500 Cubic inch MPG

[grubby65]

Previously I had submitted a post concerning the addition of a Holley Sniper FI unit to my 1964 Dodge Polara 500. The question was asked at to what kind of fuel mileage I was getting with the car. So I decided to start keeping track of it. I knew the speedometer was off substantially so I did a couple of tests to determine the extent of error. The first was a 10 mile test using the odometer of the car and mile markers along the road the other involved a direct comparison between the speedometer and GPS speed. The calculations showed the speedometer was off by 1.23. Here are some of the specifics for the car:

1. 3.54 gears, P295/55 -15 ET Street SS tires
2. 500 cubic inch stroker (400 block)
3. ProComp CNC ported Aluminum heads 325 CC intake runners
4. Heads flow 330 cfm intake, 250 cfm exhaust @ 28"
5. Harlan Sharpe, roller tip, 1.5 ratio rockers
6. 230/236 @ .050", .550" lift Comp Roller Cam
7. Torker Intake (Ports opened up to match heads)
8. TTI Headers, 1 3/4" Primary, 3" collectors
9. 1800 RPM stall, the motor is a torque monster.
10. 9-1 Compression
11. MSD 6AL box and distributor
12. TTI 2 1/2" X-Pipe Exhaust

The tests were done basically driving to work which is a 25 mile trip through rural Nebraska so not much stop and go driving. I tried to maintain 60-65 mph. Here are the results:

1) 4/20/18 9.1 mpg (3 or 4 full throttle blasts)
2) 5/8/18 10.1 mpg (the best grandma driving I could do)

 

[Mocajava]

Is this a standard 747, three speed tranny? Doesn't appear that "letting her loose" periodically has that much effect on the MPG, I am sure the massive torque vs weight has a lot to do with that difference! Are you happy with the sniper set up...ease of installation and self learning capabilities? Looking at a similar type set up only I will have a 496 stroker, six speed with 323 gears behind it. I am trying to get a feel for the combination of a Sniper EFI plus a six speed and a cross country trip from a 5k altitude down to the coast. Not sure the EFI can adjust for that drastic altitude change. I appreciate the info and that is a pristine looking car you have there. Congrats! Mocajava

 

[Sweet5ltr]

Previously I had submitted a post concerning the addition of a Holley Sniper FI unit to my 1964 Dodge Polara 500.

1. 230/236 @ .050", .550" lift Comp Roller Cam

1) 4/20/18 9.1 mpg (3 or 4 full throttle blasts)
2) 5/8/18 10.1 mpg (the best grandma driving I could do)

What's interesting is you're running a fairly mild roller camshaft. I'm wondering how much cam choice plays a role in the overall fuel economy?

 

[Sweet5ltr]

Is this a standard 747, three speed tranny? Doesn't appear that "letting her loose" periodically has that much effect on the MPG, I am sure the massive torque vs weight has a lot to do with that difference! Are you happy with the sniper set up...ease of installation and self learning capabilities? Looking at a similar type set up only I will have a 496 stroker, six speed with 323 gears behind it. I am trying to get a feel for the combination of a Sniper EFI plus a six speed and a cross country trip from a 5k altitude down to the coast. Not sure the EFI can adjust for that drastic altitude change. I appreciate the info and that is a pristine looking car you have there. Congrats! Mocajava

EFI will have no issues adjusting. Anytime the CTS reads above 160* it's constantly learning, or, 'self adjusting'. The Sniper system will simply do what it needs to do to reach the target AFR, regardless of the environment. I mounted a 12" Windows tablet in my car yesterday, this lets me take advantage of the Sniper EFI software gauge panel and do tuning on-the-fly if necessary. You can purchase a Holley 9" digital display for $840. I have $200 into mine with navigation (WLAN hardware), which may help during those cross-country drives.

This guy is running both (3.5" display / tablet) at the same time (two CAN inputs required), I don't think our Sniper kits have that ability? This may be with a terminator setup.

Originator of the idea;

 

[69 GTX]

Good info.

 

[grubby65]

Is this a standard 747, three speed tranny? Doesn't appear that "letting her loose" periodically has that much effect on the MPG, I am sure the massive torque vs weight has a lot to do with that difference! Are you happy with the sniper set up...ease of installation and self learning capabilities? Looking at a similar type set up only I will have a 496 stroker, six speed with 323 gears behind it. I am trying to get a feel for the combination of a Sniper EFI plus a six speed and a cross country trip from a 5k altitude down to the coast. Not sure the EFI can adjust for that drastic altitude change. I appreciate the info and that is a pristine looking car you have there. Congrats! Mocajava

Yes and no on the transmission. It is a 727 Push button 3 speed torqueflite, but it has had some modifications. It has a bolt in sprag, hemi drum and clutches, etc. The torque converter was built by B&R in Tahlequah, Oklahoma. At 60 mph it has about 50 rpm of slip. It does have a mild roller cam due to the fact the car also has Air Conditioning, Power Steering, and it used to have Power Brakes. I love the Sniper EFI. Honestly before installing the it I was considering selling the car. It had an 850 cfm AVS and I had taken it to a shop in Lincoln for a dyno tune it. But, it was running too rich at lower rpm's and fouling the plugs. Now it is a blast to drive. Starts right up, no hesitation, no bog, it just goes. The self learning varies between 2% and 8% now, so it is almost done. The only issue I have had with the unit is the display. It keeps locking up on me. Holley said I need to install the updates to it, but I'm going to wait until my son gets home from college to help me with that.

 

[Paul_G]

Grubby, are you running a vacuum advance?

 

[grubby65]

Grubby, are you running a vacuum advance?

Yes I am. 32 degrees total advance.

 

[rumblefish360]

32* with the vacuum hose disconnected?
What is the total with the vacuum hose hooked up?

 

[747mopar]

Sweet ride.

 

[grubby65]

32* with the vacuum hose disconnected?
What is the total with the vacuum hose hooked up?

That is total, with vacuum hooked up.

 

[grubby65]

Sweet ride.

Thanks, I love it. Fun to drive. I would like to say it is different than everything else around me, but that would indicate I was looking to be unique. More so I love the body style and Mopars. Most people really don't know what it is though. Usually the only one at most events.

 

[YY1]

Damn that is a NICE car!

 

[kiwigtx]

The tests were done basically driving to work which is a 25 mile trip through rural Nebraska so not much stop and go driving. I tried to maintain 60-65 mph. Here are the results:

1) 4/20/18 9.1 mpg (3 or 4 full throttle blasts)
2) 5/8/18 10.1 mpg (the best grandma driving I could do)

Those numbers are not terrible....BTW our gallons are bigger than yours.

Outside air temp & density has a part to play in fuel consumption.

 

[rumblefish360]

That is total, with vacuum hooked up.

Really! Hummm. Did you try setting the distributor up at 32* without the vacuum line and then add it later with its limit @ 52* or so?

 

[Paul_G]

Really! Hummm. Did you try setting the distributor up at 32* without the vacuum line and then add it later with its limit @ 52* or so?

That will give the best economy. Thats why I asked if vacuum advance was being used.

 

[grubby65]

1) 4/20/18 9.1 mpg (3 or 4 full throttle blasts)
2) 5/8/18 10.1 mpg (the best grandma driving I could do)
3) 5/23/18 10.1 mpg (one full throttle blast, ran the air conditioning a couple of times). Temperatures have warmed up here, daytime highs in the mid to upper 80's

 

[SlinktRR]

do you still have the 850 edelbrock carb?

 

[rumblefish360]

do you still have the 800 edelbrock carb?

Fixed

 

[Dennis H]

I can get mid teens babying it. Gonna add vacuum advance. Want to increase range beyond 200 miles on a tank.