DIY_EFI Digest Friday, 13 December 1996 Volume 01 : Number 381 In this issue: RE: Nissan 300ZX efi fault RE: Fwd: eddy current brake Re: Fwd: eddy current brake Re: oil pumps (not efi) Re: Weird problem RE: Fwd: eddy current brake Re: Fwd: eddy current brake Re: Nissan 300ZX efi fault RE: oil pumps (not efi) RE: Fwd: eddy current brake Re: Fwd: eddy current brake Re: Fwd: eddy current brake RE: oil pumps (not efi) RE: oil pumps (not efi) Re: Fwd: eddy current brake Re: Fwd: eddy current brake Re: Fwd: eddy current brake Re: Weird problem Re: oil pumps (not efi) RE: oil pumps (not efi) Re: Fwd: eddy current brake See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: "Bob R. McElroy" Date: Fri, 13 Dec 1996 05:53:00 -0600 Subject: RE: Nissan 300ZX efi fault I had a similar problem with a 1979 280ZX. The local Nissan dealer = couldn't find the problem, but suspected the computer was failing. I = was in college at the time so I went to a salvage yard and purchased a = used computer out of a wrecked 280ZX (NOT RECOMMENDED.) I got lucky and = it solved my problem, but when I look back at it, I shudder when I = realize the problems I could have had. Later, I wrecked the '79 and purchased an '81 280ZX (this one had T-tops = and 145 hp instead of the '79's 130 hp.) That car gave me no problems = with surging like the '79 did. Interestingly, the '81 succumbed to body = cancer while the '79's body isn't terribly rusted (I still have the '79 = and I plan on doing something with it, but what I'm not sure.) You state that the '86 300ZX has two (2) computers? Both of them can't = be used for fuel injection control, can they? As I recall, mid-'80's = 300ZX's could be optioned with digital instrument display panels or an = electronically (computer?) controlled selective shock damping system. = Is one of the computers for either of these options? I like the looks of the Nissan Z-cars and applaud your associates = purchase of the 300ZX turbo. My advice would be to try and unload the = current Z on some sucker :) and purchase a used Z car from a Nissan = dealer. As I understand it, Nissan is currently offering reconditioned, = used Z-cars for sale at selected dealers. These used Z-cars even come = with a warranty. I'm not sure of the availability of this offering from = Nissan, but it may be something of interest. I hate to suggest dumping the car instead of fixing it. No Z-car = deserves that fate. Maybe someone else has a better solution. Bob McElroy PS - I had a thought before I press the send button. Could a plugged = or damaged turbo cause surging? That is, could it be fouled so that it = sometimes produces a surge of air pressure that the engine isn't = expecting? Or the turbo shaft bearings so gummed up that the turbo = stops spinning at low exhaust flow and stops up the exhaust system? I = guess one way to test the turbo is to watch the boost gauge (I think = Turbo-Z's all came with boost gauges.) If the boost suddenly falls off = or spikes up, that would be a sign to investigate the turbo further. BTW, in my dealings with Nissan dealerships (all in small towns in = Midwestern America, specifically South Dakota) I have found them to be = very knowledgeable and helpful. That is very dependent upon the dealer = though. - -------------------------------------------------------------------------= - ------------------------------------ The car is a Nissan 300ZX model listed below. Anyway long story short, he bought second hand from a local car dealer after lots of warning from myself. Has spent lots of $$'s fixing the usual faults with cars, (hoses, leaking fuel seals etc ...) but there is one fault that even the local Nissan (real 100% factory appointed) cannot resolve. I have About 80% of the time the engine has a problem of surging then dying = when at 1700-1900 RPM it refuses to cruise at this RPM level. The engine = still accelerates and decelerates smoothly but will not run evenly whilst = trying to keep at a constant speed. ------------------------------ From: "Bob R. McElroy" Date: Fri, 13 Dec 1996 06:39:11 -0600 Subject: RE: Fwd: eddy current brake With a 4-point crank wheel and one sensor for that wheel, you would have = 4 pulses, each 90=B0 apart. A sensor wheel could be constructed so that = it gives a rising edge and a falling edge four times per revolution, = with the falling edge 45=B0 out of phase with the rising edge. This = provides the 8 points necessary to have a resolution of one event every = 45=B0. I'm responding to this post because it took me a couple seconds to = understand what was intended. I first thought a wheel with four small = (a couple degrees wide) teeth was being described. I then realized that = Tom was describing a wheel with teeth that spanned 45=B0 each. However, = I'm still puzzled when he states "2 revs =3D 360". One revolution = equals 360=B0. Two crankshaft revolutions, however, does equal 360=B0 = of camshaft revolution (oh, now I get it. Never mind.) When you start talking about PLL, however, I'm lost. What exactly does = a PLL do or tell you? Sorry if everyone else considers this question = trivial, but I only studied basic electronics in college. I was lucky = enough to take a class on internal combustion engines, but that mainly = centered on the thermo-chemistry involved with combustion, and not many = practical exercises (like most of my engineering courses.) On the plus = side, I did get to use the Heywood text book that I see listed under the = recommended reading list for EFI information. Thanks for any help. Bob McElroy - ---------- Lessee, 600 at idle to 6000 is 10:1, which is enough for me. With a = 4-star crank sensor, you get a pulse every 45 degrees, since 2 revs =3D 360, = right? Then, if you PLL'd the freq by 45, you'd have 1 degree pulses, by 90, .5 degree. Am I right? I think I understand the need for 'reasonable' accuracy with firing, but you've already got a hardware (crank) 45 = degree reference. The PLL jitter shouldn't give but only a few tenths of a = degree error, if that much. Capture shouldn't be a problem, as I don't see how = you can rev or decelerate the engine fast enough to lose lock. Remember, I'm just positing here -- never actually tried this. Tom Cloud ------------------------------ From: Matt Sale Date: Fri, 13 Dec 1996 07:54:17 -0500 (EST) Subject: Re: Fwd: eddy current brake 600 RPM is a typical V8 idle speed, but cranking speed may be more in the 200-400 RPM range, and the accel and decel's in the crank to run transition are quite severe, making a PLL approach like this problematic. As others have mentioned, PLL jitter is not your largest error source, accel, decel, and just the sinusoidal nature of crankshaft speed due to the firing events cause errors. Thats why more reference points are better, up to some realistic limit. I think a PLL based system can work, though; if its thoroughly thought out. > > >It's my understanding that the dynamic range, 20:1, is difficult for a > >simple PLL. I think the confuser would have to adjust the feedback based on > >the current RPM range to keep it locked. me > > > > Lessee, 600 at idle to 6000 is 10:1, which is enough for me. With a 4-star > > Remember, I'm just positing here -- never actually tried this. > > Tom Cloud - -- Matthew D. Sale msale@xxx.com/~msale '69 Mustang 351W 5-spd (13.656@xxx. All responses are my own and should not be mistaken for those of Delco Electronics or General Motors. ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Fri, 13 Dec 1996 07:34:14 -0600 Subject: Re: oil pumps (not efi) Coupla things: 1 - I've just found another area where you can mark me dummy: to wit, the reason the oil pressure in my truck has remained constant for five years and 107,000 ++ miles is that the 'gauge' is really just a switch that moves the pointer to the same place regardless of the pressure. I thought the oil system in my truck was pretty remarkable -- now I know why! ANY OF YOU FORD GUYS OUT THERE ??? You can tell corporate for me that I am some ticked!!! If I'd wanted an idiot light, I'd passed on the "gauges". I feel like I got cheated ... no, I *KNOW* I got cheated. I ordered gauges and I got an on / off indicator. A light would have been better. And what'd Ford save? They still had to have the gauge (and that probably only costs a coupla bucks), all the wiring is there, so the price savings, if any, is simply the diff between the cost of the pressure switch and a pressure sensor -- couldn't be much. If they'll do that, wonder what other wonderful surprises I have yet to discover? 2 - regarding Darrell Norquay 's reply, below, it is my understanding that the oil pump has a pressure relief or control bleeder (I don't have one here in front of me, but I'm pretty sure of that). If so, the volume the pump can deliver is not necessarily the volume it will deliver. It will pump oil against the engine until the pressure builds to the pre-set limit and then the bypass will divert the unused oil back into the pan or into the pump's intake (dunno which). Ergo, the pressure stays the same and the volume is no more than a stock pump's, assuming that the stock pump could maintain the same pressure. Course, if there are sloppy tolerances, etc, the hi-vol pump would come nearer keeping the pressure at the desired level than the stock -- least that's how I understand it. >At 07:20 AM 12/11/96 -0600, Tom Cloud wrote: > >>The high volume pump does not increase pressure, so no more oil >>flows through the engine than for a normal pump, unless there's >>a loose fitting or such, right? > >A high volume pump will, in fact, increase oil pressure in most cases. I say >in most cases since if bearing clearances are loose, it may not increase >pressure over stock, but it will have higher pressure over a stock pump, >which would be below normal in this case. This is a band-aid solution, >however, if the engine has proper clearances, the high volume pump will not >be necessary. > >> - same volume of oil will be pumped by stock and hi-vol pump (i.e. >>hi-vol pump will just recirculate and 'froth' the oil). The only >>time the hi-vol capability will be needed is when the engine is >>very old or has an internal 'leak'. > >WRONG. Why the heck would it be called a high volume pump if it didn't pump >more volume per revolution?!?!? If you carefully compare the stock pump >with a high volume pump, you will note the body of the pump is longer, >denoting longer gears in the pump, and thus more swept area of the rotors. >More area x same RPM = higher volume. This will equate to higher average >oil pressure, all else being equal. The only circumstance the oil pump >recirculates is if the filter is allowed to clog up, at which point there is >a bypass valve in the block which still allows oil to circulate, albeit >unfiltered. > >> - you are advised to buy a hardened, stronger oil pump drive shaft >>when you get a hi-vol pump ...... this implies to me that there's >>more of a load on the shaft, hence on the cam gears, on the cam >>'bearings',on the timing chain and gears. Why would you do that? > >The increased load is proportional to RPM. If you plan on redlining the >engine at 8000 RPM, I would recommend the hardened shaft, if you don't plan >on running above 5500 or 6000 RPM, don't bother. > >> - my 302 in my F150 with 107,918 (as of this morning) reads very >near the >same oil pressure it did when it was new (on the "A" of >"NORMAL", heh-heh). >It does this even when hot, down a quart and at >idle of 650 rpm (once >again, as of this morn). > >All this means is that your engine is still in reasonable shape internally. >A high volume pump doesn't last any longer than a stock pump under the same >conditions. > >>Neither my mentor/guru nor my part$ guru could tell me why I should >>use a high volume pump. Seems to me to really just be a waste of >>_precious_ horsepower and a source of unnecessary wear on the cam >>and related components. > >This is true. Having cleared up a few inconsistencies in your above >comments, there are very few reasons to use a high volume pump. To quote >David Vizard (How to Build Horsepower, S-A Design Books): > >"Most stock oil pumps supply sufficient oil flow for modified street engines." > >"In most engines, abnormally high oil pressure (above 45-50 PSI), increases >pump drag, absorbs engine power, increases the chance of oil entering the >combustion chambers, and does not provide improved bearing lubrication or >extend component life." > >"Higher oil pressure will almost always do only one thing: rob horsepower, >often as much as 10-15 HP when pressures of 100 PSI are used." > >BTW, don't even think of re-using the old pump. >regards >dn >dnorquay@xxx.com > > > Tom Cloud ------------------------------ From: "Gregory Chan" Date: Fri, 13 Dec 1996 08:47:17 EDT Subject: Re: Weird problem > Greg, > So what seems to be the relationship between 5th gear and the engine > revving up. Almost sounds like a speed limiter to me. > Just out of curiosity, what's your speed at 7500 in 4th versus 6000 in > 5th, can you go faster in 4th than 5th? At 7500 rpm in 4th I would be doing around 115 mph. At 6000 in 5th about 120 mph. > When in 4th gear does the thing have good power all the way to 7500, or > does it significantly fall off? The thing has good power all the way through the gears until I get to 6000 rpm in 5th where it just stays at around 120 mph. > Any other changes, trans, tire, something else that may have affected > it? The only thing I changed was the muffler. From a Supertrapp glasspack to a Dynomax Super Turbo. I have the same tranny, wheel/tire combination and the same fuel injection system. I now have more power so I should be able to get up to the same top speed at least. > > gchan@xxx.ca ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Fri, 13 Dec 1996 08:25:01 -0600 Subject: RE: Fwd: eddy current brake >With a 4-point crank wheel and one sensor for that wheel, you would have 4 pulses, each 90=B0 apart. A sensor wheel could be constructed so that it gives a rising edge and a falling edge four times per revolution, with the falling edge 45=B0 out of phase with the rising edge. This provides the 8 points necessary to have a resolution of one event every 45=B0. > >I'm responding to this post because it took me a couple seconds to understand what was intended. I first thought a wheel with four small (a couple degrees wide) teeth was being described. I then realized that Tom was describing a wheel with teeth that spanned 45=B0 each. However, I'm= still puzzled when he states "2 revs =3D 360". One revolution equals 360=B0. Two crankshaft revolutions, however, does equal 360=B0 of camshaft revolution= (oh, now I get it. Never mind.) > >When you start talking about PLL, however, I'm lost. What exactly does a PLL do A PLL (phase locked loop) works like an op-amp, except its two inputs are pulse waveforms (i.e. frequency) rather than analog voltages. Basically, it outputs a DC voltage corresponding to the diff in the phase or freq of the two inputs. You can feed a freq into one input (say the pulses from your crank) and let the DC output control a VCO (voltage controlled oscillator). Take the output of the VCO and feed it into a divide by 'n' counter whose MSB goes back into the other input of the VCO. That forces the VCO freq to be 'n' times the "reference" (our crank signal). |crank pulses| ----> | | | PLL | --> | VCO | ------> {output 'n' times} ----> | | | {crank PRR } | | ----- [ divider ] <-------------- "PRR" =3D=3D=3D>> pulse repetition rate Actually, the above is a little misleading. The "PLL" above is actually the phase comparator. A PLL consists of both the phase comparator and the VCO. Two major problems with a PLL. "Capture" -- ability to 'lock on' to an input. It will 'hunt' while seeking capture and the output will be erroneous / unrelated to the phase relationship of the inputs. "Lock Range" is the range of frequencies it can effectively output. The capture range is smaller than the lock range. The problem, I believe, in the auto app here is -- will the PLL capture quickly enough for you to start your car? and will it be able to track the entire rpm range you want without going out of lock (which would be bad). Tom Cloud ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Fri, 13 Dec 1996 08:30:38 -0600 Subject: Re: Fwd: eddy current brake >600 RPM is a typical V8 idle speed, but cranking speed may be more >in the 200-400 RPM range, and the accel and decel's in the crank to >run transition are quite severe, making a PLL approach like this >problematic. As others have mentioned, PLL jitter is not your >largest error source, accel, decel, and just the sinusoidal nature >of crankshaft speed due to the firing events cause errors. Thats >why more reference points are better, up to some realistic limit. > >I think a PLL based system can work, though; if its thoroughly >thought out. My '82 Bronco and my son's '86 both use 4-lobed crank sensors with no other inputs from the distributor or other. The PLL solution must be how they operated these vehicles ????? Anyone know about how they did that? Why don't they still do that -- or do they? Tom Cloud ------------------------------ From: kleenair@xxx.com Date: Fri, 13 Dec 1996 09:46:31 -0800 Subject: Re: Nissan 300ZX efi fault Ross Forgione wrote: > > Hi all, > > I work with a high flying sales person type dude, who is in his 30's and > is suffering from the old mid life crisis problem. Soultion to problem, > purchase a sporty type car. > > The car is a Nissan 300ZX model listed below. Anyway long story short, > he bought second hand from a local car dealer after lots of warning > from myself. Has spent lots of $$'s fixing the usual faults with cars, > (hoses, leaking fuel seals etc ...) but there is one fault that even > the local Nissan (real 100% factory appointed) cannot resolve. I have > listed it below in the hope that somebody out there may be able to > light a small candle showing the direction we should take in resolving > the fault. > > Have pity on the guy, It real hard to look cool when the cars on tow > as the pretty ladies go by. > > Any help at all will be greatly appreciated. > > The problem as follows: > > Make: Nissan 300ZX Turbo 1986 - Fuel Injected > > About 80% of the time the engine has a problem of surging then dying when > at 1700-1900 RPM it refuses to cruise at this RPM level. The engine still > accelerates and decelerates smoothly but will not run evenly whilst trying > to keep at a constant speed. > > The problem can be fixed 100% successfully after driving a few KMs by > putting the car into neutral and switching the ignition off for 2 or more > seconds the restarting the engine. > > If I park the car and leave it for an hour or so the majority of the > time I will need to start the engine drive for a few KMs the switch the > engine off and on to get it to run smoothly again. > > If I start the engine then stop it immediately then start it again when > I first get into the car it still will not cruise at 17-1900 RPM most of > the time. > > Hot or Cold weather makes no discernable differance to the behavior of > the car. > > It is a bit of nuisance having to switch the engine off every time I > drive it. > > I have taken the car to a Nissan Service Centre but they are not sure what > the problem is. They think it may be one of the computers being faulty > but they are not sure which. I dont think much of having to pay $1500 to > have both computers replaced when they are not certain which one it is > or even if it is actually a computer fault. > > If you can find anyone that has had similar gremlims let me know. > > Thanks, > > Ross. > I don't know any specifics about the Nissan system, but try checking the following: - -EGR valve operation: Is it getting stuck. Try disconnecting it and see what happens. - -O2 sensor(s): Are they still working? Put a volt meter on it to see. It's possible the computer is attempting to go to closed loop. Does it have heated O2 sensors? Is the heater working. Best Regards, Mazda ------------------------------ From: John Hess Date: Fri, 13 Dec 1996 09:24:09 -0600 Subject: RE: oil pumps (not efi) I have been reading this thread over the last few days and feel compelled to interject the following; It is my understanding that on a Chevy small block, it is not recommended to utilize a high volume oil pump. This can cause the oil to be pumped in a manner that will fill up the lifter valley while choking off oil supply to the bottom end. The recommendation appears to use a high pressure pump, instead. This would imply that there is, in fact, a difference. John - ---------- From: Darrell Norquay[SMTP:dnorquay@xxx.com] Sent: Thursday, December 12, 1996 9:47 PM To: diy_efi@xxx.edu Subject: Re: oil pumps (not efi) At 07:20 AM 12/11/96 -0600, Tom Cloud wrote: >The high volume pump does not increase pressure, so no more oil >flows through the engine than for a normal pump, unless there's >a loose fitting or such, right? A high volume pump will, in fact, increase oil pressure in most cases. I say in most cases since if bearing clearances are loose, it may not increase pressure over stock, but it will have higher pressure over a stock pump, which would be below normal in this case. This is a band-aid solution, however, if the engine has proper clearances, the high volume pump will not be necessary. > - same volume of oil will be pumped by stock and hi-vol pump (i.e. >hi-vol pump will just recirculate and 'froth' the oil). The only >time the hi-vol capability will be needed is when the engine is >very old or has an internal 'leak'. WRONG. Why the heck would it be called a high volume pump if it didn't pump more volume per revolution?!?!? If you carefully compare the stock pump with a high volume pump, you will note the body of the pump is longer, denoting longer gears in the pump, and thus more swept area of the rotors. More area x same RPM = higher volume. This will equate to higher average oil pressure, all else being equal. The only circumstance the oil pump recirculates is if the filter is allowed to clog up, at which point there is a bypass valve in the block which still allows oil to circulate, albeit unfiltered. > - you are advised to buy a hardened, stronger oil pump drive shaft >when you get a hi-vol pump ...... this implies to me that there's >more of a load on the shaft, hence on the cam gears, on the cam >'bearings',on the timing chain and gears. Why would you do that? The increased load is proportional to RPM. If you plan on redlining the engine at 8000 RPM, I would recommend the hardened shaft, if you don't plan on running above 5500 or 6000 RPM, don't bother. > - my 302 in my F150 with 107,918 (as of this morning) reads very >near the same oil pressure it did when it was new (on the "A" of >"NORMAL", heh-heh). It does this even when hot, down a quart and at >idle of 650 rpm (once again, as of this morn). All this means is that your engine is still in reasonable shape internally. A high volume pump doesn't last any longer than a stock pump under the same conditions. >Neither my mentor/guru nor my part$ guru could tell me why I should >use a high volume pump. Seems to me to really just be a waste of >_precious_ horsepower and a source of unnecessary wear on the cam >and related components. This is true. Having cleared up a few inconsistencies in your above comments, there are very few reasons to use a high volume pump. To quote David Vizard (How to Build Horsepower, S-A Design Books): "Most stock oil pumps supply sufficient oil flow for modified street engines." "In most engines, abnormally high oil pressure (above 45-50 PSI), increases pump drag, absorbs engine power, increases the chance of oil entering the combustion chambers, and does not provide improved bearing lubrication or extend component life." "Higher oil pressure will almost always do only one thing: rob horsepower, often as much as 10-15 HP when pressures of 100 PSI are used." BTW, don't even think of re-using the old pump. regards dn dnorquay@xxx.com ------------------------------ From: John Hess Date: Fri, 13 Dec 1996 09:29:48 -0600 Subject: RE: Fwd: eddy current brake The way these systems actually work is a whole lot simpler than that.=20 They simple fire 360 degree pairs simultaneously. In other words,=20 the fire one cylinder at the actual point required to ignite the=20 mixture in the cylinder, while firing its twin, simultaneously,. at or=20 near the end of the exhaust stroke. No attempt is made to break this=20 up into 8 firing cycles, 4 is quite adequate for an 8 cylinder=20 engine. John - ---------- From: Bob R. McElroy[SMTP:rmcelroy@xxx.com] Sent: Friday, December 13, 1996 6:39 AM To: 'diy_efi@xxx.edu' Subject: RE: Fwd: eddy current brake With a 4-point crank wheel and one sensor for that wheel, you would=20 have 4 pulses, each 90=B0 apart. A sensor wheel could be constructed so = that it gives a rising edge and a falling edge four times per=20 revolution, with the falling edge 45=B0 out of phase with the rising=20 edge. This provides the 8 points necessary to have a resolution of=20 one event every 45=B0. I'm responding to this post because it took me a couple seconds to=20 understand what was intended. I first thought a wheel with four small=20 (a couple degrees wide) teeth was being described. I then realized=20 that Tom was describing a wheel with teeth that spanned 45=B0 each.=20 However, I'm still puzzled when he states "2 revs =3D 360". One=20 revolution equals 360=B0. Two crankshaft revolutions, however, does=20 equal 360=B0 of camshaft revolution (oh, now I get it. Never mind.) When you start talking about PLL, however, I'm lost. What exactly=20 does a PLL do or tell you? Sorry if everyone else considers this=20 question trivial, but I only studied basic electronics in college. I=20 was lucky enough to take a class on internal combustion engines, but=20 that mainly centered on the thermo-chemistry involved with combustion,=20 and not many practical exercises (like most of my engineering=20 courses.) On the plus side, I did get to use the Heywood text book=20 that I see listed under the recommended reading list for EFI=20 information. Thanks for any help. Bob McElroy - ---------- Lessee, 600 at idle to 6000 is 10:1, which is enough for me. With a=20 4-star crank sensor, you get a pulse every 45 degrees, since 2 revs =3D 360,=20 right? Then, if you PLL'd the freq by 45, you'd have 1 degree pulses, by 90, .5 degree. Am I right? I think I understand the need for=20 'reasonable' accuracy with firing, but you've already got a hardware (crank) 45=20 degree reference. The PLL jitter shouldn't give but only a few tenths of a=20 degree error, if that much. Capture shouldn't be a problem, as I don't see=20 how you can rev or decelerate the engine fast enough to lose lock. Remember, I'm just positing here -- never actually tried this. Tom Cloud ------------------------------ From: Mark Eidson Date: Fri, 13 Dec 1996 09:03:50 -0700 Subject: Re: Fwd: eddy current brake The engine cranks at 100-200 RPM so it will have to run down that low to start the engine. The on chip PLL VCOs we use have a range of 2:1 and run in the MHz range. The divide down chain is programmable and would have to be set to keep the VCO in its operational range. This would require some confuser intervention but this would be part of the RPM code that is required anyway. My idea is to have the PLL frequency generate some 2^10 pulses per cam rotation and use decoders to generate the required injector and spark signals. A distributor similar to the Ford signature type gives all the information required for sequential operation. me At 04:51 PM 12/12/96 -0600, you wrote: >>It's my understanding that the dynamic range, 20:1, is difficult for a >>simple PLL. I think the confuser would have to adjust the feedback based on >>the current RPM range to keep it locked. me >> > >Lessee, 600 at idle to 6000 is 10:1, which is enough for me. With a 4-star >crank sensor, you get a pulse every 45 degrees, since 2 revs = 360, right? >Then, if you PLL'd the freq by 45, you'd have 1 degree pulses, by 90, >.5 degree. Am I right? I think I understand the need for 'reasonable' >accuracy with firing, but you've already got a hardware (crank) 45 degree >reference. The PLL jitter shouldn't give but only a few tenths of a degree >error, if that much. Capture shouldn't be a problem, as I don't see how you >can rev or decelerate the engine fast enough to lose lock. > >Remember, I'm just positing here -- never actually tried this. > > >Tom Cloud > > > *************************************************************************** * Mark Eidson Voice: (602)752-6513 * * Staff Design Engineer Fax: (602)752-6000 * * Manager System Integration and Home: (602)831-6079 * * Verification E-Mail: mark.eidson@xxx.com * * VLSI Technology, Inc. * * 8375 South River Parkway * * M/S 265 * * Tempe, Arizona 85284 * *************************************************************************** ------------------------------ From: Jim Davies Date: Fri, 13 Dec 1996 08:04:35 -0800 (PST) Subject: Re: Fwd: eddy current brake On Fri, 13 Dec 1996, Matt Sale wrote: > 600 RPM is a typical V8 idle speed, but cranking speed may be more > in the 200-400 RPM range, FWIW, most engines have a cranking speed in the 100 to 200 rpm range, based on my observations on 'scope readouts during tuneups, etc. JD ------------------------------ From: Jim Davies Date: Fri, 13 Dec 1996 08:14:57 -0800 (PST) Subject: RE: oil pumps (not efi) On Fri, 13 Dec 1996, John Hess wrote: > I have been reading this thread over the last few days and feel > compelled to interject the following; > > It is my understanding that on a Chevy small block, it is not > recommended to utilize a high volume oil pump. This can cause the oil > to be pumped in a manner that will fill up the lifter valley while > choking off oil supply to the bottom end. The recommendation appears > to use a high pressure pump, instead. This would imply that there is, > in fact, a difference. > > Its unlikely that you would fill the lifter area, but very likely that you will fill the top of the cylinder head area, this can be done with a stock pump if revs are over, say, about 5000 for long periods of time. been there... Other engines have restricted oil returns from the head area, too, with the best of all being the 426 hemi, IIRC the figure is 5 qts on the heads when revs are over 5K for any period. If you see any pictures of NASCAR hemi's, they will invariably have an external oil return pipe/hose from each rocker cover back to the pan. I learned this the hard way ;-) JD ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Fri, 13 Dec 1996 10:49:22 -0600 Subject: RE: oil pumps (not efi) >I have been reading this thread over the last few days and feel >compelled to interject the following; > >It is my understanding that on a Chevy small block, it is not >recommended to utilize a high volume oil pump. This can cause the oil >to be pumped in a manner that will fill up the lifter valley while >choking off oil supply to the bottom end. The recommendation appears >to use a high pressure pump, instead. This would imply that there is, >in fact, a difference. > >John Oh, there is -- look in your Summit or Jegs or ASAP catalog. You can buy 'stock', 'high vol.', or 'hi-pressure' pumps. And I 'spect the onliest difference in a hi-pressure pump is the size of the relief spring (just like in electric fuel pumps). Tom Cloud ------------------------------ From: Clint Corbin Date: Fri, 13 Dec 1996 09:47:29 -0700 Subject: Re: Fwd: eddy current brake At 04:51 PM 12/12/96 -0600, you wrote: Lessee, 600 at idle to 6000 is 10:1, which is enough for me. With a 4-star >crank sensor, you get a pulse every 45 degrees, since 2 revs = 360, right? > >Tom Cloud Actually, 2 revs of the engine is 720 degrees (360 per crankshaft revolution). So your pulses from a 4 point sensor would be coming every 90 degrees or so. Clint Corbin ccorbin@xxx.com ccorbin@xxx.com ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Fri, 13 Dec 1996 11:14:31 -0600 Subject: Re: Fwd: eddy current brake > > >On Fri, 13 Dec 1996, Matt Sale wrote: > >> 600 RPM is a typical V8 idle speed, but cranking speed may be more >> in the 200-400 RPM range, > >FWIW, most engines have a cranking speed in the 100 to 200 rpm range, >based on my observations on 'scope readouts during tuneups, etc. > >JD I still don't know how the Ford system works! (BTW, MSD sells a crank pick up ignition system now!) But, if you set the crank pickup to give pulses at some standard, nominal crank angle, like 10 deg BTDC, you could use the pickup pulses to fire your engine and then throw in the required time / angle offset to get the desired firing angle. Of course, the time required to get a desired crank angle offset from the base pulse position varies with rpm. Tom Cloud ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Fri, 13 Dec 1996 11:54:26 -0600 Subject: Re: Fwd: eddy current brake >At 04:51 PM 12/12/96 -0600, you wrote: >Lessee, 600 at idle to 6000 is 10:1, which is enough for me. With a 4-star >>crank sensor, you get a pulse every 45 degrees, since 2 revs = 360, right? > >> >>Tom Cloud > >Actually, 2 revs of the engine is 720 degrees (360 per crankshaft revolution). >So your pulses from a 4 point sensor would be coming every 90 degrees or so. > >Clint Corbin >ccorbin@xxx.com >ccorbin@xxx.com ???? On a 4-cycle engine, the cam turns 360 deg for two rotations of the crank, and it's the cam timing you're interested in. So 720 degrees of crank equals 360 degrees of cam -- now you've got me wondering ..... when one looks for ignition timing, are you looking at crank or cam??? Tom Cloud ------------------------------ From: Todd Knighton Date: Fri, 13 Dec 1996 10:18:13 -0800 Subject: Re: Weird problem Gregory Chan wrote: > > At 7500 rpm in 4th I would be doing around 115 mph. At 6000 in 5th about 120 > mph. Greg, Many cars have a speed limiter at 120-125 mph, sure sounds like you've found it. I don't know however, why you say that you used to be able to go higher rev's in top gear. From your explanations this sounds like about what's happening. I'd try to contact Jim Wolf at his business where they do a lot of Japaneese cars and see what they have to say. I remember in a bunch of Turbo Mag articles that they pulled or moved the speed limiter from 125 mph. That's about all I can come up with for now without further analysis of fuel/spark at these conditions. Todd Knighton Protomotive Engineering ------------------------------ From: "Chuck Tomlinson" Date: Fri, 13 Dec 1996 13:37:02 -0500 Subject: Re: oil pumps (not efi) > From: tom cloud > >The recommendation appears > >to use a high pressure pump, instead. This would imply that there is, > >in fact, a difference. > > Oh, there is -- look in your Summit or Jegs or ASAP catalog. You > can buy 'stock', 'high vol.', or 'hi-pressure' pumps. And I 'spect > the onliest difference in a hi-pressure pump is the size of the > relief spring (just like in electric fuel pumps). Tom, that's true in Chevys, and I'd guess it's true for Fords too. IMHO, a high volume oil pump in a street engine is the result of a *mistake*: either running excessive clearances, or thinking that reaching relief pressure at very low rpm is worthwhile (it is not). Use the std volume pump and run good synthetic oil. - -- Chuck Tomlinson ------------------------------ From: peter paul fenske Date: Thu, 12 Dec 1996 22:46:19 -0800 Subject: RE: oil pumps (not efi) Hi All Having had some fun building Chev motors about the only thing I've done to a stock chev(or mellings whatever replacement)is add a Z28 relief spring(colored white) which costs about 2$ at a chev dealer. This brings the cold pressure up to about 65 PSI but does not really affect hot idle. But you do have more pressure at higher revs. This works well if you keep clearances to about 2 thou on the rods and mains. Like my biker pals who keep clearances around 3 to 4 (rebuild??????) a high volume pump is a necessity to even see the oil pressure guage move at hot idle. Especially if you want to rejuvinate a 100 thou mile clunker. Thats where high volume pumps are used in a chev. As for ford they are a different animal. I have yet to see a chev fail for lack of oiling. But I've seen quite a few 5.0s fail admititly they were rather punished. Buicks for instance need very high pressures. I would think motors with large oil passage restrictions need high pressure. However leaky engines with huge clearances need much more volume. To wit I've not seen anyone high problems with increasing the oil flow by 20% since most engines in use are not that tight to float the bearings. Also for the ford I believe you can get a replacement transducer to fix the idiot lite guage. The impala SS crowd has a similiar dilema. Later and GL: peter ------------------------------ From: Kalle Pihlajasaari Date: Fri, 13 Dec 1996 20:48:44 +0200 (sat) Subject: Re: Fwd: eddy current brake Hi Tom, > ???? On a 4-cycle engine, the cam turns 360 deg for two rotations of > the crank, and it's the cam timing you're interested in. So 720 degrees > of crank equals 360 degrees of cam -- now you've got me wondering ..... > when one looks for ignition timing, are you looking at crank or cam??? 4 Stroke has cams that make one rev per spark, so timing is from the cam, BUT the angle of timing advance that is doccumented is given in crank degrees because that is where it was measured in the past from the fanbelt pulley. Cheers *<<<-| - -- Kalle Pihlajasaari kalle@xxx.za/ip Interface Products P O Box 15775, DOORNFONTEIN, 2028, South Africa + 27 (11) 402-7750 Fax: 402-7751 http://www.ip.co.za/people/kalle ------------------------------ End of DIY_EFI Digest V1 #381 ***************************** 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".