D17 intake/exhaust manifold work
Printed From: Unofficial Allis
Category: Other Topics
Forum Name: Pulling Forum
Forum Description: Forum dedicated to Tractor and Garden Pulling
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=206905
Printed Date: 01 Jun 2025 at 3:53pm
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Topic: D17 intake/exhaust manifold work
Posted By: AintCheatnAintTryn
Subject: D17 intake/exhaust manifold work
Date Posted: 29 May 2025 at 11:54pm
| i have a 1958 series 1 D17 226 that I'm using for both pulling and farming, i cant do any major work to the motor so I'm trying to find little things i can do. my current thought it essentially to smooth out and polish the exhaust tubes and enlarging/roughing the intake tubes, as if i were porting the heads. I'm not sure if this would give me any noticeable increase in air flow without porting the heads so i wanted to ask here before i spent the time to do it. incase it makes a difference, the manifold is off a series 3 or 4. |
Replies:
Posted By: WF owner
Date Posted: 30 May 2025 at 5:30am
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I have no idea about your question, but I remember reading some of Marty Nelson's posts about reworking the manifolds on a 226 engine. He said that the reworked manifold flowed much better, but I believe it was on a stroked engine. I think he went by wi50 on here. You might try Googling him.
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Posted By: DrAllis
Date Posted: 30 May 2025 at 10:13am
| Manifold work at this point would be a HP gain in your mind, but if actually tested before/after on a dyno would be a great big nothing. Still need to farm with it you say ?? Your best results for HP increase are these in order: #1. Increase compression from stock 7.25 to 1 up to 8.0 or 8.25 to 1. This is good for 4 to maybe 5 HP and can still be used on the farm. #2. If you can find some 4 1/8" flat top pistons that calculate out to 8.0 to 1 or more compression ratio, this is another gain over the first suggestion. Probably 6+HP from stock. #3. A D-19 carburetor made to fit your engine. This is good for 5 HP and the throat opening on the manifold should then be opened up a bit to match the carburetor. This could be taken on and off for pulling/farming, but could stay on for farming if desired. #4. An off to the side paper air filter to make it easier to get fresh air over your (probably) dirty and partially plugged oil bath air cleaner. This could be made permanent under the hood and throw away the oil bath style. #5. Remove camshaft and have reground to higher lift that match a model 175 gas tractor engine. There you go !! Probably a 15+ HP gain and you can still farm with it. Your flywheel HP could go from 63 to 78 HP. |
Posted By: AintCheatnAintTryn
Date Posted: 30 May 2025 at 2:00pm
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I'm going to do some reading on Marty Nelsons findings as WF recommended, I doubt that manifold work alone will do much of anything but as stated, can really only do small things at the moment, new pistons, rods, crank and regrinding the cam is on the list but will have to be done next year or the year after as hay season is already here and i cant afford to have the tractor down long enough to do that work. you mentioned using a carb off of a d19, ill see about finding one as they do all seem to be much bigger than the one i have on now, a marvel schebler tsx853, 7/8 venturi, i did do a little work to the carb i have to increase air flow and am thinking about making a larger venturi for it but not sure how that would work. as far as the air filter, the air cleaner gets disconnected when going down the track. possibly not wise but its the common practice at the pulls we go to, really do dust with a clay track. i do appreciate the feedback and will at some point be doing the engine work as suggested, my only concern with upping the compression ratio is at what point will i need to change the gas to high octane? a cousin of mine that pulls in the heavier class cant run anything but 110
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Posted By: DrAllis
Date Posted: 30 May 2025 at 9:03pm
| When you get over 8.5 to 1 compression ratio on a farm tractor, you start needing more octane accordingly. 110 octane is probably good up to 12 to 1 ratio. I know on my 13 to 1 ratio puller engine I had to use 114 octane. |
Posted By: AintCheatnAintTryn
Date Posted: 30 May 2025 at 9:48pm
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thank you, after i posted that reply i tried to check google but all i was finding was for sports cars/bikes telling me i could use 87 for up to 12:1. ill may buy a separate tractor, thinking a d19 gas and build that for pulling but i may stick with the d17's as they're easier to find and cheaper to build. if i stick with my farm tractor for pulling though ill aim for that 8:1 or 8.5:1 so i can keep running the cheaper gas. thank you. also, on another thread of mine you seemed surprised by my brother pulling in the 9k# class, if allowed here i can post a link to the youtube videos or can dm them, unfortunately i don't recall the sled weight but cousins of mine have pulled in the unlimited class with 17s
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Posted By: DrAllis
Date Posted: 30 May 2025 at 10:34pm
| I pulled 7500 lbs several times one summer 35 years ago with an old D-17. I had 100 HP and 18.4 x 38 cut rear F-151 Firestone tires. I ripped a tooth off the right bull gear at one pull and decided it was too much weight and traction for that much torque. Replaced the bull gear and went down to 4500-5000-5500 lb classes and never broke anything else again. Series 3 and 4 final drives have stronger bull gears and bull pinions in them. |
Posted By: DaveKamp
Date Posted: 31 May 2025 at 1:57am
Go ahead and push your D17 right up to 12:1, and wind it up against the sled on 87 octane... You'll find out that sports cars spinning 6800rpm, and sport bikes running 11,000rpm, with aluminum heads and over-square bore/stroke ratios are in a totally different realm from a pulling tractor governed for farming... Flame propogation and flame speed/pressure curve, Brake Mean Effective Pressure, coefficient of thermal transfer... Here's two better resources: Internal Combustion Engineering Science & Technology by John H. Weaving The Internal Combustion Engine in Theory and Practice: Vol 1 and 2, by Charles Fayette Taylor. They're both long reads, but after you do, what Dr Allis advised will make perfect sense. Internal combustion engines are 'bandwidth sensitive'... meaning, because it's working in cycles, the velocity at which things operate become elements of simple harmonic motion, and in general, it occurs in three places: intake, chamber, and exhaust. You can 'tune' all three elements to produce a high peak, but the result of optimizing for that one point, is a serious weakness at any other point. Farming is a tractible-stability operation- to work smoothly, the powerband needs to be very smooth, no aggressive peak or dip, and it has to be able to run well regardless of wether it's cold or hot, wether it's running light or loaded hard. Tuning for a sport application means you're accepting the sacrifice elsewhere. ------------- Ten Amendments, Ten Commandments, and one Golden Rule solve most every problem. Citrus hand-cleaner with Pumice does the rest. |
AintCheatnAintTryn wrote: