DIY_EFI Digest Thursday, May 20 1999 Volume 04 : Number 295 In this issue: Re: EGR? Re: EGR? Re: alternative engines, WARPED Re: Limited cooling space Re: Mr Helmholz - simple model Re: EGR? Re: alternative engines, WARPED Re: alternative engines, WARPED Re: Variable Restrictiveness Exhaust - Meet Mr Helmholz Re: O2 Volts Re: O2 Volts My Subaru's Knock Sensor Re: Limited cooling space See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Wed, 19 May 1999 21:55:06 -0400 From: "CLsnyder" Subject: Re: EGR? - ----- Original Message ----- From: Todd Israels To: Sent: Wednesday, May 19, 1999 9:32 PM Subject: Re: EGR? > At 04:49 PM 5/19/99 PDT, you wrote: > >What is the purpose of an EGR and why is it used. I'm trying to decide if I > >should connect the EGR for my street hot rod. > > EGR reduces the tendancy to detonate. Connect it, particularly on a Chevy small=block. > >_______________________________________________________________ > >Get Free Email and Do More On The Web. Visit http://www.msn.com > > > > > From my understanding EGR basicaly takes up space and lowers combustion > temperature helping emmisions. I am not sure of the effect on detonation > if the engine is prone to this but suspect it is not positive. The other > effect is lots of carbon(black gunk) buildup in the intake that tends to > cause driveability problems when IAC pasages are pluged. > I personaly wouldnt use EGR if I dident need to. > > Todd Israels > > ------------------------------ Date: Wed, 19 May 1999 18:56:53 -0700 From: "John T. Luyster" Subject: Re: EGR? David, Exhaust Gas Recirculation. The purpose is to reduce emissions by reducing combustion temps. Too high temp would create Nox. Bottom line if you don't have to have this vehicle emssion legal and it is a "off-road" vehicle then leave it off. John L. David Sagers wrote: > What is the purpose of an EGR and why is it used. I'm trying to decide if I > should connect the EGR for my street hot rod. > > _______________________________________________________________ > Get Free Email and Do More On The Web. Visit http://www.msn.com ------------------------------ Date: Wed, 19 May 1999 21:03:45 -0500 From: Tom Sharpe Subject: Re: alternative engines, WARPED EFISYSTEMS@xxx.com wrote: > Hi Todd, > I think it's great you have noticed all the bore/stroke combos for some > of the chevs,,,,,,,,,somehow, someone at chrysler read grumpys or smokeys > book about rod ratio and never learned anything else... Ever notice how the 427 wedge's (Chevy Ford Chry) all sound different than all other engines????same for 440's... Then there's the Hemi... you can sure pick up their song in a crowd. Nuff said ------------------------------ Date: Wed, 19 May 1999 20:15:18 -0600 From: bearbvd@xxx.net (Greg Hermann) Subject: Re: Limited cooling space >Frederic Breitwieser wrote: >> >> > The way I see it, the coolant now "sees" a radiator that is 1/3 as high and >> > 3 times longer. Why does this cool better than normal. The log delta T is >> > the same, no? Is it a flow turbulence thing? That is the only change I >> > see. >> >> Here would be my guess... >> >> If you increase the width of the radiator, the coolant has to move >> further to reach the other side and be sucked back into the system, >> therefore its exposed to the ambient (and hopefully cooler) air >> temperature, which reduces the temperature of the coolant going back >> in. > >But, heat lost is proportional to the temperature delta. As the water >passes through this longer radiator you dump less and less heat because >the temp delta is getting closer to zero. Maybe Gary can weigh in here >but I think you want the radiator at the highest possible average >temperature to maximize heat transfer. That situation is achieved by >the "parallel" radiator, not the serial radiator. Only thing you are doing besides increasing the pressure drop across the radiator is increasing the turbulence in the tubes--which can increase the heat transfer coefficient from the fluid to the tubes from a little to a lot, depending on whether the radiator was a good or bad design in the first place. Regards, Greg > > >--steve > >-- >Steve Ravet >steve.ravet@xxx.com >Advanced Risc Machines, Inc. >www.arm.com ------------------------------ Date: Wed, 19 May 1999 22:02:14 -0400 From: "Gary Derian" Subject: Re: Mr Helmholz - simple model Doesn't cutting the collector change the standing waves and therefore the place where you want to cut it. Maybe an iterative process. I have no technical explanation for this either. I don't know why pressure waves would cause the paint to burn. What if you had high temp paint that didn't burn, or low temp paint that burned all over? Do you have to hold a constant rpm? Gary Derian > I have heard exactly the same for an H-Pipe. Paint it, and where the paint > has blistered up is where the crossover needs to go. > > > > >The way I was taught to roughly but effectively 'tune' my exhaust system > >on my 4 stroke v-8's engine's is to bolt about a 2 or 3 foot pipe to the > >header collector paint it black with some spray paint (preferably BEFORE > >installing the pipe) then do a run down the strip... > > > >After runnin the car at WOT for a 1/4, there will be a point on the > >'tuning' pipe where the paint has been burned off, and a point further > >up towards the header where the paint isn't burnt at all! > > > >At the point where the paint begins being burnt is where ya cut the > >pipe.. Whalaa instantly tuned exhaust... > > > >I've never heard a technical explanation of why this works or even if it > >helps or hurts or is just a guess at the correct length of exhaust > >pipe... > ------------------------------ Date: Wed, 19 May 1999 22:22:13 -0400 From: "Gary Derian" Subject: Re: EGR? Exhaust is an inert gas as far as an engine is concerned. EGR is used to reduce peak combustion chamber temps which limits the formation of NOx. In the bad old days (1970's), EGR was added and ignition timing was retarded. This combo made for badly running engines. Of course back then, it was easy to plug the vacuum line to the EGR, remove any impediments to vacuum advance, and remove a spring from the mechanical advance. Instant power, smoothness and economy. If the ignition timing is advanced when EGR is added, most if not all the economy loss can be recovered. Additionally, the engine now cruises at lower vacuum which improves economy more. Of course, without EGR, that same engine could pull a taller gear which also reduces engine vacuum and improves economy. I would not use EGR in a hot rod unless you are using a fuel injected engine which already has a good EGR setup. In that case, removing the EGR and recalibrating everything is a lot of work for little benefit (opinion here, no data). Although I did have an Eagle Talon with the turbo engine. I plugged the EGR valve and improved the economy from 23 to 25 mpg. I tried it in my wife's Volvo and only managed to set the check engine light. Gary Derian Dave Sagers wrote: > What is the purpose of an EGR and why is it used. I'm trying to decide if I > should connect the EGR for my street hot rod. > ------------------------------ Date: Wed, 19 May 1999 19:57:05 -0700 (PDT) From: Jim Davies Subject: Re: alternative engines, WARPED On Wed, 19 May 1999, Tom Sharpe wrote: > Ever notice how the 427 wedge's (Chevy Ford Chry) all sound different than all > other engines????same for 440's... Then there's the Hemi... you can sure pick up > their song in a crowd. Nuff said > In the latest Automobile Quarterly there is an article which mentions dyno development at Mopar on the 426. Apparently the dyno engines headers dumped into a high stack, no mufflers. They said the whole area knew when they were playing with them, especially when they were packed tight. They even mention some of the early engines, both developmental and production. First I have seen about the A16, a 6 cylinder development engine, and also a "330 inch" v8 [A182] developmental engine which ran in 1948. Heck, they even mention the 2220 although not too accurately. ------------------------------ Date: Wed, 19 May 1999 22:54:00 -0400 From: Shannen Durphey Subject: Re: alternative engines, WARPED Todd....!! wrote: > > So Shannen, > > do ya think I could get away with the 2 sizes bigger since I'm at or > below sea level? I'm not about to guess. You're there, I'm here, and it's your car. I was relating what I did. > > What size exactly IS two sizes bigger than what ya had(What are your > current jets in the carb right now?) Read the number off your primary jets, add two, gets ya two sizes bigger. No way in the world you should use my jet size as a starting point for your car. I've spent lotsa hours learning to tune carbs. Won't try to relate it all in 2-8 kb messages. But you've got a good idea what a carb that's too lean runs like, and prolly too rich also. So work with that as a starting point. Shannen > > Thanks! > > Todd....!! > > Shannen Durphey wrote: > > > > Todd....!! wrote: > > > > > > I have a 72 Buick 455 in my 72 Jaguar, but the carb that was on it was > > > jetted for Cheyenne, Wyoming, I already messed up my first 455 that I > > > put in the Jag due to this carbs' pretetonation causing lean > > > condition... broke a couple of peices of ring crowns off the top of a > > > couple a the pistons.... Damage was already done long before I swapped > > > out the carb for a sea level configured rochester... > > > > Well, I don't believe Cheyenne is too much higher than Hardin, MT. > > Before I left Hardin, I swapped the primary jets for jets that were 2 > > sizes larger. Once I arrived here (900 ft above sea level) I had to > > retard the timing slightly. The car is slightly rich now, but I don't > > use it much so I haven't finished the tuning. This is a 455 buick, > > 3.08 rear gear, 18mpg on the highway. > > Shannen ------------------------------ Date: Wed, 19 May 1999 23:33:00 -0400 From: "Bruce Plecan" Subject: Re: Variable Restrictiveness Exhaust - Meet Mr Helmholz > This talk of fancy tuning is interesting and certainly improves the power > per displacement but my question is does all this work actually make a > better vehicle. Isn't it easier to just use a larger engine with > appropriate gearing to achieve the same power and economy without all the > extra parts? Too a certain degree, no. BUT, depending on how fussy you are about drivability, YES. Depending on where your starting the gains may be small. OR, so stagering you'll be speachless. I have started at ground zero, and done a total calibration, and I don't think any one less than the 400 chips I burnt was a waste of time for what the end result was. I could not come up with a combination of driving style where the engine was less than 100%. Trailing throttle to WOT braking, cornering sudden steering loads low speed, nothing was lacking at any time. So for me it was worth it, your results may vary. Bruce ------------------------------ Date: Thu, 20 May 1999 01:50:34 -0400 From: Shannen Durphey Subject: Re: O2 Volts soren wrote: > > >>> Bruce, I don't know why you say this, if you douse the o2 sensor > >>> with butane, you block out the o2, so it will read high, as in a > >>> rich fuel mixture. (No o2 present). > >>> All of your above sounds correct, and with all respect, the > >>> exception of your conclusion... > >>> BobR. > > > >>Is butane not a Hydro Carbon?. > >>Bruce > > > >(I'm chuckle'ing to myself), you've a point there. I have > >to head out to the garage, I have, lets see; propane, argon, > >acytelene (sp!), I'll see about butane. I have to try some > >things out here... (as Arnie would say, in that low, deep > >voice, 'I'll be back'). > > So go out, try the argon, and see how it compares to any of the HC gases > and the pure O2 that Bruce tried earlier. If the argon/O2 readings are the > same, it is a HC sensor. If the argon/HC readings are the same, it is an O2 > sensor. Either way, it seems to me as if whichever gas actually produces > voltage is the one it is sensing. > > Soren No, because exhaust is mixed gasses. Varying the amounts of HC, CO, CO2, and NOx don't affect the sensor. Only O2 quantity in relation to the sensor's reference changes voltage. TPS senses TP whether output voltage increases or decreases with increased throttle angle. Why do you think an "inverted" output from the O2 sensor makes it a Not O2 sensor? Shannen ------------------------------ Date: Thu, 20 May 1999 02:03:00 -0400 From: Shannen Durphey Subject: Re: O2 Volts rr wrote: > > >> Bruce Wrote: > > >>(Some stuff about o2 sensor response's {rr}) > > Ok, back from the garage, I think you may be on to something > here. > > I put a realsquash heated Bosch o2 sensor, tip down, clamped to > the inside of a small can. With the tip below the rim, and the > body above. Covered at rim height with plastic sheet (yes it > was melting to the sensor) > > Hooked up twelve volts to the heater, fluke on the output. > > Nominal volts: ~-40mv in free air, returned to this > after each test by fanning above can with piece of paper. > > > Response's to different gases: > > propane: rapid and long lasting, > 850mv. > R12: light response, quick to return to nominal, ~475mv. > acetylene: rapid and long lasted, > 750mv. > hold breath, breath through tube into can: no effect... > argon: light response, very short lived: ~70mv. > contact cleaner: medium response, ~650mv. > (tricloroethane + diclorodifluoromethane) > > (couldn't find any butane) > > Thinking about this, it makes sense. Once you reach stoich (450mv), > how can you go higher? Only if the excess hc takes it there... > > The argon response, or lack thereof, is interesting. You didn't report on the duration of the gas "shot". Not sure it matters, but I would have left whatever gas "running" for a fixed amount of time in the can. Or better yet, continously until end of test. Methinks I may have been motivated enough to do my own experiments. Shannen ------------------------------ Date: Wed, 19 May 1999 23:52:18 -0700 From: GARY Subject: My Subaru's Knock Sensor Well Gentlemen, I want to thank you for all your input and ideas before I check out of the group. I have been overwhelmed in trying to keep up to all the email the list provides. But it certainly has been an educational experience and a pleasure too! As for now, I am working with various derivatives of a voltage divider to attenuate the KS signal, one including a potentiometer. I am making progress and will certainly sign back onto the group to let you all know how I end up settling on this over sensitive knock sensor thing. (I'll be back) So good-bye for now and thanks again for the camaraderie!! Sincerely Yours, GARY http://home.earthlink.net/~hobiegary/hesitation.htm ------------------------------ Date: Thu, 20 May 1999 01:14:27 -0700 From: Aaron Willis Subject: Re: Limited cooling space At 05:49 PM 5/19/99 -0400, you wrote: The final "trick" is what i >discribed, and it worked. Why, I haven't a clue, just that it did. > Whatza Aero-K-Whopper??. >Bruce Damn, wish I'd been following this thread. Always seem to miss the tricks that save the day... I reckon he means aerodynamic (slope-nose) Kenworth semi. Aaron Willis ICQ #27386985 AOL IM: hemiyota http://surf.to/garage-te51 Garage TE51 International ------------------------------ End of DIY_EFI Digest V4 #295 ***************************** 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".