DIY_EFI Digest Friday, 22 March 1996 Volume 01 : Number 083 In this issue: thermal effects of combustion chamber Blackbird Re: BMW 323 Injection Blackbird Re: thermal effects of combustion chamber Re: thermal effects of combustion chamber Re: Blackbird Re: BMW 323 Injection Re: Blackbird Re: BMW 323 Injection Re: BMW 323 Injection Re: BMW 323 Injection Re: Blackbird Re: Blackbird See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Talltom Date: Thu, 21 Mar 1996 04:15:31 -0800 Subject: thermal effects of combustion chamber One last try. Looking for somebody to bite on the discussion of aluminum pistons, valves, ceramic piston tops or coatings with respect to fuel and ignition requirements. I have an 84 jag with aluminum heads, 11.5-1 compression(factory) that went thru emmissions with 20 hydrocarbons and no CO. It's a completly stock v-12, and a dog. It does not ping on regular fuel. I have a 54 cornbinder with a turbocharged 500 cadilac eng. that pings on the same fuel at 9in. vacuum(it idles at 12) Cadilacs have been famous for being detonators but the combustion chamber looks reasonable to me.(Reassuring huh?) Yes I've played all the timing games. My question is could the difference in thermal conductivity between aluminum and cast iron and or inadequate coolant circulation in the heads be the cause? If heads have hot spots does anybody with an oz or two more IQ than me have any suggestions as to how to eleviate the problem? Yes I have thought of making like a canibal and drilling out the coolant holes in the bottom of the headgasket, but this seems just a little to close to neanderthal for me even. I would like to modify the cooling somehow so that it could take a 30 minute full throttle blast.(without nitrous) P.S. For you guys complaining about 12 mpg, I've got a 5.00-1 diff, and 27" tires behind a turboed 500 caddy, without an overdrive tranny. I'd be elated to bring it up to 6. ------------------------------ From: Jim Steck <72614.557@xxx.com> Date: 21 Mar 96 07:48:49 EST Subject: Blackbird >About the Blackbird leaking, the skin of the aircraft (it has wet tanks) >was made with super thin slits in them. When the airframe heated up at >speed, the titanium expanded and forced these slits closed. Without them, >the skin would buckle at high temperature. You have to admit, it takes >balls to design a plane with holes in the fuel tank! Am I correct that the fuel was more of a jelly than a liquid? - -Jim Steck ------------------------------ From: WERNER_HAUSSMANN@xxx.com Date: Thu, 21 Mar 96 07:43:38 -0700 Subject: Re: BMW 323 Injection Hi Sandy One of the features of the L-Jetronic EFIs is that if the rpm are higher than 1500 when the trottle is closed (idle) then the fuel is cut off. This presents a problem if the idle is set too high. If the idle is set too high, the engine will rev up to about 1500, cut out, and then come back on at about 500-600 rpm. This will keep up all day until the trottle is opened slightly. This is especially annoying when trying to get started with a manual transmission. If you engage the clutch as the fuel is cut out, the engine dies. ...this is only one of many possibilities or course....but it's worth a try Werner ______________________________ Reply Separator _________________________________ Subject: BMW 323 Injection Author: Non-HP-owner-diy-efi (owner-diy_efi@xxx.edu) at HP-ColSprings,mimegw2 Date: 3/20/96 7:43 AM This is a change of pace for me, I just got a 1980 BMW 323i Alpina with a great 2.3L 6 cylinder! One problem with it however, is that the idle is unstable. It will 'motor boat' up and down, usually stalling out. Other times it is stable. I haven't as yet found out much about the system, I think it is a bosch j-tronic, it is all mechanical, fuel distributer, etc. Any ideas where to start looking? Sandy ------------------------------ From: "Kenneth C. King" Date: Thu, 21 Mar 1996 09:10:05 -0600 (CST) Subject: Blackbird ]>About the Blackbird leaking, the skin of the aircraft (it has wet tanks) ]>was made with super thin slits in them. When the airframe heated up at ]>speed, the titanium expanded and forced these slits closed. Without them, ]>the skin would buckle at high temperature. You have to admit, it takes ]>balls to design a plane with holes in the fuel tank! ] ]Am I correct that the fuel was more of a jelly than a liquid? ] ]-Jim Steck greetings: my understanding was that the blackbird's *real* fuel was a jel at normal (for people) temperatures. i believe they used another (more liquid) fuel to get it rolling. the thinner fuel combined with the cold (and contracted) skin lead to the worst of the leaks. once at a 'reasonable' altitude, a big tanker would feed the bird the jel (preheated for flow?). this reduced the bird's takeoff weight and allowed the hot skins to be cooled by the fuel. once the plane was up to speed, the skin would expand and seal all the fuel in before too much could leak out. later, kc - -- "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: ehernan3@xxx.com (Edward Hernandez (R)) Date: Thu, 21 Mar 1996 12:16:53 +0500 Subject: Re: thermal effects of combustion chamber "Looking for somebody to bite on the discussion of aluminum pistons, valves, ceramic piston tops or coatings with respect to fuel and ignition requirements....500 Caddy vs '84 Jag V12" There are lots of reasons why the Caddy and the Jag react differently to the same fuel inspite of the Jag's higher compression: 1) The Jag is a 5.3L V12 while the Caddy is a whopping 8.2L V8. That means that each cylinder of the Jag is less than HALF the size of the Caddy. At equal burn rates, the Jag is much more likely to finish combustion before the end gas detonates than the Caddy. That said, I would venture an educated guess that the Jag chambers burn faster than the Caddy's, giving it another advantage. 2) Al has 3 three time the thermal conductivity of Fe. Therefore, you can run higher compression since Al heads will absorb more heat of compression than Fe. Incidentally, this heat gets transferred to the coolant, sent to the radiator and dumped to atmosphere INSTEAD of turning the wheels, so the only way to win with Al is to run higher compression. 3) Al has about twice the specific heat of Fe. Therefore, Fe heads are more susceptible to developing and maintaining hot spots than Al. If you'd like, you can polish the Caddy's combustion chambers to help, but I'm not sure you'd notice the difference. 4) You didn't mention the use of an intercooler, so assuming you don't have one, you've just raised the charge air temp before any compression takes place in the cylinders. See how this all stacks up against the Caddy? One way to take advantage of Fe is to run lower coolant temps. I wouldn't play with improving coolant circualtion in the heads unless you know where the problems are and how to fix them. It's easy to make it worse if you're guessing. Ed Hernandez Ford Motor Company ehernan3@xxx.com ------------------------------ From: Frank Parker Date: Thu, 21 Mar 1996 12:57:24 -0500 (EST) Subject: Re: thermal effects of combustion chamber > inadequate coolant circulation in the heads be the cause? If heads have hot > spots > does anybody with an oz or two more IQ than me have any suggestions as to > how to eleviate the problem? Yes I have thought of making like a canibal and > drilling out > the coolant holes in the bottom of the headgasket, but this seems just a > little to > close to neanderthal for me even. I would like to modify the cooling somehow > so that > it could take a 30 minute full throttle blast.(without nitrous) What is your timing on cad?? Probably way too aggressive. Do you have any sort of boost retard?? Best would be to replace stock ign with J&S knock retard system which is closed loop and usues Bosch sensor with DSP electronics to retard is hears knock. I use on turbo vtec engine @xxx.25 c/r with 8psi intercooled without any ping. Yes, alum heads help alot. > > ------------------------------ From: gtk110@xxx.edu Date: Thu, 21 Mar 1996 13:53:12 -0500 Subject: Re: Blackbird >"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 > What the heck is this stuff??????..Please explain..is the soup made of LPG? and is "jim" the star trek jim? ------------------------------ From: "S. McManus" Date: Thu, 21 Mar 1996 11:01:13 -0800 (PST) Subject: Re: BMW 323 Injection If it's all mechanical, that's K-jet (CIS). My '79 320i did exactly the same thing, extremely annoying. The fix for my car was to set the idle mixture to factory specs using an exhaust gas analyzer. First check for vacuum leaks, also pull the boot on the air flow meter and make sure the plate is centered (that's a fun one). Sean McManus On Wed, 20 Mar 1996, Sandy wrote: > This is a change of pace for me, I just got a 1980 BMW 323i Alpina with a > great 2.3L 6 cylinder! One problem with it however, is that the idle is > unstable. It will 'motor boat' up and down, usually stalling out. Other > times it is stable. I haven't as yet found out much about the system, I > think it is a bosch j-tronic, it is all mechanical, fuel distributer, etc. > Any ideas where to start looking? > > Sandy > > > ------------------------------ From: gtk110@xxx.edu Date: Thu, 21 Mar 1996 13:53:59 -0500 Subject: Re: Blackbird >"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 > What the heck does this mean...Ist the soup made of LPG anddoes it have a mixer???? is "jim" the Captain James T. Kirk of the Enterprise??? anyway.. Now that I am new to this list, and have viewed it for the last couple of days, I finally have something to add I remember reading an article on natural gas injection that was put in a 302cid Ford Mustang which, incidentally, utilized the FACTORY ECU. I think it was the April??(don't quote me on this) '95 issue of Muscle Mustangs and Fast Fords.... I also recall that the stated octane rating of the gas is 130....could anybody verify this, and if so, why not run a 10:1 compression, bump the timing up a little, and run 10 psi of boost???(can't do that with gasoline). This seems to be a logical alternative to gasoline. What's the cumbustion potential as compared with that of gasoline. It's a shame that such a useful petroleum product is usually burned of at the oil well.....Forgive me if these questions seem stupid...I'm only 20 yr old junior at Penn State majoring in Mechanical engineering and I hav'nt had the thermal engineering or heat transfer classes yet... Gannon Kupko gtk110@xxx.edu ------------------------------ From: Seth Allen Date: Thu, 21 Mar 1996 15:29:53 -0800 (PST) Subject: Re: BMW 323 Injection The early K-Jetronics have a slightly unstable idle, and you have a gray markett car if you are in the US. Check all the ignition parts, and do a tune up, and check for vacuum leaks. This is the same system that was on VW Rabbits. People think that the FI messes things up, and start to fiddle. Usually the problem is a small maintenance issue. The basic idle setting is not elegant, but it works. Seth Allen, Owner of more CIS VWs than I care to admit. > Date: Thu, 21 Mar 1996 01:22:11 -0500 > From: Russ Highton Jr. > To: diy_efi@xxx.edu > Subject: Re: BMW 323 Injection > > At 09:43 AM 3/20/96 -0500, you wrote: > >This is a change of pace for me, I just got a 1980 BMW 323i Alpina with a > >great 2.3L 6 cylinder! One problem with it however, is that the idle is > >unstable. It will 'motor boat' up and down, usually stalling out. Other > >times it is stable. I haven't as yet found out much about the system, I > >think it is a bosch j-tronic, it is all mechanical, fuel distributer, etc. > >Any ideas where to start looking? > > > >Sandy > > > > > > > > I don't know exactly what is wrong with your car, but if you run it > by the guys on the BMW digest mailing list(email me if you want info its > great) they will surely be able to help. > Russ Highton Jr. > reh5@xxx.edu > 1982 320i 55k > > ------------------------------ From: Bohdan.L.Bodnar@xxx.com Date: Thu, 21 Mar 1996 13:24:17 -0600 Subject: Re: BMW 323 Injection And, if the system is KE-Jetronic, setting the air/fuel mixture to the correct value merely requires a high impedance dwell meter. Connect the meter across the fuel pressure controling "injector" (for lack of a better term) and set the a/f mixture for a 50% average duty cycle (e.g., on 6 cylinders setting, adjust mixture for average reading of 30 degrees). Regards, Bohdan Bodnar ------------------------------ From: Sandy Date: Thu, 21 Mar 1996 10:43:31 -0500 Subject: Re: BMW 323 Injection At 11:01 AM 3/21/96 -0800, you wrote: I'll be getting into it soon, that a good tip. Something odd, I found the wire to the O2 sensor disconnected just now, and will try reconnecting that an see if it helps. The odd thing is that I can guess what an O2 sensor function is with a mechanical injection???? Thanks again Sandy >If it's all mechanical, that's K-jet (CIS). My '79 320i did exactly the ------------------------------ From: lambs@xxx.au (Stephen Lamb) Date: Fri, 22 Mar 1996 11:45:48 +1100 Subject: Re: Blackbird > I also recall that the stated octane rating of the gas is >130....could anybody verify this, and if so, why not run a 10:1 compression, I understood the RON for LPG was in the 105-110 range, or about the same as avgas >bump the timing up a little, and run 10 psi of boost???(can't do that with >gasoline). This seems to be a logical alternative to gasoline. What's the Certainly if you are running straight LPG with its higher octane rating, there would be great benefit from boosting the CR and having more suitable cam timeing. In Oz the vast majority of conversions are 'dual-fuel' meaning that you retain the petrol option. This made sense when LPG conversions were something of a novelty, but these days it has wide acceptance and there are now many, many LPG outlets - especially in the urban areas. In fact the local LPG associations don't recommend dual fuel conversions because of the 'compromise' tuning requirements which reduces efficiency on both fuels, but most people still appear to want the 'peace-of-mind' of having the petrol option. >cumbustion potential as compared with that of gasoline. It's a shame that >such a useful petroleum product is usually burned of at the oil... No argument there 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: markus@xxx.com (Markus Lien) Date: Fri, 22 Mar 1996 02:24:21 -0500 Subject: Re: Blackbird > I remember reading an article on natural gas injection that was put >in a 302cid Ford Mustang which, incidentally, utilized the FACTORY ECU. I >think it was the April??(don't quote me on this) '95 issue of Muscle >Mustangs and Fast Fords.... I talked to a fellow who used a bone stock 350 chevy with TBI and the stock ECU and connected the LPG fuel line to it and it ran!! after about 10 minutes the manifold plugged with ice, a port injection may have the advantage of simply consuming any ice particles. > I also recall that the stated octane rating of the gas is >130....could anybody verify this, and if so, why not run a 10:1 compression, >bump the timing up a little, and run 10 psi of boost???(can't do that with >gasoline). This seems to be a logical alternative to gasoline. What's the >cumbustion potential as compared with that of gasoline. It's a shame that >such a useful petroleum product is usually burned of at the oil I am running a 350 chev stroked to 383 with shaved 64cc heads, should yield about 11:1 compression on propane and only have problems if I get stupid with timing. I am also running a cam which conserves cylinder pressure at low RPM. I read in a subsequent message that single fuel is a better option, STRONGLY agree, I doubt if my engine would run on pump gas without a knock sensor and an electronic distributor. >well.....Forgive me if these questions seem stupid...I'm only 20 yr old >junior at Penn State majoring in Mechanical engineering and I hav'nt had the >thermal engineering or heat transfer classes yet... > Gannon Kupko > gtk110@xxx.edu > no stupid questions, only un-answered ones! Markus ------------------------------ End of DIY_EFI Digest V1 #83 **************************** 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".