Author Topic: what MPG do you get? (Read 5498 times)

brads70 · « **Reply #15 on:** August 24, 2010 - 07:23:06 PM »

Quote from: MEK-Dangerfield on August 24, 2010 - 06:30:29 PM

Brad,

You cheated using Canadian gallons.

Still, that isn't bad at all with 3:55's. Is your engine basically stock, or has it been hopped up some?

Mike

I used an online convertor so I think it was US gallons. I installed a Holley street dominator intake and a Demon 850, but other than that I have no idea whats inside, but it idles at 750 OK so I'm sure it's pretty mild.

Cooter · « **Reply #16 on:** August 25, 2010 - 06:44:19 AM »

My cars aren't rated in MPG, they are rated in GPM (Gallons Per Mile)...

73EStroker · « **Reply #17 on:** August 25, 2010 - 11:05:53 PM »

15MPG (Imperial) with fairly wild 451 and PassonOD on 3.73 rear. Still haven't set up the IAB in the Proform 950 yet and may go with the 25 power valve instead of the 35.

MJS73 · « **Reply #18 on:** August 26, 2010 - 10:29:57 AM »

My mileage went from 11-13 MPG with the carb to 18-20 with the EFI and engine management system.

Mike

Chryco Psycho · « **Reply #19 on:** August 27, 2010 - 12:48:57 AM »

not surprising EFI is far more efficient

BB 70 Challenger · « **Reply #20 on:** August 27, 2010 - 06:36:11 AM »

Hello.

14 miles per gallon here (17 litres per 100 kilometer).

- measured a month ago during a 594 mile (980km) trip.
- speeds were from 50 to 75mph (80-120kmh), mostly around 62mph (100kmh).
- pump gas 95 US octane (98 North European octane).
- very stock and very mild 440cid, TF727, 3.23:1 gears, no AC.
- about 3000rmin at 62mph.

Some time ago I found a road test in one of those old car magazines from 1970. They road tested a �70 RT Challenger with 440/727/3.23 and the gas mileage was only slightly worse than mine, almost the same.

ShelbyDogg · « **Reply #21 on:** August 27, 2010 - 10:53:12 AM »

I drove up to Detroit for the Woodward Dream Cruise and got back on Sunday. 10-1/2 hrs each way.
Weekend before that I drove to the Nationals in Columbus, 8 hours each way. For Columbus trip, I had my 3:55 gears in and stayed around the 2300 rpm range while driving down the highway. I got about 19.6 MPG

For the Michigan trip 4 days later, I dropped in my 3:23s and cruised the whole way at 2000 rpm and got the same MPG and the engine was a little less noisy when I hit 80-85.

I run 255/50/15s now and my MPG was over 20 mpg when I had my 275/60/15s on.

440, 484-284 purple cam, 833 OD, 1-7/8 hooker headers, multi point fuel injection. (10 to 1, 93 octane)

brads70 · « **Reply #22 on:** August 27, 2010 - 12:08:18 PM »

Quote from: ShelbyDogg on August 27, 2010 - 10:53:12 AM

I drove up to Detroit for the Woodward Dream Cruise and got back on Sunday. 10-1/2 hrs each way.
Weekend before that I drove to the Nationals in Columbus, 8 hours each way. For Columbus trip, I had my 3:55 gears in and stayed around the 2300 rpm range while driving down the highway. I got about 19.6 MPG

For the Michigan trip 4 days later, I dropped in my 3:23s and cruised the whole way at 2000 rpm and got the same MPG and the engine was a little less noisy when I hit 80-85.

I run 255/50/15s now and my MPG was over 20 mpg when I had my 275/60/15s on.

440, 484-284 purple cam, 833 OD, 1-7/8 hooker headers, multi point fuel injection. (10 to 1, 93 octane)

That's pretty good!

tommyg29 · « **Reply #23 on:** August 27, 2010 - 01:31:41 PM »

Quote from: Chryco Psycho on August 24, 2010 - 05:59:07 PM

I bnet that could be tuned to run far better , more timing , possibly a lower Power valve depending on vacuum etc

Ive got a 8.5 powervalve in it now (jets are 80), which you have mentioned should be set at about 1/2 the vacuum reading. I dont know what the vacuum readings are, but I think the car was setup by Moper, though he may not have had a chance to fine tune it for the prior owner a couple years ago. The carbs havent been touched since (about 4,000 miles ago)
In any case, would dropping the valve to say a 6.5 make that much difference in mpg? Obviously, like everyone else in here, the priority is to increase performance and efficiency, without increasing chances of a lean condition anywhere in the power band.

ShelbyDogg · « **Reply #24 on:** August 27, 2010 - 02:13:07 PM »

Quote from: brads70 on August 27, 2010 - 12:08:18 PM

That's pretty good!

The only real way to tell if you are wasting any gas or running rich, is to put in an oxygen sensor and a O2 Guage. For you cheapies out there, you can get a narrow band O2 sensor out of a junk yard car for almost nothing, then buy the guage from autometer or build one yourself for less that $10 from Radio Shack parts. All it is is a 0-1v voltmeter. When you drive down the highway, if you are rich, you put smaller jets in. Right now you have no way of knowing if you are wasting fuel.

For guys that want to go self tuning EFI. F.A.S.T. sells the EZ-EFI that bolts on in place of your carb ans does all of the tuning for you. If you are getting 6-10 MPG, the system will pay for itself in gas saving and you wont believe your increased power levels. FASTMANEFI.COM sells the whole kit without a fuel pump for around $1700. If you setup your own manifold, fuel rails, and fuel pump, all you need is the $825 kit. This is the kit I wish I had gone with.

http://www.fastmanefi.com/EZEFI-1.htm

brads70 · « **Reply #25 on:** August 28, 2010 - 12:52:48 AM »

Quote from: ShelbyDogg on August 27, 2010 - 02:13:07 PM

The only real way to tell if you are wasting any gas or running rich, is to put in an oxygen sensor and a O2 Guage. For you cheapies out there, you can get a narrow band O2 sensor out of a junk yard car for almost nothing, then buy the guage from autometer or build one yourself for less that $10 from Radio Shack parts. All it is is a 0-1v voltmeter. When you drive down the highway, if you are rich, you put smaller jets in. Right now you have no way of knowing if you are wasting fuel.

Interesting? I know mine is rich when I get into the secondaries. Do you think it would make a real difference on a 4 bbl carb tuning it with a gauge?Economy and performance?
Such as http://www.autometer.com/cat_gaugedetail.aspx?gid=3603&sid=15
I know it's all relative to how much it's wasting now. I'm burning oil as well ,I believe the valve seals need replacing.

ShelbyDogg · « **Reply #26 on:** August 28, 2010 - 04:07:41 PM »

Quote from: brads70 on August 28, 2010 - 12:52:48 AM

Interesting? I know mine is rich when I get into the secondaries. Do you think it would make a real difference on a 4 bbl carb tuning it with a gauge?Economy and performance?
Such as http://www.autometer.com/cat_gaugedetail.aspx?gid=3603&sid=15
I know it's all relative to how much it's wasting now. I'm burning oil as well ,I believe the valve seals need replacing.

Knowing your air-fuel ratio can't hurt but only help your perfomance and economy.

That autometer wideband is a little more expensive than a narrow band but is the perfect one to use for tuning your 4-bbl.

BB 70 Challenger · « **Reply #27 on:** August 29, 2010 - 02:02:17 PM »

When I was tuning my rebuilt 440 I bought a wideband O2 sensor and gauge from Autometer. That was a good thing to do.

I got so familiar with the thing that it is still attached, I ended up hiding the gauge in the ash tray

and it is there ever still. So anytime I want to see if I am running rich or lean or close to the optimum I just open the ash tray and see that Autometer O2 gauge.

My 750cfm vacuum Holley has the following tuning, now:
- front/main jets are #72
- secondary jets are #73 (yes, I�ve got the Holley conversion kit from metering plate to jets)
- power valve is 8.5"
- idle screw 3/4 turns open from close
- vacuum secondary canister spring is "white"

Distributor advance numbers:
- initial advance is 14 degrees (at idle, vacuum advance hose not connnected), total advance is 36 degrees (at 3000rpm, vacuum advance hose not connnected), adjustable vacuum advance is set to maximum = all the way to the right = clockwise
- idle is 800rpm and then the vacuum is 17" on P or N, 14"-15" on D

Attached picture (sorry, it�s a very poor old cell phone photo) shows the gauges and meters and stuff I used when tuning the engine:
- vacuum gauge just outside the wind screen to help me finding the right power valve vacuum number while driving around
- G-Tech to show if the changes I made to the carb or ignition made any changes to the speed at 1/4 mile, ie. more hp or less
- O2 sensor/gauge to tell me when the engine is rich or lean or optimum when driving around in diffferent situations (cruising, passing, WOT, idling...)

ShelbyDogg · « **Reply #28 on:** August 29, 2010 - 07:41:49 PM »

Very cool! Everyone should have one. There are many big and small block owners that I talk to that say they only get 8 or 9 mpg. This is even after they rebuilt and stroked their engines.

brads70 · « **Reply #29 on:** August 29, 2010 - 09:50:16 PM »

I like it! I'm gonna have to look into getting one. Makes perfect sense! Sure is easier than shutting it off after a full throttle run and checking plugs!

Author Topic: what MPG do you get? (Read 5498 times)

brads70

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Cooter

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73EStroker

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MJS73

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Chryco Psycho

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BB 70 Challenger

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ShelbyDogg

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brads70

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tommyg29

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ShelbyDogg

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brads70

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ShelbyDogg

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BB 70 Challenger

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ShelbyDogg

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brads70

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