_GOTOBOTTOM
Modeling in General
General discussions about modeling topics.
Weight vs. Horsepower
TreadHead
Visit this Community
Colorado, United States
Member Since: January 12, 2002
entire network: 5,000 Posts
KitMaker Network: 1,210 Posts
Posted: Friday, December 05, 2003 - 03:15 AM UTC
Howdy all,

There's something that has bugged me for quite sometime, and reading the article on the British Leyland Retriever workshop truck in the newest edition of MMIR (No. 34), it really hit me again!
Here's my point;
In the article it begins by describing the powerplant in this vehicle, I will qoute.

"......The Leyland Retriever was an older design of the three ton truck, dating from the mid-1930's. It was designed by Leyland Motors and powered by a 360 cubic inch, four-cylinder petrol engine. It delivered 73 BHP at 2120 r.p.m....."

Now.....taking the above information, you can extrapolate that at 360 cubic inches and four-cylinders, this would equate to an approximately 720 cubic inch V-8 engine!
Add to that the fact that at operating RPM's it puts out 73 horsepower!?! This is a 3-Ton truck, transporting a cargo bed full of machine shop tools (large lathes, drill presses, acetylene tanks, etc) and only sporting 73 horsepower? My snowblower almost puts out that much horsepower! #:-)
I know, our U.S. Halftracks were severely underpowered as well, but sometimes when I read articles covering WW II era vehicles and their engine outputs, I feel it's a wonder the things moved at all!!

Tread.
RotorHead67
Visit this Community
Virginia, United States
Member Since: May 07, 2003
entire network: 1,174 Posts
KitMaker Network: 161 Posts
Posted: Friday, December 05, 2003 - 03:43 AM UTC
Tread<
Yes it's a wonder, but ..........BHP is not the only factor involved. You can take a small
HP output engine and get more work ie (motion) w/ a transfer and/or trans that is geared
for the maximum torque. Which produces more actual abilaty. Consider this comparison:
US M1 Tank = 1500 HP turbine 70 tons moves @ top speed of 60mph
US Top Fuel Drag = 3000 HP V8 3400lbs moves 1/4 mile in 4.5 sec. @ 385mph
ITS ALL ABOUT GEARING.
viper29_ca
Visit this Community
New Brunswick, Canada
Member Since: October 18, 2002
entire network: 2,247 Posts
KitMaker Network: 718 Posts
Posted: Friday, December 05, 2003 - 03:28 PM UTC
Yes....its not all about horsepower.

Horsepower is only one part of the equation.....the other part is gearing and transmissions.

Take the Dodge Viper.....the new one is 500cu in, 500hp, and 500lb/ft torque....great for racing and straight line speed.....but I wouldn't want to try and tow a travel trailer with it.


Now take that same engine...and drop it in a RAM truck...4X4 trannie and the rear end geared right....and you can pull to your heart's content...but you won't be winning any races against too many Porsches, Ferraris and Corvettes...(although it would be fun trying!!!)

Like the old saying goes.....horsepower is for bragging rights.....but its the torque that puts the power to pavement.
KiwiDave
Visit this Community
Wellington, New Zealand
Member Since: January 14, 2003
entire network: 248 Posts
KitMaker Network: 0 Posts
Posted: Friday, December 05, 2003 - 03:31 PM UTC
The first thing you should realise is that we are talking British Brake Horesepower which is different from USA hp.

Second, you are looking at an old engine. Within my lifetime I can remember the best racing engines struggling to achieve 100bhp per litre. I now own two road going vehicles with outputs greater than that.

Second point is that horsepower is not necessarily very important in motors of this type. Steam stationary engines used during the 19th century offered only a few horsepower at maybe 500 rpm. But they developed thousands of pounds of torque at the output shaft. If you are driving stationary plant, large heavy vehicles or any other application requiring a large mass to be moved from standstill then torque is much better than hp.

Diesel engines have always been preferred in torque applications - trucks, tractors, stationary engines, - rather than power applications like motor racing. This is because they generally have low max rpm, relatively low hp and very high torque.

To draw a modern comparison a three litre Formula One engine delivers close to a thousand horsepower, yet it is very difficult to get a 1200kg F1 car off the start line without stalling. The hp of the F1 engine is achieved at the top end of the rev range and only in a band of about a thousand revs. Put an F1 engine into a Mack truck and despite the thousand horspeower the truck would never move.

Does that make sense?

Regards Dave

RotorHead67
Visit this Community
Virginia, United States
Member Since: May 07, 2003
entire network: 1,174 Posts
KitMaker Network: 161 Posts
Posted: Friday, December 05, 2003 - 04:30 PM UTC

Quoted Text

The first thing you should realise is that we are talking British Brake Horesepower which is different from USA hp.
Second point is that horsepower is not necessarily very important in motors of this type. Steam stationary engines used during the 19th century offered only a few horsepower at maybe 500 rpm. But they developed thousands of pounds of torque at the output shaft. If you are driving stationary plant, large heavy vehicles or any other application requiring a large mass to be moved from standstill then torque is much better than hp.
Diesel engines have always been preferred in torque applications - trucks, tractors, stationary engines, - rather than power applications like motor racing. This is because they generally have low max rpm, relatively low hp and very high torque.
To draw a modern comparison a three litre Formula One engine delivers close to a thousand horsepower, yet it is very difficult to get a 1200kg F1 car off the start line without stalling. The hp of the F1 engine is achieved at the top end of the rev range and only in a band of about a thousand revs. Put an F1 engine into a Mack truck and despite the thousand horspeower the truck would never move.
Does that make sense?
Regards Dave



Dave,
I believe my previous post was the fact....Torque is the key and not horsepower. I FULLY
understand this whole concept. I race SUPERBIKES. Finished 3rd in the Northeast region last year. I race a 350cc bike against 650cc and HAVE A JOLLY while they stair @ me ARSE all the wat to the checkers. THE DOMINANT factor in this Equation is TWO STROKE
NEED I SAY MORE. LOL
The one thing the US market will never share in. !!!! WHAT A SHAME
TreadHead
Visit this Community
Colorado, United States
Member Since: January 12, 2002
entire network: 5,000 Posts
KitMaker Network: 1,210 Posts
Posted: Saturday, December 06, 2003 - 02:47 AM UTC
Howdy guys,

Many thx for the input. I honestly appreciate the HP vs. Torque basics class 101....sincerely. But, being an Architect by trade, I was taught a fairly decent amount of Engineering along the way as well! .
I understand the principle's you were so kind to share with me. What I was trying to point out is the idea that simply by accident a (in principle) 720 cubic inch engine should put out more than (formulaic) 146 horsepower!
I have talked personally with many WW II veterans, and several of them had both driven and driven in the U.S. Halftracks. To a person, they all agreed the thing was 'gutless'. Sure, it would move, and keep moving, but unless they were fighting the war strictly in the Alp's, towing heavy artillery up the bloody things, I think they could have squeezed just a wee bit more 'meat' out of all those cubic inches........that's all.
Just as a reminder..........torque is good, but horsepower is good as well!

Tread.

Ya know, I'm just thinkin'.....All the new Ford deisel pick up's I've been looking at have been sporting some pretty impressive horsepower figures in their sales literature. They also advertise how their trucks can pull a house up a tree! .........I guess those Ford guys simply forgot how horsepower is not really the important factor , and that they should have stuck a 360 cubic inch four cylinder engine putting out 73 horsepower and accomplished the same thing for a lot less investment of R & D, and a lot less money! Heck, those new Ford pick-up trucks are only 1-Ton or less, can you imagine how much more 'pulling' power that 73 horsepower engine would have driving a 1-Ton truck, as opposed to a 3-Ton truck!!!

#:-) #:-) #:-) #:-) #:-) #:-) #:-) #:-) #:-) #:-)

"Heaven's ta Betsy!"
RotorHead67
Visit this Community
Virginia, United States
Member Since: May 07, 2003
entire network: 1,174 Posts
KitMaker Network: 161 Posts
Posted: Saturday, December 06, 2003 - 06:44 PM UTC
TREAD
I didn't want to pull the rug out from under you. !! LOL

HMMM,, I wanted to be an Architect once, it took 3 yrs of college before I changed my mind.
Became a Mechanic instead........MAKES MORE MONEY!!!!! Huh imagine that , coulda
had a V8. LOL
Oh and if you think Fords rockin the boat......wait till the NEW NISSAN hits the street. 9500lb
towing capacity. Which happens to be the LARGEST to date in a pick-up truck.
Leave it to those little asian guys w/ the funny eyes. Hey didnt we Nuke them in WW2
viper29_ca
Visit this Community
New Brunswick, Canada
Member Since: October 18, 2002
entire network: 2,247 Posts
KitMaker Network: 718 Posts
Posted: Sunday, December 07, 2003 - 05:50 AM UTC
Hey Tread....

The only thing I can think as to why that 360cuin would be rated so low is where the hp was measured from.

You would have a different rating if it was measured at the flywheel, then you would if it is measured at the rear wheels. Once your power goes through your tranny and rearend, the hp rating will go down....sometimes a great amount depending on the rearend gearing.

The Leyland Retriever I am sure would have gone alot faster and had alot more horsepower if it wasn't to be designed as a cargo truck. I am sure if it was looking into...that the 73hp was at the drive wheels and not at the engine. Again...I am sure if you looked....the torque at the rear wheels with that 73hp...was probably quite high....thus allowing the truck to carry heavy loads pretty much anywhere.
RotorHead67
Visit this Community
Virginia, United States
Member Since: May 07, 2003
entire network: 1,174 Posts
KitMaker Network: 161 Posts
Posted: Sunday, December 07, 2003 - 12:21 PM UTC

Quoted Text

Hey Tread....

The Leyland Retriever I am sure would have gone alot faster and had alot more horsepower if it wasn't to be designed as a cargo truck. I am sure if it was looking into...that the 73hp was at the drive wheels and not at the engine. Again...I am sure if you looked....the torque at the rear wheels with that 73hp...was probably quite high....thus allowing the truck to carry heavy loads pretty much anywhere.



CASE IN POINT
 _GOTOTOP