Tecumseh Engine question - Snowblower Forum : Snow Blower Forums
Reply
 
LinkBack Thread Tools
post #1 of 22 Old 11-14-2019, 04:05 PM Thread Starter
Senior Member
 
micah68kj's Avatar
 
Join Date: Oct 2011
Location: 39.755928, -77.577766
Posts: 5,013
Post Thanks / Like
Thanks (Given): 159
Thanks (Received): 292
Likes (Given): 390
Likes (Received): 968
Question Tecumseh Engine question

On my 921001 824 the engine is an LH318SA rated at 8.0 HP. On the 921004 mdl the LH318SA engine is rated at 9.25 HP. How does Tecumseh do this? I'm guessing difference in carburetion? How do they do it or am I missing something? Valves? Head configuration?
Attached Thumbnails
Click image for larger version

Name:	Tecu,seh engine sizes.PNG
Views:	17
Size:	30.2 KB
ID:	159011  

Joe
Sent from my wife's old Toshiba
Ariens 921001
Toro 38074- sold
Toro CCR 3650E-sold
Toro 5/21 sold
Ariens 5/22 ss
Ariens Sno Tek 7/24 sold.
Old green plastic snow shovel... Sent.to shovel Heaven
Old quarry shovel for ice.
New.green shovel
micah68kj is online now  
Sponsored Links
Advertisement
 
post #2 of 22 Old 11-14-2019, 04:10 PM
Senior Member
 
ST1100A's Avatar
 
Join Date: Feb 2015
Location: Northeast, Easton, Pa
Posts: 519
Post Thanks / Like
Thanks (Given): 79
Thanks (Received): 90
Likes (Given): 157
Likes (Received): 126
Carburetion, RPM's or Gross to Net H.P. ratings. Sometimes that is done for insurance reasons.
ST1100A is offline  
post #3 of 22 Old 11-14-2019, 04:44 PM
Senior Member
 
Join Date: Dec 2018
Location: Near Colorado Springs
Posts: 128
Post Thanks / Like
Thanks (Given): 1
Thanks (Received): 11
Likes (Given): 40
Likes (Received): 21
https://www.smallenginesuppliers.com...l-Engines.html


Not sure that one's age but back in the day the engine only had to be 85% of the rated output. Worked great for advertising...


Otherwise, to change hp it is as simple as a different thickness of head gasket to change compression ratio. Or a different cam with different timing or amounts of valve lift. Or carburetion as now you can't adjust anything on a carb, whereas before you could adjust low and high circuits easily.
notabiker is offline  
post #4 of 22 Old 11-14-2019, 04:55 PM
Super Moderator
 
sscotsman's Avatar
 
Join Date: Dec 2010
Location: Western NY, USA
Posts: 3,714
Post Thanks / Like
Thanks (Given): 61
Thanks (Received): 361
Likes (Given): 152
Likes (Received): 804
Quote:
Originally Posted by micah68kj View Post
How do they do it or am I missing something? Valves? Head configuration?
There is likely no actual differences in the engines. the HP ratings are different, but the engines are not different.

These models are from 2008..there was a lawsuit over this, not just Tecumseh, I think Briggs and other engine manufacturers were doing it too..finessing the numbers, using creative math and tweaking the definition and calculation of HP to arrive at different ratings for the exact same engine model.

The result of the lawsuit was: no more engine ratings in HP. We now get cc's of displacement (cubic centimeters) and torque ratings, but no more HP. This began in 2010.

Scot


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
sscotsman is online now  
Post Thanks / Like - 1 Thanks, 0 Likes, 0 Dislikes
Thanks micah68kj thanked for this post
post #5 of 22 Old 11-14-2019, 05:00 PM
Member
 
Join Date: Sep 2019
Posts: 87
Post Thanks / Like
Thanks (Given): 0
Thanks (Received): 13
Likes (Given): 1
Likes (Received): 9
Quote:
Originally Posted by micah68kj View Post
On my 921001 824 the engine is an LH318SA rated at 8.0 HP. On the 921004 mdl the LH318SA engine is rated at 9.25 HP. How does Tecumseh do this? I'm guessing difference in carburetion? How do they do it or am I missing something? Valves? Head configuration?
I did a lot of research on that and I couldn't find a good answer. Some people compared the parts on both engines and they were pretty much the same (same carb and everything). Maybe a little tweak here and there, but you can't really tell. Ariens techs don't even know either. Some of them said this, while others said something else.

I think it has mostly to do with engine rpm and company BS stuff. They want you to pay more for the same engine.

My tecumseh LH318SA was set to 3500 rpm. Horse power was rated at 3600 rpm, so I don't even know how many HP my engine has at 3500 rpm. Some companies lied about HP, so now, they stopped HP rating all together.

I heard flat head engines have high low end torque (big displacements), but they have trouble breathing at high rpm. Also Tecumseh engines can't rev above 3600 rpm. Not only that, but they have non-adjustable carbs that were designed to run lean (to meet government regulations). For those reasons, I haven't increased my engine rpm and messed with it, yet. I thought about re-jet, but afraid it would not run well and give good result. I wish there are examples out there, then I would follow.

I have toro R-Tek engine and that thing was rated 5HP, 6HP and 7HP on different snowblowers, so what the heck.
dman2 is offline  
Post Thanks / Like - 1 Thanks, 0 Likes, 0 Dislikes
Thanks micah68kj thanked for this post
post #6 of 22 Old 11-14-2019, 05:07 PM
Senior Member
 
ST1100A's Avatar
 
Join Date: Feb 2015
Location: Northeast, Easton, Pa
Posts: 519
Post Thanks / Like
Thanks (Given): 79
Thanks (Received): 90
Likes (Given): 157
Likes (Received): 126
Sscot is right about that.
Everybody was buying off of the higher numbers that they were putting on the engines, like horsepower numbers.
The same thing can be said of portable generators with their wattage numbers. Honda put the rated numbers on theirs which were lower, and everyone else was putting the Peak numbers on theirs, which were higher.
The Honda generator still out performed all the other higher numbered generators.
ST1100A is offline  
post #7 of 22 Old 11-14-2019, 07:18 PM
Member
 
badbmwbrad's Avatar
 
Join Date: Jul 2019
Location: Massachusetts
Posts: 53
Post Thanks / Like
Thanks (Given): 0
Thanks (Received): 7
Likes (Given): 0
Likes (Received): 27
Horsepower is a function of engine speed (RPM). The same engine will develop a different horsepower rating dependent upon the RPM at which the torque is measured. For a snowblower engine, it is more informative to know what the maximum engine torque is. Horsepower = (Torque x RPMs) / 5252

Torque is simply a force acting on something from a distance (i.e. a piston pushing down on a crankshaft, using that leverage to rotate it), while horsepower is torque multiplied by RPM, or a measurement of how quickly an engine can accomplish a certain amount of work - Road & Track



Last edited by badbmwbrad; 11-14-2019 at 07:23 PM.
badbmwbrad is offline  
post #8 of 22 Old 11-15-2019, 12:12 AM
Senior Member
 
SimplicitySolid22's Avatar
 
Join Date: Nov 2018
Location: Massachusetts
Posts: 643
Post Thanks / Like
Thanks (Given): 56
Thanks (Received): 74
Likes (Given): 66
Likes (Received): 110
That is so weird you posted this question...I saw a photo of a manual on top of a free craftsman on Facebook marketplace today in great shape. Well the manual said LH318sa/LH358SA and then in parentheses it said HMSK80.

Meaning all of the above...will try to find the photo.
SimplicitySolid22 is offline  
post #9 of 22 Old 11-15-2019, 12:15 AM
Senior Member
 
SimplicitySolid22's Avatar
 
Join Date: Nov 2018
Location: Massachusetts
Posts: 643
Post Thanks / Like
Thanks (Given): 56
Thanks (Received): 74
Likes (Given): 66
Likes (Received): 110
Here it is:
Attached Thumbnails
Click image for larger version

Name:	72394990_10218349104377840_6891908740266590208_n.jpg
Views:	14
Size:	208.4 KB
ID:	159037  
SimplicitySolid22 is offline  
Post Thanks / Like - 0 Thanks, 1 Likes, 0 Dislikes
Likes notabiker liked this post
post #10 of 22 Old 11-15-2019, 11:06 AM
Senior Member
 
Join Date: Feb 2015
Location: Wilmington, MA
Posts: 827
Post Thanks / Like
Thanks (Given): 10
Thanks (Received): 104
Likes (Given): 19
Likes (Received): 274
I've done some research on this too, and I think at least some of it has to do with torque curves, which probably relate to valve timing and/or lift.

I had an HMSK110 and an OH318 Tecumseh engine... both rated 11 HP but the HMSK was 358cc displacement and the OH was 318cc.

If you look at the torque curves for both motors, the OHV engine peaks at about 3600 RPM, and as RPM drops it gets lower. The l-head engine torque curve peaked at a much lower RPM - I don't remember the number but I'm thinking it was around 3000 RPM - then actually dropped as RPM increased toward the 3600 RPM normal operating speed.

What that meant was that since HP is a product of torque and RPM, at 3600 RPM they would both make 11 HP. But as RPM dropped, the torque on the l-head engine would go up, whereas on the OHV engine it would drop. The effect of that on my snowblower was that as long as each engine was running at full speed it was fine, but when the load increased, the l-head engine would pull harder whereas the OHV engine would bog down as its torque decreased. For me that made the l-head much better as a snowblower engine.

Then I got a 414cc LCT engine and all my problems disappeared...

~1994 Ariens 924084 (ST1032) "papa bear": restored, re-engined, real nice!
1991 Ariens 924050 (ST824) "mama bear"
Toro PowerCurve 1800 "baby bear"

Be alert! America needs more lerts.
ELaw is offline  
Post Thanks / Like - 1 Thanks, 0 Likes, 0 Dislikes
Thanks micah68kj thanked for this post
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Snowblower Forum : Snow Blower Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome