What if... they made a modern flathead?

[Flatie46]

I've often wondered what if someone took a flathead six and modernized it. What if the engineers at Chysler took it on as a project to see how much power/ fuel economy they could milk out of one if they put all the computerized crap and fuel injection on it. I know valve and chamber design handicap the flatie but the engines in modern cars would be slugs if it weren't for all that stuff. I saw someone posted one once with a turbo on here and when I saw that it got me to thinking, why stop there? Anybody else ever think about such things?

[greg g]

Well I guess they did go for the improvement when they went to the OHV /6. However, when we were in Detroit for the national, we had a couple of discussions with 2 fellows who are probably unfortunately now former Chrysler engineers.

We were talked some what ifs regarding flathead performance. The limiting factors seem to revolver around (pardon the pun) the rotating mass and the stroke lenght more than the head and valve design.

We talked a bit about turbo charging, and fuel injection. One of the possibilities included using a couple of the simple throttle body fuel injectors used on K cars and Omni Horizon plateforms, on a split intake. These used a simple circuit and throttle position sensor with an O2 sensor. Shaved head would be cool with this set up. The other would be the blow through injectors from the same platforms with a small low pressure turbo air to air intercooler and stock head.

Probably still not looking at much more than 150 or so hp in reliable street trim. You would need to have switched to 12v to run what ever feed back the FI needs and the electric fuel pump the system would require.

Someone else suggested the similar set up from the later GM V6 would work that used the distributor fired port injectors but rewiring them to fire three nozzels one in each intake runner so that each one would feed the adjoining pair of cylinders. But agian the gain probably would be limited.

Graham Paige and Kaiser had supercharged versions of thier flat 6 engines.

The GP used a 218 cubic in L 6 that made 95 HP with the carb, and 125 with the blower.

The 226 inch Continental engine used by Kaiser made 118 and 140 with the blower.

Kaiser did the blower in order to make their 6 cylinder car drive like the buick/olds and cadillac v8'sitwated to compete against. Guess it was not a succesful tactic.

[Dodgefran]

A rant and a Rave........ I can't believe the cost of parts to fix our wonderful modern cars. They cost 20,000 plus and when it comes time to fix out modern miracles, an O2 sensor costs near $200; AND there are at least 2 of them. I bought my house in "72" for $29,000. My next one will require a second mortgage. The electronics are so delecate that when one fails, the dominoes fall. Your gas milage falls and it costs an arm and a leg to fix it. I too would like to see what they could do with our flatheads. We don't need to get from zero to 60 in 4 seconds any more (well, maybe trying to get on the highway). I hate to see the cost of driving in 30 years. When I finish restoring my "ride", It is going to be my main car. It will be less expensive to fix than my wifes '03' Mustang GT. Thanks guys..........I needed that.

[Tim Keith]

I suppose a large bore L-head designed for turbo

charging could do okay as for power output but I don't

think it would be too fuel efficient, although Plymouth

was claiming 24+ MPG in the 1930s. A high swirl chamber

with quench would tolerate more cylinder pressure.

The typical shovel shaped L-head designed on the Ricardo

research is all I've ever seen, like a Briggs and Stratton.

Direct injection would get the most out of the turbo

boost as the timed charge would cool the intake

charge just as heat peaks from compression. L-heads

can have larger valves as the valves can't shroud the

pistons. The L-head valve train is light and efficient,

but usually tied to a low RPM bottom end.

A problem with the L-heads is the large offset chamber

with 6 head bolts is hard to seal, especially when the

motor runs hot. From time to time the Ford flathead

people talk about theoretical chamber designs and so

forth. If its likely to be attempted, the flathead Ford

people will likely be first. The old Harley Davidson race

motorcycles might be a place to look for ideas.

There have been inline L-head Mopar that have done

respectable speeds at Bonneville. Modern thin ring

pistons can cut down on friction on our long stroke

motors, if you can pony up for the custom pistons.

The Toyota Supra 7MGE is a long stoke motor with

the same stroke as a Mopar 360 V8, but about the

same bore as the 218. These small bore motors like

higher RPMs just fine. A bottom end such as that

with an L-head and turbo/supercharger would do

okay, if everything were designed as a package.

[Frank Elder]

WOW, that's a lot of information...I was thinking a dual intake and an injector on each runner, blah, blah, lol,extra fuel line, etc.

It sure does take a little brainpower:)

[Robert Horne]

I've often wondered what if someone took a flathead six and modernized it. What if the engineers at Chysler took it on as a project to see how much power/ fuel economy they could milk out of one if they put all the computerized crap and fuel injection on it. I know valve and chamber design handicap the flatie but the engines in modern cars would be slugs if it weren't for all that stuff. I saw someone posted one once with a turbo on here and when I saw that it got me to thinking, why stop there? Anybody else ever think about such things?

You may gain more power with many modern improvements, but I believe fuel economy will stay the same. My 1971 Chevy truck gets better MPG than my 1999 Chevy truck, with about the same size engine. My 1990 99HP 4 cyl Plymouth got 30MPG, where as my 2000 Avenger V6 132HP gets 35MPG. Good fuel economy comes from many factors, like total weight, wind design, good power to weight ratio, trans, gearing, tires, etc. Not enough power, or too much power can lower fuel economy, 90HP not enough, but 200HP too much. I read that turbo, and superchargers give alot more power, but do not change the MPG. My 36 engine is rated at 84 HP, and my 56 engine is rated at 132Hp. I believe the 56 with a 5 speed trans will be more fun to drive.

[Troganin]

I've aways wondered the opposite. How efficient could you make a new car if it was as simple as our old ones. Remove all the smog controls, motors for the head rests, 17 speaker sound system, ect. Drop all the restrictions to the engine breathing and get rid of the parasitic loss of all the toys. All while having a lighter engine and body all optimally designed.

[Plymouthy Adams]

no flathead but Chrysler not long ago built a prototype with a straight eight...

[Troganin]

Doesn't the jeep have a straight six option? Wouldn't that be close to what you are talking about?

[Plymouthy Adams]

Late model Jeep strickly overhead valve engine..the flattie with its in-block valves and flat head restricts a lot of things as to power and economy

but given that with todays electronic controlled injections system on one of these with a modern profile cam, sealed cooling system with about 21 lbs of pressure so running at 195-205 temp would be normal..the ability to run this baby with greater power and fuel economy would be a given. Not to mention that the already smooth flattie would be smoother yet. For the power play option, TURBO..

The area needing major work in this block is nothing more than the oiling system..

Edited March 28, 2010 by Tim Adams

[BeBop138]

I think someone over on the Inliners forum did a conversion with a 265 flattie and used the fuel system from a Chev V-6. They made there own intake and said it works well.

[Tom Skinner]

Off the subject just a tad...........

How about that old sturdy Slant Six being bought back.

A new owner could do all the maintenance and save tons.

Oh well we were just dreaming.

[Flatie46]

Late model Jeep strickly overhead valve engine..the flattie with its in-block valves and flat head restricts a lot of things as to power and economy

but given that with todays electronic controlled injections system on one of these with a modern profile cam, sealed cooling system with about 21 lbs of pressure so running at 195-205 temp would be normal..the ability to run this baby with greater power and fuel economy would be a given. Not to mention that the already smooth flattie would be smoother yet. For the power play option, TURBO..

The area needing major work in this block is nothing more than the oiling system..

Ok, whats to be gained by the sealed cooling system and 195-205 temp? I've read in other posts that these engines run fine at higher temps. Seems like I'd read that running them cooler would cause crud in the valve area? I know in hydraulics you loose effeciency through heat but didn't think it would apply to a combustion engine. When you mention the oiling system needing major work, what do you mean? I've heard crossdrilling the crank mentioned several times in performance engines.

Robert, I do agree weight plays a big part in both peformance/fuel economy but my business coupe is lighter than most new cars so thats a bonus. There are many other factors, it's a matching game. You mentioned wind design, I think these cars have alot going for them being as rounded as they are. If they were lower that would help. It'd be interesting to see wind tunnel tests on these cars.

[Plymouthy Adams]

the margin of error for increased protection against boil over in a non pressureized system you are just seconds from boil over..slight grade in the road ahead and you just hit a major snag with cooling..see you beside the road....also that margin will be rapidly approaced as the turbo is running...also if the engine temp is maintained at a higher temp...not only is condensation going to be dealt with swiftly but the engine can be leaned to run a bit more efficeintly..remember that was part of my equation also..

most will agree cross drilling does improve lubing, the filtration systems should be upgraded..and if you run a oil fed turbo (don't do like a few other folks and not lube this unit).. I also recommend an external oil coller...this would also make a high volume oil pump beneficial..and as the design of the oil pick up is to float near the surface of the oil..I still think I would want it down near the bottom for absoletly no chance of foaming and sucking a pcoket of air in a major road manuever..the whole idea here in performance and driven to places other than the grocery store or church..

[Tim Keith]

The 2.2/2.5 four was designed by members of the team which built the

slant six. The 2.4 is influenced by that design. The slant six was a good

motor which was allowed to quietly expire. Jeep redesigned its classic six

because it was still acceptable from a packaging point of view as Jeeps

were rear drive. Too bad that Jeep didn't make another round of improvements

to the Jeep 4.0 as I've never heard much praise for the 3.7 V6 in the Liberty

as is common for the 4.0.

I also never liked the Mopar 3.9 V6 based on the 318 which replaced the slant six in

trucks. A redesigned slant six would have been smoother than the V6 and

the torque might have made it feel like a larger motor. The slant six could have

had better fuel economy and power with a new cylinder head and port injection

as a single one carb is not the best for in inline six.

The slant six had surprisingly few modifications over its long production life.

The block was never made into a thin wall casting. The 225 comes alive

with cylinder head improvements. Modern ring technology radically decreases

cylinder wear and could have made the slant six a forever motor.

Too bad for all the fans of the Chevy six, that no aftermarket head based on

the LS1 is not built for that motor. The classic inline sixes were canceled just

as fuel injection could have given them new life as crossflow designs.

[Tim Keith]

One of the disadvantages of an L-head is there is more surface area

in the combustion chamber so that there can be more heat losses,

which can impact combustion efficiency, leading to spots where

unburned fuel can hide and create carbon deposits. The classic

Ricardo head was designed to cause turbulence to eliminate many

of the cold spots. The old motor manuals prescribed regular head

removal to scrape away carbon, but perhaps that was due to poor

fuel quality. The aluminum heads help to reduce the cool spots as

the heat travels quickly through the alloy.

It would seem that an L-head might require a larger radiator than

an OHV, but I don't know whether this is true in practice. I've read

on Inliners that a drag race flathead can glow red on the top of the

motor after a hard run.

[Plymouthy Adams]

I hated also to learn of the slant 6 demise and the replacement being of the V6 (cylinder neutered V8) andyway..the V6 was I think the shorter engine to be used in the vehicle in which it debuted..the Dakota...actually I like the V6...though I would rather have the DOHV 3.5 over the 3.9..as the only rearwheel drive this was in is the Prowler..but in the LHS series this engine is just flat awesome in that is has plenty of pwer, very quiet, smooth like you read about and almost bullet proof in design..non interferrence fit and squared in power per CI..plus it just flat out look huge and powerful..the LHS series are no light weights either..very heavy automobile..

[Robert Horne]

Ok, whats to be gained by the sealed cooling system and 195-205 temp? I've read in other posts that these engines run fine at higher temps. Seems like I'd read that running them cooler would cause crud in the valve area? I know in hydraulics you loose effeciency through heat but didn't think it would apply to a combustion engine. When you mention the oiling system needing major work, what do you mean? I've heard crossdrilling the crank mentioned several times in performance engines.

Robert, I do agree weight plays a big part in both peformance/fuel economy but my business coupe is lighter than most new cars so thats a bonus. There are many other factors, it's a matching game. You mentioned wind design, I think these cars have alot going for them being as rounded as they are. If they were lower that would help. It'd be interesting to see wind tunnel tests on these cars.

Wind tunnel tests would be very interesting on our older cars. The square bodied cars of the 80s like my 90 Plymouth Acclaim would have a poor wind tunnel test. My 2000 Avenger I believe would have an excellent wind tunnel test. My 38 Coupe test would be very interesting.

[bearheart]

Seems like some of the modern do-dads on our engines are there to help reduce air pollution/ by-products of combustion. I'm guessing that our flat-heads are maybe not as "clean" as newer engines. But--It would be neat to see how our flatties compare on that issue too.

[TodFitch]

Wind tunnel tests would be very interesting on our older cars. The square bodied cars of the 80s like my 90 Plymouth Acclaim would have a poor wind tunnel test. My 2000 Avenger I believe would have an excellent wind tunnel test. My 38 Coupe test would be very interesting.

Its not just a matter of squared off corners the overall shape matters too. The aerodynamics of my 1933 are so bad that it actually has less drag going backwards than it does going forward. Chrysler figured that out when they did wind tunnel testing while developing designs for the Airflow.

[Plymouthy Adams]

So basically if you did have a good tail wind you still would not benefit from it...

[TodFitch]

So basically if you did have a good tail wind you still would not benefit from it...

To the contrary... The power needed to over come wind resistance goes up as the cube of the air speed. If you are driving 50 MPH with a 10 MPH tail wind your air speed has dropped to 40 MPH. That will result in a reduction in power needed to overcome wind resistance of about 49%.

Formula for force is Cd * Frontal Area * Windspeed * Windspeed. For power you need to multiply the force times the speed and get your units correct.

Anyway you can see that a small car with a low frontal area has a big advantage over a large car even if it has a lousy shape with a high Cd (Coefficient of Drag).

[Plymouthy Adams]

you had said you had less drag going backwards..better aerodymanics from the rear..so if the rear split wind better than the front..I was being a smart-ash by saying the tailwind would be ineffective due to better rear dynamics and thus flow around the cars and give no real benefit..

[TodFitch]

you had said you had less drag going backwards..better aerodymanics from the rear..so if the rear split wind better than the front..I was being a smart-ash by saying the tailwind would be ineffective due to better rear dynamics and thus flow around the cars and give no real benefit..

I am often too literal for my own good.

[Plymouthy Adams]

and me..90% of all comedians are out of work and I'm trying to make jokes..