Lars...Will this really increase mpg
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Joined: May 2006
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From: Derby Kansas
Lars...Will this really increase mpg
In a different thread, this link was provided as an option for increasing mpg. I drive my '73 as often as possible, and I would also like to increase the mpg, but I wonder if this will work, and what the down side might be. http://community-2.webtv.net/MATTGRU/carb/
Thanks in advance for your input.
-Jim
Thanks in advance for your input.
-Jim
Melting Slicks
Joined: May 2006
Posts: 3,438
Likes: 41
From: Raleigh NC
St. Jude Donor '13-'14
In a different thread, this link was provided as an option for increasing mpg. I drive my '73 as often as possible, and I would also like to increase the mpg, but I wonder if this will work, and what the down side might be. http://community-2.webtv.net/MATTGRU/carb/
Thanks in advance for your input.
-Jim
Thanks in advance for your input.
-Jim
While I see Matt as a pretty knowledgable guy, I think this icon >
comes up pretty frequently. Not that I could ever come close to topping his knowledge or prove him wrong, I tend to take his recommendations with a grain of salt, or wait for someone else I trust to concur.Can anyone comment on Matt's claim?
Melting Slicks
Joined: May 2001
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From: May help you? You can sure as hell try!
My guess is that the plywood spacer he fabricated saved more fuel by preventing any fuel bowl boil-overs than did blocking the passages under the base of the carb. Going from 11 to 18 mpg is a pretty drastic change, especially with 4:11 gears.
As a previous poster noted, I gotta give this one a too.
As a previous poster noted, I gotta give this one a
too.
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
My guess is that the plywood spacer he fabricated saved more fuel by preventing any fuel bowl boil-overs than did blocking the passages under the base of the carb. Going from 11 to 18 mpg is a pretty drastic change, especially with 4:11 gears.
As a previous poster noted, I gotta give this one a too.
As a previous poster noted, I gotta give this one a
too.
Race Director
Joined: Oct 2000
Posts: 15,009
Likes: 79
From: central FL, near the beach.
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Melting Slicks
Joined: May 2006
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From: Raleigh NC
St. Jude Donor '13-'14
Q: Wouldn't there be a patent on this if it really worked?
A: As far as I know, there were patents, and they have expired. Every V8 I have ever seen, came from the factory with a dual plane and a 4 hole manifold. This is old school engineering, nothing new. Hot rodders have made it very clear, that they don't care about mpg, and aftermarket manifold makers have provided products that they want. Edelbrock sells a 4 hole spacer for those that want to reduce the effects of reversion and improve off-idle torque. It costs extra.
A: As far as I know, there were patents, and they have expired. Every V8 I have ever seen, came from the factory with a dual plane and a 4 hole manifold. This is old school engineering, nothing new. Hot rodders have made it very clear, that they don't care about mpg, and aftermarket manifold makers have provided products that they want. Edelbrock sells a 4 hole spacer for those that want to reduce the effects of reversion and improve off-idle torque. It costs extra.
If I go to Summits site, I don't see one 4-hole manifold. I see a bunch of twos, and a single hole.
Now how is it that your idea, which basically boils down to a 4-hole manifold, not only increases gas mileage over these manifolds, but you also claim gives better low end torque?
So are you saying it absolutely kills high end? If we slapped your car on a dyno, would we see it die around 4000 rpm?
Race Director
Joined: Oct 2000
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From: central FL, near the beach.
good catch! i deleted the poor wording, and added another Q. Within a month the report will be ready for publication.
my reason for wanting a bigger cam, is, it has TOO MUCH low rpm torque(before the mod), and i want to shift the powerband higher, so it won't spin the tires too easily. Now, the truth is, I can DRIVE it, and not let it drive me. Simply put, I have to ease down the pedal,not jump on it. This technique is apparently beyond most people, and they buy a single plane and jump on it.
And yes, my 61 has the original exhaust on it, and backpressure jumps up to 4.5 psi past 4500.
So i have always traded street manners for high rpm power. I love the sound of the stock exhaust. Zora Duntov made a record of the 61 and gave it out as a promo
the 2101 is idle-5500. it is not a drag strip maniold. 4 holes don't, imo, alter its' max rpm, how in the world can it?
the 2101 was a poor choice
(too small)
i am much happier with the weiand 8004 on my 72. the stealth might be even better.
my reason for wanting a bigger cam, is, it has TOO MUCH low rpm torque(before the mod), and i want to shift the powerband higher, so it won't spin the tires too easily. Now, the truth is, I can DRIVE it, and not let it drive me. Simply put, I have to ease down the pedal,not jump on it. This technique is apparently beyond most people, and they buy a single plane and jump on it.
And yes, my 61 has the original exhaust on it, and backpressure jumps up to 4.5 psi past 4500.
So i have always traded street manners for high rpm power. I love the sound of the stock exhaust. Zora Duntov made a record of the 61 and gave it out as a promo
the 2101 is idle-5500. it is not a drag strip maniold. 4 holes don't, imo, alter its' max rpm, how in the world can it?
the 2101 was a poor choice
(too small)i am much happier with the weiand 8004 on my 72. the stealth might be even better.
Last edited by Matt Gruber; Nov 17, 2007 at 01:45 PM.
Melting Slicks
Joined: May 2006
Posts: 3,438
Likes: 41
From: Raleigh NC
St. Jude Donor '13-'14
I'm still confused. So you're still saying that you'll get better low RPM torque with a 4-hole manifold, and all you have to do is get a higher CFM carburetor to maintain higher RPM torque?
You got a bigger cam to move your powerband up the RPM scale, but then you modified your carb or manifold to give you more power at the lower end?
So... you're increasing your powerband... and increasing gas mileage???
Gruber, any negative notes??
You got a bigger cam to move your powerband up the RPM scale, but then you modified your carb or manifold to give you more power at the lower end?
So... you're increasing your powerband... and increasing gas mileage???
Gruber, any negative notes??
Racer
Joined: Jul 2007
Posts: 311
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From: Visalia CA
regarding spacers, you have two kinds
one is an open plenum spacer, the other is the four hole spacer
the open plenum increase's plenum volume allowing more air into the manifold essentially which moves the powerband up
the four hole however does not do that, it allows the fuel to gain more velocity, this is because it has to travel further before it is allowed to dissapate into the manifold. the extra fuel velocity would make it more efficient and like everything else that makes the motor more effcient-results in better mpg. these are also advertised as a means of gaining low end torque......
one is an open plenum spacer, the other is the four hole spacer
the open plenum increase's plenum volume allowing more air into the manifold essentially which moves the powerband up
the four hole however does not do that, it allows the fuel to gain more velocity, this is because it has to travel further before it is allowed to dissapate into the manifold. the extra fuel velocity would make it more efficient and like everything else that makes the motor more effcient-results in better mpg. these are also advertised as a means of gaining low end torque......
Pro
Joined: Feb 2006
Posts: 718
Likes: 7
From: Jacksonville , NC
Carb spacers
Interesting read I found while surfing the net. Granted BG is in the business of selling theses but at least it provides the concept behind them.
http://www.gnetworks.com/v4files/bar...h%20images.pdf
and an interesting CF article:
http://www.corvettefever.com/techart...nfo/index.html
Bob
http://www.gnetworks.com/v4files/bar...h%20images.pdf
and an interesting CF article:
http://www.corvettefever.com/techart...nfo/index.html
Bob
Race Director
Joined: Oct 2000
Posts: 15,009
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From: central FL, near the beach.
thanks Bob & joe
.
off-idle torque is not in the powerband, imo.
it lets u avoid downshifting as u slow down in traffic. helps it stay in OD too if u have it..
.
well i'm moving on to my next experiment, making my 61 steer easier.
.
.
off-idle torque is not in the powerband, imo.
it lets u avoid downshifting as u slow down in traffic. helps it stay in OD too if u have it..
.
well i'm moving on to my next experiment, making my 61 steer easier.
.
Race Director
Joined: Oct 2000
Posts: 15,009
Likes: 79
From: central FL, near the beach.
ideas keep pouring in, page updated AGAIN!
i am sometimes 10-20 years ahead of the crowd,
but this is rediculous
in '78 i went to true duals on my 76(sold in 1982) and cruise mpg went from 13 to 17.6
Guys here never check mpg and have NO IDEA u can get more HP WOT and higher mpg at cruise. And Nearly nobody knew(knows) how much the exhaust is worth
29 YEARS LATER
do these guys here live isolated in a cave
don't u guys know mpg is a routine HEALTH CHECK for ANY car?
i am sometimes 10-20 years ahead of the crowd,
but this is rediculous
in '78 i went to true duals on my 76(sold in 1982) and cruise mpg went from 13 to 17.6
Guys here never check mpg and have NO IDEA u can get more HP WOT and higher mpg at cruise. And Nearly nobody knew(knows) how much the exhaust is worth
29 YEARS LATER
do these guys here live isolated in a cave
don't u guys know mpg is a routine HEALTH CHECK for ANY car?
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
regarding spacers, you have two kinds
one is an open plenum spacer, the other is the four hole spacer
the open plenum increase's plenum volume allowing more air into the manifold essentially which moves the powerband up
the four hole however does not do that, it allows the fuel to gain more velocity, this is because it has to travel further before it is allowed to dissapate into the manifold. the extra fuel velocity would make it more efficient and like everything else that makes the motor more effcient-results in better mpg. these are also advertised as a means of gaining low end torque......
one is an open plenum spacer, the other is the four hole spacer
the open plenum increase's plenum volume allowing more air into the manifold essentially which moves the powerband up
the four hole however does not do that, it allows the fuel to gain more velocity, this is because it has to travel further before it is allowed to dissapate into the manifold. the extra fuel velocity would make it more efficient and like everything else that makes the motor more effcient-results in better mpg. these are also advertised as a means of gaining low end torque......
Last edited by 63mako; Nov 20, 2007 at 09:16 AM.
Pro
Joined: Oct 2007
Posts: 587
Likes: 0
From: Overland Park Kansas
Hrm. Well I'm willing to try this to see how it goes since I currently get <10mpg even with my 700R4 w/the 383. I have an Edelbrock 1903 Q-Jet, any links to what spacer I'd need? I have a 2" rise hood so I'm not worried about the height, I just don't know which to get.
Thanks
-Josh
Thanks
-Josh
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Hrm. Well I'm willing to try this to see how it goes since I currently get <10mpg even with my 700R4 w/the 383. I have an Edelbrock 1903 Q-Jet, any links to what spacer I'd need? I have a 2" rise hood so I'm not worried about the height, I just don't know which to get.
Thanks
-Josh
Thanks
-Josh