8ba RPM

[Fibber Mcgee]

Quick easy question just for my knowledge,what is the "redline"of a stock 8ba flathead?

[FHFD]

A lot of variables here, but you did say stock 8ba. Most all of the printed max HP ratings were based on rpm ranges between 3200 RPM to 3800RPM.

[Mike51Merc]

I asked the same question on the HAMB and couldn't get a straight simple answer. Most answers said a flattie, because of breathing limitations, can not rev high enough to grenade itself.

[Walt Dupont--Me.]

I'd readline it at 4000 if you can get it that high. We'er talking stock now. Walt

[Bruce Lancaster]

I would agree that the real world redline is just the end of the power curve...you reach a point, certainly by about 4,000 in a stocker, beyond which you are just getting a whirring noise and no power. Assuming decent condition, you won't be able to approach destructive speed or valve float.
According to some published lore, the origin of Duntov's idea of making heads for the Ford was his discovery that his heavily loaded '37 Ford used for smuggling in Europe after the war would run up to very high RPM, higher than his prewar French OHC race car, without damage on the downhill parts of his runs. He realized that he had found a platform that could support better breathing...

[kendall]

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sooooo, in other words a flathead will run out of breath before it falls apart?

[19Fordy]

My Mercury Manual says that the 1951 stock Merc engine puts out 112 HP at 3600 RPM. Compression ratio is 6.8 to 1.

[Ol' Ron]

This is a good time to read JWL's book. During his tests of the stock engine he didn't measure any torque readings after 3700 rpm untill he changed cams. The most Horsepower he could get from a stock 8BA was 80HP and reguardlass of any exhaust, intake or compression changes, could not exceed 100 HP Many of your questions can be answered by reading this bood, which can save you allot of momney when you start your rebuild.

I've run several modified Flathead son my friends Superflow Dyno and found that power falls off rather fast after 4800 RPM. This engine was built for a Hydroplane and would not be suitable for street, Max HP was 175 @ 4650. Just love em!

[Walt Dupont--Me.]

my 286 dragster goes throught the traps right on the rev limiter 5500 every time. My boy shifter into 4th one time at 5500 and he said it still set him back in the seat. Walt

[Shadetree]

Is it true that a new modern engine at the factory is run wide open for several minutes before they install it? Seems awful harsh! Years ago I had heard they ran the new engines by compressed air, which makes more sense.

Shadetree

[Bruce Lancaster]

Another source...if you look at the various year factory dyno curves in the service Bulletins, you will see the curves starting to drop like a rock at the point they end the charts. The stock engine has simply run out of air. Curves are shown up to about 4500, by which point they are headed DOWN dramatically. Hot rods I would say commonly add about a thousand, uncommonly a lot more.
Interesting factoid: If you look at a factory 60HP curve, the lines are still heading UP at the point the chart ends...the 60 quite clearly made more power above the point at which the factory chose to rate it.

[kendall]

at what RPM do you guys think the flathead will start to destory its self? anything over 5,000?

[Bruce Lancaster]

I think the bottom end is good for a lot more than that.
In the Duntov anecdote I read, he found himself running well beyond 6,000 down long hills in a heavily overloaded '37 Ford smuggling car that had to struggle to get the loads UP the same hills at all...supposedly this led him to realize that he had found a cheap and sturdy platform that could handle some serious development upstairs.
His racecar was some sort of little DOHC Frnch sportscar that could not rev nearly that high...
In Duntov's immediate postwar Europe, there were stll tightly controlled borders and each country had a different range of items in short supply...so D stepped up running foods, tobacco, gold, etc. across low country and French and German borders to take advantage.

[Bruce Lancaster]

Now...I need to go dig in the basement and compare 221 and 239 prewar curves, just out of curiosity. Since everthing in the flow path was the between 221's and 239's of same year, seems like there should be a tiny difference in the RPM level where torque drops dead...I want to see if there's anything discernable in the dyno charts.

[Flathead]

Flathead dragster: 296cid, Potvin 425 eliminator, four 97's on gasoline, vertex mag, a lot of valve, port, and head work, stock rods, stock main caps with fabricated steel supports. Told the young (but good) driver to shift around 5500 RPM. It would run the quarter in the high 12's. Then one day he decides to run it out till it stops pulling and then shift. Well he ran it to 7000 RPM before shifting, car went 12 flat. After that, 7 was the new redline. Many races no engine problems or tear downs. Believe it or not, but a true story.

[kendall]

flatheads are remarkable, 7000 rpm? that seems very high, but i can believe it. i wouldnt try it with mine, any of you guys push the limit and have one blow? i remember grandpa going down a hill with a load on his truck, breaking with the engine, it was loud and i was about ready to jump ship....gramps just hung on to the wheel and kepted yelling whoa whoa!!!.....thinking back, ...he was better with horses.

[rooboy]

Bruce your comments on the quick fall off of power is exactly the reason why i have never run any of my engines with tight combustion chambers and high comp. ...after 3000rpm they start to die, no matter what "fruit" is on the engine ...The above is not much use when trying to pass a semi...specially when your halfway past him and somebody is is heading towards you in the opposite direction.?.......The Baron .630 heads plus the L100 cam keeps her pulling easily upto the 5000rpm mark........

Never had problems running stock engines around 3500 - 4000..But i've always balanced the engines......modified or not.......Ya just can't have too much insurance eh ?.............

[Ol' Ron]

Be nice if you had 8.5 CR those Barons only have 6 or 7 at best

[quickchange34]

I agree with Bruce the bottom end will take alot more than the breathing will allow. You really cant over rev one. They will run out of air before they blow. The valves will float. Even with a roots blower and all of the port and relief work they will give it up at 5500

[BUBBAS IGNITION]

A FACTORY ANSWER TO THE QUESTION I GUESS ??

[Pete]

Originally Posted by quickchange34

I agree with Bruce the bottom end will take alot more than the breathing will allow. You really cant over rev one. They will run out of air before they blow. The valves will float. Even with a roots blower and all of the port and relief work they will give it up at 5500

Is that the absolute last word?

[Bruce Lancaster]

The last word, until you dangerous radicals chime in!!

[Frank Miller]

Ok I am going to hijack the thread a bit. The chart posted was interesting but I notice the hp and torque curves crossing at below 3000 rpms. Modern charts will always cross at 5252 because hp = torque x rpm/5252. Was there some other method used to calculate hp back then. I like the way the chart includes the cylinder pressure. It is easy to see when the motor stops breathing. It was explained to me a long time ago that torque measures how much work a motor will do while hp tells you how fast it can do that work. Here is a link that gives some explanation.
http://www.vettenet.org/torquehp.html

[BrianCT]

Interesting to note on the chart that they are using 40 wt oil.
Wonder how much HP that cost them.

[flatjack9]

Originally Posted by Frank Miller

Ok I am going to hijack the thread a bit. The chart posted was interesting but I notice the hp and torque curves crossing at below 3000 rpms. Modern charts will always cross at 5252 because hp = torque x rpm/5252. Was there some other method used to calculate hp back then. I like the way the chart includes the cylinder pressure. It is easy to see when the motor stops breathing. It was explained to me a long time ago that torque measures how much work a motor will do while hp tells you how fast it can do that work. Here is a link that gives some explanation.
http://www.vettenet.org/torquehp.html

The equation shows that hp equals torque at 5252 rpm. In this case torque and hp are different at around the 2000 mark. Torque and hp curves are going to cross at at least two occasions in all engines as the horsepower increases. In this case, both figures would be very low if the engine could indeed rev to 5252 rpm. Off the chart in this example.

[BUBBAS IGNITION]

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INTERESTING THREAD FOR SURE ....

I have been watching this rpm issue for some time.
Our Bonneville flathead is a 276 C.I. in a 1949 Ford F100, we built this project for Bonneville in 2006 and ran there at 97.6mph on a (then) 101 record.
We ran the three mile section and at the 1-2 and three mile mark engine would turn 4300 rpm. All of us learned a bunch about the (air pump) engine and altitude on the salt. The engine performed perfectly and i knew at the end of the three mile it wasnt going to get any better without a bigger better pump.
We came back after a few same speed runs and found another 40hp in the engine on the dyno.
Now we are getting ready for the Willmington Ohio mile run and have made a few more changes including a five speed transmission. Looks like we need a few local test runs to attempt the correct gearing etc...
I will get some rpm numbers as soon as the weather clears up a bit.
BTW the record at Willmington ECTA is 101.349 mph.
We all know we can do that , right ???????????????

[Frank Miller]

Flatjack, Thanks for that. With the modern motors we see the cross at 5252 but they never go high enough for when the hp drops off and crosses again. Shows how low end these motors are.

[RooDog]

Please note that the HP scale is on the left margin and the TQ numbers, on a different scale, are on the right margin. If the number were sync'd, (50 Ft Lb & 50 HP on the same horizontal line, for instance), the graphs would look quite different. Since the graph stops at about 4200 RPM, the two curves would not cross at all and the torque peak would far excede the HP peak. Since Horse Power was, and still is, a magical marketing figure, it is stressed over torque, which in the real world, outside of racing, is more significant. Since HP is a function of Tq X RPM they will not cross a second time as long as the engine is still making power and not been shut off, or blowed up.... RooDog

[Bassman/NZ]

Charts, schmarts..... JWLs book is the real life proof of the pudding. Dozens of dyno pulls, real life facts and figures, not Fords made up figures.

[Ol' Ron]

Hard to believe, you can't get a100 hp from a 239 engine, no mater what you bolt on it. unless it's a supercharger. But install a cam, and!!!!

[Ronnie]

Originally Posted by Bassman/NZ

Charts, schmarts..... JWLs book is the real life proof of the pudding. Dozens of dyno pulls, real life facts and figures, not Fords made up figures.

Yup some dyno numbers are bogus but sound good when bench racing.Its not easy to get much more than 175 hp normally aspirated for the street.

R

[RooDog]

OK, Fellas, Who's "JWL" and what's the name of his book? Share the secret.....

[BillM]

OK, Fells, Who's "JWL" and what's the name of his book?

http://www.vanpeltsales.com/FH_web/f...oksforsale.htm

[RandyZ]

If you wind it up too high, the valves float and the exhaust will tag the spark plug, closing the gap!

Yup...come home a couple of times on only 4 cylinders.

Damn those L-100 cams pull hard.

[Ol' Ron]

I think JWL's book is the best Flathead book ever written. And I've never heard a flathead float it's valves, and don't know anybody that has.

[Ronnie]

Exhaust tagging ????

R

[Pete]

Originally Posted by Ol' Ron

And I've never heard a flathead float it's valves, and don't know anybody that has.

Not on a stock engine but I have heard it many times on race engines.

[Fourdy]

So what level of rpm do you fella's recommend using the crank journal support? Maybe I missed it.

Fourdy

[Pete]

Originally Posted by Fourdy

So what level of rpm do you fella's recommend using the crank journal support? Maybe I missed it.

Fourdy

It's not so much the rpm level as it is the hp level.
An engine that is designed to make 200 hp or more will live longer if it has steel main caps or some kind of girdle.

[Walt Dupont--Me.]

My dragster, 286 I made a strap for the center main, turns 5500 at the traps every run, broke the drive shaft at the tree and the tack went to 7100, it's still running strong. Potvin 425 and 3 carbs. Walt

[Fourdy]

Thanks. I have a center main strap also. My blown 276 with c4 I force shift out of passing gear at 5200.

Fourdy

[Cheaterpete]

my 304ci with L100 cam 1.6 valves, hit the 5500rpm a few times with no trouble...

But on a regulary basis a never go over 5k

[3340]

So Running My Roadster 50 mph @2400 Rpm Is Ok? Stock Flat head (51 Engine)

[JWL]

Thanks for the generous endorsement of my book Ron. There have been many myths and much mis-information about Flathead performance and I tried to put the facts on the table along with explaining how and why things work the way they do.

[JSeery]

Anyone else notice in the Ford's River Rouge plant thread video that they were running a test engine on the dyno at around 4500 rpm. Apparently Ford thought that was a good test point. That also matches up with the max scale on the factory Horsepower/Torque charts.

[RandyZ]

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I was talking with a bunch of the old time dirt track racers and they all said that the great thing about the flatheads is that you couldn't blow one up! They just didn't rev. up enough to throw the rods. Of course this is not true if you have a defective part or the bearings start to seize up.

[scooder]

Originally Posted by 3340

So Running My Roadster 50 mph @2400 Rpm Is Ok? Stock Flat head (51 Engine)

Yep, perfectly fine, it would be ok driving to the moon and back at that rpm. Add another 1500rpm and it would still not scatter parts, for the same moon and back journey. It's been said that a stock flathead can't rev high enough to kill its self, in good order this is pretty much true. They wernt the Hot Rod engine choice for years for no reason.
Its a real strong engine, I've said it before and I'll say it again, they are not made of chocolate and cheese, they be a good engine made of good stuff!
Use it and enjoy it.
Martin.

[3340]

Scooter, Thank You, Wayne

[RooDog]

John W Lawson....."Flathead Facts"

[V8COOPMAN]

Originally Posted by RooDog

OK, I see this is going to be like pulling teeth. How about a name to go with "JWL" or is that a secret? Jest Won't telL....RooDog

John W. Lawson me thinks! DD

[1937pickup]

I thought torgue was king-if so 2000 rpms is the sweet spot. We have a lot of discussions about this at our Wednesday breakfasts and guys who know swear by torgue.