How big a pistons in a WC block?
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=23972
Printed Date: 18 Jul 2025 at 9:35pm
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Topic: How big a pistons in a WC block?
Posted By: JM
Subject: How big a pistons in a WC block?
Date Posted: 12 Jan 2011 at 7:41pm
| Is 4.625 as big as you can go? Thanks,JM |
Replies:
Posted By: mlpankey
Date Posted: 12 Jan 2011 at 8:38pm
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No I am kicking around cutting two blocks and welding them back to increase the deck height so the sleeve don't have to protrude past the camshaft and going into 2 cylinder jd size. In my magic ball I see 491 ci in the future. ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: JM
Date Posted: 12 Jan 2011 at 9:32pm
| can the block bores be offset to increase clearance for bigger sleeves? What is the biggest bore we can get? |
Posted By: wild child
Date Posted: 12 Jan 2011 at 10:20pm
| 4.750 is the biggest. You do run into a few problems but nothing major. Rod |
Posted By: mlpankey
Date Posted: 13 Jan 2011 at 6:04am
------------- people if they don't already know it you can't tell them. quote yogi berra |
JM wrote:Posted By: Lonn
Date Posted: 13 Jan 2011 at 6:18am
Say that again? Why not just make a spacer and use two head gaskets? Maybe I'm not following or does it have to look like a block and not a block with a spacer? ------------- -- --- .... .- -- -- .- -.. / .-- .- ... / .- / -- ..- .-. -.. . .-. .. -. --. / -.-. .... .. .-.. -.. / .-. .- .--. .. ... - Wink I am a Russian Bot |
Posted By: mlpankey
Date Posted: 13 Jan 2011 at 8:47am
------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: mlpankey
Date Posted: 13 Jan 2011 at 6:36pm
here is a pic of a d17 block with 5 inch od sleeves
 ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: mlpankey
Date Posted: 13 Jan 2011 at 6:44pm
one of them ready to hone.
 ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: mlpankey
Date Posted: 13 Jan 2011 at 7:37pm
You can see here why the sleeve couldnt come through the bottom deck at 5.125 sleeve from the bottom side with rotating goodies. It woold need a ledge in the bottom stopping it from coming through then a longer rod to keep the piston from pulling out of the sleeve but a longer rod would set the piston higher at tdc requiring a taller deck height. .
 ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: wi50
Date Posted: 14 Jan 2011 at 3:52pm
|
I've got about 120 runs on my engine that is apart, the cylinders are out of round about .006 or a tad more now, and we honed them quite a bit. Piston skirt clearance is getting to high, the liners are hard, remade from a diesel application, but wear has taken it's toll.
4.75 will fit decent, but I really like them in the 4.58 to 4.61 range leaving enough room to bore again to 4.625 or larger. Parts are more reasonable priced, lots of off the shelf pistons available as well as nice used ones from many raceing applications. If you decide to change compression ratio or some other factors in the engine there's lots of stuff available without going to a totally custom piston.
It will be hard enough to fill the cylinder to any reasonable degree of efficiency no matter what size it is, but at low speeds time is your friend, then keeping a mixture suspended and good flame travel.
One of the toughest engines I've seen in a low speed or RPM regulated tractor, cast manifolds uses a 4.8 bore and a 4.5 stroke, 325 CID it's a little 4 cyl, not an allis but another color. It's beat on many built engines with a ton more inches and stroke has taken advantage of many 4020 Deeres at 9000 pounds. They don't have to be huge, they just have to breathe like it.
A WC block isnt' the best cantidate to start with, it's just a little weak and it's narrow compared to later ones. If you have the option to use another block or have to buy one, you will likely be money ahead in time. ------------- "see what happens when you have no practical experience doing something...... you end up playing with calculators and looking stupid on the internet" |
Posted By: mlpankey
Date Posted: 14 Jan 2011 at 4:22pm
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Pistons shows yellowish brown tent that alcohol shows in place of carbon color for gas all the way across the piston top . I also know what the head flows and use a short connecting rod to keep reversion away. Crank stroke gives you piston speed .  ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: wi50
Date Posted: 14 Jan 2011 at 4:51pm
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short rods are good at limeting power output of an engine. They bend, or the crank breaks. I've got friends that think the shorter the better, same story all the time, bent or broken parts. Monkey see monkey do, again and again. I see people wonder why the crank broke or a rod bent, but the answer is alwayse the same. It was to weak, but the same rod in a better ratio is stronger. I can't think of how many times the rod ratio horse has been beat to death, but I've seen enough to know and will keep my opinions. ------------- "see what happens when you have no practical experience doing something...... you end up playing with calculators and looking stupid on the internet" |
Posted By: mlpankey
Date Posted: 14 Jan 2011 at 5:10pm
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yeap it gets beat to death but short rods still help a ineffecient head breath better and so does piston speed. hard to say a engine breaking stuff is power limited. If a small cubic inch would out pull a large cubic inch engine they would be no need for cubic inch rule would they or a market for large cubic inch engines. ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: wi50
Date Posted: 14 Jan 2011 at 5:15pm
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it's all in how it's fed.
Piston speed is good to a point and after that, it's just negative horsepower. If a head is choked (which all these heads are) , and the cylinder is drawing air at a higher rate, the vaccuume goes up. The higher the vac. the more power being robbed. ------------- "see what happens when you have no practical experience doing something...... you end up playing with calculators and looking stupid on the internet" |
Posted By: mlpankey
Date Posted: 14 Jan 2011 at 5:19pm
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I dont know how much was robbed .I knew 200 was a good enough for third gear on hard track and fourth gear on soft . Reminds me of my cousin and his red camaro. He had a 388 cubic inch small block built . 6.125 rods light pistons with short skirts big headers big cam aluminum heads list goes on . Sounded good made alot of noise anywhere it went . It never could get to the end of a quarter mile as quick as my 396 325 hp camaro but it sure made my old dumptruck engine sound good where the crowd gathers at the staging lane and starting line. quote wi 50 One of the toughest engines I've seen in a low speed or RPM regulated tractor, cast manifolds uses a 4.8 bore and a 4.5 stroke, 325 CID it's a little 4 cyl. I agree big bore is better than stroke when it comes to a cubic inch limit rule always go with bore . ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: mlpankey
Date Posted: 14 Jan 2011 at 7:43pm
------------- people if they don't already know it you can't tell them. quote yogi berra |
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Posted By: mlpankey
Date Posted: 14 Jan 2011 at 7:49pm
a 324 ci with stroke instead of bore.
------------- people if they don't already know it you can't tell them. quote yogi berra |
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Posted By: wi50
Date Posted: 14 Jan 2011 at 8:11pm
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how realistic is 6000 ft/min piston speed? half that or less is more realistic in a lot of these tractor engines. I know a few that going over 4000 ft/min. ------------- "see what happens when you have no practical experience doing something...... you end up playing with calculators and looking stupid on the internet" |
Posted By: mlpankey
Date Posted: 14 Jan 2011 at 8:18pm
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if you turn a 6 inch stroke 6000 rpms its realistic . That's the beauty of a 6 inch stroke actual rpm is actual piston speed . Math it just works ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: mlpankey
Date Posted: 15 Jan 2011 at 9:15am
heres why piston bore out performs stroke at a given piston speed
------------- people if they don't already know it you can't tell them. quote yogi berra |
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Posted By: GBACBFan
Date Posted: 15 Jan 2011 at 9:19am
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I gotta tell you, Pankey as much as I worry about you on a couple of subjects, you are smarter than the average bear on these hot rod tractors. ------------- "The trouble with quotes on the Internet is that you can never know if they are genuine." - Mark Twain |
Posted By: mlpankey
Date Posted: 15 Jan 2011 at 10:10am
------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: wi50
Date Posted: 16 Jan 2011 at 8:18am
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I love computer simulations, they alwayse print out results for values put in. In the real world though unfortunatly the engine runs out of breath somewhere allong the way. Airflow is limeted and then the powerband happens at different ranges for a given setup. ------------- "see what happens when you have no practical experience doing something...... you end up playing with calculators and looking stupid on the internet" |
Posted By: mlpankey
Date Posted: 16 Jan 2011 at 8:29am
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Thats what they say and even the computer says that but real world my engine turned 2000 rpms more than the computer said it would for a rpm on the tattle tale tack of 6000rpms.You know when pulling you generally want to take the rpms above where peak occurs and pull back down into peak power rpm range. I would rather have a computer for checking my thinking than going head strong and blind into a project. I would definitely need a computer when designing a head. Could get the velocities and swirl off bad without a computer and flow bench. Just for kicks when you reach 200 hp till me how much over 194 cfm at 28 inches of depression your head is running? No doubt your a talented guy . So I leave you with a quote from Grumpy Jenkins . When you run into that engine that runs better than you think it should its time to change your way of thinking. It happens to me to. ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: wi50
Date Posted: 16 Jan 2011 at 8:44am
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I beleve that shape is worth more than flow, velocity is worth more than shape. A head only makes big "flow numbers" in a verry small part of it's operating range, verry small range in comparison to what it does on the way up and down from that number in relationship to rotation. I could make up numbers all day long, I could say my head flows 170 cfm or 230 and someone will beleve it and someone will never beleve it. I could test it on a dozen different setups and have 15% different readings from one to another. ------------- "see what happens when you have no practical experience doing something...... you end up playing with calculators and looking stupid on the internet" |
Posted By: mlpankey
Date Posted: 16 Jan 2011 at 2:03pm
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I believe it takes airflow in the form of cfms to produce the btus to convert energy into horsepower . I believe that the cfms to produce power have a effect on the rpm in range at which a engine produces this power number from. Cfms of air flow is based on the cubic inch size of the engine the cylinder head is on. I believe it takes 194 cfm at 28 inches of cylinder head flow to produce 200 horsepower .now a 226 ci engine with this head flow is capable of making the 200 hp if it is spun to the rpm that's required . I believe a 400 ci engine will do it at a significantly lower rpm. Here is what I have learned by doing and observing tractor pulling . The small engine that gets its breath to produce power at a high rpm is dependent on the mechanical advantage of gearing to keep it in its breath. The large engine that is in a taller gear and spun past peak rpm and pulls down into peak and past it to the point of snuffing the engine out will be farther in distance than the engine which a lower gear held its rpm but spun out. First reason the large engine in taller gear generated more ground speed and a object in motion stays in motion till a force equal stops it. Reason two the tractor that pulls higher gear and lugs his engine down is hooked to the ground and loosing rpm due to it.This engine is always the winner. The 15 percent difference in readings you talk about is people wanting best numbers and not using corrected numbers to obtain the standard but the formulas are out there for a standard no matter the elevation or barometric pressure may be at time tested . Do you really believe what you write ? You just typed you believe velocity is better than shape but in a above post wrote velocity can hurt horsepower . Qoute Wi 50 The higher the vac. the more power being robbed. Unless your running a charger or turbo how do get air to move to fill a void without vacuum ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: Steve M C/IL
Date Posted: 16 Jan 2011 at 2:22pm
| quality air beats volume air any day |
Posted By: mlpankey
Date Posted: 16 Jan 2011 at 2:28pm
------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: Steve M C/IL
Date Posted: 16 Jan 2011 at 2:50pm
| Yes it will.You just have to get it in there.That's why the size of the hole has less to do with it than the shape.Then there is dead air and moving air.Some even think that forced induction overrides port design.LOL |
Posted By: mlpankey
Date Posted: 16 Jan 2011 at 2:54pm
------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: wi50
Date Posted: 16 Jan 2011 at 7:04pm
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I'll add a couple little stories, if nothing else it gives something to ponder or laugh about.
One night there was an Allis up at 380-390 inches. The fellas who built it were verry good with engines and knew their stuff. THey had flywheel dynoed the engine to be at 170 HP, now it's been a few years and I can't say an exact number, maybe it was 176 or 171, doesn't matter. It had a fabricated manifolding and ran at a pretty good RPM. They hooked in 3rd gear that night and put down a good run. We had hours to talk before we pulled and we talked quite abit about different things in the engines we had, I don't beleve that any of us were hideing anything from each other. It turned out that I bought a few parts from them and ran into them a few times over the years.
I knew I didn' have the torque to hook 3rd but went in 2nd. UP against 170 hp I figured I was in for a good butt kicking. I snuffed mine in 2nd that night, but I was 80 feet, that's right 80 feet in front. THe sled pulled just hard enough that I could hang on, but the ones with torque boiled the tires. The larger engines made more torque but did it at a slow enough speed that they had lost a lot of momentum. In the times we pulled, the big one never won. There were a few smaller engines at 280, 310, 360 that were really tough, one at 410 that wasn't tough
Another time when I locked up the engine and scored the pistons, hence the smoke, in Northwood Iowa. 3600 pound class and they ran a floating finish line. We all chewed a long ways to something like 360 feet. To long to run a dry engine, or I should have had a little more skirt clearance, when the engine came down I hit the clutch and it just died. Pulled the starter rod and it just shook the exhaust pipe.
It cooled off and I figured it was already trashed so I hooked in the 4500 class, there was a 540 inch Olliver 88 there with a "Gengrich" (sorry on the spelling) engine. We both pulled through and there were a few other allises and 460 farmalls, M's etc that couldn't quite make it. When we re pulled the Olliver spun the tires with good authority, I snuffed mine but it was about 18 feet in front. It gave all it could give but it was wound so tight that the ground speed was pretty high when the load came on. Momentum saved me, cubic inches and torque did no favors that night.
Another night a Olliver 77 that didn't have much power just keept on lugging and dieing down, I came through blazing away and spun out, totally got my butt kicked by several tractors that couldn't go near as fast.
And another time we ended up with a 10 mph speed limet, I got waxed, couldn't get the engine up in it's powerband to take off well. It just stumbled. bumbled and wasn't going to do anything.
My point is that you don't have to outpull them, you just have to outrun them on a modern type sled, most of the time, but it doesn't alwayse work. But if anyone thinks that they can be dominent it doesn't happen. We all got allong and could laugh and joke about things and see who was going where the next weekend
How much torque would it take to spin the tires in a given situation in a certain gear? Now drop a gear and see how much torque it will take. Now figure out how much faster an engine has to turn a gear lower to achieve the same ground speed. It also does not need to have the torque reserve as in a higher gear and can maintain the high speed longer.
Look at how much happens in the last 3 seconds of a run. How many revolutions of a crankshaft happen in the last 3 seconds? By that time the run is over, it's already been made. Say the typical group of tractors in a class is spinning out at 275 feet. By 230 feet you can tell who is going to win, the one going slightly faster, or has the ability to maintain a higher speed for longer.
I've seen a lot of guys sling shot it to the front of the pack. When debateing what gear to run in, alwayse pick the higher one, it may not be right, but it's usually less wrong than the lower one would be.
On another note,
If someone wants to see a neat video or likes Minne Mo's, search on youtube for "tom larsen-draggin-rose". I was messing around and found it. An old friend and heck of a good guy with a UB moline he worked hard on, it runs verry well. ------------- "see what happens when you have no practical experience doing something...... you end up playing with calculators and looking stupid on the internet" |
Posted By: mlpankey
Date Posted: 16 Jan 2011 at 7:23pm
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so we agree that high gears and ground speed rules. we have got away from the original post. Always go with the biggest bore if cubic inch limited if money limited go with stroke you simply get more cubic inches for the same amount of money . Bigger bore will always make more power. ------------- people if they don't already know it you can't tell them. quote yogi berra |