V-Twin BEC
JF - 18/4/10 at 08:57 PM
I've wondered about this for a while, and after searching I couldn't find a single post about it on here. So if there is a topic about it I
apologise.
But is there a clear reason why every BEC project I've come across uses a 4 cyl?
I've been dreaming about building a 7ish car for years, but haven't got the time/money/space/etc... you all know the lame excuses...
When I do have some time to spare I like to take my bike out... a V-Twin Honda Allroad (750cc Africa Twin) And although the engine is pretty much
bullitproof I'd never put it in a car. Just hasn't got that oomph. But I really love the character of a V-Twin. Much more then a screaming
4cyl bike engine.
But what about a Honda VTR SP1/2 engine? 1000cc V-twin with over 130 horse and over 100 Nm torque. Would this be suitable for a 7ish BEC? If not, then
why so?
Paul TigerB6 - 18/4/10 at 09:01 PM
The SP1 and 2 have been used by Stuart Taylor (now taken over by Aries Motorsport) in their cars. There's also a couple of Aprillia RSV engined
cars out there - Richard Quinn built one (I helped / hindered a bit)
PS welcome to the nut-house
link
[Edited on 18/4/10 by Paul TigerB6]
StevieB - 18/4/10 at 09:02 PM
I think maybe the SP1/2 lacks the power of more easily available 4 cylinder units.
However, the Aprilia RSV Mille has quite a lot of clout, with the most recent version being a real screamer. There's also probably more of them
about than the relatively limited Honda's.
I think someone on here is running a Mille engine in a se7en too...
franky - 18/4/10 at 09:12 PM
Should be a great idea, the sp1/2 motor is a real gem, a real jewel. they make more power low down than 4 pot bike engines. My current bike is a
moto morini which is a 1200cc V-twin and makes more poke on a dyno than just about every bike, including a busa etc till it runs out of revs at 9.5 k
but the shear torque would be awesome in a BEC.
Have you looked for a 1200cc ducati engine or the likes?
it would be nice to have a sp1 motor though as the crankcases have HRC on them! much better motors than the aprilia IMO having owned both.
MakeEverything - 18/4/10 at 09:28 PM
someone on here has used a TL1000R engine. Forget who though.
I can vouch for the TL having looooads of torque and plenty of power for a lightweight. In fact, i was going to put one in at Plan A (which is not
Plan J revision 12!!) 
bi22le - 18/4/10 at 09:34 PM
Welcome to the nut house!
I asked the same question when I started on here about 2 years ago. I had a quick search for the post to put a link in here but could not find it.
Shame because it answered alot of my original questions that you might also have.
One thing I will say is that there are people on here that have v-twin BEC but they are really hard to do.
The main problem is that the v engines are very tall. This makes them hard to fit under the bonnet. You also need two exhausts and two cans which is
extra expense.
I know that SDR now do an exo style kit that has the firestorm or RSV engine in it. Mid engine rear wheel drive 3 seater!
If I was building one of those kits though I would take the Scooby chasiss, 400bhp boxer would ruin a BEC!
scootz - 18/4/10 at 10:12 PM
quote:
Originally posted by JF
But what about a Honda VTR SP1/2 engine? 1000cc V-twin with over 130 horse and over 100 Nm torque. Would this be suitable for a 7ish BEC? If not, then
why so?
Nothing wrong with it, but most modern Litre 4-cyl sports-bikes still put out a little more torque than the TL's and VTR's of the world, and
50-odd more HP!
Move on to a ZX12, ZZR14 or Busa and they're trumped further still!
Only reason to go for an older V-twin (IMHO) is they are cheap as chips!
FFTS - 18/4/10 at 11:50 PM
Just had a test drive in a mid engines VTR SP1 and I have to say I was most unimpressed with the performance even with Dynojet, power commander and
powerflow exhaust, My ZX9R would have eaten it for breakfast so my interest was gone. I was REALLY noisy too so much so it was unpleasant to be in for
10 mins.
franky - 19/4/10 at 06:09 AM
Thats surprising as a sp1 with that set-up will make the same power as a zx9 but more torque and less rev's, twins do always feel like
you're going slower though. IL4's do make more torque but at more revs, thats why they make more power, if you get a new v-twin powerplant
though you should have the best of both worlds, IL4 power with the brute torque of a twin
Ivan - 19/4/10 at 06:26 AM
Most of the incredible performance of 4 cyl BEC's is down to their work rate which is another way of saying Brake Horse Power and this all
revolves about lots of revs to compensate for low torque. This means that because they rev up to 30% more than the twins they can have a much higher
gearing for the same top speed (30% higher) so will always outperform the same BHP lower revving motor.
Of course cruising at 70MPH for long distances with the gearing set to achieve top speed at peak revs can be a royal pain in the ear so that is where
the twins might be at an advantage if you want to go road car only - but then you might as well go CEC.
Richard Quinn - 19/4/10 at 09:40 AM
quote:
Originally posted by FFTS
I was REALLY noisy too so much so it was unpleasant to be in for 10 mins.
Didn't the driver tell you to shut up?
As said above - I've got one with a Mille in it. The main reason for this is that I already had two of them sat in the garage.
The Mille might be a bit easier to do as it is a 60 deg v twin as opposed to the 90 deg twins that would make it a bit tight in the engine bay.
You need to be prepared to do a bit of work as prop adaptors, exhausts, cradles etc are not available off the shelf.
I haven't got two exhausts as we've just taken two into one in front of the engine and brought one pipe out.
I find it to be plenty quick enough for me and it just sounds a little diiferent (doesn't scream like an IL4 but it's not a thumper like the
TL etc). Even though the torque is down when compared to an IL4 but it is delivered across a fairly wide range so it is fairly forgiving and will pull
well through corners even where you should really have changed down. I can even pull away in 2nd. I don't think that it "feels" as fast
as IL4's as it is that bit less frantic, if that makes sense?
Richard Quinn - 19/4/10 at 10:53 AM
quote:
Originally posted by Paul TigerB6
The SP1 and 2 have been used by Stuart Taylor (now taken over by Aries Motorsport) in their cars. There's also a couple of Aprillia RSV engined
cars out there - Richard Quinn built one (I helped / hindered a bit)
PS welcome to the nut-house
link
[Edited on 18/4/10 by Paul TigerB6]
That link is Thom's Mille engined car. My first start up is here. It's not quite that
noisy now as that was just running on the headers.
JF - 19/4/10 at 12:48 PM
First of all great to get so many responses in barely one day. And it's good to know that it's being done.
quote:
Originally posted by Richard Quinn
The Mille might be a bit easier to do as it is a 60 deg v twin as opposed to the 90 deg twins that would make it a bit tight in the engine bay.
And yes I was mainly looking at 90 deg twins, and yes you're right not a real V-twin, but close enough.
Reason I took the Honda VTR as an example is because I know they're build to last. What frankly can't be said about some others.
And although I respect everyones opinion. I totally disagree with the comments that a 2cyl isn't worth it and you'd just as well build a
CEC. If I wanted the easy way I'd simply buy another second hand car. Cheaper too!
The 4il screamers just don't do it for me. They sound alright when idling, but you need revs to drive, certainly in a much heavier car then the
usual bike. And then they're awfull if you ask me. If I wanted screamers around I'd volunteer as a babysitter, again much cheaper and easier
then building a 7.
And well the lack of power... I know there is a guy up in Sweden who's running a VTR bike at 260bhp and clocking over 210mph. Ok with the aid of
a turbo and ethanol fuel, but still.
And well getting it up to those specs will probably ruin it's reliabilty and cost more then the average locost builder spends on it's whole
car. But it does show there is much more to gain and I don't think it would be that expensive.
All that being said, I'd love to build a 7ish car from the ground up. But I doubt it will be a true locost. I can do most of the work myself and
have a tax free supply for my steel. But knowing me it will still become expensive. Whatever I build must be to my likings, is original and is build
to last.
So I consider it a good thing that there are much more logical and possibly cheaper options around
Richard Quinn - 19/4/10 at 03:46 PM
quote:
Originally posted by JF
and yes you're right not a real V-twin, but close enough.
I never said it wasn't a real V-twin! It has two cylinders arranged in a V <--- and that there is definitely a real V and looks more like 60
deg than 90deg!
phelpsa - 19/4/10 at 04:06 PM
If you want to use a V-twin then do it! I would encourage it. Just dont try and justify it, it'll drive you mad. Sometimes you have to admit that
you're doing it because you want to!
There is no obvious reason for me to use a 20 year old oil cooled engine in my Locost, other than that's the engine I ended up with and it makes
a good story
JF - 19/4/10 at 05:57 PM
quote:
Originally posted by phelpsa
If you want to use a V-twin then do it! I would encourage it. Just dont try and justify it, it'll drive you mad. Sometimes you have to admit that
you're doing it because you want to!
There is no obvious reason for me to use a 20 year old oil cooled engine in my Locost, other than that's the engine I ended up with and it makes
a good story
LOL I fully agree with you there. I have a habit of making my own life difficult because I set my mind on something. This topic isn't so much to
justify a project like this. But to see if others thought of problems I might have missed.
And well I have many things to think over, but the good thing is that I have enough time for it aswell. I don't expect building for several
years. But you never know what the future brings.
Maybe I'll go back to another idea of using a Nissan SR20DET in a CEC. Or maybe I end up building a 5 wheeled monster... but hey atleast it
won't be to standard...
trifield - 19/4/10 at 08:32 PM
I'm currently riding a MT-01, 1,670 cc Air-cooled, 4-stroke, V-type 2-cylinder, 2-valves, OHV
Maximum power: 66.3 kW (90 PS) @ 4,750 rpm
Maximum torque: 150.3 Nm (15.3 kg-m) @ 3,750 rpm
Can't help thinking that the low down torque it has would make it an ideal donor
http://www.yamaha-motor.co.uk/products/motorcycles/mt-series/mt-01.jsp?view=techspecs
[Edited on 19/4/10 by trifield]