D15 Horse Power
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=207123
Printed Date: 18 Jun 2025 at 9:41am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: D15 Horse Power
Posted By: Justin Vandy
Subject: D15 Horse Power
Date Posted: 16 Jun 2025 at 8:08pm
Engine HP question. Have a series 2 D15 engine that I am going to put in a C allis for pulling. When the engine was put in the D15 it’s currently in it was put on the PTO dyno and showed 46hp. Stock healthy engine. Since the dyno run years ago the following changes were made. Pertonix electronic ignition. Increased rpms. 175 Venturi put inside the stock carburetor.
This weekend before transferring the engine to the C we decided to stick it back in the dyno. We could only get 30-32hp. Adjusted the timing and fuel while on the dyno to get the most out of it and still only 30-32hp. I checked compression on the engine and each hole measures between 150-160psi.
We then pulled another D15 series 2 over to the dyno to insure it wasn’t reading incorrectly and that one is a bone stock farm tractor turning less than factory rpms and it showed 45hp.
Could the larger Venturi be too big for the little cubic inch engine? What else could cause 15hp loss?
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Replies:
Posted By: DrAllis
Date Posted: 16 Jun 2025 at 10:02pm
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I doubt it. I would suspect you aren't reading the dyno properly. A model "C" engine is rated at 1500 RPM and I imagine that is 540 on the PTO and 23 HP. So, if that is true, you need to measure the D-15 engine power at 720 RPM on the "C" PTO at which the engine would be running 2,000 RPM and calculate correct HP from there. A D-15 II when tested at 540 PTO speed only makes 42 HP as it has been slowed down to 1760 RPM from 2000 RPM. If you really think it's a carb problem, borrow the KNOWN good carb from the other tractor. Main jet would surely need to be screwed out a lot with a 1 inch venturi over a 7/8" venturi.
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Posted By: Justin Vandy
Date Posted: 17 Jun 2025 at 8:10am
For clarification the engine is still in a D15 and that is what we dyno’d. The C is still waiting for the transplant. We are going to stick a series 1 engine in the D15 that is in a parts tractor so it can still be used to blade and pull a small brush hog.
We dyno’d three tractors over the weekend. All three checked on the same dial. This D15 (which is a series 1) with the series 2 engine. It’s stamped “160” on the side of the block. 30-32hp
Parts tractor series 1 D15. 34-35hp. It had some blow by and smoked a little.
And an actual series 2 D15. 45hp. The book with the dyno said to check it on the 620rpm dial. If read on the 535rpm dial all three would have read even less.
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Posted By: DrAllis
Date Posted: 17 Jun 2025 at 10:25am
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Like I said, swap carburetors between the D-15II that actually has 45 HP and the D-15II t**d. Determine if the carb is your issue or not. Ignition timing changes really can't ever make more than the rated 45-46 HP, so using a timing light, time it at the FIRE/F-25 mark with the engine at wide open throttle.
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