435 horsepower in 1955.....

[cuzncletus]

.....from a FLATHEAD!! I was in the attic and stumbled on some old Rod and Custom little pages. One that caught my eye had a heading of "435 Horsepower Flathead V8". Returning to where it was considerably cooler to read the article, it seems this motor dyno'd at 435 with only 248 cubic inches (.060 over 59a). The motor used a 3-71 GMC and a 50% load of nitro, injectors from Stu Hilborn, and 17.5 lbs. of boost.

The engine was put in Art Chrisman's dragster and was at 140 mph 250 ft. before the traps, where it blew off the water hoses and Chrisman shut it off, coasting thru at 131. It would be interesting if there was a follow-up to what this motor eventually did. The end of one paragraph pretty much echoed my thoughts. "In spite of what the dynomometer proved and the number of witnesses present, the skeptics continued to say; "Impossible-the lower end would never stand it." No details were given of modifications to the block, but I'll bet we've all got the same cocked eyebrow on this one.

The engine was built by Don Yates and a (?) Newmire. (My mind seems to think there was a Leroy Newmire I read about at an early age.) The article was written by Barney Navarro who obviously had a lot of input, and parts, in this engine. No wonder many of these early legends have been beatified in flathead lore.

Anybody got any more links in this chain of history?

[Flathead]

Dynos can be a "little" off sometimes. However, with 17.5 lbs of boost on a 50% load of nitro, I'm sure there was some HP being made. I too would question the rods and the rest of the bottom end.

Didn't Barney himself run a similar motor at either the lakes or Bonneville? Small cid with a blower?

A good blower setup makes those old Flatheads forget their asthma problems.

[38 coupe]

How much overdriven would a 3-71 have to be to get 17.5 p.s.i. on a 248 inch flathead?

[BUBBAS IGNITION]

Originally Posted by 38 coupe

How much overdriven would a 3-71 have to be to get 17.5 p.s.i. on a 248 inch flathead?

I had read somewhere that the 3-71 would feed 3x71=213 cu in 8 lbs of boost at 1-1.
If thats real then we would need a 15% over drive to feed the 248 at 8 lbs.
Now to double that to 16 lbs, who knows but it would be a bunch. Over 100%??

Am i thinking correct here ????

[Henry Floored]

Regarding the 3- main bottom end: we have to remember that there is almost as much main bearing surface area in a 3- main Flathead Ford as there was in many 5- main brg OHV V8's that followed. The famous Miller- Offy and even the Novi V8 pure race engines used 3- main brg bottom ends if I'm not mistaken. Another thing to think about is those long 7" rods combined with a slightly offset crank and you have a considerably less thrust loads on the cyl walls. Notice this was a small cube engine with moderate over boring and short crank stroke.This drastically lessens the mechanical strain on the bottom end. I suspect the power was intended to be made at a relatively low RPM with nitro and boost. The lower end was pretty much along for the ride much like today's nitro engines.

[Henry Floored]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by BUBBAS IGNITION

I had read somewhere that the 3-71 would feed 3x71=213 cu in 8 lbs of boost at 1-1.
If thats real then we would need a 15% over drive to feed the 248 at 8 lbs.
Now to double that to 16 lbs, who knows but it would be a bunch. Over 100%??

Am i thinking correct here ????

I believe the same supercharging system placed on two different engines of the same displacement can have very different boost pressures along the rpm curve. An engine that breathes very well will always show lower boost pressure that an engine with a fairly restrictive intake manifold, port, valve system.

[Fordors]

Boost, especially high numbers, will not necessarily equate to better performance. A GMC blower is really just that, a blower, and as such will only make "boost" as it packs the intake tract from the valves to the intake manifold. Picture a plastic bag laying on the table, it is at atmospheric pressure. Now take the bag and blow it up, we have artificially "boosted" it's internal pressure.
Depending on the cam timing and how efficiently the complete intake tract of any engine is designed/refined will have an effect on HP. Spinning the blower faster will make more boost but not necessarily more power. Many other factors will come into play; is the cam optimized for the intended purpose, is the static compression sufficient to really utilize the boost with that particular camshaft? Barney Navarro was a thinker and as such I'd bet this whole package was very well planned. It's the total combination, not just boost, that makes the best performance.

[Flathead]

[QUOTE=Henry Floored;232997]Regarding the 3- main bottom end: we have to remember that there is almost as much main bearing surface area in a 3- main Flathead Ford as there was in many 5- main brg OHV V8's that followed.

I agree, I was more concerned with main bearing caps, studs, and the webbing in the block. Blown on Nitro will really jingle the bottom end. And everything else too for that matter. I wonder if "until it blew the water hoses off" was entirely accurate.

[Pete]

It is a simple matter to run numbers through the formulas.
Back in the 50's, Lawson, Bradley, Chrisman, MacDonald and others were
all running in the mid 140's and high 8's. It takes about 400 hp at the flywheel to do this in a 1200-1300 lb car.
Assuming a dyno has been calibrated properly, a steady honest reading of 400 can be flash read easily at 435. A common practice especially in the "olden dayz".
A couple of the old timers that ran in the old days are on this forum.
Ask them how long rods and bearings lasted with 100% nitro. You will find it was quite awhile comparatively speaking.

[cuzncletus]

According to the article, Newmire had some special Gilmer belt pulleys cut at quite an expense for 1955; $300. The overdrive was 1.8:1!!!

The article said the hoses blew off "by combustion gases getting into the cooling system". It also said they overtorqued the studs in attempt to keep the heads down. Navarro went on to say the heads were completely destroyed by hot gases buring pathways through the mating surface of the Weiand heads.

On re-reading the article, Newmire's first name was 'Bud'. I'm sorry I don't have the means at home to scan this and put out the entire article for the forum. If anyone would like to help, Tuesday when I return to work I'll copy and fax the article to all who would like to read or post it.

By the way, I talked with my old friend Charlie Overfelt a couple of years ago at a nostalgia race. He had a modified roadster running in the high 9's with a flathead. He used stock rods and crank. He did say that much of a load (25+%?) would push the crank out the bottom. Still, that's a heck of a statement for those spaghetti rods and parcity of main surface area.

[4-barrel Mike]

Which little pages was it? I should have it and can scan and post it for you.

Mike

[Ole Don]

I spoke with Don Fransisco once about this subject back in 1995. He said he and some others built a flathead that dynoed 425 on a heavy load following the old methods of bore, stroke, port, relieve, and no, the engine didnt last very long. I think Hot Rod ran an article on how they did it.

[Kahuna]

Flathead Jack's dual flathead engine dragster runs 92% Nitro. Cranks appear to hold up just fine. I don't know the type of rods he runs

[ken1939]

The "where" to me of the horsepower is of interest. For example in todays top fuel cars they say they are ratedat 8,000 hp. However as they go down the track a bit, that hp is boosted to 10,000. So I wonder what part of the power band did they rate the 435 horse.

I am not saying the article is not truthful at all. I enjoy the engineering that goes behind those things, especially what they did in 55' vs crate motors today that approach 1000hp. That kind of engineering made the NHRA what it is today really.

I am sure the bottom end may have held up, wonder what the connecting rods looked like. Burn a piston mabey? Wonder what the total cost was in todays dollars

Cool stuff.

[Henry Floored]

Gives me a warm fuzzy feeling knowing that all this fantastic drag racing performance we see today was incubated and sprang up from ol' Henry's and our beloved "bent eight".

[Flathead]

I believe there was a short period in the early 50's when the Flathead V8 ran heads up against the Hemi Chryslers. The Flathead was pretty much at its peak of development and the Chrysler Hemi was still being sorted out.

I like to think it was just a cubic inch thing, but maybe there was more to it.

[Fordors]

I think it was a drive line thing. A '39 box behind the hemi was often the weak link.

[4-barrel Mike]

Magazine info passed via PM. Interesting article. Thanks!

Links to full-size images (too big, IMO, to post):

Pages 16&17: http://i233.photobucket.com/albums/e...-55pp16-17.jpg

Pages 18&19: http://i233.photobucket.com/albums/e...-55pp18-19.jpg

Pages 20&21: http://i233.photobucket.com/albums/e...-55pp20-21.jpg

Page 72: http://i233.photobucket.com/albums/e...RC4-55pg72.jpg

Page 77: http://i233.photobucket.com/albums/e...RC4-55pg77.jpg

These should print up, if desired, near full-sized. Enjoy!

Mike

[Bruce Lancaster]

On the Chryslers versus flatheads...
Go dig into HRM about 1956. Don't know where mine are right now, but I think 1956 was the last year a flathead won top eliminator at the NHRA Nationals. The Calvin Rice car...I'm sure someone here can find the HRM and post particulars as far as they are known on the engine.
Anyway...this car, a much more modern rail than the old Chrisman car in R&C, built to accept either a Hemi or a flathead. The Chrysler provided highest trap speeds, actually more important than ET in those days, while the flathead provided best ET and since that meant it got there the firstest, it was the engine chosen for the Nationals. I think the same issue of HRM has the car feature and the writeup on the Nats.
So...5 years after Chrysler kicked off a V8 useful for dragging in light cars, it was still second best...The earlier OHV's had already taken over for use in heavier classes, where their huge displacement advantage was unbeatable.

[sanborn]

Just a couple of comments.

Supercharged flatheads suffer from "Cylinder Head Flex" at high boost. It causes severe gasket blowing and often block destroying----and the head literally melts. If you look at the few "state of the art" blown flatheads around today, you will see thick billet cylinder heads with closed end cooling fins machined into the heads.

And, the sudden torque requirements of today's drag racing creates severe twisting of the crank and flexing of the block. Earlier drag racing didn't have sticky tires or sticky tracks---thus the sudden torque requirements didn't occur---we just spun the tires---and the block and cranks lived, for at least a while.

If we could get the crank/block to live, we could generate a lot of horsepower if we used enough boost and enough nitro---since nitro brings its own oxygen along.

[Cool Hand Lurker]

I remember an article at the time about the Chrisman flathead V8 making over 400 hp and under 8 seconds at the dragstrip. I think the speed was 144 but not sure. So, yes it did really run..... how long it ran I don't recall.

[Flathead]

"Flatheads battle Rocker Arms for all out supremacy". Quite a story.

[Bruce Lancaster]

At the time of the Chrisman article in R&C there was a widely discussed theory, discussed by and perhaps originated by magazine guru Roger Huntington, that 1-G was an acceleration limit for drag cars. I think the idea was that a car's traction was based entirely on its weight on the tires, so that if more power was introduced at 1-G the tires would simply spin, limiting possible acceleration to 1-G no matter what.
I think the limit worked out to something like 9 seconds and 140 MPH...the Chrisman car (was it with that engine??) ended the theoretical discussion by simply blowing right through the "limit".
Obviously, the racers have never since looked back or worried about the potential limit to their acceleration!

[Pete]

Originally Posted by Bruce Lancaster

At the time of the Chrisman article in R&C there was a widely discussed theory, discussed by and perhaps originated by magazine guru Roger Huntington, that 1-G was an acceleration limit for drag cars. I think the idea was that a car's traction was based entirely on its weight on the tires, so that if more power was introduced at 1-G the tires would simply spin, limiting possible acceleration to 1-G no matter what.
I think the limit worked out to something like 9 seconds and 140 MPH...the Chrisman car (was it with that engine??) ended the theoretical discussion by simply blowing right through the "limit".
Obviously, the racers have never since looked back or worried about the potential limit to their acceleration!

It's called coefficient of friction.
Huntington's theory was based on the tires that were available at the time. Soaking the tires in hydrogen peroxide was one of the first ways to increase the CF.

[ken1939]

Originally Posted by sanborn

Just a couple of comments.

Supercharged flatheads suffer from "Cylinder Head Flex" at high boost. It causes severe gasket blowing and often block destroying----and the head literally melts. If you look at the few "state of the art" blown flatheads around today, you will see thick billet cylinder heads with closed end cooling fins machined into the heads.

And, the sudden torque requirements of today's drag racing creates severe twisting of the crank and flexing of the block. Earlier drag racing didn't have sticky tires or sticky tracks---thus the sudden torque requirements didn't occur---we just spun the tires---and the block and cranks lived, for at least a while.

If we could get the crank/block to live, we could generate a lot of horsepower if we used enough boost and enough nitro---since nitro brings its own oxygen along.

Watching Drag Racing as I have over the years, these comments really have weight with me. With todays coverage you can really get to see the"mess" that is left behind or when things go wrong in a hurry.

I like the super slow mo to show the exhaust and you can see what the engine is doing, and of course when it is not.

Now if we dont loose any more drivers.

[max sr]

Sponsored Links (Register now to hide all advertisements)

greta discussion, suprising numbers

[LSGUN]

Great thread guys, I have this little book too and was curious about it as well.