So with the bike engines being a lot lighter than car engines, and generally about the same price they're obviously an interesting proposal, but
the questions I have when considering the options are:
What's the lifespan of the engines/clutches when put into a BEC? I suspect the pain of dragging round half a ton of metal takes a toll on the
drivetrain. Are prices comparable to car engine parts? I know the car engine I was thinking of is a bombproof bit of kit and can be pushed massively,
drivetrain is good for 500lbft of torque etc, but it does weigh 200kg. If I strayed from the engine I was thinking and went the way of the BEC, what
are the pros and cons WRT a car engine? Is registering one harder? IVA? What emissions limits do I have to work to?
I use my Blackbird Indy nearly every day for the past 18 months, goes no where slow and its mint! No clutch probs, engine issues what so ever
oooh, BEC vs CEC
That is only 12 months though alex 
I used my road car every day and went nowhere slow (300hp) and the clutch lasted 90K miles until I shattered it
one fateful launch!
Not trying to start a war here but trying to assess whether a BEC will leave me repairing it every other weekend, or mean I'm struggling to do a
long trip without worrying.
I did about 15,000 miles in my R1 bec on the clutch that came with the engine before selling the car on. Remember that the load on the clutch is the torque produced by the engine, not the weight of the vehicle reacting that torque. Peak load on the clutch is therefore the same. The car, being heavier than the bike, will take longer to accelerate. The load on the clutch during acceleration will last longer but will be no bigger.
Fair point, and one I've completely ignored, sometimes I'm a fool. I'd assume though that you'd spend more time slipping the clutch by definition so as not to bog. What's the price of a set of clutch plates in something like an R1? Since they're a lot easier to change the time/cost balance may be a lot closer than I'd thought.
The torque transmitted through the transmission can be considerably higher than that developed by the engine.
If you dump the clutch then you not only have available the torque derived from the engine combustion but also the torque derived from the stored
kinetic energy in the engine flywheel and components as the loading tries to bring the engine to a standstill.
The inertia and mass of the car is greater than that of the bike so the car will require a greater torque loading for a longer period to accelerate
it.
Therefore the car will provide a greater stress on the system.
If you slip the clutch and don't let the revs change then the stored energy in the engine rotating components remains the same and the combustion
supplies the torque for acceleration hence less loading and longer life
Don't forget that changing a clutch on a BEC is much easier than on a car.
Lift the front end of the car, remove clutch cover (12 allen bolts on mine).
Undo 6 further bolts, remove plates, fit new plates, re-fit springs (may upgrade at this point), re-fit 6 bolts.
Put cover back on (new gasket) and do up 12 allen bolts. Lower front end of car.
Job jobbed.
Gearboxes / big ends etc however are all another matter........
quote:
Originally posted by richardlee237
The inertia and mass of the car is greater than that of the bike so the car will require a greater torque loading for a longer period to accelerate it.
Therefore the car will provide a greater stress on the system.
Was talking to a westfield owner with a fireblade engine, hes done 18,000miles but always carries a spare clutch. changed numerous times, simpe procedure and only costs about £50. Its when gearboxes and pistons start vandalising themselves it gets expensive...
Well yes, kinda hoping that I won't go eating pistons regularly, but I do question the box etc. Of course the inertial load imposed by the fly
would be higher, but that's assuming you have no mechanical sympathy I guess, most of the time you don't drop the clutch at 10,000rpm.
Sometimes
I'm getting more tempted despite claiming I'd never go anywhere near the revvy noisy monsters.
Bottom line... If you want a quiet, comfortable, reliable car, buy a Lexus. If you want a fun car, get a kit and if you want a super fun car get a
BEC.
Registration is no different, except the low tax class (under 1500cc). Emmisions limits at IVA for a BEC are the same as a CEC. You'd need a cat
and power commander in most cases.
adrian
ps. have you been in a BEC?
Certainly not interested in a comfy car, that was never the point - just don't want it to be the sole thing I drop my cash into (I've
another 2 cars that takes a percentage (one of which may be sacrificed), plus my sports and a house and girlfriend lol). I do, however, want to be
able to at least /reasonably/ trust a drivetrain not to die so regularly I have to buy a new engine/box every 2 years. I'm informed by my bikey
mates that they go through engines every 40-50K in a bike chassis, hence my concern that the car chassis would accelerate that death.
Never been in a BEC, specifically. I've spent some time working on Formula Student cars (600cc bike engine single seaters) but never driven
one.
Thanks for the info on the emissions. I'll read through the IVA documentation in more detail so I understand it.
[Edited on 4/8/10 by coyoteboy]
Well it really depends what kind of engine you got. In general a Honda will last longer then a Kawa. Although many claim to have had more fun on the
Kawa in the shorter time 
Other important factor is yourself. Do you give the engine time to get up to temp and cool down. Or you go flat out 1 sec after starting etc. Always
top revs, or more moderate with an occansional top rev.
Do you use your clutch properly, or as a on/off switch. It's usually the monkey behind the wheel that breaks it...
quote:
Originally posted by adithorp
ps. have you been in a BEC?
quote:
Originally posted by coyoteboy
Never been in a BEC, specifically. I've spent some time working on Formula Student cars (600cc bike engine single seaters) but never driven one.
[Edited on 4/8/10 by coyoteboy]
Agreed, whats your location? Sure someone will let you have a ride.
Changed to a BEC last year and never looked back. Get a comfortable seat and you can drive it all day.
Well I used to be not far from Manchester myself but I'm now in Glasgow (not ideal weather or roads for a kit lol) and only visit Manchester area one a month or so these days. A quick ride along would be fun I think, might convert me as you say! I've been a low-down torque monster for a long time.
I blew up my BEC last week, was painful but I still feel the pros far outweigh the cons (by a mile). I had a fairly quick 2ltr se7en before my BEC and would never consider going back, these things are fantastic! That said, I'm very impressed by the distances covered by some of the contributors to this thread. For me, half an hour of scaring myself Sh**less is about all I can take before needing a break. Maybe avoid the Blackbird, tried and tested routes seem to be R1 or Fireblade, that's where I'm going.
depends ultimately how many miles you want/expect to get out of a bike engine ? most don;t build/buy with any real intent of trying to get say 30k
miles out of the engine.. but no doubt many do !!
part of the appeal is the simple nature of changing engine and the cheap supply - say £500-£1500 for the entire plant
The only way I would change to a CEC would be for a highly tuned 2.0 - say 225+hp to make it worthwhile.. I've been in mild 160/170hp CEC sevens
that don;t inspire me personally... Problem is, to get that 225hp+ you'd be into similar/more money for the engine/box alone than what woudl
build an entire BEC kit car..
I've every intention of using the car, I'm a bit masochistic - the idea of having to concentrate hard for a 4 hour trip to see my friends
doesn't scare me, in fact I find it rather inviting after years of driving my slow diesel commuter while the fun car is off the road 
In fact
I'd consider using it daily to brighten up my country-lane commute. I'd happily replace engines every 30K if they were £500 a pop, but it
seems that even the oldest and least powerful R1 on fleabay is £600. That said, I suppose at ~5K a year that probably works out under a hundred quid a
year for a consumable engine.
If I were going to be going CEC I'd be throwing in a 300hp/300lbft 3S-GTE, atom-style rear engine. I can source these for ~500-750 inc gearbox at
200hp standard and do the few mild modifications required to get to 300 for another few hundred. I know I could make that engine last for a decade
without effort, using it as a daily commuter. With a BEC I'd been putting the R1 first (I'm used to working with the R6 engine in a single
seat racer) and I'm no stranger to BE's anyway, I've taken a carb'd 4pot bike engine and megasquirted 'n' sparked it,
so really my concerns are solely lifespan/running costs versus versus a fairly fit and forget car engine. Of course the car engine would be approx 3x
the weight of the bike engine, require much more space and stiffer chassis.
I'm going to be designing my own from scratch (again, masochistic tendencies) so I can pick placement/layout etc myself. I've already been
developing an electronic paddle shift for the fun of it and I have people around me that are used to designing race car chassis and suspension systems
so it seems the sensible way to go.
[Edited on 5/8/10 by coyoteboy]
[Edited on 5/8/10 by coyoteboy]
quote:
Originally posted by coyoteboy
Of course the car engine would be approx 3x the weight of the bike engine, require much more space and stiffer chassis.
But on thinking about it, a 300hp CEC at 700kg is ~430hp/ton, 300lb ft @3500rpm.
A 500kg BEC with an R1 engine is only 300hp/ton, 20lbft at 10Krpm .
The tradeoff in that sense is a no-brainer. I suppose in corners and stopping the extra weight is a penalty, but the donor car copes admirably 1400kg
so I suspect that a well-designed chassis and suspension would deal with that extra pendulus weight and keep the power to the tarmac - it seems bike
engine cars spin for 50% of their acceleration!
[Edited on 5/8/10 by coyoteboy]
The donor car is a barge in comparison to a BEC. You need to get a ride in one to understand the point... and even then you don't get a true impression of what it's like with just the driver. Comparing the numbers means very little. Ride in one and you'll either have to have one or you'll never go near one again. It took about 30secs to convert me.
quote:
Originally posted by coyoteboy
Well I used to be not far from Manchester myself but I'm now in Glasgow (not ideal weather or roads for a kit lol) and only visit Manchester area one a month or so these days. A quick ride along would be fun I think, might convert me as you say! I've been a low-down torque monster for a long time.
It's also quite difficult to compare torque for BEC v CEC. There seems to be a common misconception that bike engines lack torque due to figures
being quoted at the crank. What you really need to consider, is that bike engines have a torque multiplier in the form of a primary reduction gear. In
the real world, BEC torque actually isn't as low as it would first appear............
Phil
quote:
Originally posted by Hellfire
It's also quite difficult to compare torque for BEC v CEC. There seems to be a common misconception that bike engines lack torque due to figures being quoted at the crank. What you really need to consider, is that bike engines have a torque multiplier in the form of a primary reduction gear. In the real world, BEC torque actually isn't as low as it would first appear............
Phil
With respect, I'm far from clueless about power and torque, I've a fairly reasonable engineering background While I'm still
researching the gearing behind bike engines but I would guesstimate that even taking bike gearing into account something like an R1 would struggle to
put the same values to the wheels as a much larger displacement turbocharged lump.
What are the primary and secondary reduction ratios of something like the R1? As you say, if the 70lbft is multiplied by something like 5:1 it could
be comparable. That said, what's the curve like? The 3S-GTE has a flatish curve from about 3000rpm to redline.
[Edited on 5/8/10 by coyoteboy]
Specs, found from 'tinternet;
Primary Reduction Ratio: 65/43 (1.512)
Secondary Reduction Ratio: 45/17 (2.647)
Gear Ratio - 1st Gear: 38/15 (2.533)
So looking at 1st, torque at hub, only to compare in a reasonable number of lines of text :
70lbft * 1.5 * 2.5 = 263lbft at the output sprocket. Then of course scaled further by final drive/chain-sprocket combination Typical values?
vs
300lbft * 3.583 (1st) * 3.93 (final) = 4,224lbft
I'd say my comment that the CEC posing better torque figures at 300/300 was a fair one, even after transmission unless the final drive on the BEC
is 16:1? Vmax of about the same (140ish) at redline 5th.
[Edited on 5/8/10 by coyoteboy]
quote:
Originally posted by coyoteboy
Specs, found from 'tinternet;
Primary Reduction Ratio: 65/43 (1.512)
Secondary Reduction Ratio: 45/17 (2.647)
Gear Ratio - 1st Gear: 38/15 (2.533)
So looking at 1st, torque at hub, only to compare in a reasonable number of lines of text
70lbft * 1.5 * 2.5 = 263lbft at the output sprocket. Then of course scaled further by final drive/chain-sprocket combination Typical values?
vs
300lbft * 3.583 (1st) * 3.93 (final) = 4,224lbft
I'd say my comment that the CEC posing better torque figures at 300/300 was a fair one, even after transmission unless the final drive on the BEC is 16:1? Vmax of about the same (140ish) at redline 5th.
[Edited on 5/8/10 by coyoteboy]
RR - while it was late when I was reading/writing it, I'm fairly sure I've not missed anything, in fact I have agreed with every (technical)
statement you made in that article, however you have simply ignored the fact that only certain gearings exist/are usable. You can't simply
abstract torque completely because it suits you. I don't just say "ahhh" because someone has written an article and bow without
question, TBH publishing an article in a jap performance mag might please you and offer forum willy-waving ability to those who are easily impressed,
but it means nothing. Especially as your quoted engines, in the article, are rated at the same power. The point I was making is that you cannot gear
the bike engine low enough to produce the same torque as the car engine, at the wheels. You could to out-do SOME car engines, but not the one in
question.
Well you could but you'd have a lot of sprockets to place. You may have twice the RPM to play with but that still only gives you twice the torque
at the wheels when put through appropriate gearing to bring it back to road wheel speeds, and that figure is still half that of the car when put
through appropriate gearing. In my road car ny first gear gives me approximately the same gearing as the above bike engined car with a 4:1 diff
attached, roughly 15:1. So while I get from 0-30 with 4200lb/ft at the hubs, a bke engine/box might get from 0-60 with 1050 at the hubs due to its
double RPM limits. But scale that back further so 1st is 0-30 as it is in the car (got another 2:1 sprocket somewhere?) and you have 2100lbft, still
half that of the car producing half the linear force to accelerate the same mass. Even looking at the fact that the CEC will be 50% heavier, F=ma =
At the end of the day the car engine still has the advantage due to higher torque (at the wheels)/weight ratio, regardless of engine RPM.
Your bike engine can scream away all it likes but ultimately its crank torque is limited by its low crank offset and small piston size. To compensate
it needs to be multiplied by the gearbox (as you say), but unless physics has changed significantly in the last few years, if you want to
approximately the same roadwheel speeds to keep it usable as a car, you're limited in your gearing choices and your bike engine will not compete
with a car engine of twice the torque achieved at half the revs? Your points rely on an engine of equivelent power, the ability to do work at a
certain rate. If you pitted a bike engine of 300hp/150lbft against my car engine of 300hp/300lbft then the fact that your bike can do 15000rpm would
of course mean you could scale it with a gearbox and achieve exactly the same performance (assuming area under the curve is the same and we dont have
one flat torque curve and one peaky one). But this isnt the case here, or anywhere that I'm aware of excepting maybe custom one-off turbocharged
monster bikes. You could, of course, gear it mentally so all 6 of your gears fall within my 1st gear speed ranges and you might beat the car engine
off the line, but then the CEC would just change to second and walk away as you bounce off the limiter
Gearing can get you so far, but it isn't the ultimate answer as the real world is limited. I totally agree (never even came close to making a
statement to the contrary) that some bike engine/gearing combinations can out-perform car engines with more torque, but seeing as we were discussing
two very specific examples, I can only assume you didn't read that properly or your own maths would have landed you with the same conclusion.
[Edited on 6/8/10 by coyoteboy]
If what you want is torque then yes go with a CEC. Thats not why you'd have a BEC....
You're comparing apples and oranges. You know what an apple tastes like but not an orange. Then you're asking if an orange (which
you've never tried) tastes as appley as an apple. Just taste an orange and see if you like it.
I'm comparing apples and oranges because the two in question are vastly different powerplants. The car engine is a lot heavier and less fun to
throw around, I agree. Its less noisy too. But I suspect that outside that a large percentage of the difference is psychological. This is why plenty
of BEC owners seem to try to explain away their cars lack of drag strip performance etc, relying on the cornering/braking etc of the lighter vehicle.
Thats wholely understandable and acceptable, and a perfectly justifiable position. I hope it didn't come across as "one's better than
the other" as it wasn't intended to, until our rabbit friend above jumped in and tried to teach me a gearbox lesson I was quite happy
accepting that they are apples and oranges to some degree and that an orange in my case may suit my driving better than an apple. On closer thought,
at the end of the day it boils down to mass and torque at the hubs. The BEC has lower mass but lower torque at the hubs than can be very easily
achieved with a £500 car engine/box with a little more mass. Now that higher mass will make a fairly vast difference to handling too, not just
acceleration as we're not drag merchants.
My point, at the end of all that, is that if I were looking at a zetec or an R1 it would be a much closer call as it could be geared to get the same
torque at the hubs within the same usable speed range, and the only real difference would be weight. Ths would tip it in favour of the bike engine.
But when comparing to a car engine of notably higher power AND torque, im thinking the mass of the engine is cancelled well and truly apart from when
we think about stopping and cornering. I think a large percentage of the "fun" of driving a BEC is from the psychological grin factor of
stupid RPM and ultimate cornering. That's a valid point, and could well persuade me. But in the comparison above I still would vouch that the CEC
would be better performing in any real situation not involving stupendous cornering on a track. I compare it to some rally training I had, where we
were given different cars to time trial on the same track, a group n scoobie and a 1.4 pug 106. The 106 was nearly as fast (1 second a lap off, mainly
lost on the straights) and was far more fun to throw around. I can accept that. But I'd rather be driving a scoobie on the streets as long
straights and overtakes are far more prevelant than corners requiring stupendous grip and braking (if you drive reasonably legally and with some
thinking time in bends). I'd probably pick the 106 again for the full day if I went back as it was far more fun, cheaper to fix and easier on
fuel. But I'd then hand the keys back and get into something akin to the scoobie to go home.
I suspect this is because I've not tried driving a 106 like a nutcase around the public roads, but I still am aware I'd be overtaken by a
scoobie on anything more straight/wet
[Edited on 6/8/10 by coyoteboy]