Who's Vincent/Hrd has the most power?

[Monkeypants]

David, if I recall correctly, the 5 hp gain was with the modified Prince head in place of a stock head? It would be nice to know how the unaltered Prince head would have done.
The D shaped ports are said to work very well on LS 9 Corvette engines, tho like the Prince heads, the actual exhaust port appears smallish compared to expectations.

Glen

 

[greg brillus]

Greg,
Can you provide me with contact information on John Trease. I would be interested in getting information on his cams and valve gear. A couple of years ago I came across information on Vincent roller cams made in the 1960 by K&H. They used rollers off of Harley XR750 listers and the cams profile was a XR750 race profile. I offered to buy the information and remaining parts off of the current owner of the K&H company but he doesn't want to sell.

John Mead

Hi there John, About your enquiry regarding John Trease here in Australia...I only have his contact number which i can give you. You would then have to allow for the time difference, and call him during the day. He lives in Victoria, and basically works from home....Cheers for now......Greg.

 

[johnmead]

Thank you. That would be great. My email is xxxxxxxxxxxxxxxx

John.

(Email address sent to Greg by private message. Eddy.)

 

[TouringGodet]

Back to the original question (sort of), at the 99 Intl, I believe Dan Smith was king of the strip for road going bikes.

 

[davidd]

David, if I recall correctly, the 5 hp gain was with the modified Prince head in place of a stock head? It would be nice to know how the unaltered Prince head would have done.
The D shaped ports are said to work very well on LS 9 Corvette engines, tho like the Prince heads, the actual exhaust port appears smallish compared to expectations.

Glen

Glen,

Yes, you are correct that it is not a perfect test. It is also a 500 cc head. I think it is worth pointing out that the Terry Prince heads are basically "big port" heads, except Terry's heads did not change the valve angle. The second item to note is that Terry and John built the heads for the street. They were designed to make gobs of torque, but not top end. Terry and Mal have modified their bikes at least somewhat to do the land speed racing.

For max power you really need revs. In road racing you can compromise a little more as torque to get out of corners really quickly, but on larger tracks like Daytona, you really need the revs.

I think that the considering how problematic the exhaust port is on a Vincent, it is a good idea to go with torque. If I remember correctly, when Robert did Carleton's head he thought that the D shaped exhaust would be easy and the intake would be trouble. It was just the opposite. He did the intake in a couple of days and it took him a week to do the exhaust port and the D shape went away. I think the concept of the smaller exhaust port was to increase the mean port velocity. Bell says 250 ft/sec and Denish says 280. With a 2" pipe the exhaust loafs around at an astoundingly low velocity, but it seems to work! However, the really fast bikes, like Lindsay Kyle's bike, has a 1-5/8 pipe that is quite short with a megaphone. Ken McIntosh and Lindsay have done a huge amount of development on exhaust and cams.

Finally, it is difficult to make a Vincent rev. Mk2 cams are a 4000 to 6000 cam. There is no reason to go higher, there is nothing there. So, to get back to John, I think the set-up you have will produce a great street bike. It should have lots of power and mountains of torque. I am not sure that I would stray too much from the path.

David

 

[Bill Thomas]

Any times Steve, Cheers Bill. Mine did 12.5 1/4 mile with 110 mph over the line, and 141.9 average over a flying kilo, Road bike 998cc.! Ray Elger was in the eleven's for a 1/4, But I don't think he did more than 136 on the flyers, His was an Egli, I think he did 12.3 on a standard framed twin, Bill.

 

[b'knighted]

In 1986 at the Motor 100 show at Silverstone we had an immaculate new Egli on the stand. It was ok, but parked next to it was a gorgeous used Egli with a Union Jack tank. That was Ray Elgars bike and although I don’t recall hearing it run it looked too fast for me, even standing still.

 

[vibrac]

Rays Vincent bike also did something that is rarely done nowadays

It could be ridden to competition events

I rode it down the Oxford road one day at a rider rally at Rousham house, It was a fast beast, it must have been a ride of all time to take it to Holland

 

[bmetcalf]

Steve Hamel's bike revs to at least 7000, but he also did a lot of flow bench work and has a crank that can take it.

 

[Monkeypants]

Somewhere I saw Steve talking about that engine, (maybe a Youtube Vid? ). As I recall he was commenting about the need to feed throttle to it gently, maybe result of all the port work and big carbs etc. No exactly what one wants when it's time to blast by a line of cars, but the engine makes huge power. On the Norton site, racer Doug Macrae posted up a dyno graph of one of his early Herb Becker tuned Commandos, superimposed over the same engine stock. Herb has built some really strong engines that have won at Daytona. This one made about 70RWHP vs 52 for the stock engine. it also had a big hole in the powerband right in the 3500- 4500 rpm range, which is where a standard roadgoing Commando spends about 98% of its life. The stock engine has a nice hump in the powerband at this location and would provide far more power for roaduse than the race engine. I guess that is why when I get off the 160 hp Triumph and onto the stock 850 Commando , the Commando still feels strong.