Random thoughts on piston speed and other things |
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Mark W.
Member Sponsor Member Joined: 09 Nov. 2014 Location: Silverton, OR Status: Offline Points: 7980 |
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Posted: 24 Oct. 2021 at 11:00am |
fpm = feet per minute as it relates to the piston traveling up and down in the cylinder bore. SO "Old school" tells us 2500fpm is as fast as you want your cast crank cast piston engine to travel. Though our 134L cranks are forged I am using the cast crank recommendation as its more conservative. So lets look at the 134L Bore will run from 3.125" STD. to 3.185" .060" over (at .060" over the engine displaces 140cu.in. The Stroke is 4.375" (THATS A LONG STROKE) Now lets look at the piston speed at various RPM's Mean Piston Speed (fpm)=(Stroke x 2 x RPM)/12 lets start with 4000rpm the rpm the engines rated HP happens at. 4.375" x 2 = 8.75" x 4000 = 35000" /12 = 2916 fpm now thats over our OLD SCHOOL benchmark of 2500 fpm OK how about 3000 rpm (stock 30" tall tires 5.38 gears is roughly 50mph) with a 25% OD it's 66.5mph 4.375" x 2 =8.75" x 3000 = 26250" /12= 2187.5 fpm thats well under the OLD SCHOOL benchmark of 2500 fpm A side note my CHUG is 5.38 gears 30%OD 28.5" tires at 3000rpm the speed is 67.5 mph The speed for the above 30" tire no OD example if run at 2500 fpm piston speed would be 3428rpm or 56.5mph roughly Has anyone else noticed that with all the engine bores we see on the forum and on other forums we rarely ever see much of any Cylinder ridge in a 134L The reason for this is the length of the rod. In circle track racing it is very common to use a 6.0" or even 6.125" Rod in a small block chevy that had a stock 5.7" rod length. The reason for this change in geometry is that a longer rod keeps the piston straighter in the bore as it travels up and down. This then keeps the piston from Rocking at the top and bottom of the stroke. The Willys 134L rod is 9.187" long and while the crank stroke does pull the rod to a greater angle then say in a Chevy 350 the long rod more then makes up for it. Keeping the Piston straighter in the bore. Therefore reducing the rocking at the top and bottom of the storke and the wear at those places in the cylinder. Another side note on engine stroke the Dodge 218 flat head 6 that was in my 1940 Dodge B-13 (5 window business coupe) was also 4.375" that car would cruise sweet as could be at 70mph. Chrysler used variations of this Flat head all the way up to 1964 some with strokes as long as 4.625" in passenger cars. Many of these engines were used in circle track racing as well. Edited by Mark W. - 24 Oct. 2021 at 11:29am |
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Chug A Lug
1948 2A Body Customized 1949 3A W/S 1957 CJ5 Frame Modified Late 50's 134L 9.25"clutch T90A D18 (1.25") D44/30 flanged E-Locker D25 5.38 Since 1962 |
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duffer
Member Joined: 02 Feb. 2012 Location: Bozeman, MT Status: Offline Points: 1086 |
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Mean piston speed doesn't tell the complete story. That long stroke also means the pistons are accelerated/decelerated more quickly and why I believe if you get 75K out of either 134 before you need a ring job, you did well. There is no free lunch.
You are correct about the relatively longer rod lengths reducing piston slap as there is less lateral loading with a longer rod. I'm about to test all this in what is no doubt my last engine build in my 3B with a 4.125 stroke (6.125" rods) in a small block Chevy. It has been an interesting build as I'm looking strictly for bottom end torque rather than hp and that eliminated most aftermarket offerings for a lot of items.
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1955 3B: 441sbc,AGE 4 speed transmission, Teralow D18w/Warn OD, 4.11:1 D44's/ARB's, glass tub & fenders, aluminum hood/grill, 8274, York OBA, Premier Power Welder; 67 CJ5: 225,T86AA, D18, 4.88's, OD
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Downs
Member Joined: 08 Sep. 2021 Location: Hunt County Tex Status: Offline Points: 179 |
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So basically if you want to get any life out of these keep your speeds to 50ish or less on a stock example.
Makes me want to invest in an overdrive unit. |
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wfopete
Member Joined: 27 Nov. 2020 Location: Dover, Arkansas Status: Offline Points: 305 |
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I for one, am surprised that no one came up with a drop in 4 cylinder engine that incorporated a shorter throw crank and a OHV head. Guess to many folks were replacing the engine with V6's and SBCs along with everything else they could shoehorn into that space.
Hey the new Roxer is just a few days away from it's intro!
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Suffer Fools, Gladly!
U.S. Army Iraq Veteran (ret.) |
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Ron D
Member Joined: 27 Oct. 2019 Location: South Carolina Status: Offline Points: 1431 |
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Horsepower vs. torque curve chart: http://www.nulltime.com/jeep/techtips/speeds/index.html
Edited by Ron D - 07 Nov. 2021 at 11:17pm |
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1951 M38
1951 M100 |
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cpt logger
Member Joined: 23 Sep. 2012 Location: Western Colorad Status: Offline Points: 3040 |
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They did, it is called a Pinto engine. While it is an overhead valve, it is also an overhead camshaft engine. Unless you meant by "drop in" that it needed no adapters to bolt up? The Chevy Vega four cylinder engine was just too unreliable for it to be used much & then when it was, it did not last long. Many, many, moons ago, I saw an air cooled V-4 installed in a CJ-2A. Wisconsin? As I recall it, the owner said it was a bit anemic, & overheated easily.
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wfopete
Member Joined: 27 Nov. 2020 Location: Dover, Arkansas Status: Offline Points: 305 |
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I was thinking more of an 4 cyl engine specifically for the older CJ platform that would "Bolt up" to mounts, transmission. I'm kinda surprised the Roxer engines don't work but I don't follow the engine swap stuff much.
As a prior Vega owner I know of what you speak.
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Suffer Fools, Gladly!
U.S. Army Iraq Veteran (ret.) |
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rocnroll
Member Sponsor Member Joined: 20 July 2005 Location: Tuscumbia, AL Status: Offline Points: 13583 |
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The GM 'Iron Duke's series engines make a good swap also.
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'47 CJ2A PU
'48 CJ2A Lefty "Common sense is not that common" |
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Bruce W
Member Joined: 29 July 2005 Location: Northeast Colorado Status: Offline Points: 9648 |
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I once parked an Iron Duke (came out of an ‘83 or ‘84 CJ, as I recall) and a Go-Devil side by side and did a lot of measuring and comparing. It did look almost as though it was made to replace the Go-Devil. It would have been beautiful! Sadly, and of course I regret it now, I sold the Duke to a guy that was going to use it to power a monster wood splitter.
BW
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It is NOT a Jeep Willys! It is a Willys jeep.
Happy Trails! Good-bye, Good Luck, and May the Good Lord Take a Likin' to You! We Have Miles to Jeep, Before We Sleep. |
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cpt logger
Member Joined: 23 Sep. 2012 Location: Western Colorad Status: Offline Points: 3040 |
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For any engine manufacturer to build an engine with a certain bolt pattern & engine mount placement they need a certain number of sales to engineer that into their engine. The aftermarket scene certainly did not have those numbers. Besides, Willys had their own engine, engineers & manufacturing facilities they just might not have appreciated anyone making engines to drop into their rigs. Kaiser had engines that were very similar to the Willys engines. They were a bolt in option. However, the Kaiser engines had little to no advantage over the Willys engines & they were/are harder to find. I doubt that Roxer builds their own engines. Again, they do not have the numbers for them to get to dictate the bolt pattern +/or the engine mount locations. Even if they did, why would Roxer choose a Willys pattern. Pattern & mount locations from Chevy, Ford, Dodge, Toyota, Datsun, Honda, Yamaha, or even VW would make more sense than those for a Willys would. All of these manufacturers are still in business & can supply not only engines but also parts & service after the sale. Willys can not. I will bet that Roxer also did not replicate the Willys transmission nor the axles. Willys made a good rig & it served its purpose well. However the needs & wants for today's buyers is very different than it was in 1945. Pulling a plow is not needed these days. A new rig has to be able to run in the mud & crud all week long with almost no maintenance. While I am a huge fan of the Willys, they cannot do this. Yes, some folks have their Willys in almost new shape, but to keep it that way, they do maintenance on them fairly often. Buyers today want to be driving, not wrenching. I do not believe that there is very much of a market for a rock stock Willys CJ-2a. If there were, one would be built. IMHO, Roxer comes as close as we are going to see. It encompasses all the good attributes while updating most of the "bad" ones. For example Roxers have disc brakes & a much better steering system than Willys had. I doubt that there is even one Zerk fitting on the Roxer. Will I buy a Roxer? Nope, I like the old rigs. Heck, my DD is a 1972 Ford Pinto Ranchero.
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BD1
Member Joined: 18 Dec. 2019 Location: Maine Status: Offline Points: 630 |
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I think the major issue with what you seek is the idea that any major manufacture would advance a design based on the premise of replacing the engine in the early CJ's. Civilian CJs were a post war adaptation of a military design, that did it's utilitarian job well with the power plant it already had. They were not "the wave of the future" for car sales in the US. That wave of the future was an affordable, reliable and economical family sedan geared for the new national highway system. I think the closest thing to what you are talking about may have been the Chevy 153 "Thriftmaster" which was introduced in the '62 Chevy II to compete with Ford's Falcon while stepping well back from the more innovative Corvair which had such a miserable and publicly poor crash rating. (Ralph Naders big step onto the public stage was "Unsafe at ANY Speed").
That 153 was adopted by Kaiser-Willys for the DJ-5A postal jeeps in 1967 until the end of Kaiser Corp, and it was offered in the Chevy II from '62 until '68, (although I think 194 six cylinder option outsold it). It was a good little engine and by the late '60's most of the available takeouts where snapped up by the Sprint car racers when they realized the little 5 bearing main I-4 could handle 6,000 - 7,000 rpm even when built up to 200 hp or more. It was also adopted by Mercruiser, Volvo Marine and OMC. It was used in boats until the early '80s and the bored out 181 version continued after that. Again, I believe this was due to it's ability to reliably maintain 4,500 -5,000 rpm for hours on end, day in and day out. It's a great little motor, and although used in Jeeps, it was designed around the much more universal Chevy bell housing and bolt pattern. When Kaiser put it in the postal jeeps, they weren't looking for the tradition 4x4 Jeep market, they wanted to sell a lot of units to the government, and they put it in a 2 wheel drive with a two speed automatic tranny behind it to better suit that role. I'm a fan, and I have one in my '47 CJ2a. I bought that particular Jeep primarily because it had that motor already in it. Edited by BD1 - 09 Nov. 2021 at 6:41pm |
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BD
'47 CJ2a, Shiny on top! '55 CJ5 project |
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otto
Member Joined: 26 Feb. 2012 Location: Orygun Status: Online Points: 2264 |
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X2,
One of my jeeps sports a 140HP Mercruiser. Fits like it was made for a jeep.
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47 CJ2A w/fuel injected boat engine
48 CJ2A 64 Ford Econoline Travelwagon If you can't get there in a Jeep, get a motorcycle! |
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Dutch 1960
Member Joined: 11 Feb. 2019 Location: San Diego, CA Status: Offline Points: 72 |
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There is still a GM marine 4 cylinder engine out there in their catalogue. Might that still work like the old Chevy II engine?
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otto
Member Joined: 26 Feb. 2012 Location: Orygun Status: Online Points: 2264 |
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Yes, there are two sizes of the marine engines- a 153 cid and a 181 cid. They are interchangeable with the old Chevy II engine except for the boat stuff.
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47 CJ2A w/fuel injected boat engine
48 CJ2A 64 Ford Econoline Travelwagon If you can't get there in a Jeep, get a motorcycle! |
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Greaser007
Member Joined: 16 Jan. 2018 Location: Anderson, Calif Status: Offline Points: 850 |
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I agree on the iron duke marine engine running happily for hours at 4500 rpm.
My Kodiak Marine engines in our river boats with Ford 351 windsor's and chevy Vortex's ran 4500 normal run rpm running a Kodiak 2 or 3-stage jet pump. My dad who worked in an engine machine shop in the '60's and '70's always said if you want a tough engine to buy a marine engine. :) So, what did I buy a few years back, ?? _ _ _ a '91 efi 366 Chevy mid-sized truck engine for towing. It does have a forged crank. But, it is no high rpm 1/4-miler engine. Any town in the proximity of a recreational lake will be a source for nice marine engines.
Edited by Greaser007 - 10 Nov. 2021 at 9:12pm |
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