All Big Six 300 vs 302 mpg

Relates to all big sixes

THE FRENCHTOWN FLYER

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Is that because of the roller cam in the 302 has less friction?
No, not entirely.
The 302 would make more torque with the recent updates since the era of EFI even if it still had the flat tappet cam. I have overlaid the torque curves from the two engines and the 302 beats the 300.
Everywhere
You just can't stuff enough fuel into six restricted ports as you can into eight better flowing ports.
 

THE FRENCHTOWN FLYER

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What a coincidence. I just read this reply over on the Inliners International website regarding a Chevy 292 six:

"If you wanted to, a V8 could be built with a smaller cam, valves, ports, restrictive manifold and small carburetor - which is where the "torque monster" fable comes from.
The number of cylinder confers no benefit except packaging."

"
 

King_Kong

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No, not entirely.
The 302 would make more torque with the recent updates since the era of EFI even if it still had the flat tappet cam. I have overlaid the torque curves from the two engines and the 302 beats the 300.
Everywhere
You just can't stuff enough fuel into six restricted ports as you can into eight better flowing ports.

The question I always have is "how much do WOT dyno figures tell you about the part throttle characteristics of an engine on the street?"

For instance, 2 disimilar engines that have similar dyno numbers at WOT. But 1 engine gets those numbers with a 10lb flywheel and the other engine gets its numbers with a 35lb flywheel. Both are installed in 4,000lb vehicles with a manual transmission. Are they going to feel the same when you let the clutch out in stop & go traffic? Or are you going to have to rev that 10lb flywheeled engine to keep it from stalling each time you creep up in traffic?

Maybe another way to ask: if a dyno shows a certain exhaust system improves WOT numbers across the board, does that always equate to more part-throttle power in stop & go traffic?

If you can shed some light on how that works, Ive really been wondering.
 
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xctasy

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Brake specific fuel consumption is pounds of fuel per hp per hour. The 5.0 SEFi and 5.0 Bank Fire Port EFi car and truck engines with E7 heads are better than any of the 4.9 EFis. The factory use BSFC to determine the effectiveness of engine tune after they've gotten the power, torque and emissions compliance sorted. The 12 phase 7 mile LA Basin FTP75 emission cyclr measures US mpg on a supplied vehicle, Detroit supply the road load and aerodynamic figures, and it's an automated laboratory test that bag houses four gases and does a shed hydrocarbon teat with an overnight cycle. FoMoCo don't do an Apples Verses Apples BSFC curve for public, but they do produce Ciry and 55 mph mpg figures. The 4.9 gives better CAFE averages than any of the 5.0 Port Injection engines, but the 5.0 is able to make better fleet fuel consumption because in real world situations, it's extra 20 to 25 hp is offset by not needing as much throttle opening in real world conditions.

Back in 1983, Modern Motor in Australia did an interesting comparison. Ford had a 4.1 liter 250 cross flow six that made 5 hp less than the dual exhaust GM 253 4.2 liter Holden Quadrajet 4 bbl V8, 26 lb-ft more torque. Both did 16.9 second quarter miles, the Falcon S pack 4.1 EFi did 112 mph, the Holden Commodore SLX 4.2 did the same. Real world fuel consumption with 4 speed manual gearboxes, 2.92 and 3.08 axle ratios....just the same. So it will be with the bigger 4.9 and 5.0. Despite a 13% improvement with a state of the art Honda cylinder head on the Ford Six, and BMW 635i Fuel injection, the 14 year old Holden V8 had one of the best intake manifolds in the business and made a 25% improvement on the 1979 2bbl Bendix Strombeeg WW carb the car was saddled with since 1969. V8 technology then leaped ahead with Port Fuel injection.
 

THE FRENCHTOWN FLYER

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What a coincidence. I just read this reply over on the Inliners International website regarding a Chevy 292 six:

"If you wanted to, a V8 could be built with a smaller cam, valves, ports, restrictive manifold and small carburetor - which is where the "torque monster" fable comes from.
The number of cylinder confers no benefit except packaging."

"
Here's another little relevant fun fact:
The 4.9 six has the lowest Brake Mean Effective Pressure (BMEP) in all of Ford's families of engines. Simply put BMEP means how hard the moving parts in the engine are worked - the average pressure put on the top of the pistons.
One can make the argument then, that the reason the 4.9 six has a reputation for being a torque monster, and rugged, durable engine is that it is not worked very hard, particularly at its upper end of its power band, where small ports and cams tuned for low end torque make it a relatively weak top end performer.
 

Blairsville Ed

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A dirty little secret: A late model 302 makes more low end torque than a 300. Especially with a torque converter you will not see a loss in low end performance with the 302.
I should have been more specific with my initial question.
The comparison that I’m looking at is a carbureted 300 vs a carbureted 302. One benefit to the 302 is an ample parts selection.
I‘m looking at a 1976 F100 with a 300 and automatic trans. I’m guessing its a C-4. Would a carbed 302 be a direct drop in replacement in this truck?
 

xctasy

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Blairsville Ed. You just need the frame mounts and the right kind of non 390 FE engine mounts, which are the same as the F100 Big Six.

Then the SBF 5.0 carb is a straight swap.

In terms of aceing the class, forget anything to do with

1.gross hp,
2.volumetric efficency
3. BSFC
4. BMEP
and hold fast to that which only improves actual torque per cube, and peak power per cube per rpm.

Efficency is about what the late Australian Phil Irving taught us in the 1970s after he retired making the first successful Formula One V8 in 1966 and the then fastest Motorbike engine, the Rolls Royce supercharged 195 mph V-twin Vincent Black Shaddow of 1951.

All the other BS...forget it.

The rabbit hole is about BSFC and BMEP. Phil Irving, and Race Engineer Larry Perkins, upset nearly everyone, nearly all the time, especially trained engineers. Because both guys could get target MPG, hp and torque with whatever air cooled, water cooled engine they worked on. And win races for there team's.

A few exceptions occur if you are comparing other more advanced engine types, but generally,
Any engine can eclipse any other engine if you make the right modifications.

Be steadfast, and find out What Works. The why's and wherefore's, we can explain, but it probably doesn't matter a hoot if you can't get the 32 MPG Laister gets in his loaded 5 speed 4.9 EFi truck with 2.47 gears. That is where Fords state of the art was before the EcoBoosts and a lot of extra weight hit town.

Good luck, but don't ever change an engine type because an Engineering person Hoodwinks you with other things. Ask simply...what makes better MPG, hp and torque. Why better MPG, hp and torque exist..
Well. That's for the Scientists....

Enjoy your quest! Don't spend too much....
 

THE FRENCHTOWN FLYER

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... Australian Phil Irving taught us in the 1970s after he retired making the first successful Formula One V8 in 1966 and the then fastest Motorbike...195 mph V-twin Vincent Black Shaddow of 1951...
A co-worker at R&E had Vincents. One was a '50s Black Shadow that was totally reworked inside and out with extensive use of titanium, etc. It had a tag that said "...officially timed at the Bonneville Salt Flats at 203 mph."
 

Blairsville Ed

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I’ve been pleased with the mods that I have done to my 240, and I’m not opposed to building a 300. It appears that others on this site have commented on the 300 engine as being difficult to get good mpgs especially a carbed motor and the propensity for the 300 to ping. I really like zero decking a motor and running flat top pistons. It has worked well with my 240 and I have no issues with pinging.
Does the 300 have a heavier rotating mass than a 302?
 

THE FRENCHTOWN FLYER

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Due to its longer stroke the 300 crank is heavier than the 240. Probably by about 30 lbs. I'd say the pistons and rods are a wash.
 

MechRick

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The comparison that I’m looking at is a carbureted 300 vs a carbureted 302.

I've never been able to get good fuel economy out of a carbed 302. All else being equal (gearing, trans), an EFI 5.0L will get much better fuel economy than a carbed 5.0/302. Best I've gotten with a carb is 14 mpg.

For some strange reason this doesn't apply to the 4.9. Not sure why, but even when saddled with a 4 bbl they do ok.
 

King_Kong

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I should have been more specific with my initial question.
The comparison that I’m looking at is a carbureted 300 vs a carbureted 302. One benefit to the 302 is an ample parts selection.
I‘m looking at a 1976 F100 with a 300 and automatic trans. I’m guessing its a C-4. Would a carbed 302 be a direct drop in replacement in this truck?

Personally, that is the ONLY reason I would put a 302 in a truck. Cheaper & more readily available high-perfomance parts. But Ive never been impressed with the perfomance of a 302 in any truck. Or the mpg of a 300 or 302 for that matter.
 

Blairsville Ed

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I can’t believe that I forgot about a car that I had. It was a 1979 Capri with a 302 and and a 4 speed overdrive manual trans. I bought it brand new and it got 12 to 15 mpg. No matter how easy I drove it.
 

bubba22349

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I’ve been pleased with the mods that I have done to my 240, and I’m not opposed to building a 300. It appears that others on this site have commented on the 300 engine as being difficult to get good mpgs especially a carbed motor and the propensity for the 300 to ping. I really like zero decking a motor and running flat top pistons. It has worked well with my 240 and I have no issues with pinging.
Does the 300 have a heavier rotating mass than a 302?
Yes a Zero decked 300 with a flat top piston would have some great potential along with the right combustion chamber size my guess it would all depend on the C. R. and camshaft that you plan to run, that is if you still want to run it on 87 Reg. Fuel. I never had any trouble with Pinging, or overheating with my 300's but then they were all built for hard work and the Static C. R. was in the 8.0 to 8.5 to 1 range using the stock type dished Pistons and the mild Melling Torque Cam. I could get up to 15 MPG without trying very hard and the trucks gearing was not the best for Freeway use. The 300 was in a 1965 F350 with a NP 435 Trans, a Dana 70 with a 4.89 gear, and 235 75 X 16 Radials, bolting that same engine combo into a light weight F100 with better gearing and it should get 17 to 18 MPG and maybe more with some work. I think going by feel in the past that the 300's rotating assembly is going to be lighter in mass than the 302 V8 is. Best of luck on your new pick up build.
 

Blairsville Ed

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Is there any difference in building a 300 with an automatic trans vs a manual trans?
With the stock cam, does the Chevy rockers change the static CR ?
Does a zero deck change the burn speed and if so, can the max timing be reduced?
 

sixtseventwo4d

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Just for comparing milage: bone stock 89 F-150 5.0, AOD. 2wd. a to and from commuter vehicle. the best milage I recorded was 16, less when in town. The other vehicles Ive had with the 300 were automatics and would get around 12-14 but they didn't have the overdrive.

I say build what you like, how you like it; as long as it puts a grin on your face the rest doesn't compare.
 

xctasy

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Weight and areodynamic drag create rolling resistance an inability to carry tall gearing and all if it acts as extra horsepower requite at highway speeds. Ford USA saw what the Rover 3500 was doing on 1976...
126 mph from 155 European Horsepower and 27 miles per gallon at 55 mph in a 3000 pound car. When emis sins control required a drop in compression, removal of the 2 Stromberg Zenith carbs for EFI, and whammo, the CAFE average went down to 23 US Mpg. So Fords 140 hp 1979 16.7 second two barrel 5.0 got denoted and went from 21 Mpg at 55 to a 23.5 Mpg auto 4.2 liter in 1980-1982. Then, every year from 1983 to 1995, the fuel consumption of auto 5.0 Mustangs flatlined.

The passenger car spec crash tests, sterner federal emissions, and all the extra weight and appointment's are what killed 5.0 fuel economy. 1979' to 1983's 4 speed SROD gear ratio's were the worst, with none of the Super T10 or Top loader 4 speed close ratio spreads. On the highway, the huge gap between 3 Rd and top killed fuel mileage. All Foxes and F trucks or E vans with the gearboxes....they had their necks "wrung". Ford eventually git subcontractors to supply, ahem, world Class stick shifts. Borg Warner, Z-F Gear, Tremec. It killed off its manual gearboxes, and couldn't afford to make Five speeds at the cost targets required to make money. So most of the issues with the 5.0 iron OHV Small block MPG was not being able to tailor the 195 and 225 hp port EFI or earlier 140 hp 2bbl or CFi''s to suit a nice Rover 3500 style 5 speed. Hence the lumbering 1650 rpm stall FMX, C5, C6 or AOD. Each with the same in terminate to top gear GAP that just sucks up highway fuel when moving from 55 to 75 mph. Real world driving always favours a 5 speed manual 4.9 liter truck six...but none of those got the 5 speed gearbox until the Big Six was injected. The YFA 1bbl was a 114 to 120 hp engine that would match the 165 hp EFI 4.9 if the gearing wa's right.

In the Maliase era, FoMoCo were unable to get the strong ZF 5 speed or World Class T5 behind the 1978 to 1985 carb 4.9 and 5.0's. The 240 was always 4 speed, no power steering and if it had the right axle, that little 95 hp net engine outdid the 4.9 Big Six with FMX for economy. Every extra appointment, power steering, air conditioning, taller axle ratio, stronger , heavier 8.8 inch axle rather than the down graded 8.7 or 9-3/4 pressed third member... they stole Mpg from the 5.0.

Ford Australia didn't have tightening crash and emissons, so it's lightest Falcon cars lost between 250 and in the V8s, 1000 pounds from 1976 to 1983. And gained 15 Mpg on the Highway Mpg figures. A 76 might have done 13.6 Mpg. An 83, 28.6 Mpg. All due to weight reduction and 5 speed gearboxes, with the 1983 3.3 liter version making a 17.9 second quarter mile from just 123 hp in a 2900 pound car, while the 4.9 liter Cleveland 302 with C4
 
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