I do not believe anything they do. I can guarantee you that following a Semi will add to mpg, just do not get too close, they do not like that. Used to run cross country and did that all the time. Watch a vacuum gage and try it sometime.
Daughter needs Gas mileage from 273 commando
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I do not believe anything they do. I can guarantee you that following a Semi will add to mpg, just do not get too close, they do not like that. Used to run cross country and did that all the time. Watch a vacuum gage and try it sometime.
I did see that Mythbusters also. Didn't they find that it did get better mileage when they were tooooo close?
I've also heard that when you draft the truck, that the truck gets less economy than if you do, Mythbusters didn't check that out.
However, you are not allowed to tailgate. As per the warning at the beginning of the show, "Don't try this at home, we're experts...." So, since you watched the show, you are not allowed to follow that close.
Just like, now I'm not allowed to eat poppy seed muffins. I watched that show and they told us not to do this at home because they are experts. Now I can't eat poppy seed muffins..... Because they told me.... I'm not an expert at that like they are.... Only they can eat poppyseed muffins now... Oh, the humanity....
Both toolmanmike and I have an Isky E-4 solid cam in our 273's. You can listen to them under the sound bites sticky under exhaust. The E-4 is 260 duration and .425 lift, up to 625 cfm carb. Power from 2,000 to 5,500 RPM. I can get 20+ mpg cruising at 70 on the highway with the stock 500 cfm AFB. The next step up for an Isky solid is a B-777 with 280 duration and .480 lift, 650 to 750 cfm carb. Power from 3,000 to 7,000 RPM. If you know what you are doing, You will easily bury the speedometer in a 65 Barracuda with those gears and tires. When I first put my 64 273 together I was running a 284 duration TRW solid cam TP-141 and a 600 Holley. Luckily I had a 4 speed. I think your cam would be great in the 273, but I would not give it to my daughter, I have two, for a first car. I'll be in Greenwood somewhere in the middle of March. I run almost to Greenville before turning south on I-26.
That would probably be the best cam for fuel economy in a solid grind. It sounds very interesting.
DaveBonds
Garage Trash
The air valve secondary carb suggestion, with the D4B and an overdrive would be ideal.
I bought the new Street Demon, because it's based off of a ThermoQuad, but has a better idle circuit and a redirecting air bleed valve that works in conjunction with it's sandwiched gaskets/ baseplate to redirect air at the primaries, to the center of the intake and further help with atomization.
I was able to tune within increments of 30rpm on that carb and I've never heared an engine idle so smoothly. It's a 625cfm carb, but the primaries are smaller than my Carter BBD 2 barrel.
They sell them with metal and composite bodies. The composite lowers the fuel temp to help with charge and the exhaust crossover in the D4B will help atomization.
Multiple spark is also very helpful, along with tuning the carb on an o2 sensor and reader. That would help any carb tune to proper AFR without doing it blind.
Ultimately, an overdrive would help you more than anything, along with driving habit, which can be measured and corrected by monitoring a vacuum/ economy gauge.
The idea behind the closed chamber, tight ports and small primary is to dump as much torque into the engine as you can at low RPM, so it doesn't need much assistance from throttle position to get the car moving. The less the throttle plate moves/ more the car moves, the better fuel economy you will see.
I bought the new Street Demon, because it's based off of a ThermoQuad, but has a better idle circuit and a redirecting air bleed valve that works in conjunction with it's sandwiched gaskets/ baseplate to redirect air at the primaries, to the center of the intake and further help with atomization.
I was able to tune within increments of 30rpm on that carb and I've never heared an engine idle so smoothly. It's a 625cfm carb, but the primaries are smaller than my Carter BBD 2 barrel.
They sell them with metal and composite bodies. The composite lowers the fuel temp to help with charge and the exhaust crossover in the D4B will help atomization.
Multiple spark is also very helpful, along with tuning the carb on an o2 sensor and reader. That would help any carb tune to proper AFR without doing it blind.
Ultimately, an overdrive would help you more than anything, along with driving habit, which can be measured and corrected by monitoring a vacuum/ economy gauge.
The idea behind the closed chamber, tight ports and small primary is to dump as much torque into the engine as you can at low RPM, so it doesn't need much assistance from throttle position to get the car moving. The less the throttle plate moves/ more the car moves, the better fuel economy you will see.
Exactly! Good info about the Street Demon. Didn't know about that carb. Sounds like a well designed one. The whole concept is mileage. Low rear gear and a overdrive means low engine rpm. A low rpm torque engine combination is what's needed. You'll spend most of the time between idle and 2250 rpm. you need a cam that works well there, a intake that flows there, and heads that compliment the two. Multispark ignition set correctly will help the efficiency as well as a smooth flowing exhaust. Stock manifolds although restrictive would be good with a HP single system or a x or h pipe dual system no bigger than 2 1/4". My opinion of course. tmm
one mile
Well-Known Member
Thanks DaveBonds for the info ! Yes , I do already have a Hal Tech air fuel ratio setup for the car and would like to install an overdrive trans. in car later on but can't right now. Hey toolmanmike , can these Cams be advanced to lower the power band closer into the RPM range I would need to be in ? I have to work the best I can with what I have @ this point.
I tell you 66fs those E-4 Cams have exactly the sound I love ! Not too much, just enough over a stock muscle car sound for a Gear Head to know the difference. Top of the list of changes AFTER I get it on the road and $ to put towards it. Rustyratrod do you have any thoughts on this updated Idea on Advance/Retard the Camshaft ? Thanks everyone for your Input ! I love this Forum ! We both thank you, Tim (Dad)
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I tell you 66fs those E-4 Cams have exactly the sound I love ! Not too much, just enough over a stock muscle car sound for a Gear Head to know the difference. Top of the list of changes AFTER I get it on the road and $ to put towards it. Rustyratrod do you have any thoughts on this updated Idea on Advance/Retard the Camshaft ? Thanks everyone for your Input ! I love this Forum ! We both thank you, Tim (Dad)
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I advanced mine a couple degrees and without trying it both ways I don't have a baseline to compare to. I really don't think advancing it did much. It did shorten up my redline by a few hundred rpm and did really narrow my sweet spot for initial timing. I won't advance it next time. tmm
one mile
Well-Known Member
Rumblefish360 F.Y.I. - Not just because I have one, but the Offenhauser 360 split plane Intake is the best Intake I have ever used for bottom end torque. I bought it for this car but bolt angle was a problem for me.(found this out later) "Wallowing" out the bolt holes to make it fit was not an option for me. I was into offroad heavily years ago (still love it) and it was THE Intake to have along with a offroad Cam and Kit on ANYTHING you wanted torque low down. you can tell Seat of the pants difference with intake only change. Hope that helps, Tim
DaveBonds
Garage Trash
The Offy is comperable to the D4B series. LD4B LD340, etc, without quite as much upper end RPM range.
Advancing the cam cycle will put RPM down a touch, depending on duration and overlap. On a low overlap/ duration, you won't see high RPM anyway. I put mine in at 3°, so it would hold above 0 longer on a double roller chain. I also greased the daylights out of it with bearing lube before installing it.
What it will do is set your dynamic compression up higher. It depends on what you're looking for in final cylinder pressure and what kind of gas you want to use.
The 273 and 318 have a niche, with closed chamber heads and a good compression distance, because they have a short enough stroke to obtain quench distance, without bringing the compression ratio into the 10s for street use on mid grade. This is one of the reasons why I elected to build a 318 instead of one of my 360s. Quench benefit and mid 9s, on a dynamic 7.8 at 5400ft
I would get that 273 nice and warm and do a cylinder pressure check on all 8 and read the plugs, before deciding on what to do next with a tune.
Advancing the cam cycle will put RPM down a touch, depending on duration and overlap. On a low overlap/ duration, you won't see high RPM anyway. I put mine in at 3°, so it would hold above 0 longer on a double roller chain. I also greased the daylights out of it with bearing lube before installing it.
What it will do is set your dynamic compression up higher. It depends on what you're looking for in final cylinder pressure and what kind of gas you want to use.
The 273 and 318 have a niche, with closed chamber heads and a good compression distance, because they have a short enough stroke to obtain quench distance, without bringing the compression ratio into the 10s for street use on mid grade. This is one of the reasons why I elected to build a 318 instead of one of my 360s. Quench benefit and mid 9s, on a dynamic 7.8 at 5400ft
I would get that 273 nice and warm and do a cylinder pressure check on all 8 and read the plugs, before deciding on what to do next with a tune.
one mile
Well-Known Member
What is this A-833 O.D. trans. I have seen mentioned ? Will it fit a '65 Barracuda? Any clearance issues ? Is the cam I have too big for this type of Trans. ? What did they originally come in? How hard are they to find ? Thanks DaveBonds , I have read Tech articles about "Cranking Pressures" I will have to give it a try on this one.....
one mile
Well-Known Member
nevermind on the transmission Dad checked and we need an automatic. thank you all.
one mile
Well-Known Member
I will study this Thread forward and backward , we do thank all of you for your input. I will try to get this car dialed in and let you all know how it works out ! Thanks again ! Tim (Dad)
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You can do a lot of little things to gain mpg like, royal puple oil and gear fluids, electric fan, under drive pulleys, low restrictions exhaust and intake track as longs it maintains velocity, compression, lighting the rotational weight and car weight, lowering the car and 1.5 degree rake and other aerodynamics etc.... but the biggest is to run the car at a lower rpm for any given speed. A 273 running let say 1500 rpms is the same as a 225 /6 running at 1820 rpms but bottom line it takes a certain amount of hp (fuel) to move your cars weight and aerodynamics at a certain speed no matter how much money and technology you throw at it.
2 Darts
A-body Addicted
I hadn't seen the Mythbusters episode, so I looked up on YouTube.
[ame="http://www.youtube.com/watch?v=lttgT1XZVvE"]Drafting Semi - YouTube[/ame]
Watch all of it. Besides getting closer, steady throttle work gets better mileage. In my experience, higher speeds gives better results against a same speed baseline. i.e. If I run at 75 mph without drafting I get 22 mpg, with a 75 foot lead at 75 mph behind a box trailer semi, I get a little over 30 mpg. I'm usually able to see a mirror from 75 feet back. How could I tell I was "in the draft"? Wind noise and pressure on the throttle needed to make speed drops dramatically the closer you get.
I do not make it a habit to draft semis. I have some CDL experience with busses and semi with a lowboy carrying 50t + dozers. It wasn't fun to know someone was riding my tail. Not really worried though, as lowboy trailers are very stout and with the load, 2 tons isn't going to hurt 75 tons very much. The guys that used to bother me were the kamikaze pilots that would come racing up the left lane, nail the brakes, and cut across the nose of the truck to make it into a rest area. 75 tons will go through 2 tons (most frequently, Honda Civics, so call it 1½ tons) like a hot knife through soft butter.
[ame="http://www.youtube.com/watch?v=lttgT1XZVvE"]Drafting Semi - YouTube[/ame]
Watch all of it. Besides getting closer, steady throttle work gets better mileage. In my experience, higher speeds gives better results against a same speed baseline. i.e. If I run at 75 mph without drafting I get 22 mpg, with a 75 foot lead at 75 mph behind a box trailer semi, I get a little over 30 mpg. I'm usually able to see a mirror from 75 feet back. How could I tell I was "in the draft"? Wind noise and pressure on the throttle needed to make speed drops dramatically the closer you get.
I do not make it a habit to draft semis. I have some CDL experience with busses and semi with a lowboy carrying 50t + dozers. It wasn't fun to know someone was riding my tail. Not really worried though, as lowboy trailers are very stout and with the load, 2 tons isn't going to hurt 75 tons very much. The guys that used to bother me were the kamikaze pilots that would come racing up the left lane, nail the brakes, and cut across the nose of the truck to make it into a rest area. 75 tons will go through 2 tons (most frequently, Honda Civics, so call it 1½ tons) like a hot knife through soft butter.
greymouser7
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http://mythbustersresults.com/episode80
Drafting behind a big rig will improve your car’s fuel efficiency.
confirmed
To test this myth, the build team procured a car, a big rig, and a device that could measure a car’s fuel efficiency. They then drove the car behind a moving big rig at various distances ranging from 100 to 2 feet and measured the amount of fuel the car consumed. The Build Team discovered that the closer the car was to the big rig, the less drag is produced, thus the more fuel saved. At just ten feet, the car managed to increase its fuel efficiency by 40%. Drafting at two feet was slightly lower than the ten foot distance, mainly because Grant had to keep working the car pedal to maintain distance from the truck. However, that did not dispute the fact that drafting actually can increase your car’s fuel efficiency. However, the Build Team has warned that drafting is incredibly dangerous because the truck driver may not able to see you and you may not be able to react in time if the truck were to make a sudden stop.
I doubt you would even feel it in either case.
Rustyratrod is having storm issues. His power is out, he has a hole in his garage roof now, and is running a power generator. He pops on quick in the AM for an update and then is gone as quick as he came. :wack:
It may take a few days for him to get things under control. But if you don't hear much from him for a few days, that's why. He posted this morning.
Here are the threads where he's posted:
http://www.forabodiesonly.com/mopar/showthread.php?t=266876
http://www.forabodiesonly.com/mopar/showthread.php?t=266812
He has an "excused absence"... (like back in high school)....
Rumblefish360 F.Y.I. - Not just because I have one, but the Offenhauser 360 split plane Intake is the best Intake I have ever used for bottom end torque. I bought it for this car but bolt angle was a problem for me.(found this out later) "Wallowing" out the bolt holes to make it fit was not an option for me. I was into offroad heavily years ago (still love it) and it was THE Intake to have along with a offroad Cam and Kit on ANYTHING you wanted torque low down. you can tell Seat of the pants difference with intake only change. Hope that helps, Tim
Are you referring to the Offy dual-port dual-plane intake where the top of the ports are split from the bottom. That is great for low end and fuel economy. It 's a little restrictive to flow above 5000, because the split port takes away some of the area of the ports, but it works great below 5000 rpm. It would be great for a car where you don't want the daughter to hot rod. (built in restrictor without a restrictor plate...)
I found out about these from an old guy that had one on a 76 Volare station wagon with a 360 4 speed, .484 lift Worshowski's cam, rhoades lifters, and the Offy dual-port dual-plane who claimed he got 23 MPG with this set up. It's a good street intake. I still have one or two of them around here...
one mile
Well-Known Member
NASCAR has proven the "Draft" thing every time you watch them. You can treat Air as a fluid we have to travel through, we just don't "Feel" the resistance as much as you would standing in the water at the Beach and feeling the undertow of the water on your legs. I don't know if anyone has taken the time to figure out the "Drag Coefficent "of a '65 Barracuda, but what little I know is that lowering the car as much as is reasonable on the street and the big back glass helps more than we know. I use to go to East Coast Timming Association races in N.C. at the 1 mile standing start time trials (Gone Now) and you saw all kinds of "Tricks" at the track. The greatest thing was that Young and Old worked togeather to help a stranger (2 young Guys) join the 200 M.P.H. club when you saw them SOOO close ! Quick examples "I" have seen actually work. Thin Lexan molded over the complete front of the Car (keep factory look) with just enough air flow to cool the car and feed the carb. "Duct Tape"! @ base of windshield , remove wipers, Best was a rear belly pan up to rear diff. to allow the air to "Let go" of the car. Don't remember all the details but they made it to the 200 M.P.H. Club and they gave everyone credit and said it was a joint effort. "Car people helping Car people". "Thats all I have to say about that" (Forest Gump)
one mile
Well-Known Member
Yep krazykuda, that is what I had origionally bought. Looking deeper into the 4bbl. "Lock out" I talked about earlier. I have seen it done somewhere and can't find any info so far. Tim (Dad)
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