DIY_EFI Digest Monday, 1 April 1996 Volume 01 : Number 095 In this issue: Re: 4.3 multi-port fuel injection Re: Pneumatic Valve Springs ! Re: Pneumatic Valve Springs ! RE: Multispark stuff and other thoughts RE: Independent cylinder knock control RE: TEC Re: Multispark Jag EFI Re: Multispark RE: Independent cylinder knock control Re: Pneumatic Valve Springs ! See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Ryan Harrell Date: Thu, 31 Mar 1994 12:52:24 -0600 Subject: Re: 4.3 multi-port fuel injection john spears wrote: > > I've been observing the list for awhile, thought I'd through my $.02 in. The > 4.3L CPI engine is a huge improvement over the TBI version. Although it only > uses one injector, the CPI design allows you to deliver the fuel where it > belongs and also allows for some nice manifold air tuning in the process; > thins you just can't do when you're carrying an A/F mixture. I've done about > three of these engines and have turned out well. What would be ideal is to > find a damaged one in the junkyard and get the manifold assembly for your > engine. I use the factory ECM on most of my projects as they are fairly > cheap and have all the bases covered. A little EPROM programming to cover > your specifics and you're on your way! > > John Spears > Speartech Fuel Injection Systems As the original poster of this 4.3 discussion, I'd like to know if anybody has some information on Vortec's supercharger they are designing for the V6 engine. I called Fuel Injection Specialities, whose name I found in a magazine, for info. They stated that Vortech would have a sequential central-port injection supercharger in a couple of months. Also, FI Specialties priced the SCPI kit at $1895 and I was wondering if anybody knew of a cheaper price anywhere else. I'd like to ask Mr. Spears how hard would it be to adapt a centrifugal supercharger not designed for SCPI to it. The reason for this is because ATI Technologies makes an extremely powerful superchager that I'd like to use. Also, I plan to racing heads, roller cam, bore out the engine, and just about any other idea I can find to produce more horsepower (my goal for this engine is around 500-600HP on a $6000 budget) However, I know little about programming EPROMs, and have no idea on what equipment or software is required for reprogramming (although I am willing to learn). If you can recommend a book or other instrucion tool to help me I'd be appreciative. Finally, is there any R&D going on for a true port injected 4.3L V6? I GREATLY APPRECIATE all the help I've gotten from this mailing-list ------------------------------ From: Corey Cole Date: Sun, 31 Mar 1996 14:18:17 -0700 (MST) Subject: Re: Pneumatic Valve Springs ! On Fri, 29 Mar 1996, TAR wrote: > > What about valve float at 'higher' rpm's? I realize the pneumatic system > probably has less inertia than metal springs, but I still can't see how > they could effectively curb this problem without some type of Desmo system > (like that used on Ducati's). Any insight? > The pneumatic system has essentially no mass compared to metal springs. Plus you can use an ultra high spring rate without having to worry about how you are physically going to make that spring rate happen in the limited space available. And where they are used, you don't have to worry about breaking a spring (however, I'd like to see a pneumatic system in production cars .) Finally, you don't have to worry about resonant frequencies like you do with metal springs. Corey Cole colec@xxx.edu '65 Skylark "Knowledge is power...but cubic inches help." Go #24!!!!! I was drunk the day my mom got out of prison and I went to pick her up in the rain. But before I could get to the station in my pick up truck, she got runned over by the darned old train... David Allen Coe Steve Goodman ------------------------------ From: Chris Howard Date: Mon, 01 Apr 1996 10:31:54 +1000 Subject: Re: Pneumatic Valve Springs ! Hi, > >What about valve float at 'higher' rpm's? I realize the pneumatic system >probably has less inertia than metal springs, but I still can't see how >they could effectively curb this problem without some type of Desmo system >(like that used on Ducati's). Any insight? > Valve float is caused by resonance of the valve spring when it is excited at its natural frequency or a harmonic thereof. A typical natural frequency of a valve spring is around 700 Hz (42000 rpm). So at 7000 camshaft rpm, if there is a strong sixth harmonic in the cam lift profile, the spring will be in resonance and the effective spring force will be diminished or eliminated, unless there is adequate damping of the springs. This damping is generally provided by friction between the inner and outer springs, but is not a total solution. What is desired is that the natural frequency be much higher such that it corresponds to at least the ninth harmonic of cam speed as the higher harmonics have smaller components. A pneumatic valve spring is just a enclosed column of gas within the space previouusly occupied by the coil springs. The natural frequency of a typical such system is around the 5kHz mark (300000 rpm). So with a pneumatic valve spring at 7000 camshaft rpm, it will be the about the 40th harmonic which will excite the pneumatic spring. These higher harmonics have negligible effect, so the pnuematic spring is virtually "float free". If anyone wants any more info, reply by email as i'm not quite sure valve springs are a part of the FI system :) Chris Howard Computer Science University of New South Wales email: s2184002@xxx.au Web: http://www.usyd.edu.au/~choward ------------------------------ From: Jim Pearl Date: Sun, 31 Mar 1996 18:37:45 -0600 Subject: RE: Multispark stuff and other thoughts His explanation was that he had a rotor that had two prongs on it. However, I could never figure out this might work. It would allow the spark to take the path of least resistance and not fire the other plug? This rotor was supposedly out of a 351 truck distributor.. Why fire two plugs? Waste fire! I'd love to take a shot at burning any unused fuel left in the chamber... - ---------- >From: Edward Hernandez (R)[SMTP:ehernan3@xxx.com] Sent: Thursday, March 28, 1996 11:09 PM To: diy_efi@xxx.edu Subject: RE: Multispark stuff and other thoughts "My biggest interest would be to find a system that would allow me to fire my EFI HO Ford motor on a waste spark system. I've been told by a guy here that he's done this using some weird rotor out of another Ford application that would fire the opposing cylinders." Ford's waste spark system is distributorless, so your friend is 100% BS. Why would you want to fire two plugs at once if you have the new Accel system which is a single coil system? That would fire the coil twice as often and would give you no benefits but would definitely drop your spark energy! Ed Hernandez Ford Motor Company ehernan3@xxx.com ------------------------------ From: Jim Pearl Date: Sun, 31 Mar 1996 18:50:05 -0600 Subject: RE: Independent cylinder knock control Would like to know more about these meters. Worse comes to worse I'll purchase a set of LEDS and a an IC to drive them. As for mounting it to the lower engine - this is a 5.0 Ford - no "stock" mounting boss exists.. I've got a 351W n the stand - I'll examine it and look for likely spots but I'm betting there won't be an easy one. Duttweiler told me to use the back of the head and provided a block of threaded aluminum to assist me in bolting it up, I used the front of the head on an accessory stud. I'm not running much advance and it does retard - pulling it off allows knock - rock and a hard place I guess. This is why I want to monitor it - to try and get an idea as to how much false knock it's getting. DFI provides no adjustment to the sensitivity and no way to monitor it save through a laptop. I'm tempted to buy one of the "boxes" available to monitor it but they're not cheap and I'm fairly certain their simple inside... - ---------- >From: Frank F Parker[SMTP:fparker@xxx.edu] Sent: Friday, March 29, 1996 6:52 AM To: diy_efi@xxx.edu Subject: RE: Independent cylinder knock control > I've heard of the J&S system - it sounded great and if not for my DFI.... > Currently I use a GM sensor hooked into my DFI. I was told to mount it on > the HEAD (!) and am pretty sure I'm getting false knock from the > valvetrain. The sensor uses a small box from GM between it and the > computer. I've seen monitoring boxes for turbo GNs and would love to adapt > one for my system. Anyone have any ideas? I just want to know when it's > thinking it sees knock without having to use my laptop. I've done some > electronics work but it's been years and most of the little bit of design > knowledge I had has drained away.. TIA! > The mounting on the head is a very bad idea. Use the stock GM location on the bottom of block near oil pan rail. The gm box is a crude bandpass filter and works poorly-gives alot of false retard. A number of companies sell a monitor which appear to be a stock gm sensor connected to simple dc meter thru a diode. Frank Parker > > ------------------------------ From: Jim Pearl Date: Sun, 31 Mar 1996 19:05:15 -0600 Subject: RE: TEC It looks like a good system - until you take a look at their software prices! I was VERY close to buying one until I saw the thousand dollars worth of software I'd want to buy! Whew - almost as much as the rest of the system! Ouch! - ---------- >From: Hadzic Muhammed[SMTP:3mh31@xxx.ca] Sent: Friday, March 29, 1996 1:07 PM To: Utgarhoth@xxx.com Cc: diy_efi@xxx.edu Subject: Re: TEC On Thu, 28 Mar 1996 Utgarhoth@xxx.com wrote: > If I were them, I'd sue GM too. I'm are currently using an Electromotive > multi-coil ignition system on a '66 Coronet. I happened to be in a GM dealer > about a month ago, and I noticed the very same ignition system on a brand-new > Aurora. Looking further around the showroom, I came to the conclusion that > GM must have bought the Electromotive ignition system. Does anyone know if > this was licensed or simply stolen from Electromotive? > > > --- R. Andrew Broadhurst > My two cents... I've recently bought the TEC II system from Electromotive and part of thier sales pitch was that GM licenced the design for the coils from them. They claimed that they had the patent rights on the coils. Muhammed ------------------------------ From: William Sarkozy Date: Sun, 31 Mar 1996 20:55:05 -0800 Subject: Re: Multispark At 12:57 AM 3/31/96 PST, you wrote: >>(assuming by this you meant waste spark). In addition, half the spark >>plugs on wastespark systems erode the ground electrode faster than the >>center electrode, so if you want 100,000 mile tune up intervals, you >>need double platinum plugs OR customers/dealers/mechanics who are >>willing to take the care to install the two kinds of single platinum >>plugs in the correct cylinders. Guess how often we count on them to >problems do you see? ------------------------------ From: jgn@xxx. Napoli) Date: Sun, 31 Mar 1996 21:34:55 -0500 Subject: Jag EFI Hi, all, been lurking on and off for a while and now have some questions. I'm been trying to learn more about the Bosch Digital P fuel injection in my '82 Jag XJ-S HE V12. The manuals don't help much with design intent. Short term, I need to understand more about the way it works and interacts with other klugey stock systems as I maintain and modify the car. Longer term, a replacement is probably in order. To kick things off, various documentation states that the ECU combines circuits to form four sets of three into two groups of six. Each group includes the six injectors from a single bank of cylinders. What exactly does this mean, and how does it relate to how and when the injectors fire? Regards, John ------------------------------ From: Sandy Date: Sun, 31 Mar 1996 19:15:00 -0800 Subject: Re: Multispark Much of the below has been talked about, I have proposed such use for an extra TPU pin, but again, the biggest problem is the dwell time of the second set of coils... See some of the old messages from a last week. >If you really can't stand to have the plug fire on the wasted spark, could >you drive the ignition driver with a latch? The cylinders would be paired >in and "odds or evens" type system (just the way they are in the wasted >spark system) and a normal output port from the micro would select which >cylinder out of the pairs would fire. The TPU channel for the cylinder pair >would feed both cylinders. The cylinder select line would go straight to the >even cylinders and be inverted to feed the odd cylinders. The TPU and the >select line would be ANDed together to control the latch. Possible? What >problems do you see? > Sandy ------------------------------ From: Frank F Parker Date: Sun, 31 Mar 1996 23:01:24 -0500 (EST) Subject: RE: Independent cylinder knock control > Would like to know more about these meters. Worse comes to worse I'll > purchase a set of LEDS and a an IC to drive them. As for mounting it to the > lower engine - this is a 5.0 Ford - no "stock" mounting boss exists.. I've > got a 351W n the stand - I'll examine it and look for likely spots but I'm > betting there won't be an easy one. Duttweiler told me to use the back of > the head and provided a block of threaded aluminum to assist me in bolting > it up, I used the front of the head on an accessory stud. I'm not running > much advance and it does retard - pulling it off allows knock - rock and a > hard place I guess. This is why I want to monitor it - to try and get an > idea as to how much false knock it's getting. DFI provides no adjustment to > the sensitivity and no way to monitor it save through a laptop. I'm tempted > to buy one of the "boxes" available to monitor it but they're not cheap and > I'm fairly certain their simple inside... I do not know the Ford block, but get the sensor off the head. It will never work correctly up there. I would think you could find some place you could tap on lower block. The meters are available from ANS for $90 @ 708-450-1095, I assume including a gm sensor but i have no direct knowledge of their meter. I am pretty sure the GM sensor is high impedance and has a output in the volt range. Do not know if ANS meter uses any sort of bandpass filter in 5-8 KHz range to filter signal before using , I assume, either a op amp or diode before running to meter. Could also get whole gm system from junk yard and use output from gm knock box to a meter of some sort. If you are using current sensor with DFI, could build a op amp as hi Z buffer and then run to homebuilt meter. Frank Parker > > > > > ------------------------------ From: "S. McManus" Date: Sun, 31 Mar 1996 21:37:16 -0800 (PST) Subject: Re: Pneumatic Valve Springs ! "Valve float is caused by resonance of the valve spring when it is excited at its natural frequency or a harmonic thereof." - -Chris Howard I always thought it was the inertia of the lifter/valve/partial mass of the spring. In other words, the valve follows the correct path with respect to the cam until the region of the largest part of the cam lobe. But after that, the respective valve train components continue to travel (now in the wrong direction with respect to the cam) because the valve spring isn't strong enough to resist the inertia of the components. What is your reference for this information? Sean McManus University of Washington ------------------------------ End of DIY_EFI Digest V1 #95 **************************** 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".