• Welcome to the website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Hon. Editor and Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this website.

    If you have previously registered to use this forum, you should log in now. CLICK HERE.

    If you have never registered to use this website before, please CLICK HERE.

BHP measuring


Tnecniv Edipar

Well Known and Active Website User
Non-VOC Member
Theres a good chance your MZ will produce what it says on the tin comrade :D MZ were a manufacturer of principle.
Ironically , manufacturers now need to be accurate with all specifications in this litigious age.
 

Flo

Active Website User
VOC Member
I've got lots of queries just lately - Egli very very nearly back on the road again, and my brain is getting back into being a Vincent owner (ok half Vincent).

Question - How did the Vincent works measure the power of the bikes? Did they have their own dyno? Did they measure at the wheel or crank? etc

55 bhp is not a lot of power to push a heavy, unfaired bike to nearly 130 mph (probably wearing a Barbour jacket) when my 125 bhp lighter, faired Fireblade is only good for 165 mph. I know all (some of) the theory about diminishing returns, and the faster you go the more power you need to go a bit faster, but even so, there seems a big dicrepancy.

H
Hardly any discrepancy at all 55*(165/125)^3 = 126.5
 

davidd

Well Known and Active Website User
VOC Member
This is the dyno set-up that David Bowen mentioned:

Vincent Day017.JPG

Vincent Day016.JPG

Vincent Day001.JPG

The dyno was crankshaft only. In fact, no primary or transmission parasitic drag. The hydraulic pressure would have been converted to BHP.

There can always be lots of fudging. Using Benzine in the fuel is a big factor. I am sure that the operators had a good idea what the realistic numbers yielded in top speed.

This is a crude calculator:

http://www.wallaceracing.com/Calculate HP For Speed.php

It's interesting to fool around with.

Note that the UFM on the engine is the original FT1. It was never put into production because the sheet metal warped too much to be consistent. It seems it was pressed into service as an oil tank for the dyno.

David
 

vibrac

Well Known and Active Website User
VOC Member
The late Bill Mason whose funeral I went to last week told me there were two test brakes at the works an old one that was used for years to test motorcycle engines on (I think we have seen photos of that ) and ,to quote Bill " a proper one supplied much later by the MOD specifically for the life boat as the bike one was no good enough"
As for speed I was clocked at the end of the old long snetterton norwich straight at a bantam club meeting when they had been lent some timing gear and on the twn I was given a speed of 132 I did have a bikini fairing very naughty but back then racing against bikes 12 years younger you needed an edge I also needed brakes I finished (not for the last time) in the gravel trap
 

david bowen

Well Known and Active Website User
VOC Member
Bill was correct, the old brake was moved to storage 1950 and replaced with one from the MOD for Marine engine only, Bill & Paddy had a new job carry fuel from the bottom of the yard to the tank on top of the test house roof, the engine was started up on the brake and was run 24hours a day for about six weeks it seamed a life time I was working a stone through from it in the front fork section, Denis Minetts Lightning shop was closer, after the testing the old break was fitted back
 

Albervin

Well Known and Active Website User
VOC Member
And Don't ever forget that PEI defined BHP

Brochure Horse Power!
A local friend and auto engineer makes/tunes old style Jaguar engines (3.8 and 4.2). He told a very ignorant young man that he could get 265 bhp from his engine and it would be reliable. The reply was something like "that is what they had originally". My friend said "ah, yes, on paper." Apparently the E-type released for press may not have even been a 3.8. So the story goes.
 

stu spalding

Well Known and Active Website User
VOC Member
I heard that it was a 3.8 but it had been seriously "sorted" to make it a 150mph machine. Cheers, Stu.
 

Chris Launders

Well Known and Active Website User
VOC Member
Nearly as good as George Brough's 11-50, 11 (RAC rating) and 50 bhp, actually it should be called an 11-30 because about 30 bhp is all they make, mind you they will still do going on 90mph solo.
 

Albervin

Well Known and Active Website User
VOC Member
I heard that it was a 3.8 but it had been seriously "sorted" to make it a 150mph machine. Cheers, Stu.
Yes Stu it was a 3.8 in name only. The best any customer obtained was 120 mph on the M1. At one stage the longest skid marks in the world by a car was on the M1 courtesy of an E Type. (Guinness Book of Records)
 

Glenliman

Well Known and Active Website User
VOC Member
If I recall correctly the company was in for a bit of a let down with the testing of Black Shadow engines for the Picador project. Initial testing resulted in 48 bhp and many broken crankshafts, some in less than 20 minutes of running at revs in the high 5000 range.
They were looking for 60 continuous and eventually got it, new stronger crank design with bigger mainshafts, big interference fit crankpin ( nutless) and the famous Picador cams.

Glen
 
Last edited:

Top