Pondering about flathead potentials

Engine tech, for those engines, products, and technologies of yesteryear.

Moderator: Team

PackardV8
Guru
Guru
Posts: 7619
Joined: Sun Jul 30, 2006 2:03 pm
Location: Spokane, WA

Re: Pondering about flathead potentials

Post by PackardV8 »

Nikolas Ojala wrote: Thu Aug 25, 2022 2:02 pmNo variable valve timing, turbulent jet ignition, or anything like that. . . . pretty much an example of conventional engine technology.
Because he's running in a class which prohibits all of the above; conventional engine technology only allowed.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
Nikolas Ojala
Pro
Pro
Posts: 399
Joined: Sat May 03, 2014 11:57 pm
Location: Finland

Re: Pondering about flathead potentials

Post by Nikolas Ojala »

Nikolas Ojala wrote: Thu Aug 25, 2022 12:31 pm
27:29 Design for combustion chambers ... is a secret.
I just hope that some day they would reveal their secret combustion chamber design.
"Adding power makes you faster on the straights. Subtracting weight makes you faster everywhere."
– Colin Chapman, design engineer, inventor, and founder of Lotus Cars
PackardV8
Guru
Guru
Posts: 7619
Joined: Sun Jul 30, 2006 2:03 pm
Location: Spokane, WA

Re: Pondering about flathead potentials

Post by PackardV8 »

Nikolas Ojala wrote: Fri Aug 26, 2022 7:46 am
Nikolas Ojala wrote: Thu Aug 25, 2022 12:31 pm
27:29 Design for combustion chambers ... is a secret.
I just hope that some day they would reveal their secret combustion chamber design.
That would be of interest. They claim 9.2:1 compression. That's problematic in a max effort flathead. Back in the bad old days, the Harley-Davidsion Racing Division spent more than twenty years experimenting with the tradeoffs of breathing versus compression. Their best KR engines were making one horsepower per cubic inch, probably the strongest NA flatheads ever, but the compression was always less than 7:1; usually around 6.3:1.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
User avatar
Tom68
HotPass
HotPass
Posts: 2541
Joined: Mon Feb 07, 2022 3:43 am
Location: VIC OZ

Re: Pondering about flathead potentials

Post by Tom68 »

PackardV8 wrote: Fri Aug 26, 2022 11:02 am
Nikolas Ojala wrote: Fri Aug 26, 2022 7:46 am
Nikolas Ojala wrote: Thu Aug 25, 2022 12:31 pm
27:29 Design for combustion chambers ... is a secret.
I just hope that some day they would reveal their secret combustion chamber design.
That would be of interest. They claim 9.2:1 compression. That's problematic in a max effort flathead. Back in the bad old days, the Harley-Davidsion Racing Division spent more than twenty years experimenting with the tradeoffs of breathing versus compression. Their best KR engines were making one horsepower per cubic inch, probably the strongest NA flatheads ever, but the compression was always less than 7:1; usually around 6.3:1.
The air cooled Flathead Harley's were battling temperature problems to.
Ignorance leads to confidence more often than knowledge does.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
PackardV8
Guru
Guru
Posts: 7619
Joined: Sun Jul 30, 2006 2:03 pm
Location: Spokane, WA

Re: Pondering about flathead potentials

Post by PackardV8 »

Tom68 wrote: Fri Aug 26, 2022 5:27 pmThe air cooled Flathead Harley's were battling temperature problems to.
Very true; especially on the high banks at Daytona, but not so much on the flat tracks. However, temperature problems wasn't the reason for the low compression. They never found more power at higher compression when it reduced intake flow.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
65-fastford
New Member
New Member
Posts: 18
Joined: Fri Feb 14, 2020 7:05 am
Location: Fate, TX

Re: Pondering about flathead potentials

Post by 65-fastford »

https://www.youtube.com/watch?v=sJWtjChXbOw
great video of an extensively modified NA flathead
Nikolas Ojala
Pro
Pro
Posts: 399
Joined: Sat May 03, 2014 11:57 pm
Location: Finland

Re: Pondering about flathead potentials

Post by Nikolas Ojala »

They chose flat-top pistons. No dome or any other pop-up style. Probably you noticed also what they did to the heads. They added metal above pistons, and also some metal to make combustion chambers smaller.

It is much easier to squeeze air out of the thin space between a piston and a head if both surfaces are perfectly flat planes. Theorethically the same trick is possible with a dome-top piston, but that would be difficult to do.

It looks like they had detected that the worst bottlenecks were ports and valve lift, so they did a tremendous job to improve them. Also it looks like the next possible bottleneck inside the combustion chamber was not nearly as bad, so they chose to increase compression ratio.
Flat_head_with_added_metal.png
You do not have the required permissions to view the files attached to this post.
"Adding power makes you faster on the straights. Subtracting weight makes you faster everywhere."
– Colin Chapman, design engineer, inventor, and founder of Lotus Cars
PackardV8
Guru
Guru
Posts: 7619
Joined: Sun Jul 30, 2006 2:03 pm
Location: Spokane, WA

Re: Pondering about flathead potentials

Post by PackardV8 »

They're keeping the finished head a secret, but they'll be the first to have 9.3 in a high horsepower NA flathead. H-D tried for fifty years and couldn't find a way to get there.
'
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
Nikolas Ojala
Pro
Pro
Posts: 399
Joined: Sat May 03, 2014 11:57 pm
Location: Finland

Re: Pondering about flathead potentials

Post by Nikolas Ojala »

I was thinking: Which method they used to find the optimal shape? Did they accelerate the process by computer simulation or did they use a flow bench?
"Adding power makes you faster on the straights. Subtracting weight makes you faster everywhere."
– Colin Chapman, design engineer, inventor, and founder of Lotus Cars
Nikolas Ojala
Pro
Pro
Posts: 399
Joined: Sat May 03, 2014 11:57 pm
Location: Finland

Re: Pondering about flathead potentials

Post by Nikolas Ojala »

I was thinking: What if someone wanted to convert a flathead engine into Atkinson cycle or Miller cycle, how would that work?

Perhaps Atkinson cycle would not be desirable, because in that case there would be the need to make the combustion chamber even smaller, which is already difficult task with conventional Otto cycle flatheads. Unless someone wants to run such an engine low speed only, that would be a futile attempt. But Miller cycle is different, because some kind of a supercharger is used to produce the desired compression, so the effective compression ratio may be equal or even greater than with Otto cycle. There would be no need to alter the shape or size of the combustion chamber. An intercooler would be essential.

Then I thought what would be better way to alter the length of compression stroke. There are options:
  1. Late intake valve closing (LIVC)
  2. Early intake valve closing (EIVC)
Theoretically either of these could be used, but the fact that flatheads have breathing issues, makes LIVC favorable, as the intake time is not reduced. Instead it is extended, which would be advantageous when the engine is runs high speed.

Next I was thinking, what about the supercharger then? There are many options available. Fortunately I had read about a Swiss experiment. A small engine was converted to a Miller cycle engine, and there were encouraging results by using a pressure-wave supercharger (PWS).

Here is a document of the experiment: https://doi.org/10.3929/ethz-a-005214871 (Full text PDF is available and FREE for download.)

Although there seems to be great potential in the PWS, there are some issues:
The dynamic model proved to be useful to understand the mechanisms of transient exhaust gas recirculation (EGR), a phenomenon which was observed during experiments on the test bench. During tip-in maneuvers, critical situations arise when large amounts of exhaust gas are recirculated over the PWS from the exhaust to the intake manifolds. This causes the engine torque to drop sharply. In order to prevent such situations, the actuators such as throttles, valves, etc., have to be controlled in a coordinated way.
Fortunately turbocharger is a simple option compared to PWS.

I like this short presentation: https://theicct.org/sites/default/files ... Miller.pdf

If methanol fuel was chosen instead of gasoline, a valve-controlled cooled exhaust gas recirculation (EGR) could replace much of the conventional throttle control.

See the attached four page article about cooled EGR.
Clean-and-Cool.pdf
Recent studies performed by engineers at Southwest Research Institute (SwRI) have examined the role that exhaust gas recirculation (EGR) can play in reducing, or even eliminating, these sources of inefficiency in gasoline engines. In internally funded research, they determined that EGR can improve the fuel consumption of both direct-injected and port-injected gasoline engines by reducing pumping losses, mitigating knock, cooling the exhaust and eliminating the need for fuel enrichment.
The schematic on the third page may be helpful.

There is another document, and here is a link: https://www.researchgate.net/publication/265153489

Right on the first page of the document:
The results on the Audi-engine indicate that methanol is more EGR tolerant than gasoline, due to its higher flame speed. An EGR tolerance of 27% was found when methanol was used. The efficiencies of the methanol-fueled engine obtained with EGR are higher to those obtained with throttled stoichiometric operation.
Summary:
  1. A side-valve engine
  2. A conventional low compression head for better intake
  3. LIVC by altered intake valve timing
  4. Turbocharger
  5. Intercooler
  6. Methanol fuel
  7. Cooled EGR
  8. Engine control by combined throttle control and EGR valve control
You do not have the required permissions to view the files attached to this post.
"Adding power makes you faster on the straights. Subtracting weight makes you faster everywhere."
– Colin Chapman, design engineer, inventor, and founder of Lotus Cars
PackardV8
Guru
Guru
Posts: 7619
Joined: Sun Jul 30, 2006 2:03 pm
Location: Spokane, WA

Re: Pondering about flathead potentials

Post by PackardV8 »

As long as we're wasting time trying to make a flathead do things it doesn't want to do, it's much easier to make dry air follow the tortured flathead flow path. Just go with direct injection of the fuel; 90% nitromethane, 10% alcohol.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
User avatar
frnkeore
Expert
Expert
Posts: 825
Joined: Wed Dec 25, 2019 3:06 am
Location: Oregon

Re: Pondering about flathead potentials

Post by frnkeore »

If we are still talking the Ford V8, you are limited by it's intake port of 1 5/16" diameter. You can open it a little, with a lot of work but, you can't open it enough for any real power.

It only after the air goes through that little hole, that it can make it's convoluted path into the cylinder, even with a supercharger.

The whole block, that's where the ports are, would have to be entirely re-engineered to get any real HP out of it.
Isaac91n
New Member
New Member
Posts: 9
Joined: Fri Jun 24, 2022 2:22 am
Location: Nelson

Re: Pondering about flathead potentials

Post by Isaac91n »

Here is what I've pondered once or twice. Ive never laid hands on a flat head, however I have wondered with the exhaust ports exiting through between the cylinders would it be possible to machine ports like a two stroke diesel through the cylinder wall into the existing port, obviously blanking the exhaust port off below the exhaust valve. You would force feed air through this port via a super charger. Next I have seen a modification done before where the exhaust is re configured to flow out the valley of the engine, making it a non cross flow setup, if you were to do this modification but use both valves as exhaust valves. you would have much larger exhaust flow. Change the cam so the valve events mimic a two stroke diesel. This I think would get you to the most powerful flathead in the world.
PackardV8
Guru
Guru
Posts: 7619
Joined: Sun Jul 30, 2006 2:03 pm
Location: Spokane, WA

Re: Pondering about flathead potentials

Post by PackardV8 »

Isaac91n wrote: Tue Dec 27, 2022 6:41 pm Here is what I've pondered once or twice. Ive never laid hands on a flat head, however I have wondered with the exhaust ports exiting through between the cylinders would it be possible to machine ports like a two stroke diesel through the cylinder wall into the existing port, obviously blanking the exhaust port off below the exhaust valve. You would force feed air through this port via a super charger. Next I have seen a modification done before where the exhaust is re configured to flow out the valley of the engine, making it a non cross flow setup, if you were to do this modification but use both valves as exhaust valves. you would have much larger exhaust flow. Change the cam so the valve events mimic a two stroke diesel. This I think would get you to the most powerful flathead in the world.
Yes, in an imaginary block twice as tall, with a piston twice as tall and three times as heavy and limited by inertia. BTW, the Detroit Diesel has been with us for nearly 100 years and came up against those limits, which is why it isn't used any longer.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
User avatar
Tom68
HotPass
HotPass
Posts: 2541
Joined: Mon Feb 07, 2022 3:43 am
Location: VIC OZ

Re: Pondering about flathead potentials

Post by Tom68 »

Isaac91n wrote: Tue Dec 27, 2022 6:41 pm Here is what I've pondered once or twice. Ive never laid hands on a flat head, however I have wondered with the exhaust ports exiting through between the cylinders would it be possible to machine ports like a two stroke diesel through the cylinder wall into the existing port, obviously blanking the exhaust port off below the exhaust valve. You would force feed air through this port via a super charger. Next I have seen a modification done before where the exhaust is re configured to flow out the valley of the engine, making it a non cross flow setup, if you were to do this modification but use both valves as exhaust valves. you would have much larger exhaust flow. Change the cam so the valve events mimic a two stroke diesel. This I think would get you to the most powerful flathead in the world.
Just get a Caddy, bigger inches proper bores and exhausts just as crappy as the intakes.

Despite what people conjure up in their imagination, the exhaust ports between the bores on a properly modified and tuned side valve is the least of their restrictions.

Don't forget they didn't even have a satisfactory Vacuum advance system, they can be greatly improved but the exhaust isn't their biggest achilles heel.

Here's a flat head with no cam actuated valves.

https://youtu.be/RoiWpJLokEc
Ignorance leads to confidence more often than knowledge does.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
Post Reply