mechanicat16
Automotive
Why do old engines produce such little power for their displacement, for example, the 1968 426(7.2L) hemi produced 425HP.The modern 6.1 L hemi produces about 425 HP, the same as the 7.2! Why is this?
Eng-Tips is the largest engineering community on the Internet
Intelligent Work Forums for Engineering Professionals
-
Congratulations waross on being selected by the Tek-Tips community for having the most helpful posts in the forums last week. Way to Go!
Old Engines are inefficicent at creating power/torque,WHY? 3
- Thread starter mechanicat16
- Start date
- Status
To add to Greg's post:
Imaginary or computer?
I'm with you, Ross. I saw a crate motor 426 run up and, while impressive, it only made a bit over 500 hp. At the time everyone was jumping for joy...Most did not do that well.
Did get to see an 800 plus on a dyno...looong time ago. One of the Pitman bros. 390 blown Chrysler's.
Rod
Imaginary or computer?
I'm with you, Ross. I saw a crate motor 426 run up and, while impressive, it only made a bit over 500 hp. At the time everyone was jumping for joy...Most did not do that well.
Did get to see an 800 plus on a dyno...looong time ago. One of the Pitman bros. 390 blown Chrysler's.
Rod
ornerynorsk
Industrial
I'll have to pry some more info out of him. I know the 426 was derated by the factory to keep it under 1hp/cu in. The Hotrod and Car Craft editorials are not exactly white papers, either.
Just as an interesting side note, the 8000 hp mark has been breached by an aftermarket hemi (496 cubes) running nitromethane, and obviously tweaked a bit more than what you would have gotten in '64 or '65. I'll see if I can dig up my references on it.
But anyway, 2 hp/in3 is not rocket science, and easily obtainable in a streetable motor.
Just as an interesting side note, the 8000 hp mark has been breached by an aftermarket hemi (496 cubes) running nitromethane, and obviously tweaked a bit more than what you would have gotten in '64 or '65. I'll see if I can dig up my references on it.
But anyway, 2 hp/in3 is not rocket science, and easily obtainable in a streetable motor.
btrueblood
Mechanical
"But anyway, 2 hp/in3 is not rocket science"
True, that's on the wimpy end of rocket science.
True, that's on the wimpy end of rocket science.
On pump gas? Totally stock in the late '60's/early '70's, with (single or dual?) carbs, and point ignition? Factory exhaust manifolds? "Totally stock" I take to mean "as delivered to Joe Average by the corner Plymouth/Dodge dealer". Not some skunk works factory blueprinted and tweaked drag engine. Totally stock as I've described, 2 HP/ci was indeed rocket science back then for a normally aspirated OHV engine with pushrods a foot long.
ornerynorsk
Industrial
Not talking about 2hp/in3 as a stock delivered motor. As streetable, I mean one that you or I could build in our garage with available aftermarket parts, and actually be able to drive it with commonly available fuels. I'm on a different train of thought here than my first post in this thread.
NormPeterson
Structural
IIRC, the late 60's Trans-Am 5 liter engines eventually put out 475-ish HP.
It was a big deal when HRM ran an article on a small-journal SBC build-up that made 572 HP (early 1970's). Around 5.4 liters.
I think there was one tiny V8 (OHC) that claimed 240 HP from 2 liters at some time in the 1960's. In the context that Italian dynos of the time were commonly suspected of being calibrated using small horses.
None of those engines would be considered daily-driveable, and the pushrod ones still fell short of 1.75 HP/in^3.
Norm
It was a big deal when HRM ran an article on a small-journal SBC build-up that made 572 HP (early 1970's). Around 5.4 liters.
I think there was one tiny V8 (OHC) that claimed 240 HP from 2 liters at some time in the 1960's. In the context that Italian dynos of the time were commonly suspected of being calibrated using small horses.
None of those engines would be considered daily-driveable, and the pushrod ones still fell short of 1.75 HP/in^3.
Norm
ornerynorsk
Industrial
We're getting 600+ hp out of Mopar small block 360's, no blower, carbureted, pump gas (maybe a little avgas to help retard detonation). No NO3 or anything tricky. Mind you, Grandma isn't going to be using it for thursday bingo or picking up kitty food at Walmart, but it is street driveable. Yes, we do need to put TALL valve covers on them. You don't do this kind of thing with a small block chevy and expect things to last very long.
Okay...I have a couple problems with confirmed readings of ~8000 hp from > 500 cu. in....To start, where is the engine dyno that reads that high? Or is it just "guesswork"?
Largest dyno I have seen was testing a RR Merlin race engine for a P-51, about 4000 hp. I don't recall anyone publishing data on fuel diggers. I know that the claims are all in the big numbers and, I agree with some...I just don't agree with 8000 unless I see some supporting data.
Two...On pump gas? 91 octane pump gas? 600hp from 360 cu.in.? Several 600+ hp street cars out there, I agree. However, NOT 360's. Most are 500+ cubic inch monsters.
Perhaps I have been on the left coast too long and have missed out on the automotive revolution back east.
Rod
Largest dyno I have seen was testing a RR Merlin race engine for a P-51, about 4000 hp. I don't recall anyone publishing data on fuel diggers. I know that the claims are all in the big numbers and, I agree with some...I just don't agree with 8000 unless I see some supporting data.
Two...On pump gas? 91 octane pump gas? 600hp from 360 cu.in.? Several 600+ hp street cars out there, I agree. However, NOT 360's. Most are 500+ cubic inch monsters.
Perhaps I have been on the left coast too long and have missed out on the automotive revolution back east.
Rod
The 475 number is about what Traco was supposed to have been getting out of their Trans-Am 302 CSB according to what I remember. A well tuned in-the-car stock Z/28 would be around 375, sometimes a bit more. The Penske cars were another matter. A combination of motor, drivetrain, chassis, body and mystery(??) modifications.
Could be that those Italian dynos were calibrated with a team of AGIP, Ferrari's fuel sponsor before Shell, six-legged dog from their logo.
Yosh
ornerynorsk
Industrial
Hi Evelrod,
I've been trying to find a link on the web for you, no luck just yet. The 8000 hp monster I mentioned is being measured/extrapolated with torque sensors, and I don't know that the data has been certified third party yet. I have just bits and pieces myself, but I've heard that they're running in the neighborhood of 50+ psi of boost from a roots blower, force feeding a gallon per second of fuel (injectors in the blower hat, intake runners, and cylinders) at some over 8000 rpm.
In regard to the 600 hp 360's. We have twisted driveshafts, snapped u-joints, and exploded transmissions with these things. We had a 72 Satellite (big and heavy) that would toast anything less than a fueller from a dead start. The hardware is all mostly straightforward, it's the timing, mixture and ignition that is critical. Can't do it every day either, the weather plays a huge factor. There are days when we're down 50 hp or more.
I've been trying to find a link on the web for you, no luck just yet. The 8000 hp monster I mentioned is being measured/extrapolated with torque sensors, and I don't know that the data has been certified third party yet. I have just bits and pieces myself, but I've heard that they're running in the neighborhood of 50+ psi of boost from a roots blower, force feeding a gallon per second of fuel (injectors in the blower hat, intake runners, and cylinders) at some over 8000 rpm.
In regard to the 600 hp 360's. We have twisted driveshafts, snapped u-joints, and exploded transmissions with these things. We had a 72 Satellite (big and heavy) that would toast anything less than a fueller from a dead start. The hardware is all mostly straightforward, it's the timing, mixture and ignition that is critical. Can't do it every day either, the weather plays a huge factor. There are days when we're down 50 hp or more.
My own website? Hmmmm. You give me more credit than I deserve. It has taken me nine years here on ET to figure out how to post a photo. ;O)
I can make an engine from an idea...I cannot make this infernal machine do anything without help.
Rod
I can make an engine from an idea...I cannot make this infernal machine do anything without help.
Rod
LionelHutz
Electrical
800hp factory stock Hemi? I don't think anyone here, besides you, believes that one.
A bolt together in your garage parts kit to get a 600hp 360 that runs on pump gas? This could be possible but it would be very difficult. Even "new school" engine technology does not make this a easy feat for a naturally aspirated engine.
Can I borrow your dyno to do some testing? Or do you only allow the "big HP" Chrysler products....
A bolt together in your garage parts kit to get a 600hp 360 that runs on pump gas? This could be possible but it would be very difficult. Even "new school" engine technology does not make this a easy feat for a naturally aspirated engine.
Can I borrow your dyno to do some testing? Or do you only allow the "big HP" Chrysler products....
My son is up in NorCal at this moment picking up one of our Lotus/Cosworth DOHC, two valve engines. It made 197hp @ 8500 rpm from 1594cc! I have had a hand in a Cosworth BDA 1600 that made 240hp, but its a FOUR valve DOHC and injected. Those numbers certainly would have been suspect 40 years ago (I was able to get 165hp from this very same engine in 1967) when those engines were fairly new. (Supercharged 2 litre versions of this engine have been in the 1000 hp range for several years...yeah, time marches on)
So... Agreed that time marches on and things change. However,I'm sorry, but 1.7hp/cu.in. in a NA, two valve, pushrod domestic V8 running on 91 octane gasoline is just more than I can accept without some REAL numbers from a reputable, believable source. I'm sure you are convinced in your belief...So be it. I choose to remain skeptical until proven otherwise.
Rod
So... Agreed that time marches on and things change. However,I'm sorry, but 1.7hp/cu.in. in a NA, two valve, pushrod domestic V8 running on 91 octane gasoline is just more than I can accept without some REAL numbers from a reputable, believable source. I'm sure you are convinced in your belief...So be it. I choose to remain skeptical until proven otherwise.
Rod
YvesLLewelyn
Mechanical
I think some of the most impressive racing engine figures are from the Oz V-8 Supercars. 5 litre Fords and Chevies, 2-valve pushrod etc. - limited by regulation to 10:1 CR and 7,500RPM limit - and the best ones make 650HP.
patprimmer
New member
Some are certainly pleased and prepared to pay for being told they have it. They generally are not nearly so pleased if they actually get it as they find it unmanageable for road work and it generally greatly overpowers their chassis and tyres.
I was involved in one build of a 351 CI Ford Cleveland for a street/race car that was a weekend driver and street class race car.
The guy asked us to build a dual purpose engine and gave us a budget that in the day, allowed stock head and block casting, considerable head work, big SS valves, roller cam, forged pistons, stock crank casting and stock rod forgings with good prep and good bolts etc, after market inlet, big single carby, MSD ignition, avgas 115/145 fuel and a good tubular 4 into 1 exhaust.
It dynoed at 400hp at somewhere around 6500rpm.
The owner was furious at only 400hp, said he already had over 500hp from his back yard built current engine and would not even consider installing the engine.
About 6 months later he blew his old engine and needed to make a race meet next day and make a pass to qualify for some prize money, so he reluctantly fitted it as it was the only possibility to be there with a running engine.
He ran at 1/2 second under his previous best ever time with the worthless 400hp POS.
Moral of the story. There are dynos and there are dynos. There are dyno operators and there dyno operators and there are salesman and there are spin doctors and there are plain BS artists.
Magazines tend to quote numbers from the most self serving BS artists around.
In the day and age, 400 real fair dinkum hp was a very stout street/race American push rod V8 that could regularly beat engines claimed to be 50% more powerful.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
I was involved in one build of a 351 CI Ford Cleveland for a street/race car that was a weekend driver and street class race car.
The guy asked us to build a dual purpose engine and gave us a budget that in the day, allowed stock head and block casting, considerable head work, big SS valves, roller cam, forged pistons, stock crank casting and stock rod forgings with good prep and good bolts etc, after market inlet, big single carby, MSD ignition, avgas 115/145 fuel and a good tubular 4 into 1 exhaust.
It dynoed at 400hp at somewhere around 6500rpm.
The owner was furious at only 400hp, said he already had over 500hp from his back yard built current engine and would not even consider installing the engine.
About 6 months later he blew his old engine and needed to make a race meet next day and make a pass to qualify for some prize money, so he reluctantly fitted it as it was the only possibility to be there with a running engine.
He ran at 1/2 second under his previous best ever time with the worthless 400hp POS.
Moral of the story. There are dynos and there are dynos. There are dyno operators and there dyno operators and there are salesman and there are spin doctors and there are plain BS artists.
Magazines tend to quote numbers from the most self serving BS artists around.
In the day and age, 400 real fair dinkum hp was a very stout street/race American push rod V8 that could regularly beat engines claimed to be 50% more powerful.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
YvesLLewelyn
Mechanical
Do you doubt the V-8 Supercars claimed 650HP? You can never say for certain - but I am inclined to believe it.
patprimmer
New member
I never said I doubted the V8 Supercar claim.
I said that for amateur part time racers, big power numbers are often unrealistic or even fraudulent.
I said that for a street drivable Ford Cleveland with stock castings back when, that 400hp was a lot.
V8 Supercars are not street driven and do not use stock castings, do not use a cast iron crank nor stock rod forgings and certainly do not use a single carby for fuel metering.
650hp is quite believable for them.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
I said that for amateur part time racers, big power numbers are often unrealistic or even fraudulent.
I said that for a street drivable Ford Cleveland with stock castings back when, that 400hp was a lot.
V8 Supercars are not street driven and do not use stock castings, do not use a cast iron crank nor stock rod forgings and certainly do not use a single carby for fuel metering.
650hp is quite believable for them.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
- Status
Similar threads
