Early Tonti Horsepower

[swooshdave]

I've seen a wide range of hp figures for these bikes. Is there any validity to any of the numbers?

V7 750 Sport	70 hp
750S	82 hp
750S3	90 hp
850T	55 hp
850 LeMans MkI	71 hp	70 hp
850 LeMans MkII	81 hp
850T3	68.5 hp

[oldbike54]

 Shetlands 

 Dusty

[Antietam Classic Cycle]

"Brochure horsepower". 

[rocker59]

"Brochure horsepower". 

Yep.

BHP = Brochure Horsepower!

 

[Triple Jim]

My Mille is rated at 67, I think, which I have to assume would be crankshaft HP.  That feels about reasonable compared to other motorcycles of known RWHP I've ridden.

[swooshdave]

Factory published numbers are usually at the crank.

[redrider]

Crankshaft measurement under ideal conditions. RWHP will be less. I will add that any measurement taken at the rear wheel is not what the engine rating is. Gearing and such alters the torque output which in turn affects the calculation of HP.

[sdcr]

My 83 Le Mans III is rated at 78 hp according to Ian Falloon's  book on Moto Guzzi Big Twins. 

 In real world riding, it feels about right.

[rocker59]

Crankshaft measurement under ideal conditions. RWHP will be less. I will add that any measurement taken at the rear wheel is not what the engine rating is. Gearing and such alters the torque output which in turn affects the calculation of HP.

And, the early horsepower claims are just flat out lies.

[canuck750]

My fully rebuilt V7 Sport did not get over 51 hp on the dyno, not broken in at the time but I doubt it would ever be much more, this all stock spec carbs and exhaust.

The 750S I am finishing has a B10 cam other than that identical engine, carbs, exhaust to the Sport, I plan on getting the 750S on a dyno to see if there is any gain, I am guessing 1 ~ 2 hp at best.

Rocketships they are not.

[oldbike54]

 True story . At the height of the Spanish MX'ers , the Bultaco rep in England was providing specs to either the Green 'Un or the Blue 'Un on their latest 250 race bike . The journo asked about HP , to which the rep asked "what is Montesa claiming for their 250?" . The reply was 25 HP . The Bultaco guy said , "well , our's makes 26 HP then" 

 Dusty

[oldbike54]

And, the early horsepower claims are just flat out lies.

 Even today HP claims are exaggerated .

 Dusty

[arveno]

Usually who ride a guzzi does not care about hp

[Gliderjohn]

On my T-3 after a big bore kit, 36mm carbs, V-7 Sport cam, Porting and polishing and S&W valve springs it hit just over 56hp and 54ibs of torque at the rear wheel.
GliderJohn

[swooshdave]

My fully rebuilt V7 Sport did not get over 51 hp on the dyno, not broken in at the time but I doubt it would ever be much more, this all stock spec carbs and exhaust.

The 750S I am finishing has a B10 cam other than that identical engine, carbs, exhaust to the Sport, I plan on getting the 750S on a dyno to see if there is any gain, I am guessing 1 ~ 2 hp at best.

Rocketships they are not.

Fresh engines make the least power. How many miles on it did you put before getting on the dyno? Don't bother with the 750S until you have a couple thousand.

[acogoff]

     Nothing has changed in 100 years from the marketing types. That is why the Nebraska tractor test lab was set up years ago to cut out the BS from the tractor manufacturers at least. My oldest tractor is a '47 VAC Case and is rated at 16 HP. Not sure my T3 has much more than that, but a bit of a apples and oranges comparison.

[PeteS]

A friend put his 1000 LMIV on the Dyno at the Parry Sound Sport Bike Rally and got 62HP. Heads were done by Manfred along with the usual carb and exhaust mods. His bike would pull my 850 LM also with Manfred Hecht headwork so I assume mine is less.

Pete

[mjptexas]

     Nothing has changed in 100 years from the marketing types. That is why the Nebraska tractor test lab was set up years ago to cut out the BS from the tractor manufacturers at least. My oldest tractor is a '47 VAC Case and is rated at 16 HP. Not sure my T3 has much more than that, but a bit of a apples and oranges comparison.

Not sure your T3 could pull a 3 bottom plow.

[Triple Jim]

True story . At the height of the Spanish MX'ers , the Bultaco rep in England was providing specs to either the Green 'Un or the Blue 'Un on their latest 250 race bike . The journo asked about HP , to which the rep asked "what is Montesa claiming for their 250?" . The reply was 25 HP . The Bultaco guy said , "well , our's makes 26 HP then" 

That's funny.  You probably know that Denco sold high performance parts, engines, and engine work for the Kawasaki triples in the '70s.  The H2 engines were known as 120 hp, 133 hp, 149 hp, as three examples.  Later it came out that when a Denco owned and driven H2 went through the quarter mile at 120 mph, that engine was then advertised as a 120 hp engine.  As their drag racing improved, they had a 133 mph quarter, and a 149 mph quarter.

[Antietam Classic Cycle]

Years ago at VMD @ Mid-Ohio they had a dyno set up and would test anyone's bike for a nominal fee. I can't remember who it was, but one of the "Loopers" had his well-worn, completely stock 750 Ambassador tested just for the fun of it. The result? 34 hp at the rear wheel. 

Interesting thing was the next bike on was an 883 Sportster with aftermarket mufflers. Same 34 rear wheel hp. 

[Tom]

45hp at the rear wheel.  Shift and keep the rpm's up.  That's what I tell people. 

[rodekyll]

The old VW's had honest HP ratings -- 25hp in the very first, 36 by the late '50s, 40hp with the 1300, 50 and then 60 with the 1600's.  I had a 36hp in a '57 bus that could roll a ton of cargo down the highway.  It took a long time to get to speed (about 45).  the real handicap was stopping it.   

I have a 1600 Honda engine in my 90hp outboard.  If that puppy delivers 90hp it's cheating on me and giving it up to someone else.

[redrider]

I hit 47 with a not so pretty Norton. Sounds about right if the factory claim was 60 crankshaft/BHP

[bad Chad]

LeMans III stock is not making 78 hp, even at the crank, it just isn't.  I'm sure it feels good, it a kick ass bike, but how do you really tell a real 63hp from a real 78hp from your ass?  First you would need a solid true benchmark, followed by a very accurate memory, and the ability to swap to different machines, that make power in different ways.

No stock 850 Guzzi motor is putting out a real 78hp, it's just not going to happen.

[charlie b]

The T5 was advertised at 68.5hp and 54ft-lb of torque

I had a Honda NT700 for a while and it was rated at 65hp and 66.2ft-lb

Other than the Honda being a little smoother and quieter they felt the same. 

IIRC there was a big controversy back in the 70's about mfg advertised HP, especially the difference between the Duropean DIN numbers and the US stuff.  Don't remember how it came about but a standard was published about how mfgs had to record hp numbers.  I remember that one thing was that all accessories mounted in the car had to mounted to the engine on the dyno. 

So, I suspect those same standards are in use today, which means very little in real numbers.  But, what it means is that you can compare apples to apples when looking at mfg claimed hp figures and compare to another mfg claimed hp figures.

[pete roper]

Rough numbers from memory/dawn of time. Unmodified and using the stock cams.

850T?-44

T3-42

SP/G5-45

MkI/II Le Mans-51

MkIII-54

MkIV and other big valves-57/58

Sport C-61/64

Then you get to FI.

Pete

[sdcr]

LeMans III stock is not making 78 hp, even at the crank, it just isn't.  I'm sure it feels good, it a kick ass bike, but how do you really tell a real 63hp from a real 78hp from your ass?  First you would need a solid true benchmark, followed by a very accurate memory, and the ability to swap to different machines, that make power in different ways.

No stock 850 Guzzi motor is putting out a real 78hp, it's just not going to happen.

Chad,

  I was quoting Ian Falloon's figures from his book.

My comment the "it feels right" did not come across as I meant it.

My meaning was that the bike " feels right", regardless of published hp numbers.

[pmillar]

One thing to keep in mind in comparing Guzzi RWH to most other bikes is the greater pwer loss of a shaft drive in comparison to a well maintained chain. To use the 750 Ambo vs. 883 comparison, this would mean the Ambo engine was generating greater power at the crank than the Harley in order to come out even on the dyno.  This is only relevant to bench racing 

[Aaron D.]

Bevelhead Ducati Supersports according to a racer made, made 53 or so HP even with Imola cams-and that's with 40mm DellOrtos and Contis.

[bad Chad]

Its a bit of a head scratcher.   The new v9s are claimed to put out 55hp at the crank.  Yet every dyno I have seen puts them at 50-51hp to the ground?  How can that be?