nm9stheham
Well-Known Member
Hard to say.... Think of every 4 and 6 cylinder high fuel mileage engine out there, and the intake hanging out in the breeze.I would think the airgap style intake would hurt mileage.
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Hard to say.... Think of every 4 and 6 cylinder high fuel mileage engine out there, and the intake hanging out in the breeze.I would think the airgap style intake would hurt mileage.
The biggest thing anyone can do to improve mileage and efficiency is a tune up and changing your driving habits - going the speed limit most importantly.
I’d only trust GPS for distance. Not an imperfect speedometer and tire size.
And what do we do about all the different fuel blends and grades? E-free, E-10, E-15, winter blend, summer blend. Not to mention all the different fuels internationally. I run E-85 and my fuel mileage sucks! It’s pretty obvious as to why - less BTU. So many more variables to list. I think a big takeaway on discussions about fuel mileage is that when someone mentions their fuel mileage - how do you believe them? X miles per gallon is useless info unless you’ve used GPS for mileage and measured the fuel going out accurately.
I would think the airgap style intake would hurt mileage.
I was just pointing out that 18 - 20 MPG in a small block is not impossible....
Sorry we had daily drivers and didn't need 500 HP....
I threw my engine together with spare parts and only had $300 into the engine....
That innovative LM dual exhaust set up is on my hit list.
When I read these threads on mileage, I try to remember to take note of where the poster is located. It is frustrating when there location under there screen name isn’t properly listed. Some fellas I know are in the U.S., some I know ware in Canada or NZ or ....
Well! Your headed in the right direction with that air fuel gauge. A good & wise move on many fronts. The addition of the vacuum advance will add a few miles to the gallon. The engine will be happier.
What are the sizes of the;
Tires
Cam
Carb
Engine
Stall of the converter?
As these are key/contributing factors.
That’s my last build except 750 AFB, 28 inch tire & it’s a manual 4spd. (W/Hooker Super Comps in an E body.)Sorry im in Australia,will have to update my profile.
26" tyre
248@50 comp magnum solid ft cam
750 Holley HP
408/360 with 10.5:1 compression
3000rpm.stall
MSD dizzy with no vacuum advance
Wasnt sure if running vacuum advance on this engine would be a good idea or not.
I know this car is never going to get the us30mpg my old ls1 6spd daily driver got but getting the best out of it would be good.
I've been following this thread from the start,,time to chime in...I've always tried to have my cake and eat it with my cars, what you've got to do when you want to have fun on a budget.
67 cuda, 344, 10.1, Edlebrock closed chamber 63cc, zero deck flat top hyper KB's, hyd roller 222/226 @ .050, 1.6 roller rockers giving .545/.555 lift., Air gap, 3.23 rear (contemplating 3.73), manual 5 speed with .68 OD, 25.5 tires, Dougs and full 2.5 exhaust. FiTech EFI controlling timing and cold air. I didn't go the extra cost for the high precision machining. Just made sure everything was right.
couldn't go the real dyno route so for what it is Desk Top Dyno says 420 hp @5500, 466 tq @4000 with 427 tq @ 2000. Numbers weren't so important just to get the engine in the right range with different parts. The goal was TQ. But the way it drives I believe it's got to be close.
I've recorded a best of 23.8 mpg Imperial or 20.1 mpg US or 8.4 L/100 km hwy @ 120 kph or 74 mph.....I think that covers all the countries....
when I started I said I wanted 400 hp/ 24 mpg. Close enough,,,I'm happy. It can be done with on old technology engine with some modern upgrades and get more fun factor as well. Larry
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Up to 10% in most grades but some premium grade at a few station are ethanol free reportedly...I've been using Canadian Tire fuel which is supposed to be on the E Free list.Just curious- do you have any ethanol in your pump gas up North?
Nice! Slightly milder than my wife’s engine.67 cuda, 344, 10.1, Edlebrock closed chamber 63cc, zero deck flat top hyper KB's, .038" quench, hyd roller 222/226 @ .050, 1.6 roller rockers giving .545/.555 lift., Air gap, 3.23 rear (contemplating 3.73), manual 5 speed with .68 OD, 25.5 tires, Dougs and full 2.5 exhaust. FiTech EFI controlling timing and cold air. I didn't go the extra cost for the high precision machining. Just made sure everything was right.
Desk Top Dyno says 420 hp @5500, 466 tq @4000 with 427 tq @ 2000. Numbers weren't so important just to get the engine in the right range with different parts. The goal was TQ. But the way it drives I believe it's got to be close.
I've recorded a best of 20.1 mpg US or 74 mph...
when I started I said I wanted 400 hp/ 24 mpg. Close enough,,, Larry
Cruise advance is very important. But more is not always better.
At steady-state cruise rpm, the engine wants a ton of advance, until it wants not one degree more. With an unmodded Vcan in a factory D I'm pretty sure it would be almost impossible to give a high-compression engine, too much; even up to a cruise-rpm of 2800/3000.......... unless you are one of those guys who insists on running all-in-timing at 2800 or less.... lol..... even then, I suspect it could use more.
However, chasing the perfect cruise-timing is kindof a diminishing return. Your engine could plateau at some mpg with say 48/52* timing, and not show any better mpg with any more timing.
On the flip-side; if you are cruising at 2200 rpm with 25* advance and no Vcan , well, .............. you are leaving a lot under the table. My Eddie headed 10.9Scr 367 running at 205*F,likes mid to hi 50s there, being just on the plateau, with up to 63* showing very little change.I don't know that an iron-headed 360 would need/want/ or accept, that much; I suspect not.
At 2200rpm, the factory V-can D would be hard pressed to deliver more than 40/42 with 14* initial.
I agree 100%. I was given my 72 Scamp. It had been neglected, only because the P.O. had to give his wife full time care over the previous 10 years he had it. He loved the car, and took good care of it when he could.AFR gauge is a game changer.
so are you saying I have girly engine,,,lol,,,I'm happy with my strong cruiser motor.Nice! Slightly milder than my wife’s engine.
Good topic.
I run a 11.3:1cr 360ci every day in my '73 Dart. 0.030" overbore. Propane fueled.
318 '302' heads, CompCams XE256h, converted to solid, KB-pistons w/balanced crank assembly.
A518-OD (no LU), 3.55:1 gear ratio in a 8-3/4" rear axle.
MegaSquirt ECU controlling ignition only for now. Spent months tuning to come up with a curve that works nicely for the engine.
The car doesn't get even near the mileage I had hoped for... 11-12mpg, mixed highway+street.
Highway only driving barely gets 13mpg.
I'm mostly blaming the A518 currently, and its most likely unmatched mid '60s stock stall convertor currently in the mix.
Thanks for clarifying that. I think i had better keep watching this thread because it looks like i am only getting about 11mpg (US) from my 408 W2 combo. I suppose the 3.9 gears and converter probably dont help too much but im sure it could be improved.
I have bought an afr gauge to try and get it more economical when cruising and am interested in what RAMM has to say about timing and if i should be using vacuum advance when cruising as i currently run an msd dizzy with no vacuum advance.
What AFR are you tuning for at light/moderate cruise? 15-16 is what you want to be under those light load conditions to get to good fuel mileage.But I had TTi headers installed and had my guy add bungs to the headers so I could install an AFR. It was a real eye opener. It made all the difference.
Before the AFR gauge, I kept thinking I was flooding the LA 360 (750 cfm Edelbrock) when trying to crank it. After the AFR gauge I realized it just wasn't getting fuel. The AFR made it clear just how much this LA 360 loves gas. Seems like there's no way to flood this engine. It would burn a cylinder full of liquid gas! OK, just kidding. But it seems that way. Now, cranking is a breeze not that I know what's going on. I also changed to a 600 CFM carb.
Tuning for idle, tuning for off idle, cruise and WOT are simple. Unfortunately, I've tuned to the limitations of a carburetor. It is PERFECT at WOT, a bit rich on cruise, and a bit lean on primary acceleration. However, that's because the AFR gives away all the secrets. If I disconnected the AFR gauge and let anyone drive the car, they would say, "it's perfect!" And it does drive well.
As you mentioned sounds like the converter may be an issue. I did a 340 build trw 10-1 pistons, 272/455 purple cam, performer intake, thermoquad, J heads 2.02 valves, and headers, 518 non lock up w/ stock rebuilt high stall 340 converter, 3.55 gears in a Challenger that would knock down 18-20mpg on the highway. I would use more gear or a smaller duration cam if I were to do it over.