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Stuart Hooper 2014

davidd

Well Known and Active Forum Website User
VOC Member
The Lake Gairdner speed trials start this Friday and run to next Friday. Pat Manning and I heard recently from Keith Canning who is Stuart's right hand man. He sent some photos of the recent mods. As it turns out, there were not too many ambitious mods because after the 171 mph outing, the engine was stripped and it turns out the crank was broken. So, a new crank from scratch, bigger exhaust valve and new cams with a little more overlap.

I have not heard anything of the two Vincents that usually run, Mal Hewett and Stuart Penn, but I attached the DLRA link which has some photos of them in previous years if you search around a bit.

Stuart Hooper 2014 _PB_3.jpg
Stuart Hooper 2014 _PB_4.jpg

Stuart Hooper 2014 _PB_2.jpg

Stuart Hooper 2014 _PB_1.jpg


http://www.dlra.org.au/lgairdner.htm

David
 

davidd

Well Known and Active Forum Website User
VOC Member
I assume the objective of the crank design was to achieve the most weight possible?

Max,

I can certainly see why you asked, but I do not know Stuart's thinking on cranks. I do know that he chokes the cylinder like some aircraft cylinders by honing it in a taper using about 0.002" less clearance at the top of the cylinder to stabilize the piston at TDC. I thought that was interesting.

David
 

vibrac

Well Known and Active Forum Website User
VOC Member
I do know that he chokes the cylinder like some aircraft cylinders by honing it in a taper using about 0.002" less clearance at the top of the cylinder to stabilize the piston at TDC. I thought that was interesting.

David
Some engines I have stripped do that taper trick using carbon...;)
 

roy the mechanic

Well Known and Active Forum Website User
VOC Member
Taper boring seems to be one of the latest "must do's " in W R C motorsport. Apparently it maximises compression whilst allowing the motor to acheive ludicrous speed, most useful on a modern 4 cyl turbo job, maybe not so useful on a twin !
 

Bill Thomas

Well Known and Active Forum Website User
VOC Member
Hello Roy , I am out of touch, Is it 2 thou smaller at the top or 2 thou bigger at the bottom as per' what is was befor, Also how far down down does it go. Cheers Bill.
 

greg brillus

Well Known and Active Forum Website User
VOC Member
Motorcycle engines do not have to put up with massive changes in air temp, so thermal expansion is not critical. An air cooled aircraft engine has to put out maximum power on climb, thereby putting out a lot of heat. And on descent it goes to near freezing temps. The choke bores are to cope with this expansion on high power settings, allowing the cylinder walls to become closer to parallel, so as not to loose too much compression escaping past the rings. ( which on Continental engines are actually tapered top and bottom to help them seal better)......Sorry didn't mean to drift off topic........Aircraft engines are as equally interesting as Vincents.......;)...........Actually, the cylinders of a Vincent twin engine look remarkably like a pair on a large radial aero engine, methinks........Greg.
 

davidd

Well Known and Active Forum Website User
VOC Member
Greg is right about the increased sealing. Stuart runs 8-10 thou clearance at the bottom of the cylinder so some oil can get in. He did not say where he starts the .002" taper, but he does it in the finish honing. As Greg says, with the higher heat near the head the cylinder walls should end up closer to parallel.

David
 

Albervin

Well Known and Active Forum Website User
VOC Member
183.370 MPH with only one cylinder!!!! Way to go. Makes you wonder why people with FOUR cylinders can't do 600 MPH. Yeah I know, physics, money etc.
 
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Photos from the 2022 North American Rally

Photos from the 2022 Annual Rally

Photos from the 2022 French Rally


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