Home » Public Forums » GMCnet » Electric powered altitude compensation blower
| Electric powered altitude compensation blower [message #175808] |
Fri, 06 July 2012 19:14  |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
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OK, I'm probably opening up a big can o' worms here. Up front, I'll say that I fully understand that the "electric superchargers" on the market are almost entirely scams that probably slow down air flow rather than improving it. I'd thought through this before, and realized there's just no good way to put enough 12VDC through a motor to get enough boost to matter, especially not with something that fits under the hood of any of my cars.
Then I end up with a vehicle with not only cavernous empty spaces around the engine, but that has 120VAC available. Not only that, but since it's got a carb instead of fuel injection, it's going to lose power at high altitude. My feeble mind rolls all these issues around for a while, and then starts plotting.
I'm no expert on fan theory, but it looks like it just might be possible to boost a 403ci motor enough to matter at altitude (I'm not looking for "more power", just for keeping what I've got when driving at higher altitudes, which I plan to do frequently). That's done on some aircraft as well, where the only goal is to keep the sea level performance at cruising altitude (not to make heaps of power at sea level).
A fan like this one: https://www.grainger.com/Grainger/DAYTON-PSC-Blower-1TDU2?Pid=search seems to have the stones to push a fair amount of air at a reasonable amount of extra pressure. I did a crude extrapolation of the numbers (which I admit is a SWAG at best) and came up with something like a pressure of 3 inches of mercury at 650cfm (the limit of my carb). I also read that you have to apply a factor of about 1.5x to a fan's rating if you're using at 10,000 feet (presumably because it's easier to compress thinner air). Based on all that (and allowing that my numbers might be WAY off), I guess that - assuming not much loss in the system - that I could maintain the performance the motor has at 5,000 when I'm driving at 10,000 feet.
If so... whoo hoo!  Obviously, I'd only use this when my foot is planted on the floor and I'm struggling up a nasty grade.
The other reason I chose that motor is because my 1,000 watt inverter (soon to be installed) should drive it nicely, and also because the alternator could just about keep up with the need, too.
So - if anyone out there is well-versed in fan design, pressure, and all things aerodynamic, please feel free to throw cold water all over me. I could use it... it's triple digits here!
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175811 is a reply to message #175808] |
Fri, 06 July 2012 20:15  |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Interesting idea. I'd probably lean towards the blowers we use to cool transmitter tubes.. they're very similar to that. GE design, and tolerate relatively high static pressure. And they're built to take a fabric plenum at the oulet. I'll try to find a picture or drawing and send you.
--johnny
'76 23' transmode norris
'76 palm beach
From: Mark <mark@habcycles.com>
To: gmclist@temp.gmcnet.org
Sent: Friday, July 6, 2012 8:14 PM
Subject: [GMCnet] Electric powered altitude compensation blower
OK, I'm probably opening up a big can o' worms here. Up front, I'll say that I fully understand that the "electric superchargers" on the market are almost entirely scams that probably slow down air flow rather than improving it. I'd thought through this before, and realized there's just no good way to put enough 12VDC through a motor to get enough boost to matter, especially not with something that fits under the hood of any of my cars.
Then I end up with a vehicle with not only cavernous empty spaces around the engine, but that has 120VAC available. Not only that, but since it's got a carb instead of fuel injection, it's going to lose power at high altitude. My feeble mind rolls all these issues around for a while, and then starts plotting.
I'm no expert on fan theory, but it looks like it just might be possible to boost a 403ci motor enough to matter at altitude (I'm not looking for "more power", just for keeping what I've got when driving at higher altitudes, which I plan to do frequently). That's done on some aircraft as well, where the only goal is to keep the sea level performance at cruising altitude (not to make heaps of power at sea level).
A fan like this one: https://www.grainger.com/Grainger/DAYTON-PSC-Blower-1TDU2?Pid=search seems to have the stones to push a fair amount of air at a reasonable amount of extra pressure. I did a crude extrapolation of the numbers (which I admit is a SWAG at best) and came up with something like a pressure of 3 inches of mercury at 650cfm (the limit of my carb). I also read that you have to apply a factor of about 1.5x to a fan's rating if you're using at 10,000 feet (presumably because it's easier to compress thinner air). Based on all that (and allowing that my numbers might be WAY off), I guess that - assuming not much loss in the system - that I could maintain the performance the motor has at 5,000 when I'm driving at 10,000 feet.
If so... whoo hoo! :d Obviously, I'd only use this when my foot is planted on the floor and I'm struggling up a nasty grade.
The other reason I chose that motor is because my 1,000 watt inverter (soon to be installed) should drive it nicely, and also because the alternator could just about keep up with the need, too.
So - if anyone out there is well-versed in fan design, pressure, and all things aerodynamic, please feel free to throw cold water all over me. I could use it... it's triple digits here!
--
1978 Royale Center Kitchen
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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] Electric powered altitude compensation blower [message #175842 is a reply to message #175808] |
Fri, 06 July 2012 23:38 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Mark,
Someone with better math skill could figger out the volume of air that a 455
cubic inch Olds motor consumes at highway speed of around 2500 RPM.
It would take one hell of an electric blower to keep up let alone boost the
pressure!
Regards,
Rob
-----Original Message-----
From: Mark
Then I end up with a vehicle with not only cavernous empty spaces around the
engine, but that has 120VAC available. Not only that, but since it's got a
carb instead of fuel injection, it's going to lose power at high altitude.
My feeble mind rolls all these issues around for a while, and then starts
plotting.
I'm no expert on fan theory, but it looks like it just might be possible to
boost a 403ci motor enough to matter at altitude (I'm not looking for "more
power", just for keeping what I've got when driving at higher altitudes,
which I plan to do frequently). That's done on some aircraft as well, where
the only goal is to keep the sea level performance at cruising altitude (not
to make heaps of power at sea level).
A fan like this one:
https://www.grainger.com/Grainger/DAYTON-PSC-Blower-1TDU2?Pid=search seems
to have the stones to push a fair amount of air at a reasonable amount of
extra pressure. I did a crude extrapolation of the numbers (which I admit
is a SWAG at best) and came up with something like a pressure of 3 inches of
mercury at 650cfm (the limit of my carb). I also read that you have to
apply a factor of about 1.5x to a fan's rating if you're using at 10,000
feet (presumably because it's easier to compress thinner air). Based on all
that (and allowing that my numbers might be WAY off), I guess that -
assuming not much loss in the system - that I could maintain the performance
the motor has at 5,000 when I'm driving at 10,000 feet.
If so... whoo hoo! :d Obviously, I'd only use this when my foot is
planted on the floor and I'm struggling up a nasty grade.
The other reason I chose that motor is because my 1,000 watt inverter (soon
to be installed) should drive it nicely, and also because the alternator
could just about keep up with the need, too.
So - if anyone out there is well-versed in fan design, pressure, and all
things aerodynamic, please feel free to throw cold water all over me. I
could use it... it's triple digits here!
--
1978 Royale Center Kitchen
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175861 is a reply to message #175842] |
Sat, 07 July 2012 09:39 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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How about a couple of backpack leaf blowers, one for each bank of
cylinders? <grin>
Jim Hupy
Salem, OR
78 GMC Royale 403
On Fri, Jul 6, 2012 at 9:38 PM, Rob Mueller <robmueller@iinet.net.au> wrote:
> Mark,
>
> Someone with better math skill could figger out the volume of air that a
> 455
> cubic inch Olds motor consumes at highway speed of around 2500 RPM.
>
> It would take one hell of an electric blower to keep up let alone boost the
> pressure!
>
> Regards,
> Rob
>
>
> -----Original Message-----
> From: Mark
>
> Then I end up with a vehicle with not only cavernous empty spaces around
> the
> engine, but that has 120VAC available. Not only that, but since it's got a
> carb instead of fuel injection, it's going to lose power at high altitude.
> My feeble mind rolls all these issues around for a while, and then starts
> plotting.
>
> I'm no expert on fan theory, but it looks like it just might be possible to
> boost a 403ci motor enough to matter at altitude (I'm not looking for "more
> power", just for keeping what I've got when driving at higher altitudes,
> which I plan to do frequently). That's done on some aircraft as well,
> where
> the only goal is to keep the sea level performance at cruising altitude
> (not
> to make heaps of power at sea level).
>
> A fan like this one:
> https://www.grainger.com/Grainger/DAYTON-PSC-Blower-1TDU2?Pid=search seems
> to have the stones to push a fair amount of air at a reasonable amount of
> extra pressure. I did a crude extrapolation of the numbers (which I admit
> is a SWAG at best) and came up with something like a pressure of 3 inches
> of
> mercury at 650cfm (the limit of my carb). I also read that you have to
> apply a factor of about 1.5x to a fan's rating if you're using at 10,000
> feet (presumably because it's easier to compress thinner air). Based on
> all
> that (and allowing that my numbers might be WAY off), I guess that -
> assuming not much loss in the system - that I could maintain the
> performance
> the motor has at 5,000 when I'm driving at 10,000 feet.
>
> If so... whoo hoo! :d Obviously, I'd only use this when my foot is
> planted on the floor and I'm struggling up a nasty grade.
>
> The other reason I chose that motor is because my 1,000 watt inverter (soon
> to be installed) should drive it nicely, and also because the alternator
> could just about keep up with the need, too.
>
> So - if anyone out there is well-versed in fan design, pressure, and all
> things aerodynamic, please feel free to throw cold water all over me. I
> could use it... it's triple digits here!
> --
> 1978 Royale Center Kitchen
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> _______________________________________________
> GMCnet mailing list
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175869 is a reply to message #175817] |
Sat, 07 July 2012 11:19 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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| ljdavick wrote on Fri, 06 July 2012 18:59 |
I've got a buddy who has a '99 Viper and his buddy with a 2000 has supercharged the beast. I'm awestruck by the thought that went into stuffing a supercharger to the front of that engine.
If they can do it so can we. Start with the Howell intake and drill in the port fuel injection. Now bolt a blower on the thing and twist your CV joints into dust.
Me, I'm happy when she just gets us where we want to go.
|
Me too, but I want to be able to go over 10,000 feet without worrying about having enough power to get up the mountains in Colorado (where roads regularly go well over 10,000 feet). I don't expect that this mod (if it works as I think it should) would produce much in the way of extra power at sea level, but I think it would maintain a lot more of its performance at altitudes where our carb-fed engines are gasping for air.
And since I have a "mere 403" in my rig, I can add more horsepower without stressing my drive train any more than all those 1973-77 455s.
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175872 is a reply to message #175842] |
Sat, 07 July 2012 11:29 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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Senior Member |
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| Robert Mueller wrote on Fri, 06 July 2012 21:38 |
Mark,
Someone with better math skill could figger out the volume of air that a 455
cubic inch Olds motor consumes at highway speed of around 2500 RPM.
It would take one hell of an electric blower to keep up let alone boost the
pressure!
|
I agree, though I took the simple route and figured that the total air quantity needs of the engine by definition aren't going to exceed that of the carburetor. I figured that most of our rigs have carbs in the 650cfm range, so that's what I based my SWAG on.
The fan I referenced can produce 1202cfm unrestricted (no pressure), and 1040cfm at an output pressure of 0.8 inches of mercury, so it'll obviously produce a lot more output pressure when it's supplying "only" 650cfm. According to my thumbnail SWAG, it would produce something like 3 inches of mercury pressure at 650cfm flow rate at sea level, which (according to reading I did on fan theory) would be multiplied by about 1.5x at 10,000 feet, for a result of about 5 inches of mercury output pressure increase at 650cfm, which (if I didn't screw up the calculations) would effectively fool the engine into acting like it's at 5,000 feet instead of 10,000 feet (which would be a huge difference).
I'll apologize in advance for any mis-use of terminology and calculation above... I'm no airflow engineer (by a long, long shot). But I AM a cheapskate who flinches when I think of spending $1200+ on a Howell fuel injection system to allow my rig to go reliably where I want to take it. If there's an easier / cheaper / less involved way to get there, I'm all for it. I just hope there is someone out there who could validate my assumptions - or nix them, either option is fine with me.
I wanted to add this table: http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html
It's the rationale behind my use of inches of mercury as a basis for altitude compensation (with the difference between 5,000 and 10,000 feet being 4.3 inches of mercury, or about 2.1psi).
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
[Updated on: Sat, 07 July 2012 11:50] Report message to a moderator |
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175875 is a reply to message #175872] |
Sat, 07 July 2012 11:48 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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While the idea is interesting, it seems your concern is more performance at altitude than pursuing the design.
So, from an economics perspective -- $310 for blower, $35 shipping, $150 for ducting, $125 for wiring and controls, $300 for rebuilt carb (if not now, sometime in future) versus $1200 (your number) for EFI -- which also gives you spark control, better starting and such. So $900 guess/estimate on unknown vs $1200 on proven. Value buyers would go with the latter.
Oh, with a 403 you could also install an Edelbrock manifold and not raise the floor.
As for the twin leaf blowers -- I recall Jim Hall of Chapparal fame used a snow blower to hold his car to the track.
Dennis
| habbyguy wrote on Sat, 07 July 2012 11:29 |
| Robert Mueller wrote on Fri, 06 July 2012 21:38 |
Mark,
Someone with better math skill could figger out the volume of air that a 455
cubic inch Olds motor consumes at highway speed of around 2500 RPM.
It would take one hell of an electric blower to keep up let alone boost the
pressure!
|
I agree, though I took the simple route and figured that the total air quantity needs of the engine by definition aren't going to exceed that of the carburetor. I figured that most of our rigs have carbs in the 650cfm range, so that's what I based my SWAG on.
The fan I referenced can produce 1202cfm unrestricted (no pressure), and 1040cfm at an output pressure of 0.8 inches of mercury, so it'll obviously produce a lot more output pressure when it's supplying "only" 650cfm. According to my thumbnail SWAG, it would produce something like 3 inches of mercury pressure at 650cfm flow rate at sea level, which (according to reading I did on fan theory) would be multiplied by about 1.5x at 10,000 feet, for a result of about 5 inches of mercury output pressure increase at 650cfm, which (if I didn't screw up the calculations) would effectively fool the engine into acting like it's at 5,000 feet instead of 10,000 feet (which would be a huge difference).
I'll apologize in advance for any mis-use of terminology and calculation above... I'm no airflow engineer (by a long, long shot). But I AM a cheapskate who flinches when I think of spending $1200+ on a Howell fuel injection system to allow my rig to go reliably where I want to take it. If there's an easier / cheaper / less involved way to get there, I'm all for it. I just hope there is someone out there who could validate my assumptions - or nix them, either option is fine with me.
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175876 is a reply to message #175875] |
Sat, 07 July 2012 11:58 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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Senior Member |
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| Dennis S wrote on Sat, 07 July 2012 09:48 |
So, from an economics perspective -- $310 for blower, $35 shipping, $150 for ducting, $125 for wiring and controls, $300 for rebuilt carb (if not now, sometime in future) versus $1200 (your number) for EFI -- which also gives you spark control, better starting and such. So $900 guess/estimate on unknown vs $1200 on proven. Value buyers would go with the latter.
|
Thanks for the input, but I assume (maybe somewhat naively) that the costs will be considerably lower than that.
I suspect I could find hundreds of used blowers for a small fraction of that $310 WWG wants for theirs. Shipping might still apply. I doubt I'd spend anything close to $150 on ducting (essentially, just adapting whatever is on the output of the fan to a hose that can be adapted to the air horn on my air cleaner housing). "Wiring and controls" would probably involve no more than a length of Romex with a switch (either manual or connected to the carb linkage to operate only at full throttle). And I suppose a carb rebuild is always a good thing, but mine's in great shape, and I don't believe my scheme would alter that (since the end result of driving with it on at 10,000 feet would be like driving it with it off at 5,000 feet). So in the end, it's very possible that I could implement the system for $200-300 total (maybe even less, I haven't priced used fans).
FWIW, I envision that rather than using any kind of movable flappers or any other complication, that I'd simply plumb all the engine air through the fan (which would presumably have much less restriction than the air filter, because of its open "squirrel cage" design). That way, intake air would just flow through the fan when "just driving along", or be boosted carb-ward when needed.
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175877 is a reply to message #175876] |
Sat, 07 July 2012 12:22 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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In my experience projects/experimental often cost far more. And prototypes may prove out -- but you never get the full benefit until you build the final version. So, yes, respectfully, I think you are very low in your $300 estimate.
Your carb may be fine now -- the number I threw in was sooner or later -- but, here again you may wish to rebuild your own.
Maybe you want to use the coach for a trip or two and then decide on your performance concerns.
Dennis
| habbyguy wrote on Sat, 07 July 2012 11:58 |
| Dennis S wrote on Sat, 07 July 2012 09:48 |
So, from an economics perspective -- $310 for blower, $35 shipping, $150 for ducting, $125 for wiring and controls, $300 for rebuilt carb (if not now, sometime in future) versus $1200 (your number) for EFI -- which also gives you spark control, better starting and such. So $900 guess/estimate on unknown vs $1200 on proven. Value buyers would go with the latter.
|
Thanks for the input, but I assume (maybe somewhat naively) that the costs will be considerably lower than that.
I suspect I could find hundreds of used blowers for a small fraction of that $310 WWG wants for theirs. Shipping might still apply. I doubt I'd spend anything close to $150 on ducting (essentially, just adapting whatever is on the output of the fan to a hose that can be adapted to the air horn on my air cleaner housing). "Wiring and controls" would probably involve no more than a length of Romex with a switch (either manual or connected to the carb linkage to operate only at full throttle). And I suppose a carb rebuild is always a good thing, but mine's in great shape, and I don't believe my scheme would alter that (since the end result of driving with it on at 10,000 feet would be like driving it with it off at 5,000 feet). So in the end, it's very possible that I could implement the system for $200-300 total (maybe even less, I haven't priced used fans).
FWIW, I envision that rather than using any kind of movable flappers or any other complication, that I'd simply plumb all the engine air through the fan (which would presumably have much less restriction than the air filter, because of its open "squirrel cage" design). That way, intake air would just flow through the fan when "just driving along", or be boosted carb-ward when needed.
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175903 is a reply to message #175842] |
Sat, 07 July 2012 15:14 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Well, lessee...2500 RPM is 1250 IPM (intakes per minute) innit? so, 1250*445cid=568750 CI per minute. Divide that by 1758 (12 cubed) would give us just under 330 CFM at ambient pressure. Now, if we wanna run 15 psi absolute, and at 10K feet it's closer to 10PSI, we need some leeway. The blower I mentioned provides 550CFM at a fairly good pressure - probably not 5 psi, but several anyway. Consequently it oughta work. The whole idea is to hold just at 39 inches MAP all the way up the lountain, no? For this purpose however, I betcha a turbocharger and in intercooler would do a better job. Since lag isn't an issue in this service, you could hang it out in the wind someplace or duct some air to it to cool it down.
--johnny
From: Rob Mueller <robmueller@iinet.net.au>
To: gmclist@temp.gmcnet.org
Sent: Saturday, July 7, 2012 12:38 AM
Subject: Re: [GMCnet] Electric powered altitude compensation blower
Mark,
Someone with better math skill could figger out the volume of air that a 455
cubic inch Olds motor consumes at highway speed of around 2500 RPM.
It would take one hell of an electric blower to keep up let alone boost the
pressure!
Regards,
Rob
-----Original Message-----
From: Mark
Then I end up with a vehicle with not only cavernous empty spaces around the
engine, but that has 120VAC available. Not only that, but since it's got a
carb instead of fuel injection, it's going to lose power at high altitude.
My feeble mind rolls all these issues around for a while, and then starts
plotting.
I'm no expert on fan theory, but it looks like it just might be possible to
boost a 403ci motor enough to matter at altitude (I'm not looking for "more
power", just for keeping what I've got when driving at higher altitudes,
which I plan to do frequently). That's done on some aircraft as well, where
the only goal is to keep the sea level performance at cruising altitude (not
to make heaps of power at sea level).
A fan like this one:
https://www.grainger.com/Grainger/DAYTON-PSC-Blower-1TDU2?Pid=search seems
to have the stones to push a fair amount of air at a reasonable amount of
extra pressure. I did a crude extrapolation of the numbers (which I admit
is a SWAG at best) and came up with something like a pressure of 3 inches of
mercury at 650cfm (the limit of my carb). I also read that you have to
apply a factor of about 1.5x to a fan's rating if you're using at 10,000
feet (presumably because it's easier to compress thinner air). Based on all
that (and allowing that my numbers might be WAY off), I guess that -
assuming not much loss in the system - that I could maintain the performance
the motor has at 5,000 when I'm driving at 10,000 feet.
If so... whoo hoo! :d Obviously, I'd only use this when my foot is
planted on the floor and I'm struggling up a nasty grade.
The other reason I chose that motor is because my 1,000 watt inverter (soon
to be installed) should drive it nicely, and also because the alternator
could just about keep up with the need, too.
So - if anyone out there is well-versed in fan design, pressure, and all
things aerodynamic, please feel free to throw cold water all over me. I
could use it... it's triple digits here!
--
1978 Royale Center Kitchen
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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] Electric powered altitude compensation blower [message #175906 is a reply to message #175872] |
Sat, 07 July 2012 15:27 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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The manigfold problem is easy. Build a tin box which encloses the carb air tight. As long as you don't go over 30 inches MAP, it should still be balanced, because the entire carb would be subject to the same as that going down the throat.
--johnny
From: Mark <mark@habcycles.com>
To: gmclist@temp.gmcnet.org
Sent: Saturday, July 7, 2012 12:29 PM
Subject: Re: [GMCnet] Electric powered altitude compensation blower
Robert Mueller wrote on Fri, 06 July 2012 21:38
> Mark,
>
> Someone with better math skill could figger out the volume of air that a 455
> cubic inch Olds motor consumes at highway speed of around 2500 RPM.
>
> It would take one hell of an electric blower to keep up let alone boost the
> pressure!
I agree, though I took the simple route and figured that the total air quantity needs of the engine by definition aren't going to exceed that of the carburetor. I figured that most of our rigs have carbs in the 650cfm range, so that's what I based my SWAG on.
The fan I referenced can produce 1202cfm unrestricted (no pressure), and 1040cfm at an output pressure of 0.8 inches of mercury, so it'll obviously produce a lot more output pressure when it's supplying "only" 650cfm. According to my thumbnail SWAG, it would produce something like 3 inches of mercury pressure at 650cfm flow rate at sea level, which (according to reading I did on fan theory) would be multiplied by about 1.5x at 10,000 feet, for a result of about 5 inches of mercury output pressure increase at 650cfm, which (if I didn't screw up the calculations) would effectively fool the engine into acting like it's at 5,000 feet instead of 10,000 feet (which would be a huge difference).
I'll apologize in advance for any mis-use of terminology and calculation above... I'm no airflow engineer (by a long, long shot). But I AM a cheapskate who flinches when I think of spending $1200+ on a Howell fuel injection system to allow my rig to go reliably where I want to take it. :d If there's an easier / cheaper / less involved way to get there, I'm all for it. I just hope there is someone out there who could validate my assumptions - or nix them, either option is fine with me.
--
1978 Royale Center Kitchen
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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] Electric powered altitude compensation blower [message #175914 is a reply to message #175903] |
Sat, 07 July 2012 17:05 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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Senior Member |
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| Johnny Bridges wrote on Sat, 07 July 2012 13:14 |
Well, lessee...2500 RPM is 1250 IPM (intakes per minute) innit? so, 1250*445cid=568750 CI per minute. Divide that by 1758 (12 cubed) would give us just under 330 CFM at ambient pressure. Now, if we wanna run 15 psi absolute, and at 10K feet it's closer to 10PSI, we need some leeway. The blower I mentioned provides 550CFM at a fairly good pressure - probably not 5 psi, but several anyway. Consequently it oughta work. The whole idea is to hold just at 39 inches MAP all the way up the lountain, no? For this purpose however, I betcha a turbocharger and in intercooler would do a better job. Since lag isn't an issue in this service, you could hang it out in the wind someplace or duct some air to it to cool it down.
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It would be amazing to do a 1 bar (14.7 psi) boost, but that's way past where I'd be interested in going, though I agree the way to get there would be a turbocharger. And hey, I'd win most of the RV drag races I got into...  But if I could manage just 2 or 3 psi at 650cfm, I'd be good to go up the 10,000 foot+ mountains in Colorado without losing so much of the sea level power. At less than full throttle, I'd have even more "boost", as I would at anything less than close to redline RPMs (as your formula above shows).
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175915 is a reply to message #175877] |
Sat, 07 July 2012 17:05 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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| Dennis S wrote on Sat, 07 July 2012 10:22 |
Your carb may be fine now -- the number I threw in was sooner or later -- but, here again you may wish to rebuild your own.
Maybe you want to use the coach for a trip or two and then decide on your performance concerns.
Dennis
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I agree with Dennis. Use the coach for a few trips and you may find this to be a non-issue. I had some of the same concerns when I first got my coach, but I have driven it from below sea level, in Central California, to almost 8,000 ft, over Raton Pass in Colorado, with no power problems. Granted, that's not 10,000 ft, but still pretty high.
I DO have a 455, and have upgraded to a 3.70 final drive, have added an electric fuel pump, and an MSD dash timing control, but the trip to Colorado was before I did any of that, except for the elec. fuel pump. I topped out Raton Pass at about 48 mph on I-25.
I DO recommend the timing control and the electric fuel pump. The timing control allows you to optimize the timing by retarding it at low elevations and advancing it at high elevations. I DID notice that the vacuum gauge read quite a bit lower while driving across Northern New Mexico, on I-40. Most of that area is rather high in elevation also.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
[Updated on: Sat, 07 July 2012 17:46] Report message to a moderator |
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175919 is a reply to message #175915] |
Sat, 07 July 2012 17:40 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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| Carl S. wrote on Sat, 07 July 2012 15:05 |
I agree with Dennis. Use the coach for a few trips and you may find this to be a non-issue. I had some of the same concerns when I first got my coach, but I have driven it from below sea level, in Central California, to almost 8,000 ft, over Raton Pass in Colorado, with no power problems. Granted, that's not 10,000 ft, but still pretty high.
I DO have a 455, and have upgraded to a 3.70 final drive, have added an electric fuel pump, and an MSD dash timing control, but the trip to Colorado was before I did any of that, except for the elec. fuel pump. I topped out Raton Pass at about 48 mph on I-25.
I DO recommend the timing control and the electric fuel pump. The timing control allows you to optimize the timing by retarding it at low elevations and advancing it at high elevations. I DID notice that the vacuum gauge read quite a bit lower while driving across Northern New Mexico, on I-44. Most of that area is rather high in elevation also.
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My destination in CO is at 10,000 feet, but to get there, I have to go over Cottonwood Pass, which is steep, and peaks out at 12,126 feet, which means miles of steep climbing well over 10,000 feet. The way my rig runs at several thousand feet of altitude makes me think it would probably make it, but I don't want to "just" make it... I'd much prefer to have extra power when necessary (like when cranking around a tight, very steep switchback, or passing a SOB). I suspect there's quite a bit of difference in performance on a carb-fed engine between 8,000 and 10,000 feet, but certainly at 12,000+ feet. At 8,000 feet, you still have 75% of the air you do at sea level, while at 12,000 feet it's down to 63%... gettin' kinda thin.  IF my calculations are correct, my electric blower would make Cottonwood Pass feel like 6,000 feet to my engine, which I'm sure would be a piece of cake.
Anyone out there who has any input on how a GMC runs at 12,000+ feet?
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175923 is a reply to message #175919] |
Sat, 07 July 2012 17:55 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Mark,
My purpose in the earlier replies was to discuss alternatives I thought you were seeking.
But, if this is just something you want to do -- and you seem to be headed that way -- it sounds like the GMC is your best candidate given the room required for the fan and such and your performance expectiations. I would be most interested to see how you decide to proceed and hope to help if I can.
Dennis
| habbyguy wrote on Sat, 07 July 2012 17:40 |
| Carl S. wrote on Sat, 07 July 2012 15:05 |
I agree with Dennis. Use the coach for a few trips and you may find this to be a non-issue. I had some of the same concerns when I first got my coach, but I have driven it from below sea level, in Central California, to almost 8,000 ft, over Raton Pass in Colorado, with no power problems. Granted, that's not 10,000 ft, but still pretty high.
I DO have a 455, and have upgraded to a 3.70 final drive, have added an electric fuel pump, and an MSD dash timing control, but the trip to Colorado was before I did any of that, except for the elec. fuel pump. I topped out Raton Pass at about 48 mph on I-25.
I DO recommend the timing control and the electric fuel pump. The timing control allows you to optimize the timing by retarding it at low elevations and advancing it at high elevations. I DID notice that the vacuum gauge read quite a bit lower while driving across Northern New Mexico, on I-44. Most of that area is rather high in elevation also.
|
My destination in CO is at 10,000 feet, but to get there, I have to go over Cottonwood Pass, which is steep, and peaks out at 12,126 feet, which means miles of steep climbing well over 10,000 feet. The way my rig runs at several thousand feet of altitude makes me think it would probably make it, but I don't want to "just" make it... I'd much prefer to have extra power when necessary (like when cranking around a tight, very steep switchback, or passing a SOB). I suspect there's quite a bit of difference in performance on a carb-fed engine between 8,000 and 10,000 feet, but certainly at 12,000+ feet. At 8,000 feet, you still have 75% of the air you do at sea level, while at 12,000 feet it's down to 63%... gettin' kinda thin. IF my calculations are correct, my electric blower would make Cottonwood Pass feel like 6,000 feet to my engine, which I'm sure would be a piece of cake.
Anyone out there who has any input on how a GMC runs at 12,000+ feet?
|
Dennis S
73 Painted Desert 230
Memphis TN Metro
[Updated on: Sat, 07 July 2012 17:56] Report message to a moderator |
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175924 is a reply to message #175861] |
Sat, 07 July 2012 17:58 |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
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Senior Member |
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Jim,
You're too late! It's already been done, and quite successfully, by the
crazies at Car Craft Magazine, I believe, on a 1984 Corvette.
Gary Kosier
-----Original Message-----
From: James Hupy
Sent: Saturday, July 07, 2012 10:39 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Electric powered altitude compensation blower
How about a couple of backpack leaf blowers, one for each bank of
cylinders? <grin>
Jim Hupy
Salem, OR
78 GMC Royale 403
On Fri, Jul 6, 2012 at 9:38 PM, Rob Mueller <robmueller@iinet.net.au> wrote:
> Mark,
>
> Someone with better math skill could figger out the volume of air that a
> 455
> cubic inch Olds motor consumes at highway speed of around 2500 RPM.
>
> It would take one hell of an electric blower to keep up let alone boost
> the
> pressure!
>
> Regards,
> Rob
>
>
> -----Original Message-----
> From: Mark
>
> Then I end up with a vehicle with not only cavernous empty spaces around
> the
> engine, but that has 120VAC available. Not only that, but since it's got
> a
> carb instead of fuel injection, it's going to lose power at high altitude.
> My feeble mind rolls all these issues around for a while, and then starts
> plotting.
>
> I'm no expert on fan theory, but it looks like it just might be possible
> to
> boost a 403ci motor enough to matter at altitude (I'm not looking for
> "more
> power", just for keeping what I've got when driving at higher altitudes,
> which I plan to do frequently). That's done on some aircraft as well,
> where
> the only goal is to keep the sea level performance at cruising altitude
> (not
> to make heaps of power at sea level).
>
> A fan like this one:
> https://www.grainger.com/Grainger/DAYTON-PSC-Blower-1TDU2?Pid=search seems
> to have the stones to push a fair amount of air at a reasonable amount of
> extra pressure. I did a crude extrapolation of the numbers (which I admit
> is a SWAG at best) and came up with something like a pressure of 3 inches
> of
> mercury at 650cfm (the limit of my carb). I also read that you have to
> apply a factor of about 1.5x to a fan's rating if you're using at 10,000
> feet (presumably because it's easier to compress thinner air). Based on
> all
> that (and allowing that my numbers might be WAY off), I guess that -
> assuming not much loss in the system - that I could maintain the
> performance
> the motor has at 5,000 when I'm driving at 10,000 feet.
>
> If so... whoo hoo! :d Obviously, I'd only use this when my foot is
> planted on the floor and I'm struggling up a nasty grade.
>
> The other reason I chose that motor is because my 1,000 watt inverter
> (soon
> to be installed) should drive it nicely, and also because the alternator
> could just about keep up with the need, too.
>
> So - if anyone out there is well-versed in fan design, pressure, and all
> things aerodynamic, please feel free to throw cold water all over me. I
> could use it... it's triple digits here!
> --
> 1978 Royale Center Kitchen
> _______________________________________________
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175929 is a reply to message #175919] |
Sat, 07 July 2012 18:20 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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|
You're right. There is quite a bit of difference between 8,000' and 12,000+'. It sounds like you may be on the right track. I am interested to hear of the results if you proceed with this too.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Electric powered altitude compensation blower [message #175930 is a reply to message #175872] |
Sat, 07 July 2012 18:16 |
|
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
|
Senior Member |
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Mark,
Send us a link to the blower you speak of below.
Regards,
Rob M.
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces Mark
I agree, though I took the simple route and figured that the total air
quantity needs of the engine by definition aren't going to exceed that of
the carburetor. I figured that most of our rigs have carbs in the 650cfm
range, so that's what I based my SWAG on.
The fan I referenced can produce 1202cfm unrestricted (no pressure), and
1040cfm at an output pressure of 0.8 inches of mercury, so it'll obviously
produce a lot more output pressure when it's supplying "only" 650cfm.
According to my thumbnail SWAG, it would produce something like 3 inches of
mercury pressure at 650cfm flow rate at sea level, which (according to
reading I did on fan theory) would be multiplied by about 1.5x at 10,000
feet, for a result of about 5 inches of mercury output pressure increase at
650cfm, which (if I didn't screw up the calculations) would effectively fool
the engine into acting like it's at 5,000 feet instead of 10,000 feet (which
would be a huge difference).
I'll apologize in advance for any mis-use of terminology and calculation
above... I'm no airflow engineer (by a long, long shot). But I AM a
cheapskate who flinches when I think of spending $1200+ on a Howell fuel
injection system to allow my rig to go reliably where I want to take it.
:d If there's an easier / cheaper / less involved way to get there, I'm all
for it. I just hope there is someone out there who could validate my
assumptions - or nix them, either option is fine with me.
--
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Unsubscribe or Change List Options:
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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