DIY_EFI Digest Thursday, April 8 1999 Volume 04 : Number 216 In this issue: Engine load vs RPM and torque Re: Injector driver question... RE: TEC II RE: Halp Diamond Star Motored out (fuel presure specs corrected) Re: Engine load vs RPM and torque Re: DIY_EFI Digest V4 #214 Re: TEC II Re: Engine load vs RPM and torque Re: Fuel Injector Flow Bench Re: EFI Head Volume Re: Suggestions for Adjusting WOT fuel? Re: Re:Halp Diamond Star Motored out Re: [Fwd: My MAF sensor] Carl Summers please Re: Suggestions for Adjusting WOT fuel? Re: Injector driver question... See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Wed, 7 Apr 1999 16:46:32 -0600 (MDT) From: Matt Beaubien Subject: Engine load vs RPM and torque Hi all, This is a little off charter but is still related somewhat (especially to those with artificial aspiration.) I'm looking for some software or code (Matlab, Working Model etc...) that will allow me to calculate the loads seen by the piston, rod, etc for various torque/speed combinations. For instance, is it better to make 100 HP using 15 psi of boost at 5500 rpm or 100 HP at 6500 RPM using 7 psi of boost... I'd like to be able to input the weights of the piston and rod, and the torque value to obtain their loadings. Most people will tell you the largest loads are seen on the exhuast stroke at TDC, but that doesn't explain why those turbo Honda's start bending rods at 10 psi... I have a small single cyl that I'm going to be putting a blower on. In it's current configuration, the factory tells me additional revs will seriously comprimise reliability. OK, but with the blower, what is the ideal speed for my desired HP? Repond off list if you feel compelled. Thanks. Matt Beaubien mbeaubie@xxx.ca 3 x 510 1 x 300ZXT ------------------------------ Date: Wed, 7 Apr 1999 19:03:40 -0700 From: "Walter Sherwin" Subject: Re: Injector driver question... > I finally managed to obtain decent values for the injector current (high >and low impedance injectors). The problem was a faulty resistor (it was a >0.1 ohms resistor, supposedly), which gave a false reading of the current. >Now everything is normal, the current for the high impedance injector is >about 0.75A, and so my circuit (the same in fact as in the National >Semiconductors datasheet) based on the LM1949 can drive high and low >impedance injectors without modifications. > > Hugo. Glad to hear! Still wondering about your earlier questions/remarks. Disable the timer function (3.9 ms on NS's L1949 data sheet example) and hookup a high impedance injector. Does the current ever rise above the steady state value of .75-.80 A ? Be curious to know. Walt. ------------------------------ Date: Wed, 7 Apr 1999 18:19:46 -0500 From: "Falb, John" Subject: RE: TEC II Do you use an EIP turbo system? Just curious. John - -----Original Message----- From: Jason_Leone@xxx.com] Sent: Wednesday, April 07, 1999 2:14 PM To: diy_efi@xxx.edu Subject: Re: TEC II <> Hmm, and we don't need to spend money building Tomahawk cruise missles, we don't need them. Wrong. <> Well, since it takes about 1 millisec for an injector to "recover" (which has to be allowed for in the PW formula), I don't think you have to have the pulse width that low, for a street car. <> Simply using a standard Bosch 4 wire EGO is fine. Standard 0-1v scale. The EGO correction factor should not be the only control you have over the A/F ratio, anyway. <> I tapped my factory engine speed sensor (uses a 60 tooth crank wheel, like the TEC II one). had to allow for the timing difference in the software (factory reads off the 13th tooth, TEC II wants it to read off the 11th tooth). So, my advance was 12 degrees off from the start (value of "0" in the software). Shoot it w/ a digital light, plug that value into the "initial advance", and now 0=0. My Electro crank wheel appeared to be laser cut, and would still work fine. Some clean-up machine work would definitely help to get really crisp edges on the teeth. Again, mine isn't even being used... <> You don't HAVE to do anything. You CAN do a few medium power data logging runs, and then tweak values as you go. Or, you can tune for power on a dyno. I prefer a load type dyno. <> Yes...and no. You can change parameters at any time, in real time, while driving or dynoing. To download those changed values into permanent settings, the ignition must be turned off, and it takes about 10 seconds to flash the PROM. I feel your pain. It's a flaw. <> I don't understand what you're trying to say here (grammer). Are you saying that you have to wait until the turbo cools off, before you can remove the TEC II? Please explain. As for the dyno money...hey, when getting an aftermarket ECU/ignition...you should expect to hit the dyno anyway, and pay the fiddler. Headaches? I don't know of ANY ECU that tunes itself, while you crack beers. Fact is, you have to know a bit about EFI and your individual engine/car before you tackle the tuning aspect. That goes for any aftermarket set-up, not just the TEC II. <> I've noticed that the low rpm voltage compensation isn't the greatest. When the headlights are turned on, or the electric fan kicks in at idle...it stumbles, and the rpms drop. Needs work here. <> Haven't had any problems here. <> Not really. You don't have to start from scratch. You keep the same advance table, and A/F ratio, and just about every other parameter. A few "gamma" tweaks and a few IOT (injector offset) tweaks, and you're OK. What software are you using? Were you using the TEC I? I'm using PAF Blend, BTW. Bottom line: Any aftermarket ECU will constitute a large portion of your time, to install & tune. The tuning part is endless, because you always want more power...and let's face it...it's a pretty good time we all live in when you can screw around with your engine via a laptop! It serves a purpose, but it takes time, effort, and a lot of experience. Trial and error, on the dyno, usually gets the best results. The DFI and the TEC II are great values for what they offer. I went for the TEC II. The ignition is really good, and it's a single part (unlike the old TEC I). Be sure to mount the unit away from heat, if possible (it is subject to heat soak, if mounted to the engine). Heat shields go a long way to avoiding problems. The TEC II is good for about 40hp-70hp (over Bosch Motronic)on a turbo VW VR6 application (when tuned properly, and running 15psi+). 400hp@wheels in a daily driven VW Corrado? It's possible. Enjoy... Jason '93 SLC ------------------------------ Date: Wed, 7 Apr 1999 16:45:41 -0700 From: "Stegbauer, Michael" Subject: RE: Halp Diamond Star Motored out (fuel presure specs corrected) > 47psi sounds way high... I believe the fuel pressure spec for a > non-turbo is around 38psi (might be 42psi, and this is on the 92). My mistake: NT spec is 47.6psi. (Turbo/manual is 36.3 and Turbo/auto is 42.7, hence my confusion) ------------------------------ Date: Wed, 7 Apr 1999 20:16:05 -0400 From: "Bruce Plecan" Subject: Re: Engine load vs RPM and torque - ----- Original Message ----- From: Matt Beaubien To: Sent: Wednesday, April 07, 1999 6:46 PM Subject: Engine load vs RPM and torque Alan Lockheed Golden CO. Used to have a engine modeling program using parameters, thou I haven't seen hhim advertise lately. Bruce > Hi all, > > This is a little off charter but is still related somewhat (especially to > those with artificial aspiration.) > > I'm looking for some software or code (Matlab, Working Model etc...) that > will allow me to calculate the loads seen by the piston, rod, etc for > various torque/speed combinations. For instance, is it better to make 100 HP > using 15 psi of boost at 5500 rpm or 100 HP at 6500 RPM using 7 psi of > boost... > > I'd like to be able to input the weights of the piston and rod, and the > torque value to obtain their loadings. Most people will tell you the largest > loads are seen on the exhuast stroke at TDC, but that doesn't explain why > those turbo Honda's start bending rods at 10 psi... > > I have a small single cyl that I'm going to be putting a blower on. In it's > current configuration, the factory tells me additional revs will seriously > comprimise reliability. OK, but with the blower, what is the ideal speed for > my desired HP? > > Repond off list if you feel compelled. Thanks. > > > Matt Beaubien > mbeaubie@xxx.ca > 3 x 510 > 1 x 300ZXT > ------------------------------ Date: Wed, 07 Apr 1999 16:56:38 -0700 From: "Fran and Bud" Subject: Re: DIY_EFI Digest V4 #214 THOMAS, From what I have been able to glean from various sources, the location of the injectors ABOVE THE THROTTLE BLADES is a design feature of TBI. The injectors intentionally wet the throttle bore walls and the throttle blades/butterflies much of the time. Find a friend with a TBI and watch it run with the air cleaner and spacer removed. You will see accumulated sheets of liquid gasoline on the blades and on the walls - moving slowly toward the outer edges of the blades. Their appearance will remind you of water movement on the hood or on the side window as you drive in the rain. Your car is moving through the air at 60 mph but the water is moving on your hood or window very slowly (boundary layer). You will see the gasoline move along the walls and throttle blades in the same manner. As the gasoline reaches the narrow opening between the blade and wall, it is torn off and mixed with the air flow which is travelling at sonic velocity when running at idle or part throttle (cruise). The mixing is excellent and distribution is very uniform. Idle and part throttle operation are excellent as long as the pressure drop across the throttle opening, and the corresponding air velocity past the edges, remain high. WOT is also good - due to so much air mass passing through the injector spray. The biggest problem with TBI is when the intake manifold re-pressurizes rapidly (pedal to the metal) resulting in fuel condensation on the intake runner walls coupled with air velocity that is too slow to harvest it. Cleans itself out as rpm comes up and air flow increases. I have also been told that this is one of the reasons that factory TBI manifolds have so much space devoted to passages for hot water - helps the air stream to regain the lost (condensed) fuel. Like most of the stuff you will read on this (or any) list, some of the information is correct and some is less than correct. The trick is to accumulate and digest as much as you can, then think about it and draw your own conclusions to fit your own needs. My opinion is that you cant go wrong putting a GM TBI on your Cutlass, and do it as close to the way GM intended it to be done as possible. THEN FIX IT to suit yourself. BUD >From: Thomas Martin >To: diy_efi@xxx.edu >Subject: Re: DIY_EFI Digest V4 #214 >Date: Wed, Apr 7, 1999, 6:55 AM > > Has anyone pondered the idea of TBI injection with the injector spray > BELOW the throttle body? Does it NEED to be above? It seems to me that > it would be messing up the atomization running into the throttle blade. > > ------------------------------ Date: Wed, 7 Apr 1999 19:29:20 -0600 From: bearbvd@xxx.net (Greg Hermann) Subject: Re: TEC II ><big injectors..... >> > >Well, since it takes about 1 millisec for an injector to "recover" (which >has to >be allowed for in the PW formula), I don't think you have to have the pulse >width that low, for a street car. Espen was right with this--100 us resolution is JUNK!! (As is 64 us.) > ><turbo >engine with a narrow band 02 sensor is a mystery to me......>> > >Simply using a standard Bosch 4 wire EGO is fine. Standard 0-1v scale. The EGO >correction factor should not be the only control you have over the A/F ratio, >anyway. Again, he is right. Trying to calibrate anything off of stoich without a UEGO is foolishness, and asking for expensive repairs! >Bottom line: >Any aftermarket ECU will constitute a large portion of your time, to install & >tune. And the cost of repairing a properly done engine, if ruined, will dwarf the additional cost of a better ecu!! Regards, Greg ------------------------------ Date: Wed, 7 Apr 1999 19:45:39 -0600 From: bearbvd@xxx.net (Greg Hermann) Subject: Re: Engine load vs RPM and torque >Hi all, > >This is a little off charter but is still related somewhat (especially to >those with artificial aspiration.) > >I'm looking for some software or code (Matlab, Working Model etc...) that >will allow me to calculate the loads seen by the piston, rod, etc for >various torque/speed combinations. For instance, is it better to make 100 HP >using 15 psi of boost at 5500 rpm or 100 HP at 6500 RPM using 7 psi of >boost... > >I'd like to be able to input the weights of the piston and rod, and the >torque value to obtain their loadings. Most people will tell you the largest >loads are seen on the exhuast stroke at TDC, This is in tension--- but that doesn't explain why >those turbo Honda's start bending rods at 10 psi... This is instability under compressive loading (column failure. > >I have a small single cyl that I'm going to be putting a blower on. In it's >current configuration, the factory tells me additional revs will seriously >comprimise reliability. OK, but with the blower, what is the ideal speed for >my desired HP? > >Repond off list if you feel compelled. Thanks. Right off the top--I section rods are more stable under compression loading (boost), as are aluminium rods (heftier section for same weight) (which is why fuelers like them). H section rods will be lighter for same strength, to get higher revs, but not as stable under high compressive loads. Aluminium is not good for SUSTAINED high revs because of no fixed endurance limit in tension. Regards, Greg > > >Matt Beaubien >mbeaubie@xxx.ca >3 x 510 >1 x 300ZXT ------------------------------ Date: Wed, 7 Apr 1999 22:02:17 EDT From: A70Duster@xxx.com Subject: Re: Fuel Injector Flow Bench I used an existing fuel rail (anyone should work, 4, 6 or 8 cylinder) and drove the high impedance injector with a transistor controlled by a Motorola 68HC11. Pulsed the injector at various duty cycles for ten seconds. Injected the fuel into a graduated cylinder. Worked great! DO THIS IN A WELL VENTILATED AREA! Some people will cry about the fire hazard, but one generates tons of fumes gassing up a car. When was the last time you were too afraid to fill you gas tank up? Later ------------------------------ Date: Wed, 07 Apr 1999 21:10:13 -0500 From: Tom Sharpe Subject: Re: EFI Head Volume Mark Romans wrote: > I have my piston to head clearance set at .039 inch! > 11.0 to one with efi, aluminum heads and 92 octane unleaded! > Mark I'm at .035-.037 depending upon the cyl, (pistons out of cyl .002-.003) with EFI and a measured 10.8+ with no problem. (and Standard Gold 93 octane unleaded!) Sharpe ------------------------------ Date: Wed, 7 Apr 1999 21:00:07 -0500 From: "G. Scott Ponton" Subject: Re: Suggestions for Adjusting WOT fuel? Roger, I'm fairly new here as yet but may be able to help with your tuning question. This has a lot to do with my experience tuning various engines running different induction and fuel. I may get flamed for some of this but ........ it has always worked for me. Course then again ............. I used to tune with just my ears and eyes before I knew and/or could afford the proper tools. It's much easier with 8-) In all gears you want the mixture to be as close to 14:1 as possible while still making good power. If you back the timing off about 4 deg. and start leaning from 12:1 at some point power will start to fall off in the low RPM ranges. It is actually more important that the mix is proper at max torque than at max HP. Actually the trans should be upshifted sooner than most people think. During the accel stage as the engine is loaded by each gear change the mixture should stay about the same. After reaching final gear and approaching max HP then the mixture AND timing should be back off slightly until the engine HP peaks. Back before there were anything other than points and carb I used to run a car with a dual point and an adjustable restricter in the fuel line at the carb. The two points were wired to a DTSP switch such that in each possition a different set of points was controlling the ignition. This allowed be to retart the timing approx 4 deg. at max revs. The fuel line restricter when properly adjusted would cause the fuel level to drop slightly in the carb at max leaning the mixture slightly. It was good for an extra 2 or 3 MPH at the end of a 1/4 straight either drag or oval. Exhaust temp isn't the greatest indication of proper combustion until the " normal" mixture ranges are exceded. Between 12.1 and 15.1 it is going to be more or less stable and dependant on the combo and fuel being used. Alcohol will show a much greater temp variation then gasoline as you can run it at nearly 1:1 with out fouliong the plugs. The excess ( unless it hydraulics the engine ;-( ) will just go out the exhaust obviously causing the temp to drop yada yada yada. Anyhow ........ I hope this has been some help. Scott ------------------------------ Date: Wed, 7 Apr 1999 21:03:13 -0500 From: "G. Scott Ponton" Subject: Re: Re:Halp Diamond Star Motored out I agree with David. Check the coil + side during cranking first. It should be at battery (approx. 9~10 volts during extended cranking.) If less charge the battery first. Still orange? Probably a bad coil. ------------------------------ Date: Wed, 7 Apr 1999 20:32:23 -0500 From: "G. Scott Ponton" Subject: Re: [Fwd: My MAF sensor] Fred, I need to know what year and engine the MAF is off of. I can probably get the info tomorrow but without the year is questionable if it will be accurate. Scott ------------------------------ Date: Wed, 7 Apr 1999 19:15:33 -0700 From: "Mike Pilkenton" Subject: Carl Summers please Carl, I think I may have an old email address for you, could you please contact me off-list. I still need help with my 3.1L V6 project. Mike Pilkenton ------------------------------ Date: Wed, 07 Apr 1999 21:45:47 -0500 From: Tom Sharpe Subject: Re: Suggestions for Adjusting WOT fuel? Roger Heflin wrote: > I have been adjusting my wot fuel. I have was removing 3% on the > wot my 60ft times did get better each run I removed > fuel, but if I am targeting say 12.5:1 what is a safe O2 > reading to go for? Two suggestions 1-- keep removing fuel until it slows down!. 2 -- keep removing fuel until O2 says 14.6 (stio) then add 17% to the pulse width (14.6/12.5) (if you only make one pass, the motor should live). If you are worried, try an 1/8 mile track or one of those computers with 0-60. Sharpe ------------------------------ Date: Wed, 07 Apr 1999 23:33:52 -0400 From: Hugo Villeneuve Subject: Re: Injector driver question... Hi Walt, I have not disabled the timer function (because I don't have to) of the LM1949 because now, for the high impedance injector, the current is always less than 0.75A (measured on the scope). After 3.9mS, if the current has not reached 4A, the LM1949 try to adjust the injector current to exactly 1A, by varying the base current of the transistor. But, even when the transistor is in full conduction, the current of the injector will never be greater than 12V/14.9 ohms = 0.8A. Hugo. >Glad to hear! Still wondering about your earlier questions/remarks. >Disable the timer function (3.9 ms on NS's L1949 data sheet example) and >hookup a high impedance injector. Does the current ever rise above the >steady state value of .75-.80 A ? Be curious to know. > >Walt. > ------------------------------ End of DIY_EFI Digest V4 #216 ***************************** 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".