hi guys. i've been comparing the diferent kind of engines since rsv came out. i noticed the the sp model have even bigger valves then the later engine model. looking at the numbers is the sp the most powerful engine?can anyone give me details? thanks
Sorry no-one has been able to help you, but I think it's an interesting question.
I think the Aprilia has rubbish top end, and a lot of this is due to valve size- it just can't flow enough gas. It's also the small valves that give the torque- small valves mean that low gas volume can move quickly at low/medium revs.
The SP has a short stroke engine allowing high revs + big valves. Longer stroke engines give more torque but limit rpm due to the piston speed being higher.
So the question is.... which engine has the best combination of highest rev ceiling with the greatest capacity for gas flow?
Is it the early SP unit (which I would imagine is more highly stressed?) or a later unit (which may have more potential?)
Sorry Diabolico, I've not helped you out at all mate- but perhaps the thread bump will create some interest?
I think the Aprilia has rubbish top end, and a lot of this is due to valve size- it just can't flow enough gas. It's also the small valves that give the torque- small valves mean that low gas volume can move quickly at low/medium revs.
The SP has a short stroke engine allowing high revs + big valves. Longer stroke engines give more torque but limit rpm due to the piston speed being higher.
So the question is.... which engine has the best combination of highest rev ceiling with the greatest capacity for gas flow?
Is it the early SP unit (which I would imagine is more highly stressed?) or a later unit (which may have more potential?)
Sorry Diabolico, I've not helped you out at all mate- but perhaps the thread bump will create some interest?
no point comparing the normal rotax lump and the sp as this was a homolgation engine,special build..short stroke motor..you cant get hold of them ...
Joined Nov 2007
522 Posts | 0+
liverpool
i've been watching this too.
Their are so many things that alter a bikes poential to make power (exhausts , gearing etc).
I think their could be so many answers it would be imposible to know.
I'd go with a short stroke high reving engine with big valves and 57mm throttle boddies on a good race system.
Are you after just the ultimate engine or the ultimate engine as it came from aprilia with all running parts?
Their are so many things that alter a bikes poential to make power (exhausts , gearing etc).
I think their could be so many answers it would be imposible to know.
I'd go with a short stroke high reving engine with big valves and 57mm throttle boddies on a good race system.
Are you after just the ultimate engine or the ultimate engine as it came from aprilia with all running parts?
Forget the SP motor as as been said you can't get one and it has high comp cosworth pistons etc etc which make it almost a different motor.
The later Rsv/Tuono motors have different oilways in the crank which you mention is the root of your engine problems so for reliability a later rsv motor is stronger.
The lack of top end power is largely down to the very conservative cam timing Aprilia used which gives a very poor intake and exhaust velocity. Meaning getting enough fuel/air in and out of the motor at high revs is a problem. The big valve motors have the same issue and you will only improve it with slotted cam gears and altered timing of the cams.
As they come from the factory they are often widely out of spec anyway due to mass production sloppiness which makes the problem worse. I know a tuner that had one cam 14 degress out of spec when using the oem cam gears correctly aligned as per Aprilia specs.
With altered timing you can get somewhere in the region of 10bhp more at the top end with no reliability issues.
Hydraulic followers are an issue on many bikes at times and Aprilia is no exception. The V4 has just had a follower redesign because they got it wrong on the first batch and they sounded like an old Ford Cortina when hot.
At least on the rsv they are easy to change. V4 needs motor out
The later Rsv/Tuono motors have different oilways in the crank which you mention is the root of your engine problems so for reliability a later rsv motor is stronger.
The lack of top end power is largely down to the very conservative cam timing Aprilia used which gives a very poor intake and exhaust velocity. Meaning getting enough fuel/air in and out of the motor at high revs is a problem. The big valve motors have the same issue and you will only improve it with slotted cam gears and altered timing of the cams.
As they come from the factory they are often widely out of spec anyway due to mass production sloppiness which makes the problem worse. I know a tuner that had one cam 14 degress out of spec when using the oem cam gears correctly aligned as per Aprilia specs.
With altered timing you can get somewhere in the region of 10bhp more at the top end with no reliability issues.
Hydraulic followers are an issue on many bikes at times and Aprilia is no exception. The V4 has just had a follower redesign because they got it wrong on the first batch and they sounded like an old Ford Cortina when hot.
At least on the rsv they are easy to change. V4 needs motor out
I read somewhere the twin plug engines have cams that actually have the lobes pressed on an interference fit hollow tube and need a judicious bit of Tig welding to stop them rotating when higher revs are called for.
Is that true? if so a set of re-ground solid shafts would seem to be in order ?
I know the earlier twin spark engine has a far from ideal chamber shape but I'm sure it could be improved with better cams etc and still keep it's torque advantage.
Is that true? if so a set of re-ground solid shafts would seem to be in order ?
I know the earlier twin spark engine has a far from ideal chamber shape but I'm sure it could be improved with better cams etc and still keep it's torque advantage.
If you really feel you need the extra top end (and it's right at the top end) then get the cam gears slotted and the timing set for 106/109 degrees.
How big the gains depends on how far out the cams are from stock.
If they are widely out then the gains will be bigger simply because your correcting a manufacturing error as well as boosting intake velocity etc.
If you bike is close to spec as stock then the gains will be smaller. Even setting them to oem spec will reap gains if they are out anyway which most are to some degree.
Not sure about the design of the early cams but not heard of any issues regarding them.
I believe Rotax went to 1 piece cams in late 2004 before that the lobes were pressed on the shaft.
I came across some pics on the AF1 forum showing the welding needed to secure them against spinning when using high revs in a tuned motor.
Sods law tho' as I can't find them now,although I did download the pics somewhere,I'm just not sure which computer I used or where I stored them.
From what I can gather the best cams to use are 4 post 2004 one piece inlets.
I came across some pics on the AF1 forum showing the welding needed to secure them against spinning when using high revs in a tuned motor.
Sods law tho' as I can't find them now,although I did download the pics somewhere,I'm just not sure which computer I used or where I stored them.
From what I can gather the best cams to use are 4 post 2004 one piece inlets.
about the pistons as the sp engine has the cosworth,are there any better performance piston like wiseco has the high compression? i searched but they dont have for aprilia rsv. and once i dont understand too much about these engines,and i have a 2000 model,small valves then, can anyone tell me everything that can be done to be great powerfull engine,less modify to 1100. i already have 57tb's,evo filter and pc3 ready to fit.
and anyone knows the specs of the heads made from aprilia in these page? "https://www.apriliayorkshire.co.uk/catalogue/partlist.jsp?Catalogo=%3D3901&Tavola=%3D78&_NomeImmagine=68211692.gif&_bikename=RSV 1000 2001-2002&_pagename=Acc. - Performance parts IV"
and anyone knows the specs of the heads made from aprilia in these page? "https://www.apriliayorkshire.co.uk/catalogue/partlist.jsp?Catalogo=%3D3901&Tavola=%3D78&_NomeImmagine=68211692.gif&_bikename=RSV 1000 2001-2002&_pagename=Acc. - Performance parts IV"
can you fit the later single spark,bigger valve head to an earlier engine?...:dunno
as for the cam sprockets..is someone missing a trick here ..they are available for all the jap motors..but i have never seen any for the aprilia?..if they are that badly set up at the factory this could be very easy power gains
as for the cam sprockets..is someone missing a trick here ..they are available for all the jap motors..but i have never seen any for the aprilia?..if they are that badly set up at the factory this could be very easy power gains
Joined Dec 2007
158 Posts | 0+
Bristol, UK
My 00 engine (small valve, twin plug) is fine for me , it'll stay happily in the top 1/3rd of the inters group, commute daily if need be and still help me lose my license in any gear ............................:biggrin as for whats best well Aprilia havn't built a "best" V-Twin engine, youll need a Ducati for that.
Been doing some research into balance factors etc, and camshafts over on AF1 and it looks like the Rotax cam gears are thin ,hard and look to me in the pics as if they are stamped out of sheet steel and then hardened.
Better could certainly be designed,however the best way forward ( they say ) seem to be use a TIG welder to soften the material either side of the holes on both sides of the gear.
Personally speaking I would either spark erode or Wire erode the holes into slots so as not lose the temper. This is a simple op and much along the lines of the work I was doing on a wire eroder before being made redundant.
When I get round to taking the lids of my engine I will look into completely redesigning the cam gears to incorporate positive location,as in offset dowels rather than just tightening 3 bolts in 3 slots and hoping nothing slips.
When you take these gears and the pressed on cam lobes it's really amazing the engine works at all let alone this well. The more I read the more I'm sure the majority of earlier engines can be made much more efficient without spending mega bucks.
Perhaps I'll get a chance over the winter to try a few ideas.
If Spoonz is right (and I am guessing he is) then do we know where to get some slotted cams for the prilli???
Maybe Griff can help on this topic??
Joined Dec 2007
158 Posts | 0+
Bristol, UK
Showing my age here....
Slotted cams? That's a cheap bodge/half-baked solution if ever I heard one!
What we need are vernier sprockets (is that what you mean by 'offset dowels' IanG?) - see parts 10, 11 & 13 below:
(BTW, it's a Manx Norton. A similar set-up was used on the Matchless G50 and no-doubt many others.)
Slotted cams? That's a cheap bodge/half-baked solution if ever I heard one!
What we need are vernier sprockets (is that what you mean by 'offset dowels' IanG?) - see parts 10, 11 & 13 below:
(BTW, it's a Manx Norton. A similar set-up was used on the Matchless G50 and no-doubt many others.)
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Joined Jul 2007
919 Posts | 0+
Rutland, Leics, Midlands
slotted cam sprockets are well known on the rotax engines in the states on race bikes, slightly tune & standard
From memory, AF1 racing, Clarkies Motors, Ken Zeller & a few others used this method
Yep, you can fit 04 on inlet cams all round in the early motor
The weld on the early cams was to stop the lobe spining on the shaft at hard rpm or slamming it down the box to visiously
04 on heads on a early motor?
its been done but only know of one person to try it and it isn't straight forward
From memory, AF1 racing, Clarkies Motors, Ken Zeller & a few others used this method
Yep, you can fit 04 on inlet cams all round in the early motor
The weld on the early cams was to stop the lobe spining on the shaft at hard rpm or slamming it down the box to visiously
04 on heads on a early motor?
its been done but only know of one person to try it and it isn't straight forward
BRG, yes thats what I had in mind ( or something along those lines) got to be more positive than trying to clamp 3 bolts in the middle of slots with all the shear forces at work.
