DIY_EFI Digest Friday, 26 July 1996 Volume 01 : Number 211
In this issue:
RE: Throttle Body Sizing
RE: Throttle Body Sizing
RE: Throttle Body Sizing
RE: Throttle Body Sizing
Diesel MAF-sensor?
Re: [admin] volunteer needed
RE: Throttle Body Sizing
RE: Throttle Body Sizing
DIY Throttle Body
Slide Throttles
Re: Diesel MAF-sensor?
Re: water injection questions???
RE: Throttle Body Sizing
Oops
Slide throttles
Re: Throttle Body Sizing
Re: water injection questions???
Re: water injection questions???
Re: DIY Throttle Body
Re[2]: Diesel MAF-sensor?
Re: water injection questions???
Re: Throttle body sizing
Re: water injection questions???
Re: Re[2]: Diesel MAF-sensor?
Re: water injection questions???
Re: Filtering supply lines
Intercooling (was Re: water injection questions???)
MAP vs. MAF
See the end of the digest for information on subscribing to the
DIY_EFI or DIY_EFI-Digest mailing lists.
----------------------------------------------------------------------
From: Paul Shackleton
Date: Thu, 25 Jul 96 09:58:00 BST
Subject: RE: Throttle Body Sizing
>While trying to decide on the proper size throttle body for my MGB EFI
>snip<
>Here is what I think sizing should be based on. I've used my MGB's cam
data
>in this example:
>1) Peak RPM: 6,000
>2) Engine CI Displacement: 110
>3) Intake valve duration (Deg): 252
>4) Time for 1 crank revolution: 0.01 sec. (60 sec / RPM)
>5) Time for 1 deg. of crank rotation: 2.381E-05 (#4 / 360deg)
>6) Intake time per 4 cycle period: .006 seconds (#5 x #3)
>7) Intake time per minute: 21 seconds (#1 x #6)
>8) Engine CFM requirement @xxx.8 CFM
> ((#1 x #2) / 2) / 1728)
>9) Estimated Throttle Body steady state flow requirement: 636 CFM
> (60 sec./#7) x #8
>snip<
What throttle bodies are you thinking of using? Are you making your own and
if so, how? Or are you using proprietary ones? I am just about to start
making some for the 2.0l 16v Vauxhall engine in my Westfield, but have yet
to figure out how. Weber, Lumenition and Microdynamics throttle bodies seem
to be very expensive. ie more than the equivalent sized carb without any of
the complicated carb plumbing!
Any ideas on DIY throttle bodies would be gratefully received?
Also, in calculation #7, shouldn't #1 x #6 be 36 seconds? However 21 seconds
is the answer if you say in two engine rotations (4 strokes) the inlet is
open 252 degrees out of 720. Multiply this up to a minute (x60) and you get
21 seconds. I'm not sure whether the answer should be 21 or 36 though.
Paul
P.M.Shackleton@xxx.uk
------------------------------
From: Alexander.M.Lichstein@xxx. Lichstein)
Date: 25 Jul 96 05:32:17 EDT
Subject: RE: Throttle Body Sizing
We had some success in boring out a block of aluminum with the throat size we
wanted, putting some brass bushings in as bearings with a steel shaft that was
made half-round in the middle with an end-mill. The butterfly plate itself was
made on a CNC milling machine by - and here's the catch - mounting it on a
block of aluminum, and clamping that block at a 10' angle on the mill table.
We then toold the mill to make a cylinder, plunging to a depth which would
circumnavigate the brass plate. voila... chamfered edges, and the appropriate
oval shape to wedge itself in real nice. Idle bypass can be done a number of
ways (simplest with some tubing and a petcock. Not exactly a device I would
want in my street car, but just fine for racing.
- - Z
------------------------------
From: Alexander.M.Lichstein@xxx. Lichstein)
Date: 25 Jul 96 06:26:41 EDT
Subject: RE: Throttle Body Sizing
We had some success in boring out a block of aluminum with the throat size we
wanted, putting some brass bushings in as bearings with a steel shaft that was
made half-round in the middle with an end-mill. The butterfly plate itself was
made on a CNC milling machine by - and here's the catch - mounting it on a
block of aluminum, and clamping that block at a 10' angle on the mill table.
We then toold the mill to make a cylinder, plunging to a depth which would
circumnavigate the brass plate. voila... chamfered edges, and the appropriate
oval shape to wedge itself in real nice. Idle bypass can be done a number of
ways (simplest with some tubing and a petcock. Not exactly a device I would
want in my street car, but just fine for racing.
- - Z
------------------------------
From: "Orin Harding"
Date: Thu, 25 Jul 96 02:34:23 UT
Subject: RE: Throttle Body Sizing
A single 40mm TB sounds alittle restrictive for your application. But you
won't flow over 500cfm, like you calculate. I don't know enough about MGs
to recommend a specific size TB. Just as a comparison, my 5.7l V8 uses
twin 48mm TBs w/ 5800rpm redline.
Markus,
I'm going to try a twin 40 mm throttle body which should flow 400+ CFM. That
should be close to the same flow as the twin SU HS-4 (1.5") carbs that were
used on the early MGB's.
Orin
------------------------------
From: "Hans Hintermaier"
Date: Thu, 25 Jul 1996 13:39:42 MET
Subject: Diesel MAF-sensor?
Michael D. Porter wrote:
Date: Thu, 25 Jul 1996 08:58:59 -0500 (CDT)
Subject: Re: [admin] volunteer needed
I've done this before. If you don't have a taker yet I can fill in for
you.
:
:
:There's that ugly word again... volunteer.
:
:I need someone, for about three months, to take over the day-to-day
That's a long time. You might want to load up a couple of them.
I'll be glad to work as an alternate as well.
:task of managing the mailing list request that for one reason or
:another don't get resolved automatically.
:
:The volunteer can easily do this maintenance remotely through
:email. Working knowledge of Majordomo would be helpful but not
:necessary. It's really just a job of unsubscribing mail that bounces
:and rerouting posts that get sent to the wrong address or that are too
:long.
:
:Your cooperation is appreciated.... (don't make me ask twice :).
:
: John S Gwynne
: Gwynne.1@xxx.edu
:_______________________________________________________________________________
: T h e O h i o - S t a t e U n i v e r s i t y
: ElectroScience Laboratory, 1320 Kinnear Road, Columbus, Ohio 43212, USA
: Telephone: (614) 292-7981 * Fax: (614) 292-7297
:-------------------------------------------------------------------------------
:
:
:
- --
Ron Madurski
rmadursk@xxx.com
------------------------------
From: Chris Howard
Date: Thu, 25 Jul 1996 23:52:30 +1000
Subject: RE: Throttle Body Sizing
>
>Any ideas on DIY throttle bodies would be gratefully received?
>
Cars and Car Conversions magazine had an article about a year back on making
throttle bodies using weber or dellorto side-draught housings. Sorry I cant
find the issue now though.
Regards,
Chris Howard
Computer Science
University of New South Wales
email: s2184002@xxx.au
Web: http://www.usyd.edu.au/~choward
------------------------------
From: Fred Miranda
Date: Thu, 25 Jul 1996 07:24:51 -0700
Subject: RE: Throttle Body Sizing
> Weber, Lumenition and Microdynamics throttle bodies seem
>to be very expensive. ie more than the equivalent sized carb without any of
>the complicated carb plumbing!
>
>Any ideas on DIY throttle bodies would be gratefully received?
Just gut some old Webers or go with a plenum setup and use an OEM
t-body from a junkyard.
------------------------------
From: David.Haynes@xxx.uk
Date: Thu, 25 Jul 96 15:39:55 GMT
Subject: DIY Throttle Body
P.M.Shackleton@xxx.uk wrote :
>to figure out how. Weber, Lumenition and Microdynamics throttle bodies seem
>to be very expensive. ie more than the equivalent sized carb without any of
>the complicated carb plumbing!
>
>Any ideas on DIY throttle bodies would be gratefully received?
I have seen fairly recently in (I think) Car & Car Conv. a design for an FI
throttle setup done using a pair of old DCOE carbs. That might be one way to go
if you can get a second hand (Sorry, Pre Owned ;->) pair that are not too worn.
I guess that the slight air leak caused by a worn unit would be less of a
problem for FI than in the intended application, but if you are going to go to
all that effort ...
Dave H.
------------------------------
From: Paul Shackleton
Date: Thu, 25 Jul 96 15:50:00 BST
Subject: Slide Throttles
Has anyone any thoughts or comments on slide throttles? Suppliers, how they
work, costs, pros & cons compared with butterfly throttles, is it possible
to DIY?
Any info welcome
Paul
P.M.Shackleton@xxx.uk
------------------------------
From: "Michael D. Porter"
Date: Thu, 25 Jul 1996 09:24:27 -0700
Subject: Re: Diesel MAF-sensor?
Hans Hintermaier wrote:
>
>
> Can somebody tell me, what for I need MAF-sensoring in a diesel?
> I always thought a diesel takes as much air it can and regulates speed
> only with the amount of injected fuel?
>
> Hans
>
>This was not part of the diesel injection system, but rather part of
emission control system to control particulates.
Cheers.
------------------------------
From: ptimmerm@xxx.GOV
Date: Thu, 25 Jul 1996 08:33:30 -0700
Subject: Re: water injection questions???
>Paul: What kind of setup do you use for your "Intercooler sprayer"?
I have experimented with both water injection and intercooler spraying.
The intercooler spraying is a rail with two spray nozzles mounted in
the noze facia, pointing at the air to air intercooler. I run some
plastic pipe up from the trunk, tie wrapped to the underside of the car.
The trunk has a 5 gallon stainless tank and a CO2 tank and reg.
What I have noticed in testing is that with repeated runs, I normally
see a quick tail off in performance, becuase my intercooler is heating up.
I am moving slowely and sometime stop breifly between runs. The
first run will start with 20c ambient air, peak IC input of maybe 120c,
and peak output of 60c air. The next run I might get 150c from the turbo
and 80c air from the intercooler. This results in 5-10% reduction in power.
If I run the sprayer, I can run cooler runs, like my first example repeatedly.
As long as the water holds out.
My best results are runing concurrent IC spraying and water injection.
I run the water sprayer down stream of the IC, thus giving one more
cooling shot. I control the system by using turbo air output temperature,
becuase it heats up fast and I turn both on above about 65C.
I like the idea for a water to air IC, cuase you get around my heatup
problem. I don't want to do the necessary mods to make that happen in
my car, (yet?).
I can point you toward some sprayers in the McMaster Carr catalog.
I don't have it here right now but email me if you want them.
paul timmerman
------------------------------
From: "Michael T. Kasimirsky"
Date: Thu, 25 Jul 1996 11:47:33 -0400 (EDT)
Subject: RE: Throttle Body Sizing
How about suggestions for motorcycle applications? Specifically,
something that has a round flange to mount into a motorcycle intake
port. Something that could be rack mounted with 4 throttle bodies in a
row would be perfect.
Michael T. Kasimirsky ----> mtk@xxx.edu
Days: Staff Engineer or mk4u@xxx.edu
ASTM Test Monitoring Center Phi Gamma Delta,
Nights: 1992 Suzuki GSX-R750 Pilot NRA Life Member, AMA Member
1991 Suzuki GSF400 Bandit Mechanic DoD #1848
------------------------------
From: Ron Madurski
Date: Thu, 25 Jul 1996 11:14:40 -0500 (CDT)
Subject: Oops
:
:
:I've done this before. If you don't have a taker yet I can fill in for
:you.
:
Sorry about that. I didn't check to make sure I was only replying to
John.
- --
Ron Madurski
rmadursk@xxx.com
------------------------------
From: Byron Clemens
Date: Thu, 25 Jul 96 12:44:21 EDT
Subject: Slide throttles
Katech Inc.
24324 Sorrentino Ct.
Mt. Clemens, MI 48043
(810)791-4120
have made slide throttles for several unique applications of their
own in the past and may be willing to do some or sell parts. Slide
throttles open up the possibility ;-) of unique shapes and developing
a more linear throttle to area progression.
Byron
------------------------------
From: LotusM50@xxx.com
Date: Thu, 25 Jul 1996 14:02:36 -0400
Subject: Re: Throttle Body Sizing
In a message dated 96-07-24 18:18:30 EDT, eusmsrt@xxx.se (Markus
Strobl) writes:
<< A single 40mm TB sounds alittle restrictive for your application. But you
won't flow over 500cfm, like you calculate. I don't know enough about MGs
to recommend a specific size TB. Just as a comparison, my 5.7l V8 uses
twin 48mm TBs w/ 5800rpm redline.
>>
The Lotus Turbo Esprit which has a 2.2 liter engine, and in varying states of
development puts out 210 - 300 hp, uses a two twin 45mm throttle bodies in a
sidedraft type arrangement. A single 40mm throttle body does seem alittle
small for the MGB (for a 1.8 liter, with 125 - 175 hp). A side draft
carburator fitting for a MGB would take 40mm Webers or Dellortos, giving each
cylinder a 40 mm throttle plates. You might want to call TWM Induction, who
make FI throttle bodies, and ask them for their recommendation for an MGB. I
am sure it is an application with which they have dealt.
Cheers,
Bonn
------------------------------
From: "Robert E. Yorke"
Date: Thu, 25 Jul 1996 11:19:26 -0700 (PDT)
Subject: Re: water injection questions???
Paul: Don't think I can use the sprayers with my current setup. My
air-to-water intercooler is mounted inside my trunk, so a water spray onto
the intercooler would just flood hell out of everything! After re-reading
your post, I realize you're using an air-to-air vice air-to-water unit.
Your stated liking for the air-to-water type because of the desire to avoid
the heatup might be worthwhile, but you can't avoid it completely. Also,
the best the air-to-water can do is cool to ambient. Putting ice water in
the reservoir fixes THAT though, albeit for only a relatively short period
of time.
At 08:33 AM 7/25/96 -0700, you wrote:
>
>>Paul: What kind of setup do you use for your "Intercooler sprayer"?
>
>I have experimented with both water injection and intercooler spraying.
>
>The intercooler spraying is a rail with two spray nozzles mounted in
>the noze facia, pointing at the air to air intercooler. I run some
>plastic pipe up from the trunk, tie wrapped to the underside of the car.
>The trunk has a 5 gallon stainless tank and a CO2 tank and reg.
>
>What I have noticed in testing is that with repeated runs, I normally
>see a quick tail off in performance, becuase my intercooler is heating up.
>I am moving slowely and sometime stop breifly between runs. The
>first run will start with 20c ambient air, peak IC input of maybe 120c,
>and peak output of 60c air. The next run I might get 150c from the turbo
>and 80c air from the intercooler. This results in 5-10% reduction in power.
>If I run the sprayer, I can run cooler runs, like my first example repeatedly.
>As long as the water holds out.
>
>My best results are runing concurrent IC spraying and water injection.
>I run the water sprayer down stream of the IC, thus giving one more
>cooling shot. I control the system by using turbo air output temperature,
>becuase it heats up fast and I turn both on above about 65C.
>
>I like the idea for a water to air IC, cuase you get around my heatup
>problem. I don't want to do the necessary mods to make that happen in
>my car, (yet?).
>
>I can point you toward some sprayers in the McMaster Carr catalog.
>I don't have it here right now but email me if you want them.
>
>paul timmerman
>
>
Riverside, CA
2 '88 GTs!
------------------------------
From: Dig
Date: Thu, 25 Jul 1996 16:48:11 -0500
Subject: Re: water injection questions???
>
> >Paul: What kind of setup do you use for your "Intercooler sprayer"?
>
> I have experimented with both water injection and intercooler spraying.
>
> I like the idea for a water to air IC, cuase you get around my heatup
> problem. I don't want to do the necessary mods to make that happen in
> my car, (yet?).
I'm thinking about going to a beer cooler (ice chest) full of ice water
for use in my '91 GMC Syclone, which has an air/water system from the
factory.
There's also a company in the Northwest that makes a conversion kit
that allows re-routing of the A/C Freon to the liquid intercooler. 30
degree output temps are claimed, but I'm not sure how much faith I have
in such a claim. It's an interesting approach, nonetheless.
Dig
dig@xxx.edu
------------------------------
From: Gary W Harris
Date: Thu, 25 Jul 96 15:18:00 PDT
Subject: Re: DIY Throttle Body
Text item:
Another possibility is to use a throttle body injector "TBI" asssembly from a
late model GM product. These are very available at the local automotive
recycling yards, and are available in a wide range of sizes and in singal/dual
configurations. Just remove the injectors and you are left with an easy to
adapt assembly.
Regards,
Gary
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------------------------------
From: Gary W Harris
Date: Thu, 25 Jul 96 15:38:00 PDT
Subject: Re[2]: Diesel MAF-sensor?
Text item:
What about measuring the fuel flow--since the Dudsel operates at WOT, one could
use RPM/VE to calculate airflow (similar to a EFI MAP system), throttle position
to measure fuel flow, thus get some reasonable approximation allowing
particulate emission control.-- or perhaps fuel flow/injection timing needs to
modulated to control particulates
Gary
Hans Hintermaier wrote:
>
>
> Can somebody tell me, what for I need MAF-sensoring in a diesel?
> I always thought a diesel takes as much air it can and regulates speed
> only with the amount of injected fuel?
>
> Hans
>
>This was not part of the diesel injection system, but rather part of
emission control system to control particulates.
Cheers.
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Subject: Re: Diesel MAF-sensor?
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------------------------------
From: "Robert E. Yorke"
Date: Thu, 25 Jul 1996 15:48:04 -0700 (PDT)
Subject: Re: water injection questions???
Dig: For God's sake, can you provide the name/phone number of the source?
I've heard of that particular approach but have not been able to track it
down at all. Hopefully you can help!
At 04:48 PM 7/25/96 -0500, you wrote:
>>
>> >Paul: What kind of setup do you use for your "Intercooler sprayer"?
>>
>> I have experimented with both water injection and intercooler spraying.
>
>>
>> I like the idea for a water to air IC, cuase you get around my heatup
>> problem. I don't want to do the necessary mods to make that happen in
>> my car, (yet?).
>
>I'm thinking about going to a beer cooler (ice chest) full of ice water
>for use in my '91 GMC Syclone, which has an air/water system from the
>factory.
>
>There's also a company in the Northwest that makes a conversion kit
>that allows re-routing of the A/C Freon to the liquid intercooler. 30
>degree output temps are claimed, but I'm not sure how much faith I have
>in such a claim. It's an interesting approach, nonetheless.
>
>
>Dig
>dig@xxx.edu
>
>
>
Riverside, CA
2 '88 GTs!
------------------------------
From: talltom
Date: Thu, 25 Jul 1996 16:28:18 -0700 (PDT)
Subject: Re: Throttle body sizing
Alright, heads up everybody, I'm about to provide an example of ignorance
rivaled by few. Correct me if I'm wrong, but keep it under 100 mgs. eh?
All this stuff about throttle sizing, valve duration, rpm, add infinitum.
Who cares? Isn't the object to get as much velocity as possible?
Yes I know you can make the hole to big, but the reason it's to big is
that the valve flow rate isn't linear and opens too much at low speeds.
Anyhow what I'm threatening to do is use 8 2litre vw throttle bodies
that have the spherical recess that the throttle blade recesses into near
the idle position. To me it appears this will provide a gradual enough
opening, and serve to keep velocity high. Further, I'm going to make the
throttle plates all dump towards the top of the port as I believe it will
provide laminer air flow. Kinsler made fuel injection manifolds with
throttle plates that went one way on one side of the engine, and the other
way on the other side. What a riot!
PS. with a different cam and gears the computer sez my 54 cornbinder
dumptruck will do 9.79 in the quarter! :->
------------------------------
From: Craig Pugsley
Date: Fri, 26 Jul 1996 09:52:32 +1000 (EST)
Subject: Re: water injection questions???
> > I like the idea for a water to air IC, cuase you get around my heatup
> > problem. I don't want to do the necessary mods to make that happen in
> > my car, (yet?).
>
> I'm thinking about going to a beer cooler (ice chest) full of ice water
> for use in my '91 GMC Syclone, which has an air/water system from the
> factory.
>
> There's also a company in the Northwest that makes a conversion kit
> that allows re-routing of the A/C Freon to the liquid intercooler. 30
> degree output temps are claimed, but I'm not sure how much faith I have
> in such a claim. It's an interesting approach, nonetheless.
FWIW, A guy here (australia) made an intercooler system with air conditioning
parts. The part on the engine was constructed (I _think_) by having lots
of small tubes for the air to flow through and surrounded by the freon:
_____________________________________
|_______________________|
_______________________
|_______________________|
_______________________ <-- Air goes thru small tubes
|_______________________|
_______________________
______|_ ___________________ _|______
| | | |
| | | |
Freon in Freon out
This doesn't show the freon surrounding the smaller tubes.. use your
imagination.
As to the thermal efficiency and other such things.. I wouldn't have a
clue!!
The trick some people with rotary turbos use here (i/c on top of
engine, relatively flat) is to make up a set of walls to go around the
top of it and pile in ground up dry ice (for drag racing obviously).
I have heard they get air temps well below zero and a large increase in
power.
For a street application apparently a methanol-water mix
sprayed onto the i/c is reasonably effective.. I even thought about
using a CO2 fire extinguisher to spray on it, but the shock drop in temp
wouldn't be too good :-(
Cheers,
Craig.
------------------------------
From: "Michael D. Porter"
Date: Thu, 25 Jul 1996 18:29:45 -0700
Subject: Re: Re[2]: Diesel MAF-sensor?
Gary W Harris wrote:
>
> Text item:
>
> What about measuring the fuel flow--since the Dudsel operates at WOT, one could
> use RPM/VE to calculate airflow (similar to a EFI MAP system), throttle position
> to measure fuel flow, thus get some reasonable approximation allowing
> particulate emission control.-- or perhaps fuel flow/injection timing needs to
> modulated to control particulates
> Gary, the latest electronically-controlled heavy-duty diesels modulate
injector timing to control fuel flow. Most, upon start-up, use a
modified MAP sensor to establish a baseline for ambient atmospheric
pressure and ambient air temp, then, after start-up, the MAP only reads
turbo boost in the intake manifold. Most run primarily from a limited
number of sensors, including fuel pressure, and a heavily-mapped
operation cycle to include smoke reduction modes, etc., based on feedback
from the transmission and the throttle potentiometer.
The mass air-flow sensor used in the system I mentioned was linked to a
Ford computer which, I think, was used mostly to calculate inlet air
volume. Pre-programmed into the computer was a routine to initiate
heating of coils in ceramic disks which heated to a temperature capable
of burning off trapped particulates. It worked badly, and was finally
replaced by catalytic converters which work much more reliably than this
system ever did. I used that example simply to illustrate an awareness
of the problems associated with air flow through a MAF sensor.
Cheers.
>
>
------------------------------
From: Dig
Date: Thu, 25 Jul 1996 19:46:04 -0500 (CDT)
Subject: Re: water injection questions???
On Thu, 25 Jul 1996, Robert E. Yorke wrote:
> Dig: For God's sake, can you provide the name/phone number of the source?
> I've heard of that particular approach but have not been able to track it
> down at all. Hopefully you can help!
>
Kevin Moore
TTM Inc
(714)730-6018
Dig
dig@xxx.edu
------------------------------
From: "Stuart Woolford"
Date: Fri, 26 Jul 1996 13:51:33 +1100
Subject: Re: Filtering supply lines
> At 02:14 PM 7/24/96 +1100, Stuart Woolford wrote:
>
> >> The only way to guarantee you are at a true 0v ground is to run
> >> a wire back to the battery terminal.
> >
> >and what defines the battery terminal as 0v ground?
>
> The battery is the "power supply" for the entire electrical system. I think
> it was mentioned earlier that both the supply + and ground be run back to
> the battery. This helps in several key points:
no, the alternator is.. or at least, the job alternates ;)
> *The battery is extremely low internal impedence, and tends to "short out"
> high frequency noise.
not as low as a local ESR filter..
> *The battery acts as a large capacitor, absorbing both voltage spikes and
> supplying heavy load currents for short periods of time, and tending to
> average out the system voltage.
the system's + voltage, and reflecting these spikes onto the
batteries local ground (scaled down, naturally..)
> *The alternator is theoretically connected essentially directly to the
> battery, therefore absorbing most alternator noise.
the alternator is theoretically connected essenitally directly to
nothing, as there are very few theoretical connections in a working
car.. in real applications, the alternator connections are many and
varied (and often quite stupid..)
> >really - the battery terminal can be a particularly noise prone
> >ground point depending on the charging system design.. (from too much
> >car sterio install experience..)
>
> If this is the case, then the battery ground lead should be repaired or
> replaced. Any voltage drop from the battery to the chassis will affect ALL
> devices attached to the chassis. In my car I have separate 2Ga ground leads
this can also be seen as 'any voltage drop affects any
battery-earthed items only..'
> going to both the engine and the frame directly from the battery. This
> alleviated a lot of noise problems I was having with the stereo.
wrong.. if 90% of the system defines chassis ground as 0v, then that
is what it is, the battery is the item with the problem..
> Most grounding problems occur due to "ground loops", where there are several
> different paths back to the power supply (battery) from different devices
> within the car body. Each of the paths has a different finite resistance,
> and current flowing through them will generate a voltage across each of
> these resistances. This is what causes ground noise. In an ideal world,
this is not a ground loop, a ground loop is where you have a
circulating current in a finite resistance ground system, not a group
of seperate resistive grounds..
> every device in the whole vehicle would have it's own separate ground wire
> running directly back to the battery, then any noise or voltage drop
> generated on any given ground lead would have no effect on any other lead.
They would still not have stable local ground potentials, but as long
as you never connected them to each other, there would be less chance
of ground loops..
> Unfortunately, this is not the case, and auto manufacturers rely on the
> assumption that the body itself is a single homogenous conductor, which
> unfortunately it is not.
well, it is as close as you can get in a car...
it would be a REAL BAD THING for everything to run a lead back to the
battery - as each of these leads, with MUCH higher resistance than
the replaced chassis links, would both have a larger voltage drop
than the old system, and also pick up a lot more noise from the many
EMI generators carefully fitted to most cars..
remember, 90% of 'noise' problems in car electronics are EMI pickup,
not ground loops, unless the systems are incorrectly
designed/connected..
> The best you can hope to do is isolate your particular installation from the
> rest of the system by running it's own power and ground leads directly to
> the battery. There is one caveat to this approach - you must ensure that
and then not connecting it to ANYTHING..
> your ground lead is the ONLY path back to the battery from your system, if
> there are any other "hidden" connections to chassis ground from the
> installed equipment (ie a radio chassis or speaker - lead), all bets are
> off, you've now created a ground loop instead of eliminating one...
This isolates nothing, it just gives you a new ground potential, with
possibly more or less problems. unless the system has no other
connections, but then, most must have..
> >looking for a 'true' ground is usually not the solution, finding a
> >non-noisy one is quite a different job - I have usually found a good
> >solid frame ground to be good - you pick up so much noise on you
> >earth line to the battery that it gets real bad real fast. You just
> >need to find a frame ground with good conduction paths to the other
> >ground references you are linked to.
>
> This is the standard method, unfortunately it is an approach that masks the
> symptom rather than cures the disease. Sometimes it is the only thing you
> can do, to avoid, as you said, bad charging system design. Grounding and
> ground noise is a whole black art unto itself.
not really.. just design things to avoid ground related issues, it is
not that hard, just a tad more expensive, and impossible if you are
using 3rd party systems..
The problem is not ground potentials, or loops.
Most single systems will operate at any ground potential, so long as
all the internals share the same one, and then it does not matter if
you have a local chassis ground, a batter ground, or anything, so
long as they all see the same ground impedance, and it is within
allowable tolerances (unless it is a high-power application, just
about anything will be..)
The problem is with interconnected systems at different local ground
optentials/impedances, couples with EMI pickup. a battery connected
ground MAY help with the first (and may not, it depends what the
other grounds are doing..) but will add to the second.
- ----------------------------------------------------------------------
Stuart Woolford, stuart@xxx.nz
>>>>In VI Where Available<<<<
- ----------------------------------------------------------------------
------------------------------
From: Dig
Date: Thu, 25 Jul 1996 22:21:23 -0500 (CDT)
Subject: Intercooling (was Re: water injection questions???)
On Fri, 26 Jul 1996, Craig Pugsley wrote:
>
> FWIW, A guy here (australia) made an intercooler system with air conditioning
> parts. The part on the engine was constructed (I _think_) by having lots
> of small tubes for the air to flow through and surrounded by the freon:
{diagram deleted}
The TTM system for the Sy/Ty uses the stock air/water intercooler as the
"evaporator". (holes sealed up, of course) There is a catch- it requires
that you pre-cool the compressor outlet air via an external air-air
intercooler. The compressor head pressure climbs to unsafe levels when
300+ degree air meets the freon, so the air-air unit is required to get
the air temp to a level the freon intercooler can tolerate.
Dig
dig@xxx.edu
------------------------------
From: John Dammeyer
Date: Fri, 26 Jul 96 00:11 PDT
Subject: MAP vs. MAF
Can anyone point me to a FAQ or explain the difference between MAP and MAF
sensors and a why one would be better (or worse) than the other.
Thanks,
John.
Pioneers are the ones, face down in the mud,
with arrows in their backs.
Automation Artisans Inc. Ph. 604-544-4950
6468 Loganberry Place Fax 604-544-4954
Victoria BC CANADA V8Z 7E6
------------------------------
End of DIY_EFI Digest V1 #211
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