Home » Public Forums » GMCnet » Why GMCs Won't Get 20 MPG
| Why GMCs Won't Get 20 MPG [message #126845] |
Fri, 20 May 2011 23:26  |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Here is one I didn't see coming. After changing the final drive my trans burped a couple of times causing smoke and junk on my back window. No fire.
I jacked her up and cleaned everything off and tightened a couple of things.
Because it was on two stands and a strong floor jack, I decided to run it a bit in drive (to see if I could get a drip anywhere). No leaks... so far.
I know it is stupid to run a rig at 55 on jacks, but, please, just let that one go.
I happened to glance at my EBL Whats Up Display and saw that I was getting 20 mpg. This was interesting because I was only turning the engine/trans/final drive/CVs/speedometer and bearings. It was quiet and no vibration (good balance on tires) .
I decided to wait a few more seconds for LeanCruise to kick in and sure enough I was rewarded with 21mpg.
So, getting 10 mpg when actually driving is pretty good when the whole thing only gets 21 with the wheels off the ground.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: Why GMCs Won't Get 20 MPG [message #126846 is a reply to message #126845] |
Fri, 20 May 2011 23:28  |
GeorgeRud
Messages: 1380
Registered: February 2007
Location: Chicago, IL
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I imagine a lot of it comes from pushing a barn door through the wind at 60 mph - takes a lot of horsepower!
George Rudawsky
Chicago, IL
75 Palm Beach
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| Re: [GMCnet] Why GMCs Won't Get 20 MPG [message #126867 is a reply to message #126865] |
Sat, 21 May 2011 08:34 |
Gary Stoneking
Messages: 42
Registered: April 2011
Location: Minneapolis
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I've been thinking...(uh oh)
Piston aircraft are equipped with a pilot-operated mixture control that
gives the pilot the ability to lean the fuel/air mixture in flight. If
equipped with exhaust gas temperature (EGT) gauges for each cylinder, the
pilot can often lean the mixture to the lean side of peak EGT and save
pretty substantial fuel in cruise flight. Other than electronic fuel
injection, which controls the mixture for the operator automatically, is
there any way to gain control over the fuel/air mixture from the driver's
seat? I think tweaking the mixture would be a good way to increase miles
per gallon numbers, assuming the operator kept a close eye on the cylinder
head and exhaust gas temperatures.
On the other hand, if the temps get too high, detonation will ensue
(especially at high power settings) and he engine will be trashed.
Come to think of it, I guess that's why some engineer decided early on that
it would be a bad idea to put the red ball in the driver's hand...
On Sat, May 21, 2011 at 7:58 AM, Gord H <tze064v1000890@gmail.com> wrote:
>
>
> George Beckman wrote on Sat, 21 May 2011 00:26
> > I decided to wait a few more seconds for LeanCruise to kick in and sure
> enough I was rewarded with 21mpg.
> >
> > So, getting 10 mpg when actually driving is pretty good when the whole
> thing only gets 21 with the wheels off the ground.
>
>
> Hi George,
> I don't think that's a valid test really. Amusing sure, valid...well, if it
> is I would be upset if it wasn't getting in the 40 or 50 mpg range although
> I guess it is possible with the antiquated design the drivetrain is eating
> that much fuel just to rotate itself.
>
> Indeed, you're not moving weight (getting it in motion) or pushing a couple
> of sheets of plywood (i.e. the frontal area) through the wind so numbers
> have to be higher than real life - I sure would have thought they would be
> substantially higher though.
>
> Gord ;)
> --
> Scruffy 74 Canyonlands :) Use the forum - it's easy!
> http://gmc.mybirdfeeder.net/GMCforum/index.php?t=thread&frm_id=1
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| Re: [GMCnet] Why GMCs Won't Get 20 MPG [message #126870 is a reply to message #126867] |
Sat, 21 May 2011 08:56 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
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| Gary Stoneking wrote on Sat, 21 May 2011 06:34 |
I've been thinking...(uh oh)
Piston aircraft are equipped with a pilot-operated mixture control that
gives the pilot the ability to lean the fuel/air mixture in flight. ...
<< snipped >>
... I think tweaking the mixture would be a good way to increase miles
per gallon numbers, assuming the operator kept a close eye on the cylinder
head and exhaust gas temperatures.
On the other hand, if the temps get too high, detonation will ensue
(especially at high power settings) and he engine will be trashed.
Come to think of it, I guess that's why some engineer decided early on that
it would be a bad idea to put the red ball in the driver's hand...
|
I suspect that most aircraft see a wider range of air pressures (altitude) than MOST GMC's.
Might be why most aircraft have that control, and most GMC's do not.
---
From what I understand, the "best" gains in MPG seem to be from tweeking the spark advance, not the fuel mixture. With a CCD it is getting to the point of being worth the price from just a "money saved" point of view. (To install fuel injection with a CCD.)
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] Why GMCs Won't Get 20 MPG [message #126873 is a reply to message #126870] |
Sat, 21 May 2011 09:21 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Principal differences between GMC motorhomes and high flying aircraft is the
oxygen concentration in the air that they operate in. The less oxygen
present, the less fuel the engine requires. You lean that sucker out at sea
level and you are in for some very expensive repairs. P-51 Mustangs had that
ability when flying escort with B-17s, and it enabled them to fly all the
way to the heart of Germany and back. In theory, a very carefully calibrated
multi point fuel injection system with computer controlled spark should be
able to show a considerable improvement in fuel economy. Probably would too
if they would stop putting alcohol in gasoline. This GMC community contains
a very smart bunch of people, some of them formally trained, and some of
them, like me, had to gain their knowledge at the end of a wrench. None of
us like paying $4.00 a gallon for fuel, and I suspect that one of these days
we will show some progress in the economy department. But like we say,
pushing 12,000 pounds down the road with the frontal area of a barn door, at
70 MPH takes fuel.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sat, May 21, 2011 at 6:56 AM, Mike Miller <m000035@gmail.com> wrote:
>
>
> Gary Stoneking wrote on Sat, 21 May 2011 06:34
> > I've been thinking...(uh oh)
> > Piston aircraft are equipped with a pilot-operated mixture control that
> > gives the pilot the ability to lean the fuel/air mixture in flight. ...
> >
> > << snipped >>
> >
> > ... I think tweaking the mixture would be a good way to increase miles
> > per gallon numbers, assuming the operator kept a close eye on the
> cylinder
> > head and exhaust gas temperatures.
> > On the other hand, if the temps get too high, detonation will ensue
> > (especially at high power settings) and he engine will be trashed.
> > Come to think of it, I guess that's why some engineer decided early on
> that
> > it would be a bad idea to put the red ball in the driver's hand...
>
>
> I suspect that most aircraft see a wider range of air pressures (altitude)
> than MOST GMC's.
>
> Might be why most aircraft have that control, and most GMC's do not.
>
> ---
>
> From what I understand, the "best" gains in MPG seem to be from tweeking
> the spark advance, not the fuel mixture. With a CCD it is getting to the
> point of being worth the price from just a "money saved" point of view. (To
> install fuel injection with a CCD.)
> --
> Mike Miller -- Hillsboro, OR -- on the Black list
> '73 26' exPainted D. -- `78 23' Birchaven Rear Bath -- `77 23' Birchaven
> Side Bath
> http://m000035.blogspot.com
> _______________________________________________
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| Re: [GMCnet] Fwd: Why GMCs Won't Get 20 MPG [message #126877 is a reply to message #126874] |
Sat, 21 May 2011 10:16 |
Gary Stoneking
Messages: 42
Registered: April 2011
Location: Minneapolis
Karma: 0
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Emory,
Thanks for the clarification. I was wondering what the ice tongs would have
to do with fuel economy. :)
There is one more principal difference between aircraft engines and GMC Olds
engines. Aircraft engines are air-cooled. I've had both turbo and
non-turbocharged aircraft, and I can tell you that the non-turbo models poop
out real fast after about 12,000 feet. You need to lean the mixture up high
to keep it from becoming over-rich due to the decreasing barometric pressure
and resulting lack of available air for the fuel/air mixture. A turbo
simply replaces (or in some installations, increases or over-boosts) the
barometric pressure up to standard 29.92 inches (or beyond).
I think the comments on the EFI systems available are making me covet one.
On the other hand, maybe I should go to Dayton and actually LOOK at the
coach (pay for it and take delivery) before I go spending money on
upgrades. Waddya think?
On Sat, May 21, 2011 at 9:37 AM, Emery Stora <emerystora@mac.com> wrote:
>
>
> Begin forwarded message:
>
> > From: Emery Stora <emerystora@mac.com>
> > Date: May 21, 2011 8:17:38 AM MDT
> > To: "gmclist@temp.gmcnet.org" <gmclist@temp.gmcnet.org>
> > Subject: Re: [GMCnet] Why GMCs Won't Get 20 MPG
> >
> >
> >>
> >>
> >> Gary Stoneking wrote on Sat, 21 May 2011 06:34
> >>> I've been thinking...(uh oh)
> >>> Piston aircraft are equipped with a pilot-operated mixture control that
> >>> gives the pilot the ability to lean the fuel/air mixture in flight.
> ...
> >>>
> >>> << snipped >>
> >>>
> >>> ... I think tweaking the mixture would be a good way to increase miles
> >>> per gallon numbers, assuming the operator kept a close eye on the
> cylinder
> >>> head and exhaust gas temperatures.
> >>>
> >
> > Throttle body fuel injection systems will do that for you
> >
> > Something you can get is an MSD system from Jom Kanomata that will allow
> you to advance the the tong "on the fly". Get a knock sensor as well so you
> do have it advanced too far.
> >
> > Spark advance can really increase your performance if it's done properly
> >
> > Emery Stora
>
> This should have said "advance the TIMING on the fly".
> So much for automatic spell checkers! :)
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>
>
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| Re: [GMCnet] Fwd: Why GMCs Won't Get 20 MPG [message #126882 is a reply to message #126874] |
Sat, 21 May 2011 11:19 |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
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allow you to advance the the tong "on the fly". Get a knock sensor as well so you do have it advanced too far
__________________________________________________
I had thought that if the distributor adjustment could be moved with a screw type device to advance the setting ( it wouldn't take much ) that maybe it could be possible if it was worth the effort.
I was wondering how one might monitor the engine, a knock detector is kind of too much, might a dwell meter keep you tip top performance??? Isn't that what the new cars do???
I know the old distributor system is a bit crude to todays technology but it does offer some ability to work with you.
I am on the fence though, Airplanes go up where the air is thin and are adjusted for that, GMCs just climb a mountain now and then. If you were going up, would it work to just turn on a blower or some device to increase air to the carborator??? Wouldn't that do a similar function when compared to changing the dewell????
I think a blower, Maybe with a variable speed control, might be helpful. Hey I am with all of you, if we can get a couple of extra MPG, the book is open how we do it.
my thoughts
Gatsbys' CRUISER  08-18-04
74 GLACIER X, 260/455-APC-4 Bagg'r
Remflex Manifold gaskets
CampGrounds needed, Add yours to "PLACES" />
http://www.gmceast.com/travel
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| Re: [GMCnet] Fwd: Why GMCs Won't Get 20 MPG [message #126888 is a reply to message #126882] |
Sat, 21 May 2011 11:46 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Referencing back to WW2 air cooled aircraft engines in fighter aircraft that
were multistage supercharged and also adjusted so that more blower pressure
was added at higher altitudes, the blowers had to be designed so that their
effect was reduced at low altitude to prevent burning up the engines. Think
of the oxygen present at sea level and compare it to an oxy/acetelyne
cutting torch. The preheat flames, the small pinpoint ones arranged in a
circle on the outside ot the cutting tip, are adjusted so that they mix
equal parts of oxygen and acetelyne. When the torch is placed in close
proximity to a piece of steel, the preheat flames heat the steel up to red
heat. When that is achieved, pressure on the thumb lever on the torch
releases a jet of pure oxygen out of the large orfice in the center of the
torch. When that oxygen hits that preheated steel, the steel is immediately
consumed (or oxidized) and the force of the jet blows the molten slag out of
the way. Believe me when I tell you that the same thing will occur in an
internal combustion engine when too much oxygen, or not enough fuel,
unbalances the combustion mixture. Bad stuff is sure to result. I have been
on the receiving end of this equation more than once.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sat, May 21, 2011 at 9:19 AM, Larry <slawrence111@yahoo.com> wrote:
>
>
> allow you to advance the the tong "on the fly". Get a knock sensor as well
> so you do have it advanced too far
> __________________________________________________
>
> I had thought that if the distributor adjustment could be moved with a
> screw type device to advance the setting ( it wouldn't take much ) that
> maybe it could be possible if it was worth the effort.
>
> I was wondering how one might monitor the engine, a knock detector is kind
> of too much, might a dwell meter keep you tip top performance??? Isn't that
> what the new cars do???
>
> I know the old distributor system is a bit crude to todays technology but
> it does offer some ability to work with you.
>
> I am on the fence though, Airplanes go up where the air is thin and are
> adjusted for that, GMCs just climb a mountain now and then. If you were
> going up, would it work to just turn on a blower or some device to increase
> air to the carborator??? Wouldn't that do a similar function when compared
> to changing the dewell????
>
> I think a blower, Maybe with a variable speed control, might be helpful.
> Hey I am with all of you, if we can get a couple of extra MPG, the book is
> open how we do it.
>
> my thoughts
> --
> Gatsbys' CRUISER :d
> 74 GLACIER X, 260
> 455/APC/4 bagg'r(ver3)
> Remflex Manifold gaskets
> _______________________________________________
> Purchased 08-18-04
>
> _
>
>
>
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| Re: Why GMCs Won't Get 20 MPG [message #126889 is a reply to message #126845] |
Sat, 21 May 2011 11:57 |
chasingsummer
Messages: 434
Registered: May 2011
Location: asheboro, nc
Karma: 0
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or, like an aircooled porsche, with a fuel injector spray water into the air intake. the mist of water equals extra air, then if primative fuel injection tinker with heasd temp sensor which makes engine think it is cooler, so for it to increase spray and duration of fuel, no better mph, but better ump.
if i spary the water into a carb based motor, do i then open the other barrels for carb to pull in more gas? could i somehow get the increase in torque, and withincrease in torque would that equal better mph.
what does a spoiler in the front bottom do reference to the difference in air pressure on back side .
and could a small stepper motor be attached to distributer to advance it as needed,
car talk with a cold beer, crazy what a man can think is possible.
brian
asheboro, nc
75 eleganza, 74 build
119k miles and counting,
DOG HOUSE
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| Re: [GMCnet] Why GMCs Won't Get 20 MPG [message #126891 is a reply to message #126889] |
Sat, 21 May 2011 12:12 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Water injectors have been used with some success. Water when it turns to
steam, expands something like 1500 times its volume. I am unsure what that
equates to in terms of pressures but a substantial amount. Also quenches the
combustion flame front. In retrofitted engines whose combustion chambers
were not designed for such antics, the end results might not be what the
initial plan had in mind. Might be that a few more beers need to be consumed
in contemplation therof. Bench racin' usually don't involve broken parts, it
only occurs when the plans move past the sittin' and talkin' stage.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sat, May 21, 2011 at 9:57 AM, brian <chasingsummer@triad.rr.com> wrote:
>
>
> or, like an aircooled porsche, with a fuel injector spray water into the
> air intake. the mist of water equals extra air, then if primative fuel
> injection tinker with heasd temp sensor which makes engine think it is
> cooler, so for it to increase spray and duration of fuel, no better mph, but
> better ump.
> if i spary the water into a carb based motor, do i then open the other
> barrels for carb to pull in more gas? could i somehow get the increase in
> torque, and withincrease in torque would that equal better mph.
> what does a spoiler in the front bottom do reference to the difference in
> air pressure on back side .
> and could a small stepper motor be attached to distributer to advance it as
> needed,
> car talk with a cold beer, crazy what a man can think is possible.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Why GMCs Won't Get 20 MPG [message #126929 is a reply to message #126870] |
Sat, 21 May 2011 22:01 |
rvanwin
Messages: 325
Registered: April 2007
Location: Battlefield, MO
Karma: 6
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Senior Member |
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| mike miller wrote on Sat, 21 May 2011 08:56 |
From what I understand, the "best" gains in MPG seem to be from tweeking the spark advance, not the fuel mixture. With a CCD it is getting to the point of being worth the price from just a "money saved" point of view. (To install fuel injection with a CCD.)
|
Mike,
George Beckman and I (both running TBI with the EBL enhancement) have done some extensive tests changing the AFR and Spark Advance and monitoring mpg to see the effects. We have presented our findings at the last two GMCMHI rallies. We laid out a 2 mile course, fairly flat, and ran with each setting in both direction to account for elevation change and wind conditions. The EBL allows you to see the mpg both instantaneous and trip. We zeroed the trip at the start of the 2 miles and recorded the mpg at the end of the 2 miles. We started with SA at around 36 and increased SA by 3 degrees for each run to arrive at a "best case" SA for max mpg. We then allowed the EBL to go into "lean cruise" and tried different AFRs from 16:1 up to 18.5:1. We have EFTs installed for both banks so could monitor exhaust gas temps as we changed the fuel ratio. At cruise, temps are not a problem while lean - you actually see a slight drop in temps because the additional air tends to cool the combustion. However, and this is what you have to really watch, as the load increases EGT goes up extremely fast and you can quickly get into trouble. We found that for our heavy coaches, mpg started to drop off some after about 16.5:1. We also increased the SA some to compensate for the slower flame front finding that about 5 degrees additional during 16.5:1 AFR seemed to be about the best. Prior to Patterson, I ran a few additional runs to see the affect of mph on mpg. I ran at 40 mph, 50 mph, 60 mph, and 70 mph. My wife was the scribe and wouldn't let me do 80 mph  Each 10 mph cost about 2 mpg. Of course in overall driving conditions you would not get this much difference because accelerating from a stop and climbing hills, etc. is going to consume about the same fuel no matter the final cruise speed you decide to run at. Right now, I feel like I have my SA tuned fairly well for my engine. Pretty much knock limited during hard pulls and close to optimal SA for cruising (based on mpg tests).
The full presentation is posted in the members section at gmcmi.com (<http://gmcmi.com/mem-bers/tech_handouts.html>) and contains charts showing the above results.
Randy & Margie
'77 Eleganza II '403'
Battlefield, MO
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| Re: [GMCnet] Why GMCs Won't Get 20 MPG [message #127083 is a reply to message #126891] |
Mon, 23 May 2011 09:32 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Water injection helps by cooling the combustion somewhat. The amount of heat required to turn water to steam - which is substantial - is removed, cutting peak temps and (hopefully) preignition. It was also used in some jet engines for the same reason... you could get a bit more power out o the engine without melting the hot section by throwing some water into it.
--johnnny
--- On Sat, 5/21/11, James Hupy <jamesh1296@gmail.com> wrote:
From: James Hupy <jamesh1296@gmail.com>
Subject: Re: [GMCnet] Why GMCs Won't Get 20 MPG
To: gmclist@temp.gmcnet.org
Date: Saturday, May 21, 2011, 5:12 PM
Water injectors have been used with some success. Water when it turns to
steam, expands something like 1500 times its volume. I am unsure what that
equates to in terms of pressures but a substantial amount. Also quenches the
combustion flame front. In retrofitted engines whose combustion chambers
were not designed for such antics, the end results might not be what the
initial plan had in mind. Might be that a few more beers need to be consumed
in contemplation therof. Bench racin' usually don't involve broken parts, it
only occurs when the plans move past the sittin' and talkin' stage.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sat, May 21, 2011 at 9:57 AM, brian <chasingsummer@triad.rr.com> wrote:
>
>
> or, like an aircooled porsche, with a fuel injector spray water into the
> air intake. the mist of water equals extra air, then if primative fuel
> injection tinker with heasd temp sensor which makes engine think it is
> cooler, so for it to increase spray and duration of fuel, no better mph, but
> better ump.
> if i spary the water into a carb based motor, do i then open the other
> barrels for carb to pull in more gas? could i somehow get the increase in
> torque, and withincrease in torque would that equal better mph.
> what does a spoiler in the front bottom do reference to the difference in
> air pressure on back side .
> and could a small stepper motor be attached to distributer to advance it as
> needed,
> car talk with a cold beer, crazy what a man can think is possible.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Why GMCs Won't Get 20 MPG [message #127087 is a reply to message #126891] |
Mon, 23 May 2011 09:49 |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
Karma: 0
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Senior Member |
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Do we know if there is a real difference when driving in dry hot weather or driving in humid, rainy conditions or FOG. Does the MPG get affected????
Would steam, introduced to the air breather to the carb offer any enhancements without any negative problems or would it just be best to leave as it is.
Gatsbys' CRUISER 08-18-04
74 GLACIER X, 260/455-APC-4 Bagg'r
Remflex Manifold gaskets
CampGrounds needed, Add yours to "PLACES" />
http://www.gmceast.com/travel
_
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| Re: [GMCnet] Why GMCs Won't Get 20 MPG [message #127102 is a reply to message #127087] |
Mon, 23 May 2011 10:47 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Water injection would have the secondary "benefit ?" of decarbonizing the
combustion chamber and exhaust valves. I don't know if/how that would affect
performance, but I do know that KR & KRTT Harleys don't make their best
power until they have a nice soot layer on everything. I know, some of you
will ask, "What is a KR and KRTT? They are HD racing bikes from the old side
valve days. I have some experience with them in hop up mode. Cold dense
morning air makes engines that are a little too rich on the main jets run
like a scalded cat, so in this instance I would have to answer in the
affirmative. No engineering data to support this, just seat of the pants
observations.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Mon, May 23, 2011 at 7:49 AM, Larry <slawrence111@yahoo.com> wrote:
>
>
> Do we know if there is a real difference when driving in dry hot weather or
> driving in humid, rainy conditions or FOG. Does the MPG get affected????
>
> Would steam, introduced to the air breather to the carb offer any
> enhancements without any negative problems or would it just be best to leave
> as it is.
>
>
> --
> Gatsbys' CRUISER :d
> 74 GLACIER X, 260
> 455/APC/4 bagg'r(ver3)
> Remflex Manifold gaskets
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| Re: [GMCnet] Why GMCs Won't Get 20 MPG [message #127131 is a reply to message #127102] |
Mon, 23 May 2011 12:46 |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
Karma: 0
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Senior Member |
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Well, I am aware of the benefit of cool air vs hot. We used to run jet engine peaking units at out plant. in the Summer we could get about 20-21 megawatts of power versus in the Winter we would get 25-26 megawatts of power with the cool thick air.
My thought on a blower was if you were going up in the mountains, you could fire up a blower to pump in a larger volume of air to try to equalize the loss at the higher level.
My commnet on the vapour ( water ) goes many places but I don't like the idea of a spray above the carb. a malfunction could be devastating.
I asked about differences in economy dry vs rainy weather because of an interest in the humidity vs mpg.
I know, having come from a steam power plant, that a tiny bit of water creates an unbelievable amount of pressure. So for my thought if we were to introduce low psi steam to the carb air flow, would the moisture content be enough to help expand/build psi to make the mpg be affected or is it all just a wild pipe thought? I really had not considered the cleaning affect of the vapour, but I am aware of it.
Or maybe we can sell this as another " HOT GAS SAVING INVENTION ", the pot that makes the steam would be mounted on the maifold or exhaust pipes, so efficiency gained by reusing lost heat, and the low psi steam would feed to the air intake to supply the motor with vapour which would flash to steam in the cyclinders as the feul burned creating more pressure/push and upping the MPG quotient. 
Look out EBay, here I come...
Gatsbys' CRUISER 08-18-04
74 GLACIER X, 260/455-APC-4 Bagg'r
Remflex Manifold gaskets
CampGrounds needed, Add yours to "PLACES" />
http://www.gmceast.com/travel
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