DIY_EFI Digest Monday, 12 February 1996 Volume 01 : Number 040 In this issue: Re: Fuel Injector Valve Phasing... Re: Fuel Injector Valve Phasing... Re: Multiprocessor system Re: Multiprocessor system Re: Multiprocessor system Re: Fuel Injector Valve Phasing... Re: Fuel Injector Valve Phasing... Re: Injector Phasing... Re: Multiprocessor system Re: DIY_EFI Digest V1 #39 See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: dave.williams@xxx.us (Dave Williams) Date: Sun, 11 Feb 1996 00:52:00 +0000 Subject: Re: Fuel Injector Valve Phasing... - -> These produce relatively fine (about 30 micron I believe) sprays in - -> excelently controlable patterns. I read (in SAE?) that Ford is Um, yeah. Have you had a chance to observe the injector spray patterns with a stroboscope? I got a surprise when a friend hooked a strobe to his injector tester and fired it up. The first thing of interest was, all the different injectors look pretty much the same, whether pintle valve, disc valve, etc. The second was, they all sort of dribble fuel as they open, then a small stream, which gradually opens to a narrow angle stalactite(mite?) looking shape, when then contracts back down to a point before turning into mist and droplets. The typical spray pattern was about six to eight inches long. At a quick guess, probably less than half of the volume of injected fuel is dispersed in a particle size like you're talking about. The rest looks pretty much like an old-time carburetor accelerator pump shot. And most of the fuel, whether stream or spray, impinges on the manifold or port well upstream of the valve. Fortunately none of this seems to matter except for cold idle and low-RPM emissions characteristics. ====dave.williams@xxx.us========================DoD#978======= can you help me...help me get out of this place?...slow sedation... ain't my style, ain't my pace...giving me a number...NINE, SEVEN, EIGHT ==5.0 RX7 -> Tyrannosaurus RX! == SAE '82 == Denizens of Doom M/C '92== ------------------------------ From: Timothy Coste Date: Sun, 11 Feb 1996 14:11:53 -0500 Subject: Re: Fuel Injector Valve Phasing... In response to Dave Williams comments on injector spray... All of my work with injectors is based on other research here where they use stroboscopes for visual measurements of things like spray cone angle and such. The droplet sizing is measured with a Malvern Particle Droplet Sizer which uses diffraction of a lser (oops, laser) beam to measure droplet size. The number given is the Sauter Mean Diameter. I'd have to look the formula up for you if you wanted to know how it's computed. The machine also gives percent of droplets below certain diameters. i.e.- 10% below 10 microns, 30 below 20 microns, and so on. The starting dribble is called sac volume. And sac volume is why I really wish someone would explain GM's central port fuel injection to me, cause it seems it would have sac volumes (dribbles) equal to the full spray if I understand it correctly. And yes, our injectors really give sprays where MOST of the fuel is in small droplets. Even with these injectors, the sensors that I am developing and testing to measure wall wetting still "see" the walls being wetted, even under warm engine conditions. I'll let you know (maybe in an SAE paper?? :) ) the relationshop I find between wall wetting and engine performance sometime soon (I hope). Now, production injectors...man, those things stink! I hope my numbers bear this out. ;) Oh, one side note...our testing is done using Stoddard fluid in place of actual gasoline (the droplet sizing testing that is...I run the engine on gas!). THis is an out-dated dry cleaning fluid with properties very close to gasoline, but much less volatile. The silly university seems to have a problem with us spraying gas around willy nilly. Stodgy old farts. :) Tim Coste tlcoste@xxx.edu ------------------------------ From: dn Date: Sun, 11 Feb 96 13:43:53 MDT Subject: Re: Multiprocessor system Me: > >Pardon my ignorance here, but what the heck do you need more than 1 output > >compare for? You only have 1 cylinder firing at a time Peter: > Wrong. At WOT (I'm fed up with yanks pussy footing it around. Get your foot > down :), All of the injectors can be open at the same time. Whoa, now I'm really confused.... I know I'm not wrong about firing 1 cylinder at at time, last time I looked in my HEI there were 8 little posts and only 1 contact on the rotor... Your'e telling me that in a V8 port injection system, all 8 injectors can be open at the same time? How is this possible? Only 1 cylinder is at TDC on the power stroke at a time, therefore previous to that it's intake valve will be the only one open. Cylinders in the firing order are separated by 90 degrees of crank rotation. Taking into consideration that the injector can open before the valve, it is possible that 2 consecutive cylinders in the firing order could overlap somewhat on injector opening, but all 8? You'd just be dumping fuel into a port with no flow, which seems to me would be counterproductive to vaporization... Also, the injectors are supposed to be sized to deliver enough fuel at around 80% duty cycle for WOT, you can't just turn on an injector and leave it on or it dies a fiery death... With a TBI setup, I can see this happening, or on a system with less than an injector-per-cylinder, but not on a port injection setup... but then I've also been wrong before (once or twice). Enlighten me, oh guru. 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: jsturs@xxx.nl (Jim Sturcbecher) Date: Mon, 12 Feb 1996 00:15:32 -0100 Subject: Re: Multiprocessor system >Your'e telling me that in a V8 port injection system, all 8 injectors >can be open at the same time? How is this possible? Only 1 cylinder >is at TDC on the power stroke at a time, therefore previous to that >it's intake valve will be the only one open. Cylinders in the firing >order are separated by 90 degrees of crank rotation. Taking into >consideration that the injector can open before the valve, it is possible >that 2 consecutive cylinders in the firing order could overlap somewhat >on injector opening, but all 8? You'd just be dumping fuel into a port >with no flow, which seems to me would be counterproductive to vaporization... > >Also, the injectors are supposed to be sized to deliver enough fuel at >around 80% duty cycle for WOT, you can't just turn on an injector and >leave it on or it dies a fiery death... > let me see... On a V8 pulling 6000 rpm, that's 100 revs/sec. That gives 10 millisecs per rev. If I want to inject all 8 cyls in 2 revolutions (this is a four stroke after all), then thats 4 cyls per rev. Now if I don't want to inject more than one cylinder simultaneously, that gives me 2.5 millisecs per injection event. I don't think any injector would be happy at that. If you sized the injectors to give enough fuel in 2.5 millisecs, then you would never get it to accept a short enough pulse to give a decent idle. Is my reasoning correct here? Jim Sturcbecher jsturs@xxx.nl ------------------------------ From: Peter J Wales Date: Sun, 11 Feb 1996 18:35:16 -0500 (EST) Subject: Re: Multiprocessor system On Sun, 11 Feb 1996, dn wrote: > Me: > > > >Pardon my ignorance here, but what the heck do you need more than 1 output > > >compare for? You only have 1 cylinder firing at a time > > Peter: > > > Wrong. At WOT (I'm fed up with yanks pussy footing it around. Get your foot > > down :), All of the injectors can be open at the same time. > > Whoa, now I'm really confused.... > > I know I'm not wrong about firing 1 cylinder at at time, last time I > looked in my HEI there were 8 little posts and only 1 contact on the > rotor... Ignition! We are talking injection. > Your'e telling me that in a V8 port injection system, all 8 injectors > can be open at the same time? How is this possible? > Also, the injectors are supposed to be sized to deliver enough fuel at > around 80% duty cycle for WOT, you can't just turn on an injector and > leave it on or it dies a fiery death... If it is sized correctly for normal running at 80% at WOT, let's have a cold engine, cold day and flat battery. That should be good for the other 20% Now the injectors are open continuously, the fuel flowing throgh them will keep them cool. If they were to run red hot, that would help vapourisation wouldn't it? :) Peter Wales ------------------------------ From: robert dingli Date: Mon, 12 Feb 1996 12:23:04 +1100 (EST) Subject: Re: Fuel Injector Valve Phasing... Tim Coste remarked, > The silly university seems to have a problem with us spraying > gas around willy nilly. Stodgy old farts. :) You should try hydrogen as a fuel. Can't see it, can't smell it and you can't even see it when it burns. It will ignite at any air-fuel ratio and goes off with a real bang. We've got shattered inlet manifolds and exhaust systems that have been partially turned inside out to prove it. In our case, it's the 'stodgy old farts' who are most keen for us to get a better 'feel' for the engine by working inside the dyno cell. Back to the topic. Tim, your research sounds very interesting. Please keep us posted on the results of your measurements. For reference try SAE Paper # 940445 (Chen, Vincent and Gutermuth, Chrysler Corp.) This paper quantitatively describes the effects of various factors on injected droplet size including gasoline composition, initial droplet size, initial fuel temperature, charge temperature, intake manifold pressure, engine speed and distance from injector. It is very interesting to note their relative importance. I have yet to find a good reference which details the effect of droplet size and initial fraction vapourised on combustion. If I had more time, I could fit a petrol injection system onto the optical CFR and do some measurements myself but I have more important details to worry about right now. Robert Dingli - -- 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: Bob Valentine Date: Sun, 11 Feb 1996 23:20:45 -0500 (EST) Subject: Re: Fuel Injector Valve Phasing... [Hydrogen] > can't even see it when it burns. It will ignite at any air-fuel ratio and > goes off with a real bang. We've got shattered inlet manifolds and exhaust > systems that have been partially turned inside out to prove it. Off on a side note, this reminds me of a time when I used to cut junk cars in a salvage yard. Spent about an hour trying to get a old Chevy to start - finally gave up. About 1/2 hour later we flipped it on it's side to cut the motor/trans out. As I hit the exhaust pipe with the torch, all I remember was hearing a loud BOOM, then a clank. Completely unwrapped the muffler, blew the y-pipe free from the manifolds, and blew the carb *with* the air cleaner attached about 25 feet... ;^> > Robert Dingli - --> Bob ------------------------------ From: Steve Baldwin Date: Mon, 12 Feb 1996 17:48:02 +1300 (NZDT) Subject: Re: Injector Phasing... > > > Boy, I really hate (I think) to get into this one but... > > I believe Peter and Sian are saying the same thing, but from totally > different perspectives. Peter is concerned with WOT...Sian is (I > think, since hie research sounds similar to mine) concerned with > day-to-day driveability. There's no way you can meet emissions > regulations and customer (i.e.- consumer) satisfaction without being > extremely concerned with transients, not to mention cold-start/ > warm-up strategy. Increasing cycle-to-cycle variability, increasing > efficiency at part-throttle, etc. (COVimep, transient response, etc) > are all concerns of manufacturers, not tuners/racers. Show me a > racer who minds a miniscule off-idle stutter versus 20hp and a > 1000ppm increase in HC and I'll show you a big three engineer riding > with a racing team. :) Isn't the whole point of EFI to have performance and retain some driveability ? Otherwise we might as well use something like Hilborn (open 'em up and pour it in) injection. The thought of trying to park a top-fueler doesn't appeal to me. If there isn't any harm (to overall power) by reducing emmisions or consumption, why not do it ? For a street driven car, I still haven't seen the down side. I can't find the spellink chekka for yewniks. Steve. ------------------------------ From: dn Date: Sun, 11 Feb 96 22:48:54 MDT Subject: Re: Multiprocessor system > Ignition! We are talking injection. Ignition, injection, whazza diff? Both gotta happen once per cylinder per combustion cycle... > > If it is sized correctly for normal running at 80% at WOT, let's have a > cold engine, cold day and flat battery. That should be good for the > other 20% Isn't that what the cold start valve is for? All that aside, I now see the error of my ways, thanks to Jim. I was thinking in terms of events per revolution instead of the actual time for those events at high RPMs. I guess that's why they pay you guys the big bucks.... 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: Sam Stoney Date: Sun, 11 Feb 1996 22:17:02 -0800 Subject: Re: DIY_EFI Digest V1 #39 >It might be interesting to try again with fuel but this time blow through >the throttle >body. > Duh. I don't know why I didn't figure that out. Thanks, I'll try it again sometime.... I -did- get the superblend software. I will be playing with it this spring. Right now I have to sent the unit back - bad coil circuit somewhere. The thing doesn't look too easy to dig into myself. Has anybody played with Tec's superblend software? Sam ------------------------------ End of DIY_EFI Digest V1 #40 **************************** 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".