Couldn’t find his post so I’ll stick under yours if you don’t mind, anyway buy a SRT or Scat Pac my SRT gets 25 mpg hy
318 MAX fuel economy builds?
- Thread starter gagembassett
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No Duh. No one needs to know how it works. It's how to do it. What have you done and what are the numbers? I don't sit around and think about what might be.
I do not mind. My 2009 Challenger R/T 6 speed gets 28 mpg at 75 mph and my wifes Charger R/T auto gets 30 + at the same speed. We travel cross country alot
No, this is something you set up on older rides. Computers have knock sensors.
Not new, check eBay for Jacob’s ignitions.
The factory used both. EGR holes in the intake floor are opened up with a high vacuum. (I don’t remember what I tested the egr valve open up at, but it does close under a WOT condition.)
So the exhaust will heat up the floor of the intake first and the entire intake track very quickly. During warm up time.
Of course coolant temp takes longer and is more controllable than the egr gasses.
It works but only so fast and so well.
You yourself will have to be on point on this. Also, speaking from experience on this mileage hunt, and not a whole lot of it but when I was hunting for a as much as I could get and the ability to pass the tail pipe test, you can set it up really well for the time your doing it and have it fall off from target pretty badly in six months.
As mentioned and forgive the dead horse beating here, but truly the bottom line is the proper size carb for the job at hand that should be kept cool and have a reasonable primary size to allow a good cruise power without struggle. The fuel from leaving the bowl starts its journey into being mixed with the air. It starts there. Then through and out the booster. This path IMO, should have the fuel well mixed with the air and for throttle and mileage purposes, should leave a annular booster.
Once you find a good mix of air and fuel leaving the carb, the intake is the next part of the travel path that can bennifkt from a certain amount of heat. This is where the coolant temp will come into play.
After that, a multi spark ignition. Then pay attention to the spark plug gap and the ring left behind on the plug. Plug reading and style of plug as well as manufacturer will all come into play. This will be part of the experiment.
Open up the plug as much as practicable.
Many years ago N.Y. State had vehicles tested on a set of dyno like rollers the rear wheels would sit on and the car needed to come up to speed (55mph) and have the exhaust read. I had to run a catalyst and since I had dual exhaust…. Yup! I ran two cats. I grabbed a set of high flow cats from Summit.
Ran great, ran as clean as a newer car, still got 20 mpg’s.
Not awesome mileage, but not to darn bad from the kid tuner 30 years ago.
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I could do all of that while running an egr manifold and heat the mixture from the top and the bottom.
"This path IMO, should have the fuel well mixed with the air and for throttle and mileage purposes, should leave a annular booster."
I have this carb. It's the 1916 not the 1906. Both have annular discharge and the 1916 is billed as superior and close to FI as you can get.
Edelbrock's AVS2 Off-Road Carburetor #1916 with Electric Choke is a special 650 CFM version of the proven #1906 street carb with Annular Flow Booster technology for near-EFI-like drivability that you can feel as soon as you step on the gas.
This carb has an improved annular discharge. See a youtube video of the carb when running. You can see the fuel being metered through 8 metering holes around the inside of the venturi secondary. I figured this would be a great start. It has the same primary as the 500 version and I already have it.
Has anyone else used these carbs?
I have this carb. It's the 1916 not the 1906. Both have annular discharge and the 1916 is billed as superior and close to FI as you can get.
Edelbrock's AVS2 Off-Road Carburetor #1916 with Electric Choke is a special 650 CFM version of the proven #1906 street carb with Annular Flow Booster technology for near-EFI-like drivability that you can feel as soon as you step on the gas.
This carb has an improved annular discharge. See a youtube video of the carb when running. You can see the fuel being metered through 8 metering holes around the inside of the venturi secondary. I figured this would be a great start. It has the same primary as the 500 version and I already have it.
Has anyone else used these carbs?
I used a 650 AVS II electric choke on a 360 for a little while. It worked very well. No complaints.
If you take your time with any carb (IMHO) you should be able to get darn super close to a FI system. Trouble is, most people won’t take the time to size the carb and jet it as well as mess around with the ignition system over and over again to get there set up to the pinnacle of what is possible.
If you take your time with any carb (IMHO) you should be able to get darn super close to a FI system. Trouble is, most people won’t take the time to size the carb and jet it as well as mess around with the ignition system over and over again to get there set up to the pinnacle of what is possible.
omahamoparguy
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Along time ago, I pulled a 318 out of a 67 belvedere, it had a factory single plane and a 2 barrel Stromberg carb. I shoved it in my 72 Demon complete with 727 Trans. Rear was 8 34 with 2.94 gears. Engine was real loose worn. Tuned it as best as I could, points you know.Decided to move to NJ from FL so ripped out the back seat to have room for all my tools. Stuffed entire car with tools and stuff .til I could barely fit inside. Estimate 1000 lbs easy. Started on trip, thought the fuel sender might have given up the ghost cause it wasn't moving. Pulled in for. Fuel and was shocked. I was averaging 24 mpg. Of course is was only going about 60 to 65 and with the sea level air and cool night time Temps probably contributed to the mpgs. But still thought that was pretty darn good. Of course it was 1987 so better fuel quality? Alway got in the twenty plus mpgs and I had a heavy foot in those days.
A big factor in highway cruising/fuel economy is aerodynamic drag & car shape. The increase in drag is not linear, it is exponential. I found with the brick shaped cars I have owned over the years that good economy ws achieved if you kept the speed down to around 50-55 mph. Once you got to 60 & above, you used more fuel.
James Clews
Well-Known Member
Back in the seventies I had an Ex police 265 hemi six Valiant charger. I put a pacer factory 4 barrel manifold on it and factory headers. Those factory 4 barrel manifolds were very long runner manifolds with a water heated plenum in them. This car ran 14.7 sec qtrs @92 mph . The camshaft and exhaust system were standard police spec. Carb was a vac secondary holley 600 cfm.
This car ran exactly the same as the original 2 barrel and fuel economy was as good if not better than the 2 barrel. The only thing I changed when taking it to the track was to disconnect the water heating and going up 2 sizes in jets.
Until I put the water heating back on after the drag racing it would have a slight dead spot off idle but the water heating fixed that.
This car ran exactly the same as the original 2 barrel and fuel economy was as good if not better than the 2 barrel. The only thing I changed when taking it to the track was to disconnect the water heating and going up 2 sizes in jets.
Until I put the water heating back on after the drag racing it would have a slight dead spot off idle but the water heating fixed that.
Rat Bastid
Dunamis Metron
That’s interesting and not surprising. If you can’t get all the fuel vaporized in time you can certainly get a lean spot in the fuel curve.
It’s also interesting to note that there is always a puddle in the bottom of the intake manifold and that’s what fuel the engine runs on.
When manifold vacuum goes to zero (or close to it) the pressure change takes the atomized/vaporized fuel and converts it back to a liquid.
SuperFlow says it takes about 100 engine cycles to recover from that.
EDIT: BTW, was it any quicker/faster with the water not heating the intake??
James Clews
Well-Known Member
Rat Bastid! I never drag raced it with the heating connected but did notice when I disconected the heating I had to increase the jet size, or more importantly with the water heating I could decrease the jet size!
Rat Bastid
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Possibly because it needed more of the lighter fractions that vaporize at lower temps to make up for the fact that you were not vaporizing the heavier ones due to lower temps in the manifold.
Just a thought for those who may possibly want to understand the why's.......
I’m gonna have to call no way..nobody and I mean nobody moves back to Jersey from Florida
The exhaust heat will come on almost immediately (only as long as it takes to heat soak the aluminum spacer), which will allow a faster warm-up schedule. You can turn the choke spring back (less tension). I did an experiment with my '95 Jeep GC. It was about 32 degrees out (0 C). I fired the engine, and the injector pulse-width (IPW) went to around 30 milliseconds. After about 10 minutes it was down around 8 ms. Fully warmed up it's a tick over 2 milliseconds.
With the factory ECM control, the engine consumed almost 15X more fuel cold than warmed up! Fuel delivery is increased to compensate for a cold engine that cannot vaporize much fuel -- by a multiplication factor. This means climbing out our hole (steep driveway) with a cold engine chugs fuel. The faster you can turn the choke off, the better short-trip fuel economy will be.
How can I fool the PCM (Warmed up mode) on a Magnum engine?
I developed an electronic circuit I called the IATimer that starts out
"not there", then gradually ramps in (adjustable ramp time and final offset value) to an offset of the IAT Sensor value for advanced/retarded ignition timing. A similar ramp circuit could expedite the ramp-in of the coolant temp. This version definitely requires electronics & programming skills. Not sure how to do it with junk yard parts, though. I'll give it some thought.
"not there", then gradually ramps in (adjustable ramp time and final offset value) to an offset of the IAT Sensor value for advanced/retarded ignition timing. A similar ramp circuit could expedite the ramp-in of the coolant temp. This version definitely requires electronics & programming skills. Not sure how to do it with junk yard parts, though. I'll give it some thought.
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What do you use?
My own custom electronics! I can make quick test circuits on generic proto boards, which may last a week or 20 years. Something in the category of "reliable" requires automotive grade components (which are in short supply right now) and a professionally made PCB board (which I get done all the time, but they cost a lot of money in small batches). I use PIC MCU's exclusively, and the MPLABX IDE for programming them.
I’m not smart in electronics but was thinking in the same line but for the o2 sensors, showing it’s already in the warmed up loop. But I can see the temp sensor needs what you say too. My foot can keep it running till it’s really warm.
Last night when I posted, I was dileriously tired -- I taught a Fuel Efficiency Class this weekend. When I recommended turning the choke spring back, it was because something was improved that justified that action. If you have a stock vehicle, the stock tune is about as good as it's going to get (just ask any Federal judge). Accelerating the warm-up ramp will cause a stumble or even stall, and more importantly from a legal standpoint, higher emissions. Changes to factory settings should be used to compensate for other changes. With that said, if you have a more powerful ignition (Pulstar Plugs, Peaking Caps, PDI, etc) or fuel heater not tied to engine coolant or intake air heater for example, then accelerating the warm-up ramp-in would be justified.
The coolant temp sensor (CTS) is a variable resistor -- like a radio volume knob of yore -- where a change of temperature changes the knob setting. There are charts online that show what the resistance should be at different temperatures for most popular engines. Every CTS I've seen has high resistance when cold, and low resistance when hot. Therefore, if you want to show a hotter temperature, you would have to add resistance in parallel to the sensor, reducing overall resistance. To show colder temperatures, add resistance in series in either of the 2 wires. I use the resistance value at 68 degrees F. for the base value.
A quick internet search suggests a value of 2k - 3k ohms at 68 for a '98 Magnum engine. Usually the resistance ranges on both the CTS and IAT sensors are pretty close. So, if you wanted to show colder air, you would add resistance in series. Using the 2500 ohm average resistance value, we want a potentiometer with a value slightly higher than that. Cheap pots will be 2.2k, 2.7k, 3.3k, 3.9k, or 4.7k ohms in that range. I'd go for the 4.7k ohms for a bit more range. Cut one of the sensor wires and splice the pot center tap to one of the wires, and either of the 2 outer taps to the other end of the cut. Watch your Scan Tool and turn the knob slowly to see which direction increases the effect. Higher resistance will show cooler temps.
To show hotter air or engine temp, you need to splice a pot in parallel. However, here you want a value around 10X the base value. Remember, the rating of the pot is its MAX value. Turning the knob will reduce resistance where eventually it acts as a short. For this reason, you would want the pot rated at least at 10X the base PLUS a current limiting resistor rated about base value. Let's put this together: 2.7k limiting resistor (1/4 watt 20% tolerance is just fine) and a 27k pot (again, low wattage value OK). The 2.7k resistor is soldered to one of the outer legs on one end, and one of the 2 sensor wires on the other end. The center tap of the pot is soldered to the other sensor wire. Here, lower resistance will show hotter temps.
The coolant temp sensor (CTS) is a variable resistor -- like a radio volume knob of yore -- where a change of temperature changes the knob setting. There are charts online that show what the resistance should be at different temperatures for most popular engines. Every CTS I've seen has high resistance when cold, and low resistance when hot. Therefore, if you want to show a hotter temperature, you would have to add resistance in parallel to the sensor, reducing overall resistance. To show colder temperatures, add resistance in series in either of the 2 wires. I use the resistance value at 68 degrees F. for the base value.
A quick internet search suggests a value of 2k - 3k ohms at 68 for a '98 Magnum engine. Usually the resistance ranges on both the CTS and IAT sensors are pretty close. So, if you wanted to show colder air, you would add resistance in series. Using the 2500 ohm average resistance value, we want a potentiometer with a value slightly higher than that. Cheap pots will be 2.2k, 2.7k, 3.3k, 3.9k, or 4.7k ohms in that range. I'd go for the 4.7k ohms for a bit more range. Cut one of the sensor wires and splice the pot center tap to one of the wires, and either of the 2 outer taps to the other end of the cut. Watch your Scan Tool and turn the knob slowly to see which direction increases the effect. Higher resistance will show cooler temps.
To show hotter air or engine temp, you need to splice a pot in parallel. However, here you want a value around 10X the base value. Remember, the rating of the pot is its MAX value. Turning the knob will reduce resistance where eventually it acts as a short. For this reason, you would want the pot rated at least at 10X the base PLUS a current limiting resistor rated about base value. Let's put this together: 2.7k limiting resistor (1/4 watt 20% tolerance is just fine) and a 27k pot (again, low wattage value OK). The 2.7k resistor is soldered to one of the outer legs on one end, and one of the 2 sensor wires on the other end. The center tap of the pot is soldered to the other sensor wire. Here, lower resistance will show hotter temps.
Dartswinger70
Well-Known Member
Far out man...
To actually use the above circuits, you have to start with them at minimum value -- as close to "Off" as possible. Most ECUs will look at the temperature values of every temp sensor on the vehicle on Key-On; this would include the IAT, CTS, cabin temp sensor, even the cat temp sensor (heater circuit of the down-stream O2 sensor). If there is a consistent discrepancy in one of the sensors, the adaptive strategies will compensate around the calibration issue. The resistance change has to be slowly ramped in to chosen setting. For the CTS, ramp in the offset as the engine can handle it, then when the total circuit value reads normal operating temperature, it has to be ramped back down. Otherwise, the ECU sees an over-heating condition. On some vehicles, this will trigger the cooling fan -- which wastes fuel over-driving the alternator. Many vehicles will dump excess fuel to try to cool the engine from the inside.
This is why I would use a small 8-bit PIC processor and a digital pot. The whole "turning a knob" becomes software.
This is why I would use a small 8-bit PIC processor and a digital pot. The whole "turning a knob" becomes software.
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