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Hypothetical power output question?

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1986F150six
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Hypothetical power output question?

Post #1 by 1986F150six » Mon Jan 28, 2019 2:39 pm

I am curious about the power comparison of the 4.9L and the 5.0L engines. I have intentionally chosen 1984 as that was the last year [I believe] for both being carbureted in trucks and Broncos. I personally like the six cylinder and its power characteristics.

Looking at factory specification sheets, the 4.9L was rated at 120 hp @ 3K RPMs and 260 lb-ft. torque @ 1.4K RPMs. The 5.0L engine was rated @ 145 hp @ 3.4K RPMs and 250 lb-ft. torque @ 2.2K RPMs.

In my experience, with similar trucks, the 4.9L tows much more easily, but the 5.0L can spank its little brother in an unloaded acceleration test.

For the forum members with engineering and dyno experience, what do you think would be the power output of the 5.0L engine with the only modification being an adapter on the intake manifold such that the 1 barrel carburetor [from the 4.9L] was used instead of the factory 2 barrel?

Thank you in advance!

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THE FRENCHTOWN FLYER
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Re: Hypothetical power output question?

Post #2 by THE FRENCHTOWN FLYER » Mon Jan 28, 2019 6:01 pm

I think it would really suck (pun intended).

But the reason folks order the V8 is that overall the performance is better. With different gearing the 5.0 can take advantage of its higher power band also.
A better comparison would be the latter years when EFI meant relatively unrestricted throttle bodies on both engines. The 5.0 outperforms it everywhere.
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Re: Hypothetical power output question?

Post #3 by Harte3 » Mon Jan 28, 2019 6:28 pm

http://www.bgsoflex.com/auto.html

Try that site. You can plug-in all the specifications you want and get tons of hypothetical results.
'83 F150 300, 0.030 over, Offy DP, Holley 4160/1848-1 465 cfm, Comp Cam 260H. P/P head, EFI exhaust manifolds, Walker Y Pipe, Super Cat, Turbo muffler, Recurved DSII, Mallory HyFire 6a, ACCEL Super Stock Coil, Taylor 8mm Wires, EFI plugs.

1986F150six
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Re: Hypothetical power output question?

Post #4 by 1986F150six » Tue Jan 29, 2019 10:06 am

My thanks to both of you gentlemen for answering what may be a simplistic question.

Thank you, Harte3, for the link. I plugged in parameters for my stock 4.9L [compression ratio and RPMs for horsepower peak] and it spit back 119 HP [compared to claimed 120].

Frenchtown Flyer, I agree that the better comparison would be between later fuel injected engines, but [please indulge me for a moment], if the 1984 5.0L had the 1 barrel carburetor [same as the 4.9L; lets make it simpler... a Carter YF with no feedback], in what way would its horsepower and torque ratings be affected?

Thank you and there will be no more questions!

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THE FRENCHTOWN FLYER
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Re: Hypothetical power output question?

Post #5 by THE FRENCHTOWN FLYER » Tue Jan 29, 2019 2:40 pm

What would happen is the volumetric efficiency - the engines ability to "breath in" a fresh charge - would be reduced. At low rpms it would be little affected and the higher the engine revved the more the volumetric efficiency would be reduced. Similar to a plot of the torque, the vol eff is highest at the torque peak and falls of as revs increase. So the 5.0 L curves - one with the 2V and the other with a 1V - would diverge as rpms increase. A third engine you could add the the comparison would be the 1984 Mustang GT, on which I did the dynamometer development and durability testing while I was an engineer at Ford. It had a 4V carb, along with dual exhausts, a stouter cam, a bigger dual inlet air cleaner, headers, and dual exhausts with crossover, all in an effort to increase its volumetric efficiency. As a result it had 225 net SAE HP, up from the 145 HP rating of the truck engine of the same year. I think with a 1V the power would be about where the 4.9L six was, maybe a little better at hi revs and not qiute the low end torque as the 4.9.
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1986F150six
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Re: Hypothetical power output question?

Post #6 by 1986F150six » Tue Jan 29, 2019 2:57 pm

Many thanks!

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Re: Hypothetical power output question?

Post #7 by Max_Effort » Tue Jan 29, 2019 6:33 pm

THE FRENCHTOWN FLYER wrote:A third engine you could add the the comparison would be the 1984 Mustang GT, on which I did the dynamometer development and durability testing while I was an engineer at Ford. It had a 4V carb, along with dual exhausts, a stouter cam, a bigger dual inlet air cleaner, headers, and dual exhausts with crossover, all in an effort to increase its volumetric efficiency. As a result it had 225 net SAE HP, up from the 145 HP rating of the truck engine of the same year.


So you were on the GT development team. That car changed everything!

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Re: Hypothetical power output question?

Post #8 by THE FRENCHTOWN FLYER » Tue Jan 29, 2019 8:35 pm

Yes, that was my primary job function from the inception of the reborn GT in '81 through the EFI years until 1987 when I moved over to the Modular Engine Group until my retirement. Best job in the world but after 31 years there were other things I wanted to do in my lifetime so I bid adieu.
I worked with a great team of engineers, technicians and lab help. There were many fun stories and events throughout the run.
One example: My manager who initiated the re-birth of the performance Mustang, built the first prototype using a bunch of hotrod parts and techniques to build a real street screamer of a car in a bid to show the upper management (and bean counters) what a born-again pony car could do in an effort to obtain funding to make the program a go. He gave the keys to those folks in the upper floors of the "Glass House" Ford's WHQ building and asked them to drive it home for the week or weekend. He always made sure it was fully filled with gas (it needed high octane dyno test fuel because of its high compression motor) and told them not to re-fuel it. That Mustang was so quick compared to most cars of the '70s and '80s it was a blast to drive and in the short time it existed six of the execs got speeding tickets with it. But it got the funding and the rest is history, still going on today, thanks to his efforts. Of course we had to make the production car nearly as impressive on pump regular, with less race oriented parts, emissions compliant and meeting all the other requirements of a street car. Those GTs became "the '55 Chevy of the eighties".

Talk about the car that changed everything - My best friend whom I met in first grade was a die hard Chevy fan from a die hard Chevy family. Mine was Ford. His Dad had an Impala, mine had a Galaxie. He later had a string of hi-po Chevelles. One day in 1985 he called me and said he was going to buy a new Mustang GT. Should he buy the carbed '85 or the new '86 EFI? He still owns that car and it was garaged and only has 1000 miles on it.

I still get together with my old mates a couple of times a year. Its nice to see that the younger guys have continued to carry the mantle of building fun-to-drive cars. Indeed these are the good old days.
I hope my babble didn't bore you too much. 'Scuse me - I've got something in my eye.
Last edited by THE FRENCHTOWN FLYER on Thu Jan 31, 2019 12:19 pm, edited 1 time in total.
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Re: Hypothetical power output question?

Post #9 by jgregg13 » Wed Jan 30, 2019 3:42 am

THE FRENCHTOWN FLYER wrote:I hope my babble didn't bore you to much.


Absolutely not. I appreciate stories of how the auto industry developed and recognizing those people that really imagined and created the advancements. Many times the credit for brilliant ideas goes to the manager and may not mention the one who actually conceived the idea. For example the stamped rocker arm and ball brought to the table by Clayton Leach and now virtually everyone has used a version of it.

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Re: Hypothetical power output question?

Post #10 by Max_Effort » Wed Jan 30, 2019 9:53 pm

THE FRENCHTOWN FLYER wrote:Yes, that was my primary job function from the inception of the reborn GT in '81 through the EFI years until 1987 when I moved over to the Modular Engine Group until my retirement. Best job in the world but after 31 years there were other things I wanted to do in my lifetime so I bid adieu.
I worked with a great team of engineers, technicians and lab help. There were many fun stories and events throughout the run.
One example: My manager who initiated the re-birth of the performance Mustang, built the first prototype using a bunch of hotrod parts and techniques to build a real street screamer of a car in a bid to show the upper management (and bean counters) what a born-again pony car could do in an effort to obtain funding to make the program a go. He gave the keys to those folks in the upper floors of the "Glass House" Ford's WHQ building and asked them to drive it home for the week or weekend. He always made sure it was fully filled with gas (it needed high octane dyno test fuel because of its high compression motor) and told them not to re-fuel it. That Mustang was so quick compared to most cars of the '70s and '80s it was a blast to drive and in the short time it existed six of the execs got speeding tickets with it. But it got the funding and the rest is history, still going on today, thanks to his efforts. Of course we had to make the production car nearly as impressive on pump regular, with less race oriented parts, emissions compliant and meeting all the other requirements of a street car. Those GTs became "the '55 Chevy of the eighties".

Talk about the car that changed everything - My best friend whom I met in first grade was a die hard Chevy fan from a die hard Chevy family. Mine was Ford. His Dad had an Impala, mine had a Galaxie. He later had a string of hi-po Chevelles. One day in 1985 he called me and said he was going to buy a new Mustang GT. Should he buy the carbed '85 or the new '86 EFI? He still owns that car and it was garaged and only has 1000 miles on it.

I still get together with my old mates a couple of times a year. Its nice to see that the younger guys have continued to carry the mantle of building fun-to-drive cars. Indeed these are the good old days.
I hope my babble didn't bore you to much. 'Scuse me - I've got something in my eye.


It always seems it’s the motorhead engineers with their skunkwork projects that get these things started. That GT Mustang was a light, quick and affordable car. It started the rebirth/new era of the muscle car. It was years until GM and even longer until Chrysler had anything that could compete with it.

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