 
  them someone breaks down and cuts loose with some fangle. 
- In the case of the Propane Intercooler, the idea was to use a nitrous 
  solenoid and a jet to use propane for high-speed enrichment *and* charge 
  cooling.  We were talking about it wrt use on Bob's RV, but it'd be perfect 
  for a turbocharged car application.  Why blow the bucks for big injectors 
  and a revised chip when you run out of fuel on the top end? Just add a 
  microswitch or pressure switch, do a little jetting, and boogie.  Not to 
  mention it'd be a lot more stealthy than an enormous aftermarket 
  intercooler... 

Robert Harris 
fanglers  14 Jan 2000
- My purpose for using propane was for sustained load fuel enrichment - think 
  30 minutes up a grade on an RV.  Ideal behavior would be a simple step fuel 
  bias with the ECU doing the rest. 
        Phase I was the simple NOS steal system.
        Phase II: The Fanglage portion.
- Essentially the LPG pressure flow varies with temperature - the desired 
  characteristic.   Unfortunately, the energy delivered is inverse to the 
  temperature.  So how to deliver constant energy per step without regard to 
  the LPG tank pressure without complicating defecation. 
- My simplest approach so far is to simply add gasoline such that the total 
  thermal energy is approximately constant regardless of the flow of LPG.  
  When the ambient air is low temperature, make up for the BTU loss by adding 
  more gasoline - when high, reduce the gasoline.  Two injectors - unregulated 
  LPG and regulated gasoline. 
- There are available pressure vs flow for orifice size tables available.  
  There are temperature vs pressure tables for propane available.  These can 
  be easily translated to a look up table for a Basic Stamp computer. 
- Now what is needed is a simple gasoline injection system that can be adapted 
  to the basic stamp. 
- First candidate is the fuel distributer off a Bosch K-Basic system.  It 
  works by a plunger moving up and down controlling the fuel flow to a verrah 
  nice set of breakover nozzles.   Find one off an early Volvo or Saab or euro 
  whatever. 
- Next, move the plunger up and down............ normally NEXT Idea - but wait 
  -over in the corner is a FORD IAC.   Hmm.  IAC works by positioning the 
  plunger by varying the pulse width of a fixed frequency (150 hz if I 
  remember right ) pulse.  Hmmm 
- So I trick Dave into milling off every thing except the plunger and solenoid 
  assembly then fangling an adaptor for the plungers, welding up an aluminum 
  bracket to space them - Dave - you did know that this was on your "I did not 
  know about this yet because you haven't told me" list?? 
- What results is a pulse width modulated, high pressure constant flow system 
  that can be controlled by a stamp with a 150 hz major cycle. 
  - With a simple bucket calibration, we can know just sense the propane 
  pressure and adjust supplemental fuel so the energy step is about constant. 
- This then gives a simple "boost" fuel enhancement system that raises the 
  octane in response to the ambient air temperature, conserves propane, 
  constant fuel increase per step and doesn't need a rocket skyentust to build 
  and use. 
- Since what this is doing is introducing a fuel step bias, and we are using 
  liquid propane without pumps and complication defection and have built the 
  gas side anyway, a logical extension is cruise fuel bias steps. 
- Depending on the economics, gasoline or propane is spot cheaper.  During 
  cruise anything from high grade cat piss on will function nicely. It would 
  be nice when gasoline is cheap to bias the system toward more gasoline 
  starting at cruise loads.  See longing threads on Gas-o-Junque. 
- All that would be involved is adding some additional fuel at light cruise 
  either by switching on a low pressure vapor solenoid to bleed vapor propane 
  into the intake or adding a step increase in base pressure correction pulse 
  width.  This changes the direction of the total fuel bias to favor the 
  driver selected preferred fuel. 
- Inputs to the stamp are LPG pressure, TPS, and some safety and economic 
  decision switches. 
- Another simple step for the "Project Engine"