DIY_EFI Digest Wednesday, 20 March 1996 Volume 01 : Number 081 In this issue: Re: DIY_EFI Digest V1 #80 Re: B&S ENGINES direct injection propane RE: BS ENGINES Re: Alternate fuel EFI re: ICE ceramic coatings re: ICE ceramic coatings Re: Alternate fuel EFI stainless steel valves Re: Alternate fuel EFI RE: BS ENGINES Re: Alternate fuel EFI re: Propane Fuel Injection RE:Stainless steel valves See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Talltom Date: Tue, 19 Mar 1996 03:56:03 -0800 Subject: Re: DIY_EFI Digest V1 #80 Hello, hope you don't mind the ignorant asking questions.(I'm new to this list) All the talk about ceramics, aluminum, heat dissipation, coolant temperatures etc. is nice but what about fuel requirements in relation to thermal conductivity? Seems to me the less heat that is transfered out of the combustion chamber the higher the combustion chamber walls will be. Would seem that the higher the combustion chamber walls will increase temperature of air/fuel and cause preignition. An old wives tail(that's the way I want it!) says that b.b. chevy iron blocks used to make more power than similar aluminum blocks. The aluminum headed cars lately are able to get by with 11.5-1 compression on the same fuel that my cast iron headed 8.5-1 knocks on. (W/O boost) I know cummins and sae did some research on ceramics in the mid 80's but never knew results. Anybody have any ideas that would make any of this look coherent? ------------------------------ From: Bill Lewis Date: Tue, 19 Mar 1996 08:09:12 -0500 Subject: Re: B&S ENGINES > You can put bigger valves in, enlarge the ports, regrind the cam > lobes, and add a larger carburetor(throttle body) but the head design > impedes bumping up the compression ratio from its lowly value, > and without improved cooling, the engine will self-destruct from > seizing if the crank or connecting rod doesn't break first. > But I still think the're a great engine. Back in my junior high school days, we used to "shave the head" by rubbing it against sandpaper on a glass plate. Then we ate away some between the valves and the edge of the cylinder wall. Later on I learned that was a common technique used on the Flathead Ford V8. Called "relieving" I think. I always prefered the Tecumseh because you can't set the ignition timing on a Briggs. Breaking connecting rods was always a problem until we found a place selling heavy duty rods made from aluminum bar stock. These small engines are tremendous fun. Bill ------------------------------ From: Jim Steck <72614.557@xxx.com> Date: 19 Mar 96 08:37:50 EST Subject: direct injection propane >My questions are: Is my >understanding of the way a TBI regulates fuel accurate? How well would >the nozzle withstand the higher pressures of propane(up to 120 PSI)? >when the vehicle sits and under the hood heat causes vapor in the fuel >line how well would vapor blow through the nozzle at startup? How low >can the fuel pressure go before the nozzle won't work(at -40 you can >carry propane in a bucket)? finally, how many nozzles would I need to >feed enough fuel? 1) 'EFI' controls fuel delivery by adjusting pulse width of the injectors, but the pressure to the injectors has to be controlled. There are several pressures used, but for TBI it's about 1 bar above manifold pressure. The pressure regulator has a reference port to the manifold and maintains the pressure differential between fuel and manifold . . . reason . . . the injectors have a minimum 'open' time. If you had a high pressure differential across the injector at high manifold vacuum (like at idle), fuel delivery would be too much even at minimum 'open' time. If you pick a smaller injector to reduce flow at idle, you won't have enough flow at WOT. 2) I would not expect the injectors to be reliable above 6 or 7 bar (they might not open). 3) The vapor will cause hard starting, but it will surely pass through the injectors. 4) Most TBI systems I've seen (gasoline) use two injectors. Your flow rate seems to be similar. The injectors are available in different sizes. I don't know what the lubricating properties of propane are . . . perhaps none . . . or if the injectors will survive propane long term. Try calling Ak Miller in California (310) 949-2548 . . . call early (5 - 7 am Pacific time) and talk to AK. They use propane in many of their turbocharged systems (some very high horsepower). I don't know how they control (inject) it. - -Jim Steck Are you using any kind of instrument to monitor the fuel mixture? For a modest price ($130 - $180 US) there are several (some better than others) meters that read the O2 sensor and give you an immediate display of mixture. ------------------------------ From: "Kenneth C. King" Date: Tue, 19 Mar 1996 09:29:02 -0600 (CST) Subject: RE: BS ENGINES On Tue, 19 Mar 1996, Stephen Lamb wrote: > Hi, I'm new to this list, but perhaps as a metallurgist I can help with > some of this: [ munch ] > Exactly, steel certainly has poor thermal conductivity relative to > aluminium (and stainless steel is even worse). [ munch ] greetings: perhaps, then, you could explain why going to stainless steel valves is an 'upgrade'? in light of it's poor heat transfer, what might be a reasonable material for an exhaust valve (due to excessive heat)? yea i know titanium is the 'best' due to weight & fatigue factors, but how well does it conduct heat? (anna one-a, anna two-a... :) later, kc (the inquisitive one) - -- "ooooh, crumbs!"if the world is nite, shine my life like a lite"live your life with PASSION"hey waiter, there's a transvestite in my soup"hey mister, are you tall?"all alone in the nite"son of a son of a sailor"John DeArmond fanclub #13 "he's dead, jim"he's not dead, he's electroencephalographically challenged" kc ------------------------------ From: Michael Fawke Date: Wed, 20 Mar 1996 09:40:27 +1000 Subject: Re: Alternate fuel EFI At 03:46 AM 19/3/1996 -0500, you wrote: >What I was thinking >of was replacing the evaporator, mixer and fuel control valve with a TBI >nozzle controlled by a circuit which 'translates' the fuel control >valve position into an on/off pulse width. My questions are: Is my >understanding of the way a TBI regulates fuel accurate? How well would >the nozzle withstand the higher pressures of propane(up to 120 PSI)? >when the vehicle sits and under the hood heat causes vapor in the fuel >line how well would vapor blow through the nozzle at startup? How low >can the fuel pressure go before the nozzle won't work(at -40 you can >carry propane in a bucket)? finally, how many nozzles would I need to >feed enough fuel? Ford (Australia) offers an LPG conversion which uses the standard injectors (multi-point) to inject LPG. The injectors have a slot cut in the side of them and a second fuel rail fits over the outside. Liquid LPG comes from the tank and goes through the slot with unused LPG flowing out throught the normal fuel rail. I'm not quite sure how they do this last part.... The standard ECU is shut down and a second ECU is used - developed by Inject Racing Developments (Melbourne, Australia). The overall package was developed by Tickfords Engineering, but most LPG conversion centres are now making this available. Michael Fawke fawkacs@xxx.au ------------------------------ From: lambs@xxx.au (Stephen Lamb) Date: Wed, 20 Mar 1996 10:38:10 +1100 Subject: re: ICE ceramic coatings >One project I have on the go right now is a propane conversion on a 1996 >Chrysler minivan. It is a competition among major universities accross >North America sponsored in part by the SAE, called the LPGV challenge >(Liquified Petroleum Gas Vehicle). One of the fuel systems we are working >on is direct liquid propane injection and ceramic coated pistons and >cylinder heads. Should prove to be an interesting project. PS: if any of >you have tried this before, I would appreciate any information you could >give me, we are all novices with direct injection and would sure like some >insight into some solutions for this most difficult engineering problem. There is a company over here (in South Australia, from memory) that has built an LPG injection system as an 'add-on' to the existing EFI system. Unfortunately I know little about its technical details, other than the fact that a demonstrator vehicle (locally built Ford) has been in research and testing for about a year now. It was shown on one of our science programs and appeared to run well apart from minor hiccups with the control electronics. I'm sorry I can't give more detail (hardly surprising given the commercial implications). Cheers Stephen Lamb Dept. of Defence DSTO, AMRL 506 Lorimer Street Fishermans Bend VIC 3207 Australia Tel: +61 3 9626 7525 Fax: +61 3 9626 7089 IZCC #180 ------------------------------ From: William Sarkozy Date: Tue, 19 Mar 1996 18:44:24 -0800 Subject: re: ICE ceramic coatings At 09:01 PM 3/18/96 -0700, you wrote: >On Tue, 19 Mar 1996, Stephen Lamb wrote: > >> ......... although engine builders have been experimenting >> with ceramics for a number of years now - I believe some diesel engines now >> use pistons 'crowned' with a ceramic barrier. > >Stephen, > >You are absolutely correct, This technology is being used in large > > PS: if any of >you have tried this before, I would appreciate any information you could >give me, we are all novices with direct injection and would sure like some >insight into some solutions for this most difficult engineering problem. > >Thanks a million gang, > >Todd Ratke, >tratke@xxx.ca > > Pikes Peak racer and old-time-engineer extrordinaire Ak Miller probably has more experience with LPG powered vehicles than anyone in the nation. He can be reached in Pico Rivera, CA at (310) 949-2548. Cheers Bill ------------------------------ From: robert dingli Date: Wed, 20 Mar 1996 12:07:58 +1100 (EST) Subject: Re: Alternate fuel EFI Michael Fawke and Stephen Lamb have both described the same LPG injection system. The system was developed by Liquiphase Injection (formerely known as Biocom) in South Australia and has received support from Ford Australia. The LPG efi system was developed by Injec Racing Developments who previously marketted an aftermarket efi product of dubious quality. Just to expand on some of the technical details.. The injectors are modified standard Bosch injectors as used on the Ford Falcon (6 cyl 4.0 litre). To overcome LPG vapourisation problems within the injectors (which tend to freeze them), they decided to create a bottom feed injector to minimize the flow path for the delivered fuel. This modification involves machining a slot into the base of the Bosch injector and fitting a separate LPG feed fuel rail. The unsed LPG is fed back to the tank via the standard petrol fuel rail and some solenoid valves. The LPG is fed to the engine by an in-tank efi pump. While the pump creates a pressure differential required to flow the LPG, the absolute pressure of the fuel is governed by the temperature of the tank (butane/propane vapour pressure) which varies greatly. The vapour pressure is far in excess of the pump pressure and hence a fuel pressure regulator wouldn't be able to maintain a constant pressure differential. While it is an interesting approach there are a few technical problems. The injectors, now running at much higher pressures, require a much higher operating voltage to pull them open. There is also the issue of machining debris falling into the injectors during the slot cutting operation and the errosion that would be expected within the injector due to LPG vapourisation. It would be interesting to see the injector durability stats. The recirculating injection system adds a lot of heat to the fuel which is returned to the tank. During initial runs they resorted to surrounding the tank with ice but I don't know of a long term solution. The last problem is the petrol/LPG switchover which I know is slow and cumbersome. I have heard stories of LPG bubbling through the petrol tank. Since LPG is such a good fuel (very cheap and easily obtainable in Australia) I can't see why they opted to make the system dual fuel in the first place. A single LPG fuel system would make more sense and solve many of the problems. Just my thoughts. Robert - -- Robert Dingli r.dingli@xxx.au Power and Control Systems (+613) 9344 7966 Thermodynamics Research Labs (+613) 9344 7712 University of Melbourne, AUSTRALIA ** he who dies with the most toys, wins ** ------------------------------ From: Jim Steck <72614.557@xxx.com> Date: 19 Mar 96 21:52:57 EST Subject: stainless steel valves >perhaps, then, you could explain why going to stainless steel valves >is an 'upgrade'? in light of it's poor heat transfer Durability at temperature . . . strength and corrosion resistance. The stems are usually chrome plated or steel stems welded to the stainless steel head. Conductivity works both ways . . . it doesn't heat up very fast either . . . >what might be a reasonable material for an exhaust valve >(due to excessive heat)? yea i know titanium is the 'best' due to >weight & fatigue factors, but how well does it conduct heat? My first choice would be silicon nitride . . . very poor conductivity . . . but no thermal mass. It makes nice turbine blades for turbochargers (Buick GNX), and some race engines have used it. It's even more expensive than titanium, and less forgiving of shock. - -Jim Steck ------------------------------ From: lambs@xxx.au (Stephen Lamb) Date: Wed, 20 Mar 1996 14:21:32 +1100 Subject: Re: Alternate fuel EFI >Ford (Australia) offers an LPG conversion which uses the standard injectors >(multi-point) to inject LPG. The injectors have a slot cut in the side of >them and a second fuel rail fits over the outside. Liquid LPG comes from >the tank and goes through the slot with unused LPG flowing out throught >the normal fuel rail. I'm not quite sure how they do this last part.... >The standard ECU is shut down and a second ECU is used - developed by >Inject Racing Developments (Melbourne, Australia). The overall package >was developed by Tickfords Engineering, but most LPG conversion centres >are now making this available. I bow to your greater knowledge. I didn't think they'd got to the production stage yet. Cheers Stephen Lamb Dept. of Defence DSTO, AMRL 506 Lorimer Street Fishermans Bend VIC 3207 Australia Tel: +61 3 9626 7525 Fax: +61 3 9626 7089 IZCC #180 ------------------------------ From: lambs@xxx.au (Stephen Lamb) Date: Wed, 20 Mar 1996 14:24:39 +1100 Subject: RE: BS ENGINES >From pistons to valves in one fell swoop......... >> Exactly, steel certainly has poor thermal conductivity relative to >> aluminium (and stainless steel is even worse). > [ munch ] >greetings: > perhaps, then, you could explain why going to stainless steel valves >is an 'upgrade'? in light of it's poor heat transfer, what might be a It's amazing the mystique and myths surrounding stainless steels. These materials benefit from their high chromium content (>10%) which generates a strongly adhereing oxide and imparts benefits similar to the oxide 'coating' on aluminium alloys. Thus, in their austenitic form (don't ask me to explain that !), they have good high temperature oxidation resistance and this is good for use in engines. However, there are a couple of problems with their use in engines. One is relatively poor thermal conductivity which gives a greater risk of burnt valves. The other is that they have thermal expansion rates approximatelt twice that of alloy steels which means that, all other things being equal, greater clearances must be used to compensate. So it's a balance really, but unless your exploring the limits of combustion (eg a really 'hot', turbo/super-charged engine) then I'd recommend sticking with a quality, austenitic steel valve. Certainly for street performance engines these would be more than adequate. >reasonable material for an exhaust valve (due to excessive heat)? yea >i know titanium is the 'best' due to weight & fatigue factors, but how >well does it conduct heat? (anna one-a, anna two-a... :) (Very) Generally speaking, titanium has about the same thermal conductivity as stainless. The advantage of titanium would be in the lower inertia of the valve system, but the cost would be considerably greater. My titanium mets' a bit rusty but I suspect that high temperature characteristics may be less than satisfactory. Cheers Stephen Lamb Dept. of Defence DSTO, AMRL 506 Lorimer Street Fishermans Bend VIC 3207 Australia Tel: +61 3 9626 7525 Fax: +61 3 9626 7089 IZCC #180 ------------------------------ From: Darrell Norquay Date: Tue, 19 Mar 96 20:42:03 MDT Subject: Re: Alternate fuel EFI Markus wrote: > Greetings from the Great White North (Canada) How's it goin, eh? Ya hoser... > supply a presure just below atmospheric and the mixer is two plates > with a gap between them of about 1", the top plate has a smaller hole > than the bottom plate. The mixer sits on top of the existing carb and > gives the evaporator a vacuum signal. What the heck kind of a mixer is this? Thought I'd seen em all... > This system sucked! As soon as the air filter got dirty the system went > rich, if barometric pressure was much different than the day the system > was set, it went nuts, All propane mixers suck! I haven't found one yet that does a decent job of it. Tried Impco, OHG, and now I'm running a Century mixer, on my 350 Camaro engine. BTW, you can fix the air filter thing with a balance line. On your vaporizer (evaporator), on the top side where the large diaphragm is, there's a port which is normally just an atmospheric vent for the back of the regulator diaphragm. (May have a little brass screen in it) Tap this out to 1/8" NPT (it's the right size already), put in a large STRAIGHT hose barb for at least 3/8" ID hose. Run the hose to another fitting which goes through the air filter housing to the inside of the filter. This effectively references the vaporizer regulator to the pressure on the back side of the filter instead of just atmospheric. This will eliminate the running rich with a dirty filter. Or, you could just change the filter once in a while... :] > I eventually came across (I'll call it an Electronic fuel control > system) from a company called Technocarb. This system uses an O2 > sensor, TPS and input from the tach lead (its intended to be used on > and already EFI engine) it then uses a stepper motor to run a valve > placed in between the evaporator and the mixer. This controls the I'd be interested in some more details on this system, costs, who sells it, etc. > this system is good, I am consistently running 18 MPG city or highway. Damn, 18 MPG is just a dream with me, my engine gives about 12 around the city... > The problem with this system is that the air flow through the mixer is > poor, resulting in low power. Also my evaporator is starting to stick, > this will be my 3rd one at $400 each. Most propane mixers (carburetors) aren't designed for decent airflow. Add to that the fact that you usually have 2 carbs stacked one on top of the other, and you're lucky to flow 450 CFM... The Century mixer I'm using has excellent air flow, and a nifty setup for distributing the fuel into the airstream, but the fuel metering is sh*t. I want to do a TBI injection setup to start out, and possibly upgrade to port injection as time and money allow... BTW, you can buy rebuild kits for the vaporizer for around 30 bucks, beats hell out of buying a new one. Piece of cake to install, too. > of was replacing the evaporator, mixer and fuel control valve with a TBI > nozzle controlled by a circuit which 'translates' the fuel control > valve position into an on/off pulse width. My questions are: Is my > understanding of the way a TBI regulates fuel accurate? How well would > the nozzle withstand the higher pressures of propane(up to 120 PSI)? This is probably not gonna work. Problems you would encounter with liquid propane are: 1. sudden demand for fuel causes the fuel pressure to drop so fast that the propane "boils" in the fuel lines, causing gaseous fuel to go through the injector and lean out the mixture drastically, usually with nasty (read expensive) consequences. 2. Injecting liquid propane into a throttle body would freeze the thing solid in minutes. 3. I haven't found any fuel injector which would open above about 80-90 PSI. Some Aussies did some work with a port injection system running at full system pressure, but they had an in tank fuel pump which circulated fuel past the injector a la most OEM fuel injection systems. They had to jack up the voltage to the injector to something like 32 volts to get it to open. 4. It may be difficult to get the injector to work accurately with the widely varying fuel pressures you get with temperature. At low temperatures, it probably couldn't supply enough pressure for the injector to run the engine, and at high temperatures, you'd have too much pressure and couldn't get the injector to shorten up the pulse width enough. The current idea I'm working on is to use the fuel in the gaseous state, using half a standard vaporizer, (remove the fuel pressure regulator guts) and regulating it with a standard gas regulator to somewhere around 50-60 PSI (maybe higher). Feed this into a standard dual TBI type injector, and see what happens. The higher-than-normal fuel pressure should allow the injector to supply enough fuel (even though it's designed for liquid fuel) but not so high as to affect the opening time. > The engine is a 350 stroked to 383 using Kieth Black silv-o-lite Yeah, when my 350 bites it I'd like to go with a 383 conversion... Anyway, speaking of long winded... Keep in touch, man, I am serious about doing this. Propane should be the fuel of choice, at least here in Canada, an' it's CHEEP! I been running it for years, and bitching about the lack of performance the whole time. It's time we dun somethin 'bout it... regards dn - -- - --------------------------------------------------------------------- Darrell A. Norquay Internet: dn@xxx.ca Datalog Technology Inc. Bang: calgary!debug!dlogtech!darrell Calgary, Alberta, Canada Voice: +1 (403) 243-2220 Fax: +1 (403) 243-2872 @ + < __/ "Absolutum Obsoletum" - If it works, it's obsolete -------------------------------------------------------------------- ------------------------------ From: Darrell Norquay Date: Tue, 19 Mar 96 19:34:31 MDT Subject: re: Propane Fuel Injection Todd Ratke writes: > Zirconium-Oxide. Propane tends to burn a lot hotter than gasoline > engines, furthermore many people run higher compression ratios to gain > some of the horsepower lost from a propane conversion. This usually > results in decreased engine life. By using a ceramic coating, the heat I have to disagree with you there, Todd. Propane engines tend to last a LOT longer than gasoline engines (all else being equal). Higher compression ratio does not shorten engine life appreciably per se, it's just that it tends to be used in high performance applications which demand more from an engine. The other advantages which propane shows over gasoline tend to more than balance out the added stresses that propane may impart on the combustion chamber. When was the last time you saw a gasoline powered engine run 500,000 miles between rebuilds - something that propane powered Taxis do on a regular basis... > normally transferred out the piston top and cylinder head is greatly > reduced resulting in cooler oil and coolant temperatures. An added bonus > is increased engine efficiency and a cleaner tail-pipe. Not to mention added thermodynamic efficiency which tends to extract more useable power per BTU of fuel... > One project I have on the go right now is a propane conversion on a 1996 > Chrysler minivan. It is a competition among major universities accross > North America sponsored in part by the SAE, called the LPGV challenge > (Liquified Petroleum Gas Vehicle). One of the fuel systems we are working > on is direct liquid propane injection and ceramic coated pistons and > cylinder heads. Should prove to be an interesting project. I would be most interested if you kept me posted on this. I haven't heard of this competition before, but I am very interested in fuel injection for propane. Besides, you're just down the road a piece... > PS: if any of > you have tried this before, I would appreciate any information you could > give me, we are all novices with direct injection and would sure like some > insight into some solutions for this most difficult engineering problem. I started a thread on this list a couple of months ago on propane EFI, and got some interesting replies... One was from an Aussie company who were developing a dual fuel port injection system. I could forward you some of the pertinent messages if you're interested... regards dn - -- - --------------------------------------------------------------------- Darrell A. Norquay Internet: dn@xxx.ca Datalog Technology Inc. Bang: calgary!debug!dlogtech!darrell Calgary, Alberta, Canada Voice: +1 (403) 243-2220 Fax: +1 (403) 243-2872 @ + < __/ "Absolutum Obsoletum" - If it works, it's obsolete -------------------------------------------------------------------- ------------------------------ From: "Hans Hintermaier" Date: Wed, 20 Mar 1996 09:29:08 MET Subject: RE:Stainless steel valves Someone wrote about titanium valves. I think you mean Titan-nitrid coated (once seen in a Harley sportster) They have a golden-looking finish. The best currently used valve material is "Inconel", once used in Bell's X-15 aircraft (or rocket?) to resist air-friction at Mach 23 and more. It is temperatur stabil up to 1200 C.(I hope I remember right). Today they use it for race car exthaust-pipes and big-diesel valves. It contains more then 50% of nichel. (Our metallurgist would know exact values?) TiN-coating a valve has similar functions as hard chroming. Hans hiha@xxx.de ------------------------------ End of DIY_EFI Digest V1 #81 **************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".