DIY_EFI Digest V2 #29
gfulton
gfulton at salisbury.net
Thu Jan 30 22:27:29 GMT 1997
In reference to the message from Mr. Shapiro concerning dropping fuel flow
to one or more cylinders to increase economy. Cadillac did this back in
the '70's on their large displacement engines with carburetors by using
solenoid arrangement on the valve train to keep the valves shut on 4 of 8
cylinders under light load. A Popular Mechanics article explained the
concept as increasing the efficiency at light loads above about 60 mph
since with the valves closed, almost all energy used to compress air in a
cylinder would be returned as the piston was forced back down by the high
pressure. All this is from memory, mind you. I believe they did it for
only one or two years as they had a lot of trouble with the valve/solenoid
arrangement.
I don't believe the arrangement of cutting fuel to the cylinders would
increase fuel economy, as the valves would still work and energy would be
used pumping air. I would welcome any other opinions.
Garrett Fulton
gfulton at salisbury.net
----------
> From: DIY_EFI-Digest-Owner at coulomb.eng.ohio-state.edu
> To: DIY_EFI-Digest at coulomb.eng.ohio-state.edu
> Subject: DIY_EFI Digest V2 #29
> Date: Saturday, January 25, 1997 5:00 AM
>
>
> DIY_EFI Digest Saturday, 25 January 1997 Volume 02 : Number
029
>
> In this issue:
>
> GM buying from Electromotive??
> Re: natural gas
> Re: GM buying from Electromotive??
> Re: Test of Life
> Traffic
> Large displacement engines & fuel economy
> Ford Ranger
> Ford Ranger (repost)
> Re: Large displacement engines & fuel economy
> Re: Large displacement engines & fuel economy
> Test
> Factory vs aftermarket (Part2)
> Factory vs aftermarket (part1)
>
> See the end of the digest for information on subscribing to the
> DIY_EFI or DIY_EFI-Digest mailing lists.
>
> ----------------------------------------------------------------------
>
> From: john spears <speartec at iquest.net>
> Date: Fri, 24 Jan 1997 07:10:29 -0500
> Subject: GM buying from Electromotive??
>
> In digest 28 David Doddek speaks of the merits of Electromotive. And
while
> I'm glad your system is working well, your statements about GM buying
direct
> fire systems from Electromotive are completely false. All Grand National
> direct fire systems from 1984 - 1987 are manufactured by Magnavox, and
> consist of a "coil pack" of three coils molded together. GM DIS systems
came
> online, slowly, in 1986 on 3.8L SFI engines, other than the Grand
National.
> The GM DIS system eventually went on to be used on all of GM's DIS
equipped
> engines, displacing Magnavox. There was some early on development
work
> done between the two companies (Electromotive and GM), but nothing ever
came
> of it. As the years went by, the only thing Electromotive supplied GM
with
> was a bunch of pain in the ass, frivolous law suits.
>
>
> John Spears
>
> ------------------------------
>
> From: LotusM50 at aol.com
> Date: Fri, 24 Jan 1997 09:32:57 -0500 (EST)
> Subject: Re: natural gas
>
> In a message dated 97-01-23 19:47:34 EST, paul at jbc.edu (Paul Beam)
writes:
>
> << This may stray a bit, but does anyone have any experience converting a
> small
> engine to run on natural gas? We want to take a gasoline powered AC
> generator and convert it. Any info on suppliers of parts would be
> appreciated.
> >>
>
> I am interested n doing the same thing (but after my current project).
You
> may want to make a call the Amercian Gas Association in Arlington,
Virginia
> and ask for a technical person. There also is a technical person at the
> Coalition for Natural Gas Vehicles that may be aable to help as well.
There
> are also in Arlington, Va. I don't have their numbers with me but they
can
> be found with directory assistance.
>
> ------------------------------
>
> From: "George M. Dailey" <gmd at tecinfo.com>
> Date: Fri, 24 Jan 1997 10:34:21 -0600 (CST)
> Subject: Re: GM buying from Electromotive??
>
> This sounds consistent with other Electromotive users.
>
> GMD
>
> At 07:10 AM 1/24/97 -0500, you wrote:
> >In digest 28 David Doddek speaks of the merits of Electromotive. And
while
> >I'm glad your system is working well, your statements about GM buying
direct
> >fire systems from Electromotive are completely false. All Grand National
> >direct fire systems from 1984 - 1987 are manufactured by Magnavox, and
> >consist of a "coil pack" of three coils molded together. GM DIS systems
came
> >online, slowly, in 1986 on 3.8L SFI engines, other than the Grand
National.
> >The GM DIS system eventually went on to be used on all of GM's DIS
equipped
> >engines, displacing Magnavox. There was some early on development
work
> >done between the two companies (Electromotive and GM), but nothing ever
came
> >of it. As the years went by, the only thing Electromotive supplied GM
with
> >was a bunch of pain in the ass, frivolous law suits.
> >
> >
> > John Spears
> >
> >
> >
>
> ------------------------------
>
> From: "George M. Dailey" <gmd at tecinfo.com>
> Date: Fri, 24 Jan 1997 10:30:50 -0600 (CST)
> Subject: Re: Test of Life
>
> It's still kicking Peter.
> GMD
>
> At 12:35 PM 1/23/97 -0800, you wrote:
> >Hi all
> >
> >Is the old net still alive?
> >
> >I hope I didn't get excummunicated.
> >
> >Oh well till later: peter
> >
> >
> >
>
> ------------------------------
>
> From: Mark Eidson <mark.eidson at tempe.vlsi.com>
> Date: Fri, 24 Jan 1997 10:37:10 -0700
> Subject: Traffic
>
> I have not seen any traffic for 3 days. Is the list dead? me
>
***************************************************************************
> * Mark Eidson Voice: (602)752-6513
*
> * Fax: (602)752-6000
*
> * Manager System Integration and Home: (602)831-6079
*
> * Verification E-Mail: mark.eidson at tempe.vlsi.com
*
> * VLSI Technology, Inc.
*
> * 8375 South River Parkway
*
> * M/S 265
*
> * Tempe, Arizona 85284
*
>
***************************************************************************
>
> ------------------------------
>
> From: Jody Shapiro <jshapiro at Token.Net>
> Date: Fri, 24 Jan 1997 13:44:29 -0500 (EST)
> Subject: Large displacement engines & fuel economy
>
> Here's an idea/thought I've been kicking around for awhile and wanted to
> see what others thought about it:
>
> A common reason for going to larger displacement engine is for the gain
> in torque, particularly at low RPM, without having to sacrifice high-RPM
> power (by changing intake runner length).
>
> The downside is a drop in fuel economy at part/light throttle since you
> still have to "feed" the extra displacement. A good example is a
> 350" motor stroked to 383". You get all of the benefits of the extra 33"
> of displacement at WOT, but highway mileage will decrease now.
>
> Unless I'm misunderstanding something, the drop in mileage is because you
> need to maintain the same A/F ratios that you would have maintained for
> the stock displacement motor. You can lean the mixture out as much as
> you like, but there's a limit to how lean you can go. The stock fuel
maps
> will try to lean out the mixture as much as they can for a 350" motor.
> Since you now have a 383" motor, if you inject the same amount of fuel as
> you did for a 350" motor the mixture will be too lean since the motor
> will be sucking in more air into each cylinder now than it did before.
>
> Given that you can't lean out the mixture anymore, what is the best way
> to boost part/light throttle fuel economy?
>
> How about a system similar to Cadillac's on the NorthStar engine whereby
> they don't inject -any- fuel into some cylinders. The reason Cadillac
> does this is in the event of cooling system failure. Cylinders are
> starved of fuel in a preset order to allow them to just pump air in an
> effort to allow things to cool.
>
> This obviously has an adverse affect on power (I believe the NorthStar
> engine has problems going faster than 55mph or so when in this state).
>
> I don't know how frequently the Cadillac system cuts out cylinders, or
how
> many it cuts out in a given firing sequence, but couldn't this idea be
> applied to a large displacement port-fuel injected motor? In other
words,
> to conserve fuel, cut out a cylinder in every firing sequence (but make
> the cut-out cylinder a different one each time so no cylinder gets cut
out
> twice in a row).
>
> I don't know what kind of effect this would have on RPM stability, or
> engine smoothness (hopefully not too bad), but is this a feasible
> alternative so that you can have your cake and eat it, too? You get all
> of the advantages of extra ci at WOT, and you don't have the gas guzzling
> at part throttle.
>
> Obviously, this is something that we can only do via a custom programmed
> EFI system (like EFI332), but would it work?
>
> Comments?
>
> - -Jody
> - --
> http://www.token.net/~jshapiro/z28/
>
> ------------------------------
>
> From: Peter Shoebridge <peter at aspenres.com>
> Date: Fri, 24 Jan 1997 12:40:14 -0700
> Subject: Ford Ranger
>
> Some may remember a couple of weeks ago I posted a note regarding my mate
> who was having problems with his 1988 Ford Ranger.
>
> Brief synopsis:
>
> Engine occasionally stalled when coming to a stop after running.
> Happened no matter what the temp.
> Would not restart properly unless ignition was switched off then back on.
>
>
> He changed the following items without resolution:
> Ignition module
> Temp sensor
> Fuel/EEC relays
>
> After changing the temp sensor the symptoms changed, in that it now
stalled
> occasionally whilst changing gear not when coming to a stop.
>
> Finally, he had the chance to pull over once it had happened and restart
> the engine without turning the ignition off (which caused it to run very
> badly with black smoke from the exhaust) and pull up the bonnet (hood for
> yanks:>).
>
> Pulling off the MAP sensor lead caused it to run ok, not brilliant but
ok.
> Even allowed him to drive down to NAPA for a new MAP sensor.
>
> Now seems to be ok. That was only yesterday, but he seems confident that
> it's fixed.
>
> One question though: During all his testing, on one occasion he pulled
off
> the TPS connector and drove for an hour without any significant problem.
> How can this be? Yes I can except that the ECU will choose a default
value
> for a duff/missing sensor but for the TPS???
>
> Anyway if you got this far - thanks for reading!!!!
>
> Peter S
>
> ------------------------------
>
> From: Peter Shoebridge <peter at aspenres.com>
> Date: Fri, 24 Jan 1997 16:44:48 -0700
> Subject: Ford Ranger (repost)
>
> Some may remember a couple of weeks ago I posted a note regarding my mate
> who was having problems with his 1988 Ford Ranger.
>
> Brief synopsis:
>
> Engine occasionally stalled when coming to a stop after running.
> Happened no matter what the temp.
> Would not restart properly unless ignition was switched off then back on.
>
>
> He changed the following items without resolution:
> Ignition module
> Temp sensor
> Fuel/EEC relays
>
> After changing the temp sensor the symptoms changed, in that it now
stalled
> occasionally whilst changing gear not when coming to a stop.
>
> Finally, he had the chance to pull over once it had happened and restart
> the engine without turning the ignition off (which caused it to run very
> badly with black smoke from the exhaust) and pull up the bonnet (hood for
> yanks:>).
>
> Pulling off the MAP sensor lead caused it to run ok, not brilliant but
ok.
> Even allowed him to drive down to NAPA for a new MAP sensor.
>
> Now seems to be ok. That was only yesterday, but he seems confident that
> it's fixed.
>
> One question though: During all his testing, on one occasion he pulled
off
> the TPS connector and drove for an hour without any significant problem.
> How can this be? Yes I can except that the ECU will choose a default
value
> for a duff/missing sensor but for the TPS???
>
> Anyway if you got this far - thanks for reading!!!!
>
> Peter S
>
> ------------------------------
>
> From: "George Najarian" <najay at deltanet.com>
> Date: Fri, 24 Jan 97 13:09:51 -0800
> Subject: Re: Large displacement engines & fuel economy
>
> On Fri, 24 Jan 1997 13:44:29 -0500 (EST), Jody Shapiro wrote:
>
> >Here's an idea/thought I've been kicking around for awhile and wanted to
> >see what others thought about it:
> >
> >Given that you can't lean out the mixture anymore, what is the best way
> >to boost part/light throttle fuel economy?
> >
> >Comments?
> >
> >-Jody
> >--
>
> EGR is used to dilute the mixture without changing the A/F ratio. Maybe
> increasing the amount of recycled exhaust might work.
>
>
> George Najarian | '95 Ford Mustang GTS E/SP (14.21/100.81)
> najay at deltanet.com | '86 Ford Mustang GT Convertible (15.0/93)
> http://users.deltanet.com/~najay/
> Team.Net Team OS/2
>
> ------------------------------
>
> From: "George M. Dailey" <gmd at tecinfo.com>
> Date: Fri, 24 Jan 1997 18:45:58 -0600 (CST)
> Subject: Re: Large displacement engines & fuel economy
>
> At 01:44 PM 1/24/97 -0500, you wrote:
> >Here's an idea/thought I've been kicking around for awhile and wanted to
> >see what others thought about it:
>
> >
> >I don't know how frequently the Cadillac system cuts out cylinders, or
how
> >many it cuts out in a given firing sequence, but couldn't this idea be
> >applied to a large displacement port-fuel injected motor? In other
words,
> >to conserve fuel, cut out a cylinder in every firing sequence (but make
> >the cut-out cylinder a different one each time so no cylinder gets cut
out
> >twice in a row).
> >
>
> You still have the parastic loss of the dead cylinder still compressing
the
> air within it. If you could stop the inlet and exhaust valves from
opening,
> you could dramatically reduce the dead cylinder resistance. Some early
> caddys did just this. The system is remembered as junk. The Modulated
> Displacement Engine they called it. It did meet the objective of having
good
> steady state fuel economy.
>
>
> >I don't know what kind of effect this would have on RPM stability, or
> >engine smoothness (hopefully not too bad), but is this a feasible
> >alternative so that you can have your cake and eat it, too? You get all
> >of the advantages of extra ci at WOT, and you don't have the gas
guzzling
> >at part throttle.
> >
> >Obviously, this is something that we can only do via a custom programmed
> >EFI system (like EFI332), but would it work?
> >
> >Comments?
> >
> >-Jody
> >--
> >http://www.token.net/~jshapiro/z28/
>
> The best power/effiency setup would be a medium compression (9-1), medium
> displacement (3L), engine with a low boost (<8lbs/in2) intercooled
> turbocharger and an overdrive tranny. The higher compression ratio would
> give you good economy under (no to low) boost. Medium displacement would
> keep rotating mass at a minimum but not cause a power lag on the bottom
end.
> The low boost intercooled turbo would provide the high torque. The tranny
> would be geared low for the first and second gears for performance. The
> overdrive would provide steady state economy.
>
> Boost and high comp go together like Cryps and Bloods. This will require
low
> intercooled boost and water injection to controol detonation.
>
> My home built car will have a power trane that meets all of these specs.
> This is very doable and proven to work.
>
> GMD
>
> ------------------------------
>
> From: Jennifer Rose <javer96 at snowcrest.net>
> Date: Fri, 24 Jan 1997 21:47:35 -0800 (PST)
> Subject: Test
>
> Hi All
>
> Test post- Haven't got any post last three days. Any still out
there?
>
> Vance
>
> ------------------------------
>
> From: Tomchou at aol.com
> Date: Sat, 25 Jan 1997 03:52:12 -0500 (EST)
> Subject: Factory vs aftermarket (Part2)
>
> >someone building a street engine. There are numerous tradeoffs
> >between maximum horsepower, maximum torque, and drivability. One
> >thing we must understand in all this is that GM is forced to build an
> >engine that meet CAFE (Corporate Average Fuel Economy), emission
> >controls, smooth idle, low to mid-range torque, and easy cruising at
> >(in '86) 55 mph. If the end users concerns lean toward one or more of
> >these criteria, there are aftermarket products that will satisfy their
>
> This is somewhat true. There are some aftermarket items that do work
well
> when they target some compromise in the factory design; we are forced to
make
> many compromises for the reasons you state. Most effective changes are
the
> simple and logical ones, such as less restrictive exhausts (drive by
noise
> level requirements force certain compromises) and less restrictive intake
> systems (again, noise levels are a concern.), or issues such as shift
points
> and torque management to make transmissions and such survive the 100K
mile
> durability cycle as warrenty costs are a major concern.
>
> However, the problem is that most aftermarket don't understand all the
> ramifications of changes they make. For instance, MAFs are particularly
> sensitive to turbulance, and the change to an open air element or ram air
> (besides the hazards of water intrusion) could alter it's calibration.
Even
> if these things are understood, the aftermarket doesn't have the
resources to
> correctly compensate for many things they do. This results in at best,
> slight irregularities in driveability, and most people that are into
> modifications probably overlook this issue, as "race cars" are supposed
to
> drive rough.
>
> >needs. To state that these parts are fraudulent or that the people
> >who sell them are liars is irresponsible and/or stupid..
>
> Unfortunately, I've found this to be true more often than not. Many have
> really good intentions, but just don't have enough understanding of the
> issues and physical principles.
>
> >While it is true that the requirements of a particular engine may
> >vary, there are some parts that will increase horsepower and torque,
> >but were not placed on the original engine purely due to
> >economics...Headers, dual exhaust (with dual catalytic converters),
> >high flow air filters, high flow Mass Air Flow sensors, roller
> >lifters, and throttle body air foils are notable among these. Even
> >the calpak can be remapped for improved performances if done so to
> >accomodate a particular engine and driving conditions. These engines
> >(from the factory) are made for mass production. Plainly and simply,
> >they are designed so that the lowest common denominator is met.
>
> Again, this is partially true, but not completely. This is what every
> aftermarket vendor would love for everyone to believe, but don't buy into
it
> hook, line and sinker! I'm not flaming the originator of this post at
all,
> so please don't take it personally! I'm just expressing my opinion, and
this
> post happened to be the one that opened the issues!
>
> I know very well there are many compromises the OEM makes, but I've yet
to
> see an aftermarket company discover and optimize most *true* design
> compromises despite their hype to this effect! The beauty of this
particular
> list is that everyone is more or less from a technical background, and
are
> able to talk intelligently about these things. Many lists such as the
> general F body list (just picking on it - I stopped subscribing after too
> many "my car is faster than yours") do buy into the aftermarket's
advertising
> wholeheartedly, but the folks on this list have the knowledge to really
> evaluate the validity of vendor's claims.
>
> Tom Chou - Tomchou at aol.com
>
> ------------------------------
>
> From: Tomchou at aol.com
> Date: Sat, 25 Jan 1997 03:52:06 -0500 (EST)
> Subject: Factory vs aftermarket (part1)
>
> Subj: Factory vs aftermarket: was Valve train noise
> Date: 01/21/97
> To: diy_efi at coulomb.eng.ohio-state.edu
>
> Obviously my post was too long as it got kicked out the first time I sent
it.
> Since list traffic is slow, I'll split it in 2 parts and get my .02 in!
>
> >>From: George M. Dailey[SMTP:gmd at tecinfo.com]
> >>Don't feel bad. After market parts can confuse even the most seasoned
hot
> >>rodder. Some of the venders are liscened and bonded LIERS. Oh, it's not
a
> >>total loss though, I've heard that the Electromotive ECMs make
excellent
> and
> >>attractive door stops or paper weights:}
>
> >From: John Hess <JohnH at ixc-comm.net>
> >This is what I mean by an instant expert. First of all, the very fact
>
> Hey - I haven't been on this particular list very long, but I don't
believe
> George Dailey fits the term "instant expert" here! Actually, and I know
I'm
> very biased here, but I consider _almost_ every aftermarket vendor I've
met
> with a few exceptions to be "instant experts". Most have very little
formal
> education in anything remotely resembling Automotive Engineering, or
> aerospace or electronics and have no technical experience working for any
> major automotive related company. Some of the better ones at least are
> master mechanics of some sort and have considerable practical experience
in
> racing, etc. while others were probably shoe salesmen (no offense to them
-
> just thinking of Al Bundy) who picked up a Bosch Handbook and are now
giving
> all sorts of technical advice. (I'm not even remotely refering to
anybody on
> this list as I haven't been on long enough!) I'm not saying you must
have a
> degree or anything to know what you're talking about either, but most of
> these guys are really lacking in technical knowledge yet you'll think
they
> were PhD's in fluid dynamics or combustion analysis from their claims.
>
> >that GM spent those millions dictated that they were obligated to
> >cover their costs. The original TPI was designed for the 305 engine
> >and is woefully inadequate for even a mildly built 350. The air
> >foils, ported plenums, opened up MAF do, in fact, increase horsepower
> >easily measurable on a dyno, 0-60 time, quarter mile, or even the seat
> >of ones pants. I agree that the GM MAF system is the way to go for
>
> I have considerable insight into this, and we've looked at many of these
> items. I don't trust any dyno data I've seen in the popular magazines -
> they're almost always performed at either the aftermarket manufacturers
own
> dyno or some biased shop. There's just too many things you can do to get
the
> numbers you want. In general, some of these products are based on a
valid
> idea or principle but taken out of context or only beneficial under very
> specific conditions. For example, maybe airspeed needs to be near
airplane
> velocities for some concept to work, or in the case of different ignition
> schemes, their ideas may be good for alcohol or nitromethane only, or for
> specific combustion chamber profiles/turbulances, etc. We've run many of
> these products on our extremely accurate/expensive dynos that no
aftermarket
> could come close to affording, and found none to offer exactly what they
> claim or advertise. At best, some products have a measureable effect -
> usually detrimental, but if properly understood, given the proper
conditions,
> I can see them being beneficial.
>
> When there are real measureable differences or benefits, it is not always
due
> to the product under evaluation! What I mean is that the product has
somehow
> altered certain parameters to give better performance under that
condition,
> (i.e. made it richer/leaner or altered *delivered* spark timing (due to
more
> capacitance or inductance on the secondaries) and when you gather proper
data
> and determine exactly what change took place, you can remove that
product,
> change those parameters via other means, and achieve identical results.
> Well, one might say, that proves that product worked. Well, ok - that's
one
> way of looking at it, and probably the way the vendor wants it to be
viewed,
> but the problem is this is usually only beneficial under that special
> condition, and not due to the reasons the vendor claims.
>
> Look at the aftermarket companies that are tightly connected to the Big
3,
> such as McLaren, Roush, Shelby to name a few. If you talk to their
people,
> and look at what they do, you'll see they use very few of the usual
popular
> aftermarket products out there. Most of their creations use very factory
> parts or custom ones they design for that specific application with
> complementary changes in software/calibration or other components to
> compensate any side effect. No "black magic" gimmicks such as air foils
are
> used. Look at the totally factory backed high tech race teams in
endurance
> racing, off road series, Indy Car/CART, Indy Lights - you don't see the
same
> stuff being used as the popular auto mags such as Hot Rod, Car Craft and
such
> advertise/evaluate.
>
> (Continued in part 2)
>
> ------------------------------
>
> End of DIY_EFI Digest V2 #29
> ****************************
>
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