kb58
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| posted on 4/9/05 at 02:17 AM |
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Correct my impression of BECs
I'm nearing the end of my car-powered mid-engine Mini build (see sig), and I can't help but think about what might be next (if all the
stars line up...)
I know just enough about BECs to have some impressions I'd like to get out here and have you comment on them to correct my thinking. The
following assumes the drivetrain is mounted mid-engine (not in a Mini this time though.)
1. A bike engine doesn't have enough torque to push a car. I have no proof of this though, and I've never gotten a ride so don't
yell at me. (I live in southern California where it's very unlikely I'll ever get a ride in one.) What type of performance can be
expected from a injected R1 in a 450kg car?
2. With no flywheel, starting out must be very tricky. Just how annoying is it?
3. The drone of the exhaust must be tiring, is it? Do you wear ear plugs?
4. A $3200 Quaife diff/reverse/center section, while a wonderful all-in-one solution, is very expensive. While I see ways around it, what's
the consenses on the unit. Is it really worth it as opposed to the "diff in a can + electric reverse"?
5. Pushing 2-3x the weight, I'd expect the bike engine and especially the tranny won't last long.
6. How long does the clutch last? I realize this depends on a lot of things.
7. I hear the R1 can be used for track days without a dry-sump, while the Hayabusa needs one. True? This is important because the dry-sump is very
expensive. While the Haybusa has the advantage of more torque, the R1 is very attractive since it weighs less, costs less, and revs higher.
I'm looking forword to your replies.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Hellfire
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| posted on 4/9/05 at 07:03 AM |
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Hi Kimini,
Have a look at this website. http://www.zcars.org.uk/
Also, MK Engineering has done one... oh and currently doing a Fiat 500  
Answers to what i can:
2. No problems.
3. Depends how far you go and how much you like the sound, you can make them quiet you know  but generally yes it can become tiresome after 90
minuts or so.
4. Why have reverse - generally speaking we have had a BEC for over a year and only once found it a problem. Narrow road, oncoming car scenario.
5. Not true... the ratio's are higher so car weight is proportionally reduced to more like 1.5 times the weight.
6. We did 4500 miles with no problems. Clutch is MUCH easier to change. Typically 20 minutes can see a new set of plates/steelies in if you've
done it a few times/ no what you're doing.
7. Varied and strong opinions on this one. Engine specific... dry sump's have their own set of problems and are by no means a guarantee on any
bike engine. Most commentators recommend Huya/ZX12R to be DS, we haven't - we have used a z-cars chopped sump and baffle kit with no problems so
far. (No track days yet though - but the engine it was designed for did plenty of track days)
Have a look at the Z-cars Website... we have Video's on our site to HERE have a look and
see what you think!
ATB (S)
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donut
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| posted on 4/9/05 at 07:53 AM |
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If your mini really is 450kg then you should have one quick mini!!!!
The Z cars steel R1 powered mini was about 530kg ish and the guy said it was a little heavy, still went like a rocket though!!!
Have fun and tell us what it's like..... cos i fancy one but with a 2 litre zetec, front engine, rear wheel drive!!
[Edited on 4/9/05 by donut]
Andy
When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car.
http://www.flickr.com/photos/andywest1/
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JoelP
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| posted on 4/9/05 at 09:06 AM |
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he says not in a mini this time!
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smart51
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| posted on 4/9/05 at 09:17 AM |
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A 1 litre bike engine has more torque than a 1 litre car engine and there are plenty of 1 litre ordinary cars here in Europe that weigh twice as much
as a locost. No problems there.
R1 in a 450kg car = 0-60 MPH in 3.5 to 4 seconds, I'm lead to believe. They are fast. This is largely due to the fact that you can stay in 1st
upto 55 maybe where as the lower rev limit of a car engine means that you have to change into 2nd at around 30. Also a locost is about 1/3 of the
weight of a normal car which gives about 3x the acceleration.
Pulling away from rest can be a bit tricky the first few times. A bike clutch is designed for hand operation. Your left foot is not as sensitive.
Practice. Also, fitting a stiffer clutch spring helps.
Exhaust noise is not a drone, it's a wale! With a proper silencer, it's no louder than some cars.
Who want's to go backwards! Get out and push. A 450kg car is light.
A car and driver is 2x the weight of a bike and rider but the final drive ratio and smaller wheel sizes mean that the load on the engine is more like
1.5x This is just the average load. Peak load is whatever the engine can deliver and is not related to the vehicle. If the engine can dliver 100Nm
then 100Nm is sent through the transmission whether the bike and rider weigh 250kg or the car and driver weigh 500kg. Big bike engines are well up to
the job.
Most people are happy with a sump baffle in their R1 engine. Some say that overfilling the oil by 250ml is enough. You could do both of course.
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uklee70
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| posted on 4/9/05 at 10:30 AM |
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Hi I have looked at your site and what a great mini!!!
I had the Zcars R1 mini and it was a great car but !!!!!
It was so loud ear plugs all the time this car had a solid mounted engine and at 6500 rpm there was a resinance that went through the shell and was
like a drum it was a real pain
I know the cars now have rubber mounted engines so this will be better
I am also the loony that is doing the fiat 500 speedster with the tuimph triple
engine
I have used the Quaife chain diff @ £600 and no reverse even when I had the mini this was not a problem.
This is not a shopping car and If I did go to the shops I'd open the boot and find a bloody engine in the way.
I feel if you are looking for a fun weekend / trackday car you can't beat a bike engine. As soon as you do your first clutchless sequencial
gearchange you are hooked!!!!!!
Just my 2 pence worth or 2 bucks worth!!!
PS is the exchange rate that bad at the moment
Lee
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ChrisGamlin
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| posted on 4/9/05 at 10:38 AM |
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/scratched record mode on
You need to remember that torque at the engine has no relation to acceleration of the car, its torque at the wheels that counts. If you look at it
this way, the torque at the wheels produced by a BEC is about the same as an equivalently powered (bhp not torque) car engine car, but with the
advantage of less weight and a close ratio sequential gearbox.
A 450kg RWD R1 powered BEC will hit 100mph in 9-10s, plently quick enough!!
Also the weight, as Hellfire mentions, isnt such a difference as first impressions would suggest. Firstly the bikes are designed to be ridden with
people on them, ie 180kgs for the bike plus 2 x 80kgs for rider and pillion, plus probably more to cater for heavier people / luggage etc. If you add
that lot up you're looking at around 350-400kg designed laden weight. In conjuction with gearing on the BEC thats 50% lower than on the bike, I
dont think that a 500kg car with driver puts a huge amount more stress on the engine and gearbox.
As to dry sumping, if fitting in a RWD mini then you'll likely be fitting the engine transversely, same as in the bike. In this scenario, I
would say that probably neither engine would need a dry sump. I believe a lot of 'busa powered Radicals dont have dry sumps because when mounted
transversely, oil surge is less of an issue, although a lot do partially because a busa engine is a fairly large investment so people are prepared to
invest in dry sumps etc to protect the investment.
An R1 certainly shouldnt need a dry sump, just a baffle plate.
Have a look on the US based DSR Forum as they run various 1L bike engines in their cars and have a lot of knowledge
on the engines and their weaknesses, which need dry sumping etc.
Chris
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kb58
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| posted on 5/9/05 at 03:18 AM |
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Thanks guys, this moves me closer to choosing a bike engine for the next project. While it's still a ways off, it doesn't hurt to start
thinking about it now.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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G.Man
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| posted on 13/10/05 at 10:02 PM |
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Current Nurburgring record for a road legal car is held by a radical SR8, essentially a V8 made from 2 bike engines...
Prior to that it was held by the Donkervoort (see here) which was a
car engined 7...
Took one hell of a bike engine to outpace the car engine... gotta love the aerodynamics of the 7 tho..
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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Hellfire
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| posted on 13/10/05 at 10:06 PM |
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Very nice!!
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Gav
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| posted on 13/10/05 at 10:39 PM |
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id never get through the doors of that thing!
but yeah vey nice
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ChrisGamlin
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| posted on 14/10/05 at 11:50 AM |
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quote:
Originally posted by G.Man
Took one hell of a bike engine to outpace the car engine... gotta love the aerodynamics of the 7 tho..
Very nice but the Donkey was hardly a run of the mill car engine was it, supposedly about 400bhp of Audi 1.8T Turbo under the bonnet! Compare the
performance of a £1k bike engine with a £1k car engine (need to include buying gearbox etc) and Id say the bike engine'd car will give you
better performance for your money.
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Hellfire
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| posted on 14/10/05 at 11:56 AM |
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So, at what price do you reckon they'd break even power wise. (Or wouldn't they?)
Not too familiar with the prices of car engines.
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kb58
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| posted on 14/10/05 at 01:24 PM |
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I'm the guy who started this thread,
The big difference is torque. With a given bike and car engine both making 160hp, all it means is they'll have the same top speed, nothing
more. The car engine though (assuming probably twice the displacement) will have about 50% more torque. Torque is for acceleration and is infinitely
more useful day-to-day. Of course if the bike engine produces enough torque to spin the tires, that's enough already!
I finally got a ride in a Megabusa and still have mixed feelings. While it accelerated fast enough for me, overall it was rather... what, frantic?
Cruising at 60mph means about 5400rpm. I noticed the owner and driver subconsciously reaching for another gear and there wasn't one. Said
another way, it wasn't very relaxing, kind of like a Tazmanian Devel, very frantic, high strung, and energetic. That's a great thing for
the track but I'm not so sure about living with it on the street.
I realize the bike engine weighs a lot less and has the sweet tranny, but the question is, do those two features outweight the other issues. I guess
it'll always be an individual's own personal opinion. As of right now I've swayed back to a car engine.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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G.Man
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| posted on 14/10/05 at 02:35 PM |
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quote:
Originally posted by ChrisGamlin
quote:
Originally posted by G.Man
Took one hell of a bike engine to outpace the car engine... gotta love the aerodynamics of the 7 tho..
Very nice but the Donkey was hardly a run of the mill car engine was it, supposedly about 400bhp of Audi 1.8T Turbo under the bonnet! Compare the
performance of a £1k bike engine with a £1k car engine (need to include buying gearbox etc) and Id say the bike engine'd car will give you
better performance for your money.
Actually it was a 350bhp Audi 1.8T motor, my Cosworth 350bhp has cost me £2000 there is no way you will get a 350bhp Busa motor for that! or any
350bhp bike motor, however, power to weight ratio wise the cost difference is negligible...
The real comparison comes from a 175bhp Busa motor that weighs 100kgs yet a 204bhp stock cosworth motor with box weighs closer 300kgs...
Yes if you are on a budget, its likely that you will get better performance for a spend of £1k from a BEC, however, at a spend of £250 the car engine
spanks the bike again...
Everything is relative to something else, one thing you can say for certain is that the car itself will give great performance with any engine
compared to your tin box saloon car... mainly due to weight, and there is no way the bike engine would give anything like good performance in a tin
box sierra... Its the weight (or lack of it) in a 7 that means a bike engine gives great performance on the boil...
But that weight brings other issues when combined with aerodynamics... like the tendancy for the car to want to get airborne at high speeds...
Like Gav I could never get in that Donkey, not a 6' 5" so I will be happy with my MNR instead...
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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G.Man
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| posted on 14/10/05 at 02:39 PM |
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quote:
Originally posted by kb58
I'm the guy who started this thread,
The big difference is torque. With a given bike and car engine both making 160hp, all it means is they'll have the same top speed, nothing
more. The car engine though (assuming probably twice the displacement) will have about 50% more torque. Torque is for acceleration and is infinitely
more useful day-to-day. Of course if the bike engine produces enough torque to spin the tires, that's enough already!
I finally got a ride in a Megabusa and still have mixed feelings. While it accelerated fast enough for me, overall it was rather... what, frantic?
Cruising at 60mph means about 5400rpm. I noticed the owner and driver subconsciously reaching for another gear and there wasn't one. Said
another way, it wasn't very relaxing, kind of like a Tazmanian Devel, very frantic, high strung, and energetic. That's a great thing for
the track but I'm not so sure about living with it on the street.
I realize the bike engine weighs a lot less and has the sweet tranny, but the question is, do those two features outweight the other issues. I guess
it'll always be an individual's own personal opinion. As of right now I've swayed back to a car engine.
Yeah that was why I went to car engine, although now I kinda wish I had gone bike engine after seeing Cyprus car tax rates for a 2.0 car...
The Cossie will pretty much keep up with anything, will be far more forgiving of a wrong gear, I can turn the power down (greddy profec spec B type
II) to make it more economical and forgiving on the road, and for an extra £190 I have a quickshifter going on which will come close to the sequential
experience (yeah I know its not the same having raced 250 karts for many years but its good enough for me)...
BEC busa for the track, high performance car engine for the road and trackdays...
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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smart51
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| posted on 14/10/05 at 03:50 PM |
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Bike engined cars are a bit frantic but my daily driver is a bit sedate. The vortex is purely for fun. I had a ride in a car with a 2.0i Zetec engine
and it was quick but not compelling - I'm the all or nothing type. I have a ride in a hayabusa engined car and thought "I am going to
die". That, the cost and the complexity of installation of a good 4 cylinder engine led me down the BEC route. I guess it's not for
everyone.
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ChrisGamlin
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| posted on 14/10/05 at 05:29 PM |
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quote:
Originally posted by kb58
The big difference is torque. With a given bike and car engine both making 160hp, all it means is they'll have the same top speed, nothing
more. The car engine though (assuming probably twice the displacement) will have about 50% more torque. Torque is for acceleration and is infinitely
more useful day-to-day. Of course if the bike engine produces enough torque to spin the tires, that's enough already!
No offence but that is simply not true! I'll point you towards my previous reply to give the reasons why - basically a torque figure of X at the
engine gives absolutely no indication of the amount of acceleration the engine can provide!!!
As for G-Man's £250 challenge, I know what you're saying but just for a bit of fun I'll propose a CBR1000 or a GSXR1100 engine in
that price bracket which will certainly wee on the chips of any £250 car engine'd install
[Edited on 14/10/05 by ChrisGamlin]
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OX
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| posted on 14/10/05 at 05:47 PM |
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quote:
Originally posted by smart51
I had a ride in a hayabusa engined car and thought "I am going to die".
my driving isnt that bad is it
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kb58
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| posted on 14/10/05 at 06:16 PM |
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quote:
Originally posted by ChrisGamlin
No offence but that is simply not true! I'll point you towards my previous reply to give the reasons why - basically a torque figure of X at the
engine gives absolutely no indication of the amount of acceleration the engine can provide!!!
I took that into account. A Hayabusa makes 100ft-lb torque at 7000rpm. A Honda K20 makes 150ft-lb at 6000rpm. So comparing "apples to
apples", gearing the bike engine down, and torque up, means the Hayabusa makes an effective 7/6 * 100 = 116ft-lb torque at 6000rpm. Yes the
bike engine is lighter by roughly 200lbs, or around 20% of the total car weight, but it still doesn't have the equivalent torque/pound as a
modern automobile engine.
I realize the BEC will better at cornering and braking due to the lower weight, but that's a separate issue, as is the sweet tranny.
I really haven't made up my mind eithe way...
[Edited on 10/14/05 by kb58]
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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smart51
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| posted on 14/10/05 at 07:35 PM |
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quote:
my driving isnt that bad is it
No Mr. Ox. Your road manners were impecible.
I actually thought "I am going to kill myself" but people could take this another way
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smart51
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| posted on 14/10/05 at 07:46 PM |
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quote:
Originally posted by ChrisGamlin
... a torque figure of X at the engine gives absolutely no indication of the amount of acceleration the engine can provide!!!
[Edited on 14/10/05 by ChrisGamlin]
Quite right. This is a flawed arguement used by Diesel fancier.
Torque at the flywheel is multiplied by the gear ratios to give torque at the wheels. This is a guide to acceleration. If you have taller gears to
compensate for lower rev limits (diesel and to a lesser extent CEC) then the torque at the road wheel may actually be less.
Acceleration = torque x gear ratio x rev range / weight.
a 200Nm diesel making 100 BHP at 4500 RPM would only have 30% of the acceleration of
a 150Nm petrol making 100 BHP at 6000 RPM which would have 50 % of the accleration of
a 75Nm BEC making 100 BHP at 12000 RPM
with each geared to make 30 MPH in 1st gear.
OK in practice, a BEC is geared to give 50 or 60 in 1st but the comparison still stands.
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ChrisGamlin
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| posted on 14/10/05 at 07:50 PM |
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quote:
Originally posted by kb58
I took that into account. A Hayabusa makes 100ft-lb torque at 7000rpm. A Honda K20 makes 150ft-lb at 6000rpm. So comparing "apples to
apples", gearing the bike engine down, and torque up, means the Hayabusa makes an effective 7/6 * 100 = 116ft-lb torque at 6000rpm. Yes the
bike engine is lighter by roughly 200lbs, or around 20% of the total car weight, but it still doesn't have the equivalent torque/pound as a
modern automobile engine.
[Edited on 10/14/05 by kb58]
What you havent taken into account is that the busa revs to 11k whereas the K20A only revs to around 8k(?). If you add that into the equation the
bike's high rev limit allows you to gear it much lower and still achieve the same top speed, say 11mph/1000rpm in top to achieve 120mph compared
to say 15mph/1000rpm for the K20A (although Im not sure the stock box would get you anywhere near that figure, probably nearer 20mph/1000).
Basically you need to look at torque at the wheels and ignore the engine torque. The lower gearing on the bike that is facilitated by the
higher revving engine means the engine torque is multiplied up more in the BEC than the car engine, so the resulting torque at the wheels figures for
both engines are very similar, but the BEC has the weight advantage still. In other words, if the bike and car were the same weight, they'd
perform about the same.
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ChrisGamlin
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| posted on 14/10/05 at 08:44 PM |
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Very well if you could gear it low enough, but I suspect if using the standard drivetrain its still going to be geared higher than the ideal required
for best performance, ie geared for 130-140mph tops.
Either way, with 240bhp it will be quicker than a busa Im sure.
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ChrisGamlin
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| posted on 14/10/05 at 08:51 PM |
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Just found these figures for the S2000......
6-Speed Manual
Final Drive 4.10:1
1st Gear Ratio 3.12:1
2nd Gear Ratio 2.05:1
3rd Gear Ratio 1.48:1
4th Gear Ratio 1.16:1
5th Gear Ratio 0.97:1
6th Gear Ratio 0.81:1
Plumbing those into the gearcalc spreadsheet, even on 185/50-13" it tops out in 6th at 171mph, 5th tops out at 143mph and 4th at 120mph .
Are you going for a low Sierra diff or using the S2K one?
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