wd 45 compression question
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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=8081
Printed Date: 18 Jan 2025 at 6:17pm
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Topic: wd 45 compression question
Posted By: Glockhead SWMI
Subject: wd 45 compression question
Date Posted: 14 Feb 2010 at 11:45am
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What compression can one expect from the aftermarket 4 1/8th pistons? Some are advertised as medium compression kits but I have not read anywhere what the true compression will be. I would like to get close to eight to one. I need to order something and get this tractor back together. It will be time to plow before you know it. |
Replies:
Posted By: mlpankey
Date Posted: 14 Feb 2010 at 12:41pm
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Glockhead thats a hard one . Most manufacturers for tractor pistons dont advertise the compression hieght or the ccs of the dish if its a dished piston. If you could find a flat top 4 1/8 bore with a compression height of 2.316 you would have a static compression ratio of 8.091. That is also dependent on where the first compression ring is located on the piston . If its a dished piston ring land placement and ccs of dish would make for a larger compression height number by needing the piston pin hole located farther down in the piston . ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: Glockhead SWMI
Date Posted: 14 Feb 2010 at 1:03pm
| Thats what I figured. I don't want to buy a kit and end up with five to one compression. I would like to hopefully end up with a little more than original. More power is never a bad thing... |
Posted By: MikeB (SD)
Date Posted: 14 Feb 2010 at 1:56pm
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Hi Jeff
I am currently doing some research into this very subject as we speak. I have not got a response from Fel-Pro diesel (Sealed-Power)and am awating their response before I post. Clevite Heavy makes a 4-1/8" power crater but it only has a 2.359" compression height and the original measures 2.391" with a 60CC dish so it actually has about a 6:00:1 ratio. They market this as a replacement for the WD45/D17/170&175 replacement. I emailed them back and told them to stop advertising it this way unless
the D17/170/175 owners are going to be happy with about 40 horsepower. The engineer had no idea what I was talking about but my point is buyers beware.
Their is a company called Herschel-Adams that is a division of the the Alamo group and
they also own M&W gear. M&W gear division has nothing to do with pistons anymore they concentrate on hay cutting equipment, However Herschel-Adams has a SP-48 piston and sleeve kit 4-1/8" bore 2.600 compression height and a 7.4:1 compression ratio and it is the old M&W WD45 design that they market, poorly I may add, as Pow'r Seal turbo dome piston. Does anyone know of any other manufactures of A-C gas pistons other than what I've mentioned above?
Hershel-Adams is available at a lot of dealers. My hometown Ford-New Holland and Case dealers offer Hershel-Adams kits, you can locate your local dealer on their website. |
Posted By: JM
Date Posted: 14 Feb 2010 at 2:32pm
| I just bought an old original allis kit for d-17 or gleaner E, 7.25 to1. Try a Agco dealer and see I you can get a d-17 or 175 kit, probably can still get it but I dont know how they will be priced. I gave 450.00 for my NOS kit. |
Posted By: DrAllis
Date Posted: 14 Feb 2010 at 5:02pm
| I would bet that a 170 kit (4 inch bore and 8.0 to 1 comp ratio) would peform as well as the SP-48 (4 1/8" bore and 7.4 to 1 comp ratio) and it will use less gas!!! In fact M&W used to claim 57 HP in a D17 with the SP-48 kit, which is a 4 hp increase. The 8.0 to 1 ratio with a 4 inch bore would yield an almost identical HP increase and be more fuel efficient. What would be nice is if the SP-46 (WC-WD) kit was now available and could be used with the 4 1/2" stroke for 10.5 to 1 in antique pullers. |
Posted By: mlpankey
Date Posted: 14 Feb 2010 at 5:24pm
------------- people if they don't already know it you can't tell them. quote yogi berra |
DrAllis wrote:Posted By: DrAllis
Date Posted: 14 Feb 2010 at 5:42pm
| My motive here on the SP-46 M&W kit was to have a realtively inexpensive way to raise HP using racing fuel....a drop-in set of 4 1/8" sleeves and pistons that have high (approx 10.5 to 1) compression. Not everyone wants to spend $3 to 4000 dollars on a big bore/ big stroke engine. This old SP-46 kit required machining off .150" or so off the top of each piston to work with the 4 1/2" stroke crank and worked very well for what it cost to be able to install it. When it wasn't available anymore, I still haven't found a "cheap" alternative yet to replace it. |
Posted By: MikeB (SD)
Date Posted: 14 Feb 2010 at 5:46pm
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I agree Dr. Allis. One would think if your going to the drawing board they could have come with a little more compression and horsepower than that. I agree with your theory to Mitch your thinking about the dynamic compression ratio as opposed to simply the static compression ratio. I did a little checking with AGCO this past week also and they currently have the sleeve kit for the 8:00:1 compression (170) piston's marked 28% higher than the 8.25:1 compression (D17LP/175) pistons and I checked with (3) different local dealer's. Thats completely nuts it the exact same piston blank!
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Posted By: mlpankey
Date Posted: 14 Feb 2010 at 5:55pm
------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: DrAllis
Date Posted: 14 Feb 2010 at 6:13pm
| Like I said....a drop-in kit..........not a "let's tear it all the way down and find someone to offset grind the crankshaft, so we can get these brand "X" rods to work" kind of a deal. I've got someone who would machine down those piston tops for 20 bucks each. I also have another guy who used to offset grind a crank for $300, but then you'd have another $200 in bearings and then the price of the Chrysler rods and all the gaskets, etc. |
Posted By: geb
Date Posted: 14 Feb 2010 at 6:13pm
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The solution to your problem is a lot more simple than you are trying to make it. You are dealing with a flat head and if you use a stock head gasket you can assume they are 0.040 thick. Measure the deck height of your block (distance from center of crank to top of the block (deck). Do your calculations as to what compression ratio you desire to determine what the compression height of the piston should be. The good part about your needs is that 4.125 is a very popular piston size that all piston makers stock. You can call them, tell them the compression height and the pin size and all they have to do is pull 4 pistons and cut the pin hole and boss. I personally tell them that I want standard small block chev ring grooves as these rings ready available and reasonable. The price that will usually be much cheaper than you buy off shelve pistons and have a local machine shop modify them for. In the past I've used J&E and Ross and were pleased with the quality and price from both companies. Also don't forget to tell them to put lock ring grooves for the pins. Also if you want a chambered piston, you just find a chev piston with the type / size chamber you want and figure accordingly. |
Posted By: Glockhead SWMI
Date Posted: 14 Feb 2010 at 6:27pm
| You guys are all talking pullers. I am looking for a drop in kit with the most compression. I know a 170 kit would be ideal but they are expensive. I will be pissed if I rebuild this engine and end up with less than what I had. |
Posted By: DrAllis
Date Posted: 14 Feb 2010 at 6:31pm
| You will probably be disappointed. What is the cost of the two kits?? If the 175 kit is cheaper than the 170, go for it !!! it used to be the other way around. How much is the kit with no compression???? |
Posted By: mlpankey
Date Posted: 14 Feb 2010 at 6:37pm
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the lerio canted rod is 8 inches long and has the exact same bearing size as the allis.just hard to find. if you offset grind the crank you add or remove stroke and you wouldnt want to do that . the 8 inch rod 4.5 stroke 2.023 comp ht is just .383 in the hole with a 3.25 diameter .220 deep dish . they come in std.4.188 to oversizes by .020 up to .060 and a 1.094 pin. 2 -3/32 comp ring grooves and 1 -3/16 oil. thats about as drop in as you could get. be real close to the 4.250 bore you was kicking around but no custom work running a piston up tp 100 a piece. several ways to skin a cat just depends on how much you want to invest in the knife you choose to use. ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: mlpankey
Date Posted: 14 Feb 2010 at 6:57pm
------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: MikeB (SD)
Date Posted: 14 Feb 2010 at 7:14pm
| Agco has the 8.25:1 sleeve assembly kit available for about $550. They want a little over $700 for the 8.00:1 sleeve kit and the 7.25:1 kit runs about $850 bucks. I have no idea why the prices vary so much as the all use the exact same sleeve, pin, and rings as well as the same piston blank. The only difference in the pistons is where the bore the piston pin hole. The 8.25:1 kit is currently on back order. These prices were checked with (3) different dealers just last Thursday. |
Posted By: geb
Date Posted: 14 Feb 2010 at 7:36pm
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It don't matter if you're pulling or farming, if you want a specific compression ratio you will probably won't find a kit for the same. But I can tell you from experience the 241 cid with the right compression height and the right timing setting will run long and hard in the field and will give you the performance of a 60 hp tractor with no problems. The only thing you have to watch is the engine temp and an electric fan (on front in addition to standard fan) will solve that usually. |
Posted By: mlpankey
Date Posted: 14 Feb 2010 at 8:04pm
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yes geb i agree and a 247 cubic inch 4.188 six extra cubes will also or the 4.188 40 over at 252 cubes at 8.01 would plow deep. ------------- people if they don't already know it you can't tell them. quote yogi berra |