How much is too much?

[41/53dodges]

I've been brainstorming, what is the max amount of power one could get out of a flathead six before reliability becomes a concern? primarily in the lower end. The crank journals are about the same size as a small block, and they can pump around 400 HP, so theoretically 300 out of the lower end of a flatty should be ok. THEORETICALLY. What is the general consensus here, just for the heck of it?

-Josh

[Jeff Balazs]

Well just for the heck of it.......why would you? These engines were designed to be low compression....slow turning... workhorses.

Could you spin them up higher? Boost the HP? Sure you could but not without completely sacrificing the characteristics that it was actually designed for. It is supposed to be a reliable plodder. I guess what I am trying to say is that there are plenty of better candidates for this sort of treatment.

 

I have a post war Brit Bike that was built to a very high standard for the day. In many ways it's engine is similar to our L-6.....It was developed to a be ultra reliable every day beast of burden. It is a direct descendant of their mid 30's design with just a few improvements. Time of production was about the same.....early thirties to the mid sixties. The basic design started off with huge flywheels and a long stroke producing quite a lot of usable power at slow engine speeds. Almost like a locomotive. Over the early years these were renowned for their dependability....almost silent operation....and truly amazing low end grunt. Many of these bikes were fitted with sidecars and quite a few pulled trailers. All with just one cylinder. They were used for commuting....as tourers....military dispatch bikes.....and won many 6 days trials and scrambles.

 

In later years the management pushed the racing development of the old design to the extreme.....eventually turning into something very unlike the original animal. High rpms almost no flywheel and 12-1 compression took its toll though. There was almost nothing left but the look. And although they succeeded for a while....they lost the reliability and great characteristics that made them famous......and went under as a result.

 

If a factory tried and failed....it seems to me there is a lesson to be learned here.

 

Jeff

[41/53dodges]

I'm only thinking because why not? Its fun to brainstorm, and just because it's not the best candidate doesn't mean it isn't a candidate.

[Don Coatney]

You might want to check out the Mopar section of the innliners forum and also the HAMB for extreme engine modifications.

[Dave72dt]

I've heard an old adage about hp increases and reliability. Doubling the hp decreases the reliability exponentially especially with stock pieces or so I've heard. Cast cranks versus forged, better rods, better pistons, improved intake and exhaust, cam design, cooling plus all the other parts required getting it to the ground, let alone having it streetable. There are a LOT of parts between the radiator and the rear wheels not designed for that hp. The first gains are relatively easy. The farther up the hp ladder you go, the harder they come and the pricier they get.

I'd like to see some real dyno run data on output. Even with your turbo setup, guesstimates and seat of the pants really don't tell me anything about actual gain.

[HotRodTractor]

I think this is an interesting discussion point. These old engines are very reliable and stout enough to endure quite a bit of abuse. Sure they have their issues with making power, but all engines have some issues that need to be overcome when turning them up above the power they were intended for.

 

The first notable issue to overcome is the oiling system. That can be somewhat solved through cross drilling the crank and some possible bearing mods to help keep lubrication where needed at all times.

 

The next issue to overcome is flow into and out of the engine - flatheads aren't exactly noted for their breathing prowess - the amount that you improve this is going to dictate how much power you can actually build. You can do anything from minor improvements to the OEM setup to an EDGY F-head to bolting on some late model modified OHV heads to making a new OHV head from scratch.

 

The last point of contention I would like to bring up is RPMs. These old girls have heavy rotating parts that just don't like being thrown around all that much - to make power in the existing RPM band - you have to increase torque.... and torque breaks things. To make power and keep the torque lower while making that power you have to spin some RPMs and for that  I would be shaving weight.

 

So with just those points in mind - the amount of power is really dictated by how far you want to go and how much money you want to spend as well as at what point do you stop calling it an old Mopar engine and start calling it a custom built item? Some of the other hobbies I am involved in take stock 160-215hp engines and basically throw everything away, spend 6 figures and have 2500+ ponies at the flywheel for use in VERY short duration, and expect to rebuild it at least once a year. I don't have one of those engines yet... not sure I ever will... lol

[41/53dodges]

I've made some interesting observations with engines too. Look at our old flatheads, then look at a brand new direct injected engine. Not a whole lot has changed in the engine, only the subsystems that make it run like ignition and such. Yet cars last hundreds of thousands of miles where ours went around 50k out of the factory before a rebuild. The primary differences: oils, filters, and fuels. Oil is so much better than it was 50 years ago, and lasts longer. Filters can take out most anything in the air, oil, and fuel. Fuels are engineered to reduce detonation and improve emissions.

All of these things can be adapted to any old engine quite readily. There have been many discussions here how long a fresh rebuild will last with modern oils and such, I'd imagine darn near forever with the power we put out. If little honda four bangers with turbos can go up into the 200's without worrying much, why couldn't we? It's not too hard to wind our overgrown lawmower engines up to 4000, 5000, even 6000 RPM with some work. (even though it doesn't do a whole lot)

The point I'm trying to prove is that I think our engines are capable of a whole lot more than we think they are. With the additions of modern turbocharging, fuels, ignitions, etc I have no problem seeing 200+ horsepower. The legendary jeep 4.0 does it pretty well factory, why couldn't we?

[HotRodTractor]

While at a high level I agree with most of that you have missed three major changes in everything made today versus 50 plus years ago. There have been major advancements in material compositions, in design features, and in process control.

 

Material changes are happening at breakneck speeds these days with new alloys and processes being tested daily - just the other day I was talking with a company that is developing breakthrough technology in laser sintering that allows them to precisely PRINT 3D metal objects - one of their demonstrator pieces to show how strong and versatile this new process can be is a fully printed and functional 1911 hand gun printed using various stainless steel, Inconel, and titanium alloys. Major steps have been made in aluminum and iron forging and castings - the alloys are much better, the castings more refined, less porous, and just flat out stronger than those of just a decade ago.

 

Design has come leaps and bounds with the computing power afforded to us these days. Engineers like myself can now design components and do finite element analysis on the part to determine stress levels, flow rates, heat dissipation, etc... all with a few clicks of a mouse and keyboard and then refine those designs multiple times if needed to get the desired results. Out of the box we can make an engine much more efficient without lots of mechanical revisions and slow real world testing. Of course I am still a fan of the real world tests, but those just validate the design these days instead of producing mile long punch lists of issues and major design revisions to work through to try again.

 

Process control - I don't even know where to start on that one... today companies outfit the manufacturing machines such as die cast machines with thousands of sensor to collect data on the production piece of every part and trend these over thousands of pieces to actively predict issues and correct them. Today there are parts that all get x-rayed and ultra-sounded to detect potential defects. There are methods in place for repeated checks to ensure the quality is there and that it continues to be there. 50 years ago it was much more black magic and voodoo (and even today some of that still exists under certain scenarios, but its much better), they knew problems were happening when they were found, the equipment to hold tight tolerances and even measure some of those tolerances on every part just simply did not exist.

[Dan Babb]

This guy says he's getting about 200hp out of a 230cu.in.  

I think I've seen his posts over at the hamb.

 

It sounds great in this video.

 

Edited February 20, 2014 by Dan Babb

[41/53dodges]

Somewhere I heard that motor blew up pretty quickly, but I could be wrong. Race engines are kind of a dirty breed, they aren't meant to last long nor are they particularly good road engines. Great for race, not so much in daily driver. I think it's just the way they run? I will say they do sound sweet. I'm thinking a fuel injected turbocharged motor. It would be a heck of a lot smoother and more friendly than the old-fashioned racer.

[Dave72dt]

Old saying in racing is you can't win if you don't finish.  I've never met a true racer yet that wanted their engine to blow.  Without a dyno run, who really knows what it had for hp.  If professionally built and if it did in fact  have 200 hp and if it blew up, the 300 you were dreaming of isn't going to happen with reliability.

[41/53dodges]

I don't think that was proffessionally built... And it seems that the pistons are always first to go, not so much the rods or bearings. Either way, it never hurts to dream. even if it will never work!

[HotRodTractor]

Is that what failed on that engine? The pistons? I remember reading on Inliners about the same time as he was building and testing that engine, I remember that he had issues, but I don't remember what those issues specifically were.

 

The OEM pistons for these engines are big heavy cast slugs of crap. There was some discussion on Inliners and Olskoolrodz about swapping in common aftermarket forged Slant 6 pistons to take advantage of the lighter weight and offset wrist pin. the bore size is slightly different, but by playing around you could get one that would work in one of these blocks with some boring. I remember when I was looking into it long ago I thought I found a piston head to pin height discrepancy that made it a bit of trouble to make work.

 

Of course the ultimate would be to have a billet set of pop up pistons made and instead of milling the heads down to gain compression, you leave them and machine out piston pockets so the pistons come up into the heads while running to help leave the transfer slot between the cylinder and the valves as open and as large as possible.

 

Scratch that - the ultimate would be to cast a brand new cross flow OHV head.

 

The 265 that I am putting together will ultimately have fuel injection and a VS57 supercharger (with a modern compressor wheel installed). I'd love to have a reliable 200hp out of it, but its not necessary. I'm building it to go into a 1928 Ford roadster to use more as a cross country cruiser and fair weather driver with the grand goal of cruising Route 66 with a teardrop camper in tow. Reliability and smooth power with a cool package that turns heads as something different is what I am after.

[48Dodger]

HP is the ability of the engine to replenish the cylinders with fuel. Torque is the concern for the block itself...

 

Example.    400 HP small block vs. 400 HP big block...same car was used.....big block won because of greater levering of the crank and rods etc. 

 

HP and Torque always cross at 5,252 rpms....in other words HP is calculated from Torque and RPM...find the max torque the motor can handle (or built to handle) and HP will follow.

 

HP = (torque X RPM) / 5252

 

48D

 

 

[Jeff Balazs]

I would doubt very much if you could get a reliable 200 hp out of one of these engines. You would certainly have to spend gobs of money to get close. And the basic design and metallurgy probably won't support it for all that long. I think a 35% to 50% boost in power is something a lot of us might appreciate and is probably an attainable dream.  Honestly 25% more power would be easily noticed. I would be very happy with that if I could do it without changing the sweet running characteristics of the engine or creating a potential grenade.

 

When I first built the old motorcycle engine I mentioned above I had to learn some valuable lessons. Initially I used later aftermarket parts and it ran but did not perform as I expected. One of the main characteristics these engines were known for was their ability to produce good usable power at throttle settings below 200 rpm. My initial build did not want to play nice at that sort of engine speed so I started researching the issue. I went through everything I could find that was published at the time these bikes were produced. Thanks to the Brit's great tradition of documenting the crap out of things I was able to find dozens of articles and even a few videos of them in action at the Scottish 6 days trails and the like.

 

This whole process was very enlightening. I came to understand what was truly needed to get one of these engines to run like it was supposed to. The bottom line was that in order for it to behave like it was designed to it needed a very specific wire wound piston that had not been made for over 50 years. All the aftermarket pistons were of different designs than the originals ....different weight....different c/r.....different rings.....and designed to run at higher clearances. I really wanted to do this right......and I was able to find a NOS piston and rings. That combined with a re-sleeved barrel machined to the .001 clearance that these piston were designed to run at......and Bingo! the engine was transformed back into what it was designed to be.

 

I am sharing this with you because I think these engines were designed to behave very similar to that old motorcycle engine. Simply put they are plodders.....beasts of burden if you will. Plenty of low end grunt......and never created to be speedsters.

 

Jeff

[HotRodTractor]

Since we are having this discussion - does anyone have actual dyno sheets of engines or even chassis dyno sheets for vehicles with these engines installed in them?

 

Actual dynoing of a stock motor, one with the standard upgrades (dual carb, exhaust, milled head, maybe a cam).

 

I totally agree that these things are awesome in stock form, plenty of torque right off idle to keep things entertaining. I don't expect 200Hp, but I think it would be nice. The only way to make the power is to limit the torque down low and move the power curve higher, but that doesn't lend itself to a driver as well as what we already have.

[Dave72dt]

Spending the time to dyno one of these in the various configurations would be an exercise to satisfy one's curiosity.  You'd need to have all the components on hand and be able to schedule and afford a full day or more for testing as well as all the tools and gaskets needed to make the changes.  I'm curious but not that curious.

[Don Coatney]

I believe Greg G may have some dyno sheets.

 

I recall the conversation on innliners and OSR about the use of slant 6 pistons but I do not know that anyone ever tried that combination. I know that my good friend Mark Hudson and his dad were a part of that conversation. They have a CUSTOM tractor (used for pulling competition) with a highly modified 230 CI engine that they spin at five grand for short periods of time. Pictured is there tractor.

 

 

 

[HotRodTractor]

Maybe I'll get the dyno out this summer. I have a small water brake dyno that is good to 150hp (I think.... I guess I need to go look.... ). I was planning on breaking in the new engine once its built on the water brake anyway, its not that hard to hook up the torque arm and tach to be able to read the numbers instead of just using it for load. My motor won't be done this summer, but I have a a good compression low hour 265 IND out of an Oliver combine with 300 original hours on it, and I have a stock dual carb and dual exhaust setup as well as a few heads including a factory aluminum head.

 

I also have a couple of pressure transducers that I could put into the "timing" hole on the head and monitor cylinder pressure to determine if a particular state of tune is "safe".

 

Sounds like a fun couple of weekends to me. lol

[55 Fargo]

Very interesting thread, some of you Guys have a a lot of good ideas, lot's of knowledge too, Wish I had a little more skill in the engine building area....

[HotRodTractor]

Hmmm. Aparently its good for 200hp. Sounds like its perfect for this particular test. lol