Pulling Forum - 226/201 engine build

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226/201 engine build

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=207968
Printed Date: 28 Aug 2025 at 3:57pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: 226/201 engine build

Posted By: Fields 45
Subject: 226/201 engine build
Date Posted: 27 Aug 2025 at 6:02pm

I know there are a lot of engine build size of bore and stroke. What pistons or rods to use.
I'm asking what size engine make what for power.
I know head flow and carb or manifolds affect it but. A general idea how big gets you what for power.

Replies:

Posted By: DrAllis
Date Posted: 27 Aug 2025 at 8:13pm

I'm not exactly sure what you are seeking here, and not sure there is an exact answer due to soooo many variables. A model WD gas was a 201 and was rated at 34 PTO HP @ 1400 rpm. A WD-45 gas had the same 4 inch bore and a 4 1/2" stroke which gave it 25 more cubic inches. It was rated at 45 PTO hp. BUT, it wasn't all about 25 additional cubic inches. The compression was raised from 5.5 to 1 to 6.5 to 1. The carburetor and air cleaner were larger. The intake/exhaust manifold was better flowing. So, it took 3 changes to gain about 10 HP. Let's look at the WD-45 and the D-17 gas engines. Both engines were 226 cubes. The WD-45 compression was 6.5 to 1. The D-17 was 7.25 to 1 with the same 4 inch bore. The carb was identical between the two tractors. The engine speed went from 1400 rpm full load to 1650 full load speed. So, the D-17 engine got more compression and an increase in speed. The model 175 gas tractor was still 226 cubes had 8.25 to 1 compression, and higher lift camshaft, a slightly larger carburetor and rated speed was now 1800 RPM instead of 1650. It gained 10 more flywheel HP over the D-17 engine. Now, what is your question ?? You can have more cubes with lower compression and have LESS HP. Carb size affects HP output, as does engine speed.