Discussion
Hi all its my first post here.
I am looking at getting a kit car in the (hopefully) nearly future but want some thing different. I was thinking of putting a V-twin in a MK as it has more torque. Why is this not a popular choice? Is there something im missing to stop this being a beautifully sounding kit car that is rapid?
Also kit cars are nutoriously unaerodynamic so surely a rear diffuser would make a real difference to get some weight down at the back. Not many people have these and I have heard they would make any difference. I love the look of them so i might just get one for the hell of it. Sexy times!
Cheeres for the answers and dont you think we should open a photo comp of the best looking exhaust system!?
Bi22le.
I am looking at getting a kit car in the (hopefully) nearly future but want some thing different. I was thinking of putting a V-twin in a MK as it has more torque. Why is this not a popular choice? Is there something im missing to stop this being a beautifully sounding kit car that is rapid?
Also kit cars are nutoriously unaerodynamic so surely a rear diffuser would make a real difference to get some weight down at the back. Not many people have these and I have heard they would make any difference. I love the look of them so i might just get one for the hell of it. Sexy times!
Cheeres for the answers and dont you think we should open a photo comp of the best looking exhaust system!?
Bi22le.
Both have been done.
Stuart Taylor Motorsport offered a version of the Sylva Phoenix with a V-twin engine. The project is now with Rainbird racing, but you can see pics of the V-twin car here
Several people have fitted diffusers to 'Seven' type cars, but the basic aerodynamics of the car are so bad that it's difficult to tell whether it gives a worthwhile improvement. The big problem with 'Seven' type cars isn't downforce, it's just plain, old-fashioned drag. To be effective, diffusers need to run really close to the ground, anyway, so are never going to be particularly effective on a road car.
I've got an Aprilia Tuono R V-twin engine sitting in my shed, waiting for me to finish designing a lightweight road-going single seater for it, so I'm a big fan of the idea, but most people seem to prefer high-revving 4 cylinder bike engines with ultra-short gearing to the lighter, torquier, but less powerful and taller-geared twins.
Stuart Taylor Motorsport offered a version of the Sylva Phoenix with a V-twin engine. The project is now with Rainbird racing, but you can see pics of the V-twin car here
Several people have fitted diffusers to 'Seven' type cars, but the basic aerodynamics of the car are so bad that it's difficult to tell whether it gives a worthwhile improvement. The big problem with 'Seven' type cars isn't downforce, it's just plain, old-fashioned drag. To be effective, diffusers need to run really close to the ground, anyway, so are never going to be particularly effective on a road car.
I've got an Aprilia Tuono R V-twin engine sitting in my shed, waiting for me to finish designing a lightweight road-going single seater for it, so I'm a big fan of the idea, but most people seem to prefer high-revving 4 cylinder bike engines with ultra-short gearing to the lighter, torquier, but less powerful and taller-geared twins.
There was a guy in the Raf Motorsport team who built his own car around a Suzi TL lump,which may be slightly lacking in headline Hp,but is a cracking motor.
The Stuart Taylor cars used the ST1100 motor from memory, whiCh is quite possibly the most balnd and uninspiring motor ever built.
Sams choice is obviously correct, and I think will make a storming Bec.The Aprilia lump is torquey, revvy,powerfull, tuneable and strong. It also includes a factory fitted slipper clutch.
Dukes make power but have a very weak clutch set up.
The Stuart Taylor cars used the ST1100 motor from memory, whiCh is quite possibly the most balnd and uninspiring motor ever built.
Sams choice is obviously correct, and I think will make a storming Bec.The Aprilia lump is torquey, revvy,powerfull, tuneable and strong. It also includes a factory fitted slipper clutch.
Dukes make power but have a very weak clutch set up.
Furyous said:
There was a guy in the Raf Motorsport team who built his own car around a Suzi TL lump,which may be slightly lacking in headline Hp,but is a cracking motor.
The Stuart Taylor cars used the ST1100 motor from memory, whiCh is quite possibly the most balnd and uninspiring motor ever built.
STM did a phoenix with an SP1 engine in it.The Stuart Taylor cars used the ST1100 motor from memory, whiCh is quite possibly the most balnd and uninspiring motor ever built.
Furyous said:
Sams choice is obviously correct, and I think will make a storming Bec.The Aprilia lump is torquey, revvy,powerfull, tuneable and strong. It also includes a factory fitted slipper clutch.
And it's dry sumped as standard.Not sure about gearing though? You will need to research what the primary gear ratio is and also that of sixth gear. Then put them into the widely available EXCEL spreadsheet speed calculator to find out likely top speed.
V twins don't rev as high but they still do similar top speeds to other superbikes. This suggests that the gearbox sprocket ought to be revving as fast, but there is the final drive ratio (ie. sprocket sizes) to consider.
You could be looking at 110mph top speed.
And it's a tall engine. It will definately stick through the bonnet. Look at the SP1 version above then imagine an airbox on top of the trumpets!
Geoff
Furyous said:
The Stuart Taylor cars used the ST1100 motor from memory, which is quite possibly the most bland and uninspiring motor ever built.
They certainly did use the ST1100 (Honda Pan European) engine on some cars, but that's a V4 engine from a big touring bike and - as you say - pretty unexceptional by bike engine standards ('only' 101bhp from 1100cc, albeit quite torquey and relatively low revving - peak power at an almost car-like 7,500rpm).But the demonstrator used a Honda SP1 vee twin, which has a very similar spec. to my Aprilia (133bhp for the SP1 vs. 139bhp for the Tuono R, and peak power at about 9,500rpm). They also offered the VTR1000 Firestorm engine, which is basically a de-tuned version of the SP1, giving 111bhp.
The thing you have to remember with these V-twins, though, is that they tend to have much taller gearing. In the original bikes, they are designed to pull their top speed at their peak power revs of 9,500rpm, whereas a similarly powerful 4-cylinder superbike engine will be geared to be revving at about 12,000rpm to pull a similar top speed at its peak power revs.
For example (apologies to get technical); the Tuono R has a 6th gear ratio of 1.7:1 (including primary reduction), whereas the current Honda Fireblade has a 6th gear ratio of 1.95:1. That's about 15% shorter gearing (and the 'blade has a lot more power, at nearly 175bhp)! Put it another way... the top gear of the Fireblade is somewhere between 4th and 5th gear on the Tuono.
What this means in practice is that with the limited range of diff ratios available for use in 'Seven' type cars, the torque characteristics of the V-twin (and contrary to popular belief, their peak torque is no better - it's just the delivery that's different) are cancelled out by the shorter gearing of the 4-pot. The V-twin will not sound and feel anywhere near as highly stressed, but will also feel (relatively) sluggish in comparison.
The only way a V-twin will deliver its potential is if you take full advantage of its lighter weight and make sure that it's fitted in a very lightweight car. Realistically, the MK or any other 'Seven' type car is getting towards the upper limit of what is acceptable (you'll struggle to get much below 400 kilos, even with the lighter V-twin; I'm aiming for <300 kilos, but that's with a single-seater and I know it's going to cost me a lot of money in trick materials and components to get there).
Thanks for the the replies. Im doing this from my phone which does not have a return key, sorry! It does seem that due to gearing and engine height a v-twin is a bad choice of engine for a 450kg seven style car. Would an m3 engine also be too big? Im thinking of one from an e36, 300bhp. Its a big lump but also a bullet proof engine that when in a kit car would be unstressed and seriously quick. Its something different and would sound as smooth as a babies arse through the rev range. The only other problem with the m3 engine is its electronics. I know electronics in modern cars is complex and not modular so pulling just the engine ecu and associated electronics off to get the engine running again would be quite hard if not impossible! Has anyone in this forum done this? Ill ask the bmw forum too to see if it is a viable option. Thanks again for the replies. Bi22le
Got a Phoenix with big car engine, a ZX9 and Kawasaki V twin bike. I could maybe just about live with the ZXR engine in the Phoenix, (if the bike goes down and I live to tell I may try it one day, but I hope not) but the V would be awfull, it is geared to do about 110MPH in the bike, and wouuld never get there with the drag/weight of a car, 0-60 time is OK, faster than most cars, but nothing like 'bike' fast.
There was an article I read before said, V's don't produce more torque than 4's it just feels that way because the curve is flatter (and a lot lower), so the precentage of power available at lower rev's is more than a 4, but in absolute terms many twins are producing lower torque at a specifc rev than a 4 of the same size.
There was an article I read before said, V's don't produce more torque than 4's it just feels that way because the curve is flatter (and a lot lower), so the precentage of power available at lower rev's is more than a 4, but in absolute terms many twins are producing lower torque at a specifc rev than a 4 of the same size.
A mate of mine built a Firestorm engined Phoenix and I'm pretty sure he'd be the last person to recommend it. He's had all sort of bother with it and because it's a fairly uncommon thing to do, you're pretty much on your own. Issues as far as I'm concerned are as follows: Having the carbs poke through the bonnet is all well and good, but incredibly noisy. The standard bike box on there is enormous and obscures your forward vision unacceptably. Fabbing a smaller box has been a royal PITA as too small fits lovely (with a pipe to a filter in the side pod) but is far too restrictive. This is still an ongoing thing for him at the moment. Going back to noise, the twin is magnificently loud. You'll need a serious can to quieten it down (as he has had to) as you'll get about 1 lap before they boot you off on any circuit. Then finally there's the clutch that he's still wrestling with trying to get the right sized master/slave cylinders, too much/too little travel, etc, problems with it failing when hot. Basically a proper pain and I suspect he wishes he went with a Fireblade or one of the other more commonly used engines. Put it this way, he's been at it at least 4 years now, it still wont get through an SVA and I think he's pretty much got sick of it all (I think it's just sat in his garage for the last couple).
Edited by juansolo on Friday 8th May 12:10
Are you on LocostBuilders? I think he'll have more pics on there - have a look under his photo archive (Richard Quinn) as there should be a fair few in there. The emissions were pretty tough but being injected, it was a case of getting it set up at the local rolling road place and then extremely fine tuning it at the SVA test centre to get the levels right (took about 25 mins of trying!!). What is an issue with V-twins is the pulsing of the engine sucking air back into the exhaust. The SVA man didnt get his probe far enough into the exhaust to get away from this effect, and so the probe was seeing fresh air mixed with the exhaust gasses and hence lambda showing way too lean. A shroud on the exhaust tip (temporarily fitted with the tester's permission) and ensuring the probe was as far in as possible got around this though.
I'll let you know how it goes, and have another mate with a 2001 R1 Locost to compare it against as a direct comparrison. The RSV engine is definately more torquey though - and the SVA tester thought it was fantastic to drive around the test centre. He preferred it to inline 4's thats for sure - but i'm going to stick to a 4 myself (albeit with a turbo).
As for the height, well the scoop on the bonnet is effectively acting as an airbox. Maybe not the most efficient solution but certainly seems to work just fine. There's filter foam behind the mesh in the opening and only a small gap right around the throttle bodies so hopefully not too much engine bay air pulled through
I'll let you know how it goes, and have another mate with a 2001 R1 Locost to compare it against as a direct comparrison. The RSV engine is definately more torquey though - and the SVA tester thought it was fantastic to drive around the test centre. He preferred it to inline 4's thats for sure - but i'm going to stick to a 4 myself (albeit with a turbo).
As for the height, well the scoop on the bonnet is effectively acting as an airbox. Maybe not the most efficient solution but certainly seems to work just fine. There's filter foam behind the mesh in the opening and only a small gap right around the throttle bodies so hopefully not too much engine bay air pulled through
That's me then!
Paul's pretty much summed it up really. The RSV is a 60 deg v twin which will just about fit. Emissions were "interesting" but not insurmountable if you can get it there or thereabouts on a gas tester or rolling road beforehand. I didn't use the shroud made up by the rolling road people for the test (as it would've been like presenting a cheese grater for SVA) but I did chop the tail pipe off to make it easier to get the gas tester probe fully in to the can. I don't think that the noise is a problem although it was a bit close to the wire at the test. The can I've got has seen better days and because my engine is rigidly mounted there is a fair bit of vibration. The scoop/filter is a bit of a compromise but what Paul didn't say is that this was his idea!
Paul hasn't been out in the car as yet and I've only had a couple of short runs so far. What I would say is that it is very forgiving for a BEC which makes overall performance pretty satisfying. The spread of useable torque makes delivery very smooth and if, like me at the moment, you aren't quite in the right gear all of the time it will still pull brilliantly.
Paul's pretty much summed it up really. The RSV is a 60 deg v twin which will just about fit. Emissions were "interesting" but not insurmountable if you can get it there or thereabouts on a gas tester or rolling road beforehand. I didn't use the shroud made up by the rolling road people for the test (as it would've been like presenting a cheese grater for SVA) but I did chop the tail pipe off to make it easier to get the gas tester probe fully in to the can. I don't think that the noise is a problem although it was a bit close to the wire at the test. The can I've got has seen better days and because my engine is rigidly mounted there is a fair bit of vibration. The scoop/filter is a bit of a compromise but what Paul didn't say is that this was his idea!
Paul hasn't been out in the car as yet and I've only had a couple of short runs so far. What I would say is that it is very forgiving for a BEC which makes overall performance pretty satisfying. The spread of useable torque makes delivery very smooth and if, like me at the moment, you aren't quite in the right gear all of the time it will still pull brilliantly.
Cheers for getting in touch Quinny. Where abouts do you live? Are you taking it to any meets or track days this summer? Ill pop along if I can and have a look. do you think the gearing is sensible? People have said that due to the lower engine revs it will only hit about 110 mph. Im not on Locost web site so I would love to see some more pics too. You can definatly say that you have a one in a thousand car becasue many people think its just inpossible to do!! My mate has a RSV mille R bike so I might wait till he falls off and put the engine to propper use!!
The problem with the TL and Duke in a 7alike is that they are 90 degree twins. The 60 deg Aprilia is very tight as you can see from the photo that Paul posted. To get the prop down the tunnel at some sort of sensible angle, the front (as was on the bike) cylinder is quite tight to the side. You had to be prepared to do quite a bit yourself as things like headers, cradle, prop adaptor etc are not available off the shelf.
As for gearing, well it depends what diff you can get. With mine and the wheel/tyre combo on it, it should be ok for about 115. If you can get a 3.14 or a Freeloader diff then you would have a bit more at the top end at the sacrifice of a bit more time to get there.
The quoted figure for the early RSVs is 123bhp but, as I've recently discovered, is on a restricted map. Allowing it to breathe properly and cutting an earth on the ecu allegedly releases another 22bhp. Power delivery is smooth and you don't have to worry too much about "power bands".
In a pure drag race or on a circuit with long straights there are lots of other motors that would beat it but with lots of twisties it would be ok and you don't have to worry about sump baffles or stuff like that with it being dry sumped. Email me at richard.quinn1@ntlworld.com if you want any specific info or pictures.
Oh, and I'm on the Wirral.
As for gearing, well it depends what diff you can get. With mine and the wheel/tyre combo on it, it should be ok for about 115. If you can get a 3.14 or a Freeloader diff then you would have a bit more at the top end at the sacrifice of a bit more time to get there.
The quoted figure for the early RSVs is 123bhp but, as I've recently discovered, is on a restricted map. Allowing it to breathe properly and cutting an earth on the ecu allegedly releases another 22bhp. Power delivery is smooth and you don't have to worry too much about "power bands".
In a pure drag race or on a circuit with long straights there are lots of other motors that would beat it but with lots of twisties it would be ok and you don't have to worry about sump baffles or stuff like that with it being dry sumped. Email me at richard.quinn1@ntlworld.com if you want any specific info or pictures.
Oh, and I'm on the Wirral.
Edited by 66Quinny66 on Monday 8th June 21:11
Furyblade_Lee said:
Are there any Ducati engines that would be suitable to fit into a Sylva R1ot??? My knowledge of Ducati engines is somewhat limited!
Dukes use a dry clutch set up, this has a pretty short lifespan on bike, much less in a car.Plate kit is around £125 IIRC.
That and the timing belts needing changing every 2 years regardless of mileage.
And the total PITA that is shimming up a desmodromic valve train, that needS checking every 4k miles IIRC.
To sum up, good engine, but not a BEC ideal really.
I've seen a 7 on t'interweb somewhere with a HD in it. Not sure how you'd manage with the separate tranny and the engine is quite tall.
ETA - Found it! Try this link http://www.kineticvehicles.com/whippet.html
ETA - Found it! Try this link http://www.kineticvehicles.com/whippet.html
Edited by 66Quinny66 on Tuesday 9th June 19:54
Hmm thats a bit back yard bonkers for me. Ill stick to something a bit more tested so I can trust a wheel wont fall off! If I had a V engine I would love to have an exhaust per side. It would look quality and sound better. Would need ear protection though I think!!!!
Quinney I live no where near you (SE London!). The meet is a no go unless we go to the same show some day. If I see a RSV kit car ill hunt down the owner!
TL and RSV are the best engines I think Dukes are too unreliable and Harleys just dont start and never run right (I know this because I use to fix them for the hairy bikers!). I think I will just settle for a R1 or GSXR lump. Oh 12.5K let me hear you sing!!!!!
Quinney I live no where near you (SE London!). The meet is a no go unless we go to the same show some day. If I see a RSV kit car ill hunt down the owner!
TL and RSV are the best engines I think Dukes are too unreliable and Harleys just dont start and never run right (I know this because I use to fix them for the hairy bikers!). I think I will just settle for a R1 or GSXR lump. Oh 12.5K let me hear you sing!!!!!
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