Straight eight speed

[Rusty_OToole]

This is in response to a thread I read on another (Packard) board. As I am not a member over there, and as I recognise many of the same names as here, I thought I could post a few ideas here.

Road tester Tom McCahill had something to say about Packard speed and the perception of same in the 50s. In a 52 or 53 road test he said that Packard was standing aloof from the horsepower race and instead was stressing their quality, smooth silent ride, and fine upholstery. They were after the steady conservative luxury car trade in the upper medium price brackets.

He went on to say, Do not think the Packards are deadheads on the road because they definitely are not.

In a 1952 test of the 327 powered 400 sedan he reported a top speed of 101 or 102 MPH. This was only about 5 MPH slower than the Cadillac and 10 MPH slower than the Chrysler hemi.

This is academic as I doubt many luxury car owners drove their cars over 100MPH then or now.

I have a list of 1954 car specs in front of me. From it I glean the following cubic inch and HP figures for the leading luxury cars, given in order of HP.

Chrysler New Yorker Deluxe, 331 235HP. Cadillac, 331 230HP. Packard Patrician, 359 212HP.Lincoln, 317 205HP. Buick Roadmaster, 322 200HP. Packard Cavalier 327 185HP.Olds 98, 324 185HP.

These are the maximum available power figures. Standard models of other makes were considerably lower powered as Cadillac, 195 Chrysler, 195 Buick 177, 195 Olds 88,170 Packard Clipper 288, 150 Clipper Deluxe 327, 165.

It can be seen that Packard was in the middle, not trying to be the highest powered but far from the lowest.

Packard also offers the highest compression engine at 8.7:1. This is the highest compression of any car that year, rather startling for an "obsolete" flathead.

I have examined a Packard with the head off and discovered their secret. The Packard has a sophisticated flathead design with the valves tipped toward the cylinders.

This allows better breathing and better valve cooling along with higher compression.

The only other engine I know of with this feature is the legendary Hudson Hornet.

Combine the advanced design with Packard quality, stamina and the available 9 main bearing crankshaft and if I were choosing an engine to build for Bonneville's flathead class it would be the Packard.

I believe it would be a cinch to increase the HP of any postwar Packard by at least 25% with a few simple mods without harming drivability or reliability in the slightest.

Not that I think all you Packard owners are going to run right out and start hot rodding your Packards. But for those who want a little something the other fellow hasn't got, the Packard has a lot of potential.

[Restorer32]

I can tell you for a fact that a 1932 Packard 900 will do a bit in excess of 80 mph if it is on fire and you are racing to an interstate exit where you know there is a service station with a water hose.

[mrpushbutton]

Great observation Rusty. Packard had developed their venerable straight eight to a Swiss watch of a boulevard cruiser, but the industry was obsessed with brute V-8 hp (but as you point out, the Packard S-8 was no slouch). I have been drawing parallels between Packard's fates in 52-56 to the current mess our three remaining domestic auto manufacturers are in; a problem that is partially public perception and the natural American want to be identified with a winner on the way up and not with something that smacks of faded glory.

Packard's great twelve engine ('32-'39) featured a very advanced angled valve-in-block design that gave terrific flow of incoming mixture, especially in comparison to the Cadillac V-16 and V-12 engines. They were an overhead valve design, but the breathing patterns were torturous, they still used updraft carburetors (fed by dual vacuum pumps) and were not as silent in operation as the Packard twelve. For the extra four cylinders you only got 10 more hp!

[Matt Harwood]

How did the Packard do in terms of torque vs. the V8s? I think one of the big selling points of any straight-8 vs. a V configuration was the turbine-smooth acceleration. Does it make a difference? Are straight-8s inherently more balanced than V8s?

[Packard8]

I've read that the canted valve technology was derived from Packard's aircraft engine experience in WWII.

Even though the HP, TQ and performance were competitive with contemporaries, the perception and image were not. I have a review of the 1954 359 powered Pacific HT and the author sums it up quite well...."When a new car buyer in 1954 opened the hood saw a flat head and 8 spark plugs in a row he was looking at an old man's car, not a modern OHV V8."

.

[Guest imported_Speedster]

Yes, TV advertizing during the '50s, described the new Modern V-8 as almost Magical, compaired to older designs, and of Course if it was on the New TV, it Had to be True. LOL

[Guest 1926pack]

There has GOT to be a great story behind this post!

[Rusty_OToole]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Matt Harwood</div><div class="ubbcode-body">How did the Packard do in terms of torque vs. the V8s? I think one of the big selling points of any straight-8 vs. a V configuration was the turbine-smooth acceleration. Does it make a difference? Are straight-8s inherently more balanced than V8s? </div></div>

From the same chart of engine specs:

Cadillac 331 230HP@4400RPM torque 330@2700

Chrysler 331 235@4400 330@2600

Packard 359 212@4000 330@2000

Packard 327 185@4000 300@2000

Packard 288 150@4000 260@2200

Lincoln 317 205@4200 305@2650

Buick Roadmaster 322 230@4400 330@2700

Buick Super 322 177@4100 295@2000

Olds 98 324 185@4000 300@2000

As can be seen from this list the Packard engines developed similar power and torque figures to the competition but at lower RPM. This translates into more punch where you need it for everyday driving.

It also suggests Packard engines were detuned compared to some others and had more room for "improvement" as in hopping up.

The straight eight uses the same 90 degree crankshaft configuration as a V8. Both can be made equally smooth. Both require careful attention to manifold design in order to get even mixture distribution to all cylinders.

[mrpushbutton]

Inline engines balance better in threes, an in-line six would be inherently smoother than an eight. Having said that, many straight eights were great, smooth engines.

[Rusty_OToole]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mrpushbutton</div><div class="ubbcode-body">Inline engines balance better in threes, an in-line six would be inherently smoother than an eight. Having said that, many straight eights were great, smooth engines. </div></div>

You are right about balancing in 3's. An inline six is an optimum design in that it has the smallest number of cylinders giving perfect primary and secondary balance and overlapping cylinder impulses. All others are diminishing returns designs.

This is why so many makers of high grade cars such as Rolls Royce, Bentley, Mercedes, and Jaguar stuck with the 6 cylinder engine for so long.

Incidentally if you want a really smooth engine how about a straight 9? Was told on good authority that Studebaker built one in the 30s, it was an excellent smooth running powerful engine but they never produced it because they didn't think the public would accept it.

[Guest imported_Speedster]

Yep, an Odd number of cylinders, Just seems 'ODD'.

[mrpushbutton]

Mercedes made five cylinder engines for several years.

[Clipper47]

And the Volvo 850 also has a 5 cylinder inline engine.

[Guest BigKev]

Chevy Colorado's have an available 5 Cyl engine.

[Guest imported_Speedster]

Mercedes..... Odd

Volvo........ Odder

Chevy........ Oddest

Odd.... Odd.... Odd....

<span style="color: #FF6666"> <span style="font-family: 'Arial Black'"> <span style="font-size: 17pt"> ODD !!! </span> </span> </span>

My Even Semetrical World can't Take much more of This!

[34PackardRoadsta]

Aah, geez Rick, then don't start thinking about all those ONE cylinder engines...

[RShepherd]

And the Volkswagen Jetta and Rabbit have five cylinder engines. I rented one for a week recently and guess what?

It sounded uh, well, what's the word I'm looking for here?

Oh, yes..... <span style="color: #FF0000"> </span> ODD!!

Besides that, it wasn't as smooth as the four cylinder in my 2004 Jetta.

[Guest bertthemech]

a little story re packard straight eight

My father in law bought a used 52 packard convertible (think it was called a Carribean) with only about 1800 miles on it. this was in about 1957.

the car had been stored since almost new so he was quite excited about it.

It ran smooth as a kitten but seemed to lack power, also it was blowing what looked like oil smoke.

I did a compression test and it was equally low on all 8 cyls.

I figured that maybe the rings were siezed up from sitting.

After pouring penetrating oil into the cyls and letting it sit there was no difference

I wound up pulling the head and pan off and pulling all the pistons out I dicovered that none of the pistons had any rings on them.

Seems unbelievable but thats the truth.

We Contacted Studebaker and told them the story.

They supplied a new set of rings and a gasket set.

He kept the car until his death and it ran like top.

[Owen_Dyneto]

Seems hard to believe that it even had enough compression to start, much less drive over a seam in the pavement.

[alsancle]

I'm a bit skeptical myself.

[Guest John_Lawrence]

The then new over square (bore larger than stroke) over head valve V-8s were abe to make more power at higher rpms. The Packard straight 8s had a long stroke in comparison to its bore which gave them better low end torque, but limited their power output because of piston travel distance and inherent restrictive high speed breathing valve in block design. The Packard engines were low speed, high torque designs more suitable for casual driving. Using a Packard straight 8 as a competition power plant is problematic because of the long bore and l-head. The best one to use, in my opinion, would be the 288 with its 3 1/2" bore and 3 3/4" stroke. Great engines, but they could not compete with the modern OHV V-8s.

(o{I}o)

[Guest MetalFlake]

The then new over square (bore larger than stroke) over head valve V-8s were abe to make more power at higher rpms. The Packard straight 8s had a long stroke in comparison to its bore which gave them better low end torque, but limited their power output because of piston travel distance and inherent restrictive high speed breathing valve in block design. The Packard engines were low speed, high torque designs more suitable for casual driving. Using a Packard straight 8 as a competition power plant is problematic because of the long bore and l-head. The best one to use, in my opinion, would be the 288 with its 3 1/2" bore and 3 3/4" stroke. Great engines, but they could not compete with the modern OHV V-8s.

(o{I}o)

I agree with your post in part. As you note, the "side-valve" concept is inferior to the over-head valve concept - we should think of a engine as an air pump - the more volume you can pump thru it, the more power. That is why the over-head valve design with "cross-flow' is now the "industry standard". If there are "side-valve" designs still being manufactured, except, perhaps, in the cheapest lawn mowers, I am not aware of it.

Let me add to your comments by noting that torque is primarily a function of COMPRESSION. That is why diesel engines, with their 18-1 or higher compression ratios, produce so much more raw twisting force ( torque ) (typically almost twice as much) as a comparable gasoline engine. Put two motors that are otherwise similar except for "side-valve" -vs- overhead valve/cross flow "breathing", on a dyno, and the advantages of the more modern engine design become painfully obvious.

As you note, the old "side-valve" design produces what torque it is capable of, at lower engine speeds. So the idea that those old design motors were "torque monsters" is illusionary - simply a reflection of the fact that, again, what torque they had, came on at low rotational speeds.

My conclusion - there is a reason why there is little or no interest in the hot-rod set for trying to use the out-dated "side-valve" design. Just dosn't make sense from a technical standpoint.

Edited August 15, 2010 by MetalFlake (see edit history)

[Guest John_Lawrence]

MetalFlake, thanks for your constructive comments. I was under the impression that length of stroke was a major factor in the torque an engine produced. I was wrong, and I agree with you on your points. Look at what Packard did in 1955 with its new OHV V-8: The smaller version, 320 cu. in., was rated at 225 h.p. - more than the high output 1954 359 straight-8 - and this was their small motor. Clearly, Packard had developed its straight-8 to its practical maximum for a production engine. The new V-8s were in their infancy, with potential for much more power. I have a 165 h.p. 356 cu. in. engine in my '47 Custom Clipper. I also have one of the '55 Clippers with the small V-8s. They are, well, just different from each other, and I appreciate them both for what the are.

(o{I}o)

[Packard8]

Let me add to your comments by noting that torque is primarily a function of COMPRESSION. That is why diesel engines, with their 18-1 or higher compression ratios, produce so much more raw twisting force ( torque ) (typically almost twice as much) as a comparable gasoline engine.

It is my understanding that torque is more a function of mechanical leverage than compression. Long stroke engines have a greater mechanical advantage if you consider the crankshaft is the fulcrum and the "reach" of the stroke is the lever. Some of the highest torque engines are the slow turning natural gas industrial engines that have a very low compression ratios, and also steam engines although they are external combustion.

Diesels must have a high C/R to produce enough heat on the compression stroke to ignite the fuel. High torque in diesels is more of matter of long stroke than high compression

[Guest MetalFlake]

It is my understanding that torque is more a function of mechanical leverage than compression. . . . . . Diesels must have a high C/R to produce enough heat on the compression stroke to ignite the fuel. High torque in diesels is more of matter of long stroke than high compression

You are partially correct - yes, as to 1) leverage and 2) "compression ignition.

What you are losing sight of, is how much better a high compression diesel engine is at producing power. Ever noticed how long it takes for a diesel engine to warm up on a cold day, compared to a gasoline engine ? Ever noticed how much smaller, relatively, a diesel radiator needs to be to handle the same work-load, as a gas engine? Ever noticed how much larger the earleir radiators were on cars the farther back you go in automotive history ?

What you are seeing, is the fact that the more you compress the fuel/air mixture, the more MECHANICAL energy you get out of the process, and the less is lost as heat. Yes, earlier radiator designs were nowhere near as efficient as later models. But that dosnt change the fact that the farther back in time you go, meaning, the lower the compression ratio, the less powerful the engine is, because so much energy is wasted as heat.

Of course, in strictly "leverage" terms, you are right - the longer the stroke, the greater the leverage. But if you have only gasoline/type compression ratios, the same stroke / leverage with a diesel is going to give you MUCH MUCH more raw power.

[Packard8]

You are getting closer Pete. Higher c/r's will improve combustion efficiency thereby raising BOTH HP and TQ but the mechanical leverage at the crank is still the more significant factor. Comparing diesel to gas engines is somewhat “apples to oranges” in that a diesel needs at least ~ 15:1 to ignite the fuel while gasoline engines are limited to around 13:1 max due to detonation issues.

<o></o>

In an idealized model of an Otto cycle internal combustion engine, the efficiency of the engine is described by:

e = 1 - 1/r^(k-1)

where e = efficiency, r = compression ratio, and k = ratio of specific heats for the gas mixture (typically around 1.3).

Now we can use some scaling laws to find how torque varies with compression ratio:

Torque is proportional to power (at a given RPM), so

T ~ P

Power is proportional to efficiency

P ~ e

Therefore, torque is proportional to efficiency:

T ~ e

T ~ 1 - 1/r^(k-1)

Keep in mind this is only an approximation.

If we trust the model, we can predict that going from a compression ratio of 9:1 to a ratio of 11:1, the torque should go up by about 6%, not an earth shaking amount.

<o></o>

Here is some good reading that might explain it better for you:

<o></o>

Outdoor Power Equipment - Google Books

<o>

</o>

[Guest MetalFlake]

You are getting closer Pete. Higher c/r's will improve combustion efficiency thereby raising BOTH HP and TQ but the mechanical leverage at the crank is still the more significant factor <O>

</O>

If what you say is true about stroke, you could make a lot of money by straightening out all the mis-information that today's engineers have been relying on down thru the years.

Here's the problem. For some decades now, engine designers are under the illusion that no matter how long you make the stroke of a gasoline motor, the diesel motor of comparable size, with its much higher compression, is going to make more raw torque. A LOT more. And a LOT more reliable!

I am under that same illusion. Our delusion may explain why the designers encourage engine manufacturers to go to the much greater expense of making diesel motors where MUCH higher torque is required.

Edited August 16, 2010 by MetalFlake (see edit history)

[Guest bkazmer]

It's interesting to note the "new" 49 Cadillac V8 was not more powerful than the "old " 49 Packard 8

the long crank on a straight eight can be a problem with crankshaft deflection at high rpm. Packard used the beefy crank plus 9 main bearings to tame this.

The problem of getting uniform fuel mixtures to all cylinders was in my opinion never well addressed. Look at the intake tract to 1 and 8 vs 4 and 5.

[Guest MetalFlake]

. . . . . The problem of getting uniform fuel mixtures to all cylinders was in my opinion never well addressed. Look at the intake tract to 1 and 8 vs 4 and 5.

I disagree. See if you can find one of the engineering "cut-a-way" drawings showing the intake and exhaust manifolds (along with that fantastic 'wedge-shaped" combustion chamber design) of the 1932- 1939 Packard Twelve.

What you will see is how much careful engineering went into "balancing" the flow of the induction, so that all cylinders received approx. the same amount of fuel-air mixture.

The combination of the "balanced" intake system, and the "wedge-shaped" combustion chamber ( does anyone know of any other pre-war production automobile that had wedge-shaped pistons and a "squish" combustion chamber so common today ?).

As a side note, have you ever seen an exhaust system on a production auto motor (besides the Duesenburg ! ) so obviously designed to be "free breathing" and non-restrictive ?

It is my belief that the "breathing" design of the Packard Twelve explains why it is so much more powerful, cu. in. for cu. in (in REAL power - i couldn't care less about the advertising representations) than the other large-displacement compeition of its era.

But you are right - besides the 1932-1939 Packard Twelve, I am not aware of any other production car's motor designed with that much attention to a "balanced" mixture ( until we get into the modern "cross-flow" concepts of the post Korean-war era).

Edited August 16, 2010 by MetalFlake (see edit history)

[Packard8]

Here's the problem. For some decades now, engine designers are under the illusion that no matter how long you make the stroke of a gasoline motor, the diesel motor of comparable size, with its much higher compression, is going to make more raw torque.

<link rel="File-List" href="file:///C:%5CUsers%5CJohn%5CAppData%5CLocal%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--><style> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> </style><!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman";} </style> <![endif]--> Apples and oranges again. Stop and think for a moment Pete. You can’t increase TQ independently of HP with compression ratio alone. A GM LS series 6.0 gasser has 300 HP and 350lb/ft TQ. A Cummins ISB 5.9 diesel has 300 HP and 650 lb/ft TQ. The difference? The gasser has a 3.6” stroke, the Cummins has a 4.72” stroke…over one inch longer. Diesel is also a more energy dense fuel with a slower burn rate than gasoline. The higher BTU per volume along with the longer burn time and the mechanical advantage of a longer stroke give the diesel a distinct advantage in TQ compared to a similar displacement gasser. C/R plays a much lesser role.

[Packard8]

An electric car has a motor, not an engine.

Now, back to my Coke and rum........

And I bet you put motor oil in your car's engine.

Mix me one too!

[Guest MetalFlake]

<LINK rel=File-List href="file:///C:%5CUsers%5CJohn%5CAppData%5CLocal%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"><STYLE> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> </STYLE> . . .. . A GM LS series 6.0 gasser has 300 HP and 350lb/ft TQ. A Cummins ISB 5.9 diesel has 300 HP and 650 lb/ft TQ. The difference? The gasser has a 3.6” stroke, the Cummins has a 4.72” stroke…over one inch longer. . . . . . . . the mechanical advantage of a longer stroke give the diesel a distinct advantage in TQ compared to a similar displacement gasser. C/R plays a much lesser role.

Excellent argument. Strongly recommend you write a tech. paper for the SAE/ASTM and explain to them how GM could out-sell the diesel mfgs.

Using your logic, simply "stroke" their much-cheaper-to-manufacturer gassers - say, instead of a 3.6" stroke, how about going to a 4.5 or even a 5" stroke... wonder why no-one ever thought of that..?

Assuming your arguments are correct, they'd get nearly the torque of a diesel, without the cost of manufacturing the much higher compression diesel engines - then we wouldn't need diesels any more. Outstanding!

[Packard8]

Using your logic, simply "stroke" their much-cheaper-to-manufacturer gassers - say, instead of a 3.6" stroke, how about going to a 4.5 or even a 5" stroke... wonder why no-one ever thought of that..?

They did...don't you remember "DieselGate" when GM tried to make a diesel out of the Olds 350 gasser? Didn't work out too well. Have you ever wondered why diesels are built to much heavier standards re block, heads, rods, pistons etc? Do a search on "cylinder pressures"...Google is your friend!

[v12lincoln]

A lot of the earlier cars like Locomobile had 5 and 6" stroke engines with over 800-1000cubic inches. that was back in the teens and early twenties. low HP but tons of Torque.

Father in Law has a Mitchell with a 300CI 4cyl, 5" stroke and I belive a 4 1/4" bore, only 40HP but it pulls like a train.

[Guest MetalFlake]

A lot of the earlier cars like Locomobile had 5 and 6" stroke engines with over 800-1000cubic inches. . . . . .. low HP but tons of Torque.

Father in Law has a Mitchell with a 300CI 4cyl, 5" stroke and I belive a 4 1/4" bore, only 40HP but it pulls like a train.

Partially correct. Yes, early engines had VERY long strokes - a design made necessary by low compression, which in turn was made necessary by the incredibly low octane (meaning high flame speed) of the fuel then avail.

And as you correctly note, the price for that was low power.

The longer the stroke, the slower the rpm at which the engine produces useable power. If you saw the actual torque curve of one of these old monsters, you'd better understand what happens - they put all the torque they are capable of at lower rpms - spin em faster and the torque quicly drops away.

These early motors had HUGE flywheels. Combine that with the torque coming in at much lower rpms than we are accustomed to in the past 60-70 years, and you THINK they are putting out gobs of power. Yes, they might equal or even exceed a more modern short-stroke gasoline engine at LOW engine speeds, but once the more modern "short stroke" starts spinning up, it produces FAR more power.

You combine that with the overly low "final drive" gear ratios of the pre-war cars, and sure, it SEEMS like they are powerful, since some of them are SO "low geared" they can start in high gear from a dead stop.

Take one out on the highway and "punch" it at 70 mph and see what happens ! You will be impressed with the fact that NOTHING happens - they just dont have any "punch" when spun fast. ( I take that back - you "wind out" a long-stroke engine from the "poured babbit" days, and chances are you will "punch" a connecting rod right out the side of the block !

Packard 8 answered his own question in his most recent post, noting that if you take a gasoline engine and lengthen its stroke, you get a disaster. Well, not really, you just reproduce what automotive gasoline engine engineers got away from!

Which brings us back to the simple law of physics that the higher the compression, the more raw power at the crankshaft. that is why all other things being equal, a diesel motor is so much more powerful than a typical gasoline motor of the same displacement.

Edited August 18, 2010 by MetalFlake (see edit history)

[stude1946]

I've done 80mph with my '37 120CD touring sedan while going to work. One of my co-workers was following me and couldn't believe I could reach that speed with a stock straight eight. Told him I might have gone faster if traffic would have gotten out of my way.

[Guest RenegadeV8]

Horse power is the result of 2wo, exactly 2wo and ONLY 2wo things:

Piston speed and/or pressure on the piston crown.

The longer the stroke the faster the piston speed the higher the HP.

The longer the stroke the higher the compression ratio and therefore more pressure on the piston crown and therefore higher HP.

To get more pressure on the piston crown without increasing stroke can be accomplished by a variety of many different methods such as blowers or anything that will get more fuel/air mixture to the cylinder or decreasing combustion chamber volumn.

Downside of increased piston speed due to longer stroke is that wear rate increases on the moving parts. THis is why many of the long stroke engines require overhaul at say 40k to 60 k miles.

Metalurgy/foundry production control of the prewar period was certainly not as sophisticated as post war period. So the long stroke engine/ slow turning engine was a compromise to power vs mass production considerations vs public demand.

The high compression OHV short stroke engine evolved from the HP revolution of 1955. After WWII better manufacturing processes (learned out of WWII), Higher speed demands for the automobile (I'State program born ca. 1956) and manufacturers attempt to cut costs by lowering profile of car among many other factors are the only reasons that the short stroke OHV, high compression engines ever came into existence.

Again Hp is piston speed and/or pressure on the piston crown. NOTHING else.

Altho the old streight 8's will hit every bit of 80 mph or even over 100 mph they will not SUSTAIN those speeds for say 300 or 400 miles interstate travel as we do today. They are simply not strong enuf in terms of internal engine parts. They didn't have to be in the prewar era due to raod use environment of the time.

[Rusty_OToole]

When they announced the new OHV V8 in 1955 Packard put out a press release comparing engine life of the new vs old engine. They said at high speed the straight eight had a life of 18,000 miles and the new engine had a life of over 100,000 miles.

Packard had a fine high speed test track where it was possible to hold speeds of 100MPH or more indefinitely.

In normal service a well maintained straight eight would have a life of 80,000 to 100,000 miles.

Edited October 10, 2010 by Rusty_OToole (see edit history)