Performance 6, thinking outside the box
Ever since the flat head four cylinder Model T was introduced, overhead valve heads were installed by perfromance enthusiast. Frontenac for the Model T,and many many more for the Flat head 1928-1931 Model A and the B. We have all heard of Miller, Offenhouser, Crager, on and on...Along came the the flat head v8 and an overhead valve set of heads were made by speed enthusiasts. I saw a Model A that had a late model Chevrolet V8 head installed. It took two heads and some creative oven brazing to make one head. Some conversions were F head some used overhead cams. The cross flow overhead valve design with the valves over the pistons opens up some remarkable power gains. You see where I am going with this? Can you imagine a 308 that could easily handle 10:1 compression with large valves over the pistons, maybe even a hemisphereical design? Has anyone ever done any experimentation along these lines? With the computer controlled fuel injection available, the Hornet would really become a rocket ship!
Just thinking again... :eek:
Just thinking again... :eek:
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Comments
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With today's computer controlled metal working machinery, one can bypass the artisans who would have previously been needed to make the patterns and pour the castings. Making a one off for proving purposes becomes a lot more feasible.
I imagine the head would need to be made in 2 halves, split horizontally above the combustion chamber so the water passages could be machined. Weld the 2 halves together to complete the job.
The other thought is that in the 30's it was quite common for liquid cooled aircraft engine cylinder heads to be welded and fabricated from sheet and plate steel rather than being cast. Mainly because they could make a much lighter head that way. No reason why those techniques could not be resurected.
All of this sounds quite simple and feasible if you say it quickly0 -
For the longest time I have wondered why Hudson, Packard and others did not move to OHV engines, especially since they all had some experience with them from defense contracts and earlier prototypes. Packard even made OHC engines for PT boats and Frank Spring actually designed OHC engines in one of his previous employments. Flatheads are definitely cheaper to make but limited in what can ultimately be done. It would have been interesting if the 308 had made the jump to OHV, it would have been a really interesting experience to say the least!
Of course you also have the strange tale of Cadillac that first made flatheads, then OHV, and went back to flatheads, before the '49 OHV engine. With Chevy and Buick making OHV engines you would have assumed that GM would have moved everything that we, but that did not happen either!0 -
I have always wondered why one of the engine suppliers such as Continental, Waukesha, Buda, Lycoming, etc, did not manufacture a line of OHV V-8's for sale to Hudson, Kaiser, Nash, etc., along with the additional market of small pickup manufactuers (Diamond T, Reo,), and various industrial applications. The aformentioned engine companies had been making engines for assembled cars for years, prior to WWII, and still supplied Kaiser and Willys. A constant news item of that day was that the independents except for Studebaker could not afford to tool up for a V8.
This engine could have been "disguised" for various manufacuters by valve cover design changes, Generator placement, etc. Oh well, just dreaming.0 -
I've wondered about this for a very long time. Especially since I started out as an antique tractor enthusiast, where flatheads were/are almost non-existant from the very first tractor attempts.
Here is the conclusion I've come to, and have discussed this with several old-time engine builders. The engineering thought at the time was predominantly "undersquare" engines, built for maximum torque at a lower rpm range, generally the top rpm was in the 3000 range. If you look at most engine dimentions used in automobiles right on up to 1955, the bore is quite a bit smaller than the stroke. Most bores were in the 3" - 3.5" range with strokes being very long at 4.5"+. Massive torque.
However, in the OHV vs. Side Valve, the reason they early OHV's didn't perform up to the level of the flathead was valve size vs. bore diameter. If you think about it, the flathead could use larger valves relative to the cylinder bore than an ohv of the same bore diameter. We all know that the flathead breathes badly, but given the low rpm design, compression ratio being the same, and the valves in the flathead bigger due to not being restrained by the small bore size - the flathead wins.
If you compare The Hudson Super Six to its contemporary engines, the Rocket 88 Olds and the Cadillac V8, the Hudson had a larger bore AND larger valves per cylinder. The stock hp numbers on either engine really don't measure up to the Hudson Super Six. Add the inherent low end torque advantage of the inline 6 over the V8, there would seem no reason to build anything else. If you look at the hp ranges available and the weights/power ratio, there would have been little logic in investing in an engine beyond the flathead six to compete across the gamut of automotive offerings.
Cadillac went back to the flathead V-16 rather than its OHV derivative, because the flathead made more hp and was 40 lbs. lighter.
The small block chevy really did revolutionize ohv V8's. More than any engine, this one corrected the "undersquare" problem and began to venture out into larger bores (4") quicker than anyone else. It was amazing how much hp that engine produced at the time given its CID was so much less than some of its competitors. The secret was its larger bore size vs. stroke, larger valve diameters with less shrouding by the bore, and light weight. There was a collective "Oh NO!" across the engineering rooms of automakers once Zora Duntov breached the "undersquare" design rule and actually made its folly known. From '55 forward, the flathead was doomed and engines kept getting lighter with more hp being produced. As we all know, by '55, the car we love and discuss here - was basicly history.
Had the Hornet 308 revision taken the bore out to 4"+ rather than stopping just short at 3.812" - the 265/283 chevrolet would have had a much tougher time with it in 1955, had Hudson been able to keep on its feet beyond the merger. If you are much of an AMC fan, the 242 (4.0) engine is a much superior OHV inline to anything ever built before it. Secret? They finally increased the bore to 4"+. Cross breed a 258 crank into that block and you have a 300 hp capable inline without alot of headache. That is the engine I wish Hudson had been able to debut in the post '55 automotive world.
Don't forget, Mopar kept producing its venerable little 230 CID flathead and made it the standard engine in their 1/2 ton pickups into '62.
Mark Hudson0 -
Very good comments, I would say that you are pretty sharp. Most people will not realize that the flat head is a archaic design, but excellent for what it was used for in its time.`Hudsonator wrote:I've wondered about this for a very long time. Especially since I started out as an antique tractor enthusiast, where flatheads were/are almost non-existant from the very first tractor attempts.
Here is the conclusion I've come to, and have discussed this with several old-time engine builders. The engineering thought at the time was predominantly "undersquare" engines, built for maximum torque at a lower rpm range, generally the top rpm was in the 3000 range. If you look at most engine dimentions used in automobiles right on up to 1955, the bore is quite a bit smaller than the stroke. Most bores were in the 3" - 3.5" range with strokes being very long at 4.5"+. Massive torque.
However, in the OHV vs. Side Valve, the reason they early OHV's didn't perform up to the level of the flathead was valve size vs. bore diameter. If you think about it, the flathead could use larger valves relative to the cylinder bore than an ohv of the same bore diameter. We all know that the flathead breathes badly, but given the low rpm design, compression ratio being the same, and the valves in the flathead bigger due to not being restrained by the small bore size - the flathead wins.
If you compare The Hudson Super Six to its contemporary engines, the Rocket 88 Olds and the Cadillac V8, the Hudson had a larger bore AND larger valves per cylinder. The stock hp numbers on either engine really don't measure up to the Hudson Super Six. Add the inherent low end torque advantage of the inline 6 over the V8, there would seem no reason to build anything else. If you look at the hp ranges available and the weights/power ratio, there would have been little logic in investing in an engine beyond the flathead six to compete across the gamut of automotive offerings.
Cadillac went back to the flathead V-16 rather than its OHV derivative, because the flathead made more hp and was 40 lbs. lighter.
The small block chevy really did revolutionize ohv V8's. More than any engine, this one corrected the "undersquare" problem and began to venture out into larger bores (4") quicker than anyone else. It was amazing how much hp that engine produced at the time given its CID was so much less than some of its competitors. The secret was its larger bore size vs. stroke, larger valve diameters with less shrouding by the bore, and light weight. There was a collective "Oh NO!" across the engineering rooms of automakers once Zora Duntov breached the "undersquare" design rule and actually made its folly known. From '55 forward, the flathead was doomed and engines kept getting lighter with more hp being produced. As we all know, by '55, the car we love and discuss here - was basicly history.
Had the Hornet 308 revision taken the bore out to 4"+ rather than stopping just short at 3.812" - the 265/283 chevrolet would have had a much tougher time with it in 1955, had Hudson been able to keep on its feet beyond the merger. If you are much of an AMC fan, the 242 (4.0) engine is a much superior OHV inline to anything ever built before it. Secret? They finally increased the bore to 4"+. Cross breed a 258 crank into that block and you have a 300 hp capable inline without alot of headache. That is the engine I wish Hudson had been able to debut in the post '55 automotive world.
Don't forget, Mopar kept producing its venerable little 230 CID flathead and made it the standard engine in their 1/2 ton pickups into '62.
Mark Hudson0 -
Thanks Tom, I appreciate the comment.
I will say this about the Hudson Hornet engine. It is without a doubt the KING of flathead automotive engines - no exception whatsoever. All you have to do is mess around with some other flathead types of the era, and you'll quickly appreciate the performance level Hudson engineers pushed that Super Six engine to.
I was watching the same American Muscle car show that spurred the thread here, I secretly said to myself "Thank God Olds didn't reverse thier bore and stroke dimentions!". Otherwise, our little claim to NASCAR fame may never have happened.
Mark0 -
More years back than I care to remember I got a letter from a fellow out in Washington state who had raced, and played around with, Hudson and Hudson engines for a number of years. There isn't space here to reproduce all he had to say but I submit, from his letter the following tidbits:
"If the Hornet engine had a 4" bore with it's 4-1/2" stroke it would have been the biggest brute of them all. Like Nesbett (??) was telling us, the Hudson engine blocks should have been 4" cylinder bores." (NOTE: This was in the 1970's this letter was written.)"
However he got to outlining some very interesting cubic inch combinations that can be had with either the Pacemaker or Super-Six (step-down era) engines being they both have the same block with a 3-9/16" bore.
With a stock bore and stroke - 3-9/16 x 3-7/8 = 231.8 (232)
3-9/16 x 4-3/8 = 261.7 (262)
3-9/16 x 4-1/2 = 269.1 (270)
3-9/16 x 5 = 299.1 (300)
3-9/16 x 5-1/8 = 306.6
3-9/16 x 5-1/4 = 314
3-9/16 x 5-1/2 = 329
Then he goes into some overbores:
.060 over bore with 3-7/8" stroke = 240
Super-Six crank 4-3/8" stroke = 270
Hornet crank 4-1/2" stroke = 278.6
He goes on with .080 over bore using the above.
Rather interesting combinations here.
Total cubic inches that can be had with any Super-Six or Pacemaker blocks with a 5-1/2" crank stroke is 354.44 cubes. However, any more crank stroke than 5-1/8" on any Hudson six cylinder engine and the added cost of getting a stroke over 5-1/8" isn't worth the extra expense as performance and torque isn't much differnce.
Hudsonly,
Alex B0 -
hudsontech wrote:"If the Hornet engine had a 4" bore with it's 4-1/2" stroke it would have been the biggest brute of them all. Like Nesbett (??) was telling us, the Hudson engine blocks should have been 4" cylinder bores."
Hudsonly,
Alex B
I'm usually guilty of reinventing the wheel, in this case I'm guilty of restating the obvious.
I wouldn't throw away any good, not cracked, Hudson block from any of the stepdown models. Especially the wide blocks whether they are 232,262, or 308. I say this because the next Hudson engine project I undertake, will address the bore size issue. I'm really not breaking any ground with my current engine project, I'm doing pretty much what everybody before me has done with a 5" stroke.
The only new information I hope to acquire is the "why" behind the success of what's been done in the past, and then go from there on what to do in the future.
The next project (no telling how many years it will take to save up for it!), I want to increase the bore size by completely boring out the cylinders, move the cylinder centerlines away from the valves and away from the currently siamesed portion of the cylinder pairs, and replace the cylinders with press-fit wet sleeves. I have laid out and overseen changes of this type to other engines before, but never a Hudson. I'm hoping for somewhere in the neighborhood of between 4.125" and 4.250".
Assuming I can get a 4.250" bore into a wide block Hudson, that would make the dream team look like this:
3.875" stroke = 330 CID
4.250" stroke = 362 CID
4.500" stroke = 383 CID
5.00" stroke = 426 CID
Actually, my favorite in this lineup is the 362 version. I have a sneaking suspicion it would be the highest horsepower, highest rpm version in the mix.
Accomplishing this bore increase is no small endeavor. Had this engine been OHV, the job would be limited by what room I had on the deck surface. The fact we're talking about a flathead, brings on new problems. Namely, the fact that part of the cylinder periphery is not sealed off with a gasket (valve pocket area) and the valve relief is physically cut down into the cylinder at the same place is not/cannot be sealed off by a gasket.
Where I've had success in Allis, Massey Harris, and Farmall OHV engines by using a conventional step on the sleeve (much bigger bore than stock!) to secure its location vertically, I can't do that with the Hudson - due to the valve relief. I'm considering a machined taper through the deck, with a press fit through the bottom of the water jacket/crankcase.
The real danger zone is the relief area, I simply have no idea how much metal is there for the tapered sleeve to seat against. I've never seen a Hudson block with its cylinders cut out - perhaps somebody on the forum has?
Don't anybody hold thier breath, or check the forum daily for progress on this "dream project" - I have MUCH investigation to do before I'll even know if its viable. If it is, then maybe I'll get along with my roller cam idea to go along with it. It would sure be nice to see a 10 second Hudson powered Hudson, wouldn't it?
Mark0 -
If I remember the math correctly I seem to recall the most (safely) you can overbore a Hornet block is 1/8" - That should come out to, what, 3-15/16" bore?? Let's see - an eighth is 2/16 so 13 + 2 = 15. Yeah, that sounds right. Hey, in high school I was primarily interested in just 3 figures (numerically, that is).
Hudsonly,
Alex B0 -
Alex.
I'm proposing to completely machine out the existing cylinders, they'd be gone - entirely - well call it an overbore till no metal was left anywhere where the cylinder used to be. The .125 boring limit would be gone with them. The cylinder locations would be moved slightly, and the block remachined for a sleeve to entirely replace the old (GONE) cylinder. The engine would then be wet sleeved, with the sleeves being .125 thick at the finished bore size. I'm not talking about sleeving the existing cylinders - I'm talking about removing the existing cylinders altogether via machining operations. Once the old cylinders are gone, the only constraint to sleeve size is the head bolt hole locations and the water passage openings. I am pretty sure once the old cylinder is out of the picture, there is enough room to get a 4"+ WET sleeve installed.
This is probably one of those things I should have kept to myself - LOL! But, you have to admit, its REALLY out of the box thinking. We'll call it "out of the block" thinking.
I've been told that the practical limit for boring a factory cylinder is really in the .060" - .070" range. That's per Randy Maas, and I don't dispute it. Much more than that and it needs to be DRY sleeved back to standard.
Mark0 -
`Hudsonator wrote:Alex.
I'm proposing to completely machine out the existing cylinders, they'd be gone - entirely - well call it an overbore till no metal was left anywhere where the cylinder used to be. The .125 boring limit would be gone with them. The cylinder locations would be moved slightly, and the block remachined for a sleeve to entirely replace the old (GONE) cylinder. The engine would then be wet sleeved, with the sleeves being .125 thick at the finished bore size. I'm not talking about sleeving the existing cylinders - I'm talking about removing the existing cylinders altogether via machining operations. Once the old cylinders are gone, the only constraint to sleeve size is the head bolt hole locations and the water passage openings. I am pretty sure once the old cylinder is out of the picture, there is enough room to get a 4"+ WET sleeve installed.
This is probably one of those things I should have kept to myself - LOL! But, you have to admit, its REALLY out of the box thinking. We'll call it "out of the block" thinking.
I've been told that the practical limit for boring a factory cylinder is really in the .060" - .070" range. That's per Randy Maas, and I don't dispute it. Much more than that and it needs to be DRY sleeved back to standard.
Mark
Mark,
I just stumbled accross this post during a search and was wondering if you have has any success with your resleeve maxi-bore project. I've seen guys wet sleeve a Chev 409 and that kinda has a combustion chamber in the bore, so to speak., so a Hudson is possible. I think your idea is fantastic and should be persued. Just think of all the wide block 262s that could have new life as pavement pounders! LOL. Please give us an update or any new ideas on your project.0 -
It sounds like an Irish pipe specification to me " Care should taken to ensure the inside diameter does not exceed the outside deiameter of any pipe". There would be just no room left for 4" cylinders without widening and lengthening the block, and using offset rods. I still reckon the ultimate modification for the 308 would to make it an F-head.0
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Geoff C., N.Z. wrote:It sounds like an Irish pipe specification to me " Care should taken to ensure the inside diameter does not exceed the outside deiameter of any pipe". There would be just no room left for 4" cylinders without widening and lengthening the block, and using offset rods. I still reckon the ultimate modification for the 308 would to make it an F-head.
Aha! back to my original thought! I almost forgot about it. 3 years ago? seems a lot easier to just make a cylinderhead. Sure would take care of the valve shrouding problem with the flat head.0 -
An interesting discussion, but keep in mind that an engine's power comes from burning the fuel, and thus the more fuel that can be burned, the more power.
But more fuel = more air needed to keep the air/fuel ratio correct. That is why F head and OHV conversions exist...they breathe better than flatheads, thus more air is inhaled, which means more fuel, and the result is greater BMEP (brake mean effective pressure), the force of the expanding heated air upon the piston. That is where power is made. That is why increasing the displacement increases power = more air is inhaled.
Although doing an OHV conversion on a 308 is an exotic and fun idea, you should be able to gain a equivalent amount of increase in the air by supercharging the flathead, which others have already done. At least it would be easier, but not more fun.
At least then you have a true "Hudson" engine, rather than a radically-modified Hudson block.
My 2 cents.0 -
Since my economy kinda went south soon after this thread was started, I haven't really done anything with the overbored idea. As I keep messing with these engines, I keep noticing things that relate back to the original idea, but have taken no steps to make it a reality.
However, I will address one of the comments about its Irish Pipe dream. The answer is to move the bore centerlines. There isn't enough meat in some places, plenty in others. The result would be a fairly pronounced offset of the bore centerlines to the crank centerline - but in the correct direction for some additional torque efficiency. You wouldn't bore the existing cylinders out, you'd reach in the block and cut them out with a key slot milling tool to preserve the deck integrity. Then, go about re-establishing the new bore centerlines, steps, etc.
The real problem with the affair is dealing with the relief cut area and getting a sleeve seal. That, and the siamesed areas between the cylinder and valve ports - which I really didn't know about at the time I was concocting this idea. I don't know if a 262 shares this "siamesed" aspect with the 308. If not, the 262 may be the winner here.
Its a long-shot and very extreme. But a Hudson of that bore with a 232 crank would be a pretty shocking engine combination at 325 CID.
Mark0
This discussion has been closed.
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