DIY_EFI Digest Tuesday, 19 March 1996 Volume 01 : Number 080 In this issue: RE: BS ENGINES PIstons RE BS ENGINES RE: BS ENGINES Re: PIstons re: ICE ceramic coatings Ignition Controller Alternate fuel EFI Alternate fuel EFI Direct injection propane See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Ed Lansinger Date: Mon, 18 Mar 96 20:43:09 EST Subject: RE: BS ENGINES Clint Corbin wrote: >Aluminum pistons being flame proof?! Aluminum melts at around 1100F (used to >work in an aluminum foundry). Flame temp inside an IC engine is around 1600F. >[snip] >If you increase the amount of energy being generated in the combustion chamber >(say by turbocharging or just increasing the breathing of the engine) enough, >the piston will not be able to dump the extra energy to the cylinder and bam, >you melt a nice hole in the piston. >[snip] >All in all, aluminum is not the best material for a piston. Geez, Clint, that's an awfully harsh statement considering aluminum is the preferred material for production and many racing pistons these days, *including* turbocharged and supercharged engines. Aluminum being a more expensive material than steel, there must be a good reason that the OEMs use it. Actually, _exhaust gas temperature_ is around 1600F, flame temp in the combustion chamber is more like 3000F. Iron and steel are already starting to get rather weak around 1600F; 3000F will melt either. So piston durability must be a more complicated issue than simply one of material selection. As you allude, heat transfer is very important. Aluminum is a nice material from that standpoint, much nicer than steel. It's not clear to me that simply redoing the same aluminum design in steel will improve durability - strength at the same temperature goes up, but the piston temperature goes up because it can't transfer heat as quickly through itself to the walls, wrist pin, oil, intake air, etc., plus you have much greater stresses from the greater mass you are throwing around. Obviously, I'm not a piston designer. I have heard of people having lots of success with aluminum pistons and heads that use a (ceramic) thermal barrier coating. Maybe this would be a good solution to the original question (which I missed). Ed Lansinger GM Powertrain Premium V (Northstar/Aurora) Software & Calibration Group ------------------------------ From: ehernan3@xxx.com (Edward Hernandez (R)) Date: Mon, 18 Mar 1996 15:46:45 +0500 Subject: PIstons Ed Lansinger wrote "Aluminum being a more expensive material than steel, there must be a good reason that the OEMs use it." 1) It's light and won't yank the crankpins off the crank at 6000rpm. 2) It's much easier(read cheaper) to machine than steel. 3) You were correct about the rest, except than combustion temps can reach upwards of 4400 F(transient, but hot). Not bad for a calibrator; with some training, you be a decent piston engineer. Ed Hernandez Ford Motor Company ehernan3@xxx.com ------------------------------ From: ducharme@xxx.com Date: Mon, 18 Mar 96 15:56:31 EST Subject: RE BS ENGINES Ed Lansinger wrote: > I have heard of people having lots of success with aluminum pistons and heads > that use a > (ceramic) thermal barrier coating. Maybe this would be a good solution to the> original > question (which I missed). I like it - ceramic pistons/cylinders for B&S engines... >From what I have seen, the limiting factor on the B&S as far as HP production is concerned is the basic design (L-head, small valves, limited heat rejection capacity from the fin area, no pressure lubrication to cool the piston crown). 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. My project engine was purchased in 1970 when I graduated from high school, cut acres of grass for many years until the mower deck rusted away, was lucky if it saw an annual oil change, and when I dissassembled it last fall before starting my senior project, I couldn't find a ridge at the top of the cylinder! The aluminum bore still had crosshatch marks in places and, other than exterior rust, corrosion and flaked paint, showed little signs of such abuse. For its intended purpose, that's hard to argue with. What was the original question? P.S. Ed - Great article in Circuit Cellar Ink. It helped me greatly. Cliff Ducharme ------------------------------ From: lambs@xxx.au (Stephen Lamb) Date: Tue, 19 Mar 1996 10:43:02 +1100 Subject: RE: BS ENGINES Hi, I'm new to this list, but perhaps as a metallurgist I can help with some of this: >Clint Corbin wrote (in part): >>All in all, aluminum is not the best material for a piston. Ed Lansinger replied (in part): >As you allude, heat transfer is very important. Aluminum is a nice >material from that... Actually this is probably about the most important factor, but there is also the fact that aluminium alloys have a thin naturally forming protective coating of aluminium oxide which has a far higher melting point than the metal itself. Aluminium actually 'burns' in a similar manner to magnesium (ie exothermically) - remember the British ships with aluminuim superstructures which 'burned' for days after being hit with Exocet missiles during the Falklands war ?? >standpoint, much nicer than steel. It's not clear to me that simply redoing the same >aluminum design in steel will improve durability - strength at the same >temperature goes >up, but the piston temperature goes up because it can't transfer heat as >quickly through >itself to the walls, wrist pin, oil, intake air, etc., plus you have much >greater >stresses from the greater mass you are throwing around. Exactly, steel certainly has poor thermal conductivity relative to aluminium (and stainless steel is even worse). The greater reciprocating mass would mean lower engine speeds and performance, etc. Vehicles built in the early part of this century actually used cast iron pistons because aluminium metallurgy and particularly casting metallurgy, was in its infancy. But the speed of these engines was quite low, so the stresses on the cast components was kept to manageable levels. >I have heard of people having lots of success with aluminum pistons and >heads that use a >(ceramic) thermal barrier coating. Maybe this would be a good solution to >the original >question (which I missed). Just for interest, modern piston materials are actually a special aluminium/silicon alloy 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. 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: Sauron Date: Mon, 18 Mar 1996 21:08:24 -0500 (EST) Subject: Re: PIstons On Mon, 18 Mar 1996, Edward Hernandez wrote: > Ed Lansinger wrote > > "Aluminum being a more expensive material than steel, there > must be a good reason that the OEMs use it." > > 1) It's light and won't yank the crankpins off the crank at 6000rpm. > 2) It's much easier(read cheaper) to machine than steel. > 3) You were correct about the rest, except than combustion temps can > reach upwards of 4400 F(transient, but hot). Not bad for a calibrator; > with some training, you be a decent piston engineer. > > > Ed Hernandez > Ford Motor Company > ehernan3@xxx.com > Yes, aluminum is a much easier material to work with, but iron or steel would be a techinically better choice, if the weight were less. Also, manufacturers rarely retool their operations for iron or steel, if aluminum gives a similar level of performance. ------------------------------ From: TAR Date: Mon, 18 Mar 1996 21:01:26 -0700 (MST) Subject: re: ICE ceramic coatings 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 displacement diesel engines normally found in Natural Gas tranmission facilities. I believe a number of manufacturers are toying with the concept for commercial applications. There are a number of definate advantages to using a ceramic barrier on piston crowns and cylinder heads. Ceramic coating technology is a fairly new field of application for both diesel and propane powered vehicles. In fact, the most common coating material I've heard being used is a Zirconium-Oxide blend. In deisel engines, the result of ceramic coatings is lower emissions (especially during throttle transitions) and improved engine efficiency. However, the materials engineers still have problems getting an even coating and have an even harder time preventing cracks in the coatings. The distinct advantage in propane powered vehicles comes not from the lowered emmissions, but rather from the insulating properties of 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 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. 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. Thanks a million gang, Todd Ratke, tratke@xxx.ca ------------------------------ From: Warren Crowther Date: Tue, 19 Mar 1996 17:50:49 +1200 Subject: Ignition Controller Does anyone know if there is any PCB artwork for programmable ignition controller project around?? I have the schematics, and i'll do my own if i can't find any. thanks _______________________________________________________________ Warren Crowther yeeehaaa! O Mobile (025) 870-155 Software Engineer ##\\-/_, DDI +649 3610625 warren@xxx.nz -O----O-' Ph +649 3602834 x5625 Hypercom Communication Technologies Fax +649 3602840 ------------------------------ From: postmaster@xxx.com (Markus Lien)) Date: Tue, 19 Mar 1996 03:48:28 -0500 Subject: Alternate fuel EFI Greetings from the Great White North (Canada) My interest in EFI first came when I assisted my father in law in transplanting a 5.0 multiport drivetrain into a '68 meteor then my father in transplanting a 2.5l TBI into his '85 Dodge Rampage. Both cars were imense successes and I believe Dodge could have made money from this car if they were to have done this themselves! My personal EFI story started 10 years ago when I converted my '68 GMC to run on propane. The original system consisted of an evaporator and a mixer, the evaporator is basically a large welding regulator set to 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. 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, extreme temperatures seemed to throw it off. We have some extreme temperature swings of as much as 30Deg. celcius in a 24 hour period. Mileage ranged from 15 MPG to about 4 GPM (yes gallons per mile). 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 amount of vacuum the evaporator see's. The ECM is a unit built by an Italian company, I think its called AFB, and appears to run off a fuel map until the O2 sensor is up to temp. The acuracy of this system is good, I am consistently running 18 MPG city or highway. 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. The ECM has a diagnostics port which gives a reading from 0 to 256, indicating the position of the fuel control valve. 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? The engine is a 350 stroked to 383 using Kieth Black silv-o-lite pistons (on the topic of alluminum metallurgy wizardry). The cam is short duration with high lift combined with the longer stroke take better advantage of the slow burn characteristics of propane. Because propane is stable under pressure the heads are small chamber and have been shaved should give compression ratio of around 11:1 Sorry for the long-windedness but this is the result of 10 years of struggling to achieve a usable aternative fuel engine. Markus P.S. If you are wondering why anyone would do this it is because our government taxes the hell out of gasoline but leaves propane alone because it is envirnmentally sound. Go green, Save that planet! ------------------------------ From: postmaster@xxx.com (Markus Lien)) Date: Tue, 19 Mar 1996 03:46:26 -0500 Subject: Alternate fuel EFI Greetings from the Great White North (Canada) My interest in EFI first came when I assisted my father in law in transplanting a 5.0 multiport drivetrain into a '68 meteor then my father in transplanting a 2.5l TBI into his '85 Dodge Rampage. Both cars were imense successes and I believe Dodge could have made money from this car if they were to have done this themselves! My personal EFI story started 10 years ago when I converted my '68 GMC to run on propane. The original system consisted of an evaporator and a mixer, the evaporator is basically a large welding regulator set to 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. 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, extreme temperatures seemed to throw it off. We have some extreme temperature swings of as much as 30Deg. celcius in a 24 hour period. Mileage ranged from 15 MPG to about 4 GPM (yes gallons per mile). 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 amount of vacuum the evaporator see's. The ECM is a unit built by an Italian company, I think its called AFB, and appears to run off a fuel map until the O2 sensor is up to temp. The acuracy of this system is good, I am consistently running 18 MPG city or highway. 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. The ECM has a diagnostics port which gives a reading from 0 to 256, indicating the position of the fuel control valve. 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? The engine is a 350 stroked to 383 using Kieth Black silv-o-lite pistons (on the topic of alluminum metallurgy wizardry). The cam is short duration with high lift combined with the longer stroke take better advantage of the slow burn characteristics of propane. Because propane is stable under pressure the heads are small chamber and have been shaved should give compression ratio of around 11:1 Sorry for the long-windedness but this is the result of 10 years of struggling to achieve a usable aternative fuel engine. Markus P.S. If you are wondering why anyone would do this it is because our government taxes the hell out of gasoline but leaves propane alone because it is envirnmentally sound. Go green, Save that planet! ------------------------------ From: markus@xxx.com (Markus Lien) Date: Tue, 19 Mar 1996 03:55:27 -0500 Subject: Direct injection propane >Todd Ratke asked if anyone has any experience with direct injected > propane. In talking to the manufacturer I mentioned in my previous message he told me about a chev 350 they set up on a test stand and simply connected LPG to the fuel line. He said that it would run for about 10 minutes before the manifold plugged with ice. With my system I was planning on mounting the injector nozzle at the end of a tube heated with engine coolant to fully vaporize the fuel before it hits the air stream. A more elaborate system could use a number of smaller tubes to facilitate multiport injection. Markus ------------------------------ End of DIY_EFI Digest V1 #80 **************************** 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".