Oddball engines and prototypes

[husaberg]

So your memory is not so bad after all. To my knowledge it was indeed Bultaco who used the most extreme inlet timing: 240°
(a 30 mm carb on a 250 cc engine; something had got to give and in this case it was the piston intake side skirt length).
This is one of those seemingly simple but unanswerable questions. There's no limit as such; things get gradually worse. And it's not just the timing but also the crankcase volume, the carb diameter, the inlet tract length and the skill of the mechanic. But roughly I'd say that south of 190° things are becoming touchy.

Yes sorry it was a bit ambiguous.
If you recall a while back you said about running a two sided belt to run the counterbalancer in the correct direction without a set of gears. I was already going down that path anyway, but the trouble I face is those toothed belts manufacturer's normally suggest to have half the number of teeth in contact with the belt. My line of thought is if it is not the driver (just an ancillary) a few teeth in mesh should be all right its maybe wishful thinking but any suggestions or knowledge of who to ask?

[Frits Overmars]

a while back you said about running a two sided belt to run the counterbalancer in the correct direction without a set of gears. I was already going down that path anyway, but the trouble I face is those toothed belts manufacturer's normally suggest to have half the number of teeth in contact with the belt. My line of thought is if it is not the driver (just an ancillary) a few teeth in mesh should be all right its maybe wishful thinking but any suggestions or knowledge of who to ask?

Driving a balance shaft won't require much power unless the crankshaft rpm changes at a big rate, like when shifting down. Then the balance shaft has to follow suit and its inertia is not negligible, so the belt may see some fierce jerks.
Toothed belts are categorized according to the amount of power they can transmit and for the irregularity of the driving force (electromotor at one end of the scale, foul-stroke single at the other end). So don't disregard the manufacturer's advice too lightly.
Chances are that you will need a tension wheel somewhere on the belt; you can use that too increae the number of teeth in contact.

[WilDun]

Driving a balance shaft won't require much power unless the crankshaft rpm changes at a big rate, like when shifting down. Then the balance shaft has to follow suit and its inertia is not negligible, so the belt may see some fierce jerks.

I see that a lot of car manufacturers have gone back to chain drive camshafts and of course the chain is automatically two sided and suitable for the situation that Husa is talking about. They also often give plenty of warning of when they are going to give.(more than you can say for a belt!).
Taglioni was very much opposed to the use of cam belts on the Ducati but was overruled (but then of course, he was advocating gears). Look at the huge amounts of torque and jerks chains can deal with on motocrossers and road racing final drives today and if they are being properly lubricated inside an engine, then what is so wrong with using chains anyway? - maybe belts are just cool and fashionable - or cheaper?

[husaberg]

Driving a balance shaft won't require much power unless the crankshaft rpm changes at a big rate, like when shifting down. Then the balance shaft has to follow suit and its inertia is not negligible, so the belt may see some fierce jerks.
Toothed belts are categorized according to the amount of power they can transmit and for the irregularity of the driving force (electromotor at one end of the scale, foul-stroke single at the other end). So don't disregard the manufacturer's advice too lightly.
Chances are that you will need a tension wheel somewhere on the belt; you can use that too increae the number of teeth in contact.

Yes I find the belt manufacturers are very conservative though, for instance the recommended HP for one of their belts is actually about 20 percent of what they are actually used for in classic racing though with 360 cranked 900cc twins
So I don't mind the prospect of short service intervals, Also belts are cheap (Maybe not so much the two sided oddball ones I have selected though.)
I am pretty sure I will have to use a couple of idler as the spacing I intend using is pretty short and the belts are not available in too many different lengths like a chain.

I see that a lot of car manufacturers have gone back to chain drive camshafts and of course the chain is automatically two sided and suitable for the situation that Husa is talking about. They also often give plenty of warning of when they are going to give.(more than you can say for a belt!).
Taglioni was very much opposed to the use of cam belts on the Ducati but was overruled (but then of course, he was advocating gears). Look at the huge amounts of torque and jerks chains can deal with on motocrossers and road racing final drives today and if they are being properly lubricated inside an engine, then what is so wrong with using chains anyway? - maybe belts are just cool and fashionable - or cheaper?

Chains are loud and when they break they cause pandemonium, smashing all sorts of stuff.
Gears are a better and more accurate timing wise than either belts or chains , but are a more expensive solution for both primary and cam drive.
As far as I am aware the efficiency index goes belt most efficient, then chain then gear. initially at least.
Both gears and chain need lubrication. Whilst many old bikes had open primary drives and were designed for drip feed ala Manx Norton etc...but chain actually lose efficiency during a race and as they wear.
I want to use belt as its supposedly more efficient by a % or two than either gear or chain, plus due to me wanting to use a factory rather than self made crankshaft and avoid the possible cost and complication of gears.
I also want to convert to a dry clutch, thus the added benefit is less seals saving width and complication. (Note the mag is on the primary drive side)
The belt also works as a shock absorber and makes a nice whirring noise. Plus its different.

[WilDun]

Chains are loud and when they break they cause pandemonium, smashing all sorts of stuff.
Gears are a better and more accurate timing wise than either belts or chains , but are a more expensive solution for both primary and cam drive.

I guess as a balance shaft drive it won't do a lot of damage if it breaks (a belt that is) but used as a cam drive/timing belt in a road going machine (as opposed to racing) where the belt isn't necessarily changed exactly when it should be, there is always the danger of it suddenly breaking without warning (did happen to me) and will probably cause untold chaos inside the head! whereas the good old chain will complain for a long time before letting go! - matter of preference I guess.

[tjbw]

Here's another heavy machine, with 5L Rolls Royce V twin engine.

Built in Australia in 1982 by Lucky Keizer. This has 2 cylinders from a Rolls Royce Merlin 27-liter v12 engine, which was found in an abandoned Mustang fighter plane. Keizer added nitrous injection and a supercharger!

[husaberg]

Here's another heavy machine, with 5L Rolls Royce V twin engine.

Built in Australia in 1982 by Lucky Keizer. This has 2 cylinders from a Rolls Royce Merlin 27-liter v12 engine, which was found in an abandoned Mustang fighter plane. Keizer added nitrous injection and a supercharger!

I think it was from an ex RAAF aussie mosquito.
I have a write up somewhere....

[Grumph]

Here's another heavy machine, with 5L Rolls Royce V twin engine.

Built in Australia in 1982 by Lucky Keizer. This has 2 cylinders from a Rolls Royce Merlin 27-liter v12 engine, which was found in an abandoned Mustang fighter plane. Keizer added nitrous injection and a supercharger!

Pretty sure the engine work was done by a Kiwi I used to race against back in the day...Now chief engineer at the Alpine Fighter Collection in Wanaka. If i remember right the gearbox originally used was a Holden 3 speed they reckoned had done a million miles already - but was at least available.
If Husa finds the article we'll know. I think there were several writeups as it got built.

Edit - Ray Mulqueen. came up from Dunedin with a 750 Domiracer with a home made disc front brake. Used Cessna bits i think. Had some epic braking duels with him on the manx at ruapuna 71 - 72.

[WilDun]

Pretty sure the engine work was done by a Kiwi I used to race against back in the day...Now chief engineer at the Alpine Fighter Collection in Wanaka. If i remember right the gearbox originally used was a Holden 3 speed they reckoned had done a million miles already - but was at least available.
If Husa finds the article we'll know. I think there were several writeups as it got built.

Not sure, but it was probably built from the Packard version of the RR Merlin as most of the later Mozzies used those (also the Mustangs).

[husaberg]

Not sure, but it was probably built from the Packard version of the RR Merlin as most of the later Mozzies used those (also the Mustangs).

Either way the power would be adequate

[Grumph]

Either way the power would be adequate

Not really. VERY heavy, low revving - around 3500 would be tops - but plenty of torque.

I seem to remember reading that they added the NO to pep it up a bit.
I think Keizer used it to do tyre smoking demo runs at a few drag strips - not fast but plenty of smoke...

[husaberg]

Not really. VERY heavy, low revving - around 3500 would be tops - but plenty of torque.

I seem to remember reading that they added the NO to pep it up a bit.
I think Keizer used it to do tyre smoking demo runs at a few drag strips - not fast but plenty of smoke...

I think you missed the joke....

http://auto.howstuffworks.com/1959-1...-phantom-v.htm





http://www.abc.net.au/local/photos/2...19/4296075.htm
Well worth a look
http://www.diagnosis2012.co.uk/vtwinspecials.html
http://www.diagnosis2012.co.uk/vtwininnovators2.html

[Grumph]

Oh yes, the old Rolls Royce "the power is adequate, sir" answer..

If you live long enough your work pops up everywhere...Looking through the V twin link you put up, there's Eurodave's Kohler/BMW...For which i mounted the engine and gearbox - and inserted the Honda swingarm he wanted to use....had to recon the box first though - and sort a clutch too.

[husaberg]

Oh yes, the old Rolls Royce "the power is adequate, sir" answer..

If you live long enough your work pops up everywhere...Looking through the V twin link you put up, there's Eurodave's Kohler/BMW...For which i mounted the engine and gearbox - and inserted the Honda swingarm he wanted to use....had to recon the box first though - and sort a clutch too.

I did see that and recognised the EuroDave moniker.
Faster than the Robin (or was it Fuji) diesel single that was arround as well I guess.

[Grumph]

I did see that and recognised the EuroDave moniker.
Faster than the Robin (or was it Fuji) diesel single that was arround as well I guess.

Last time i saw it,Dave was putting a small Roots blower on it. Ex toyota MR2 i think. I warned him splash lubrication and skimpy finning weren't a good mix with a blower....