Bike engined cars - how does that work?
Discussion
So we stick a Hayabusa engine into a Mini, somehow make it all work, with some sort of sequential actuating stick-amy-bob, add some gubbins to get a reverse gear, etc. But what's it like to drive?
A Mini weighs (say) 700kg, and I presume there's relatively little torque, so do you always need to use LOTS of revs? What about rev-matching given that the engine has such light rotating mass? A bit lurchy? Clutches wear out very quickly? Are you stuck with a screamer when cruising (6000rpm at 70mph)? Can add overdrive, maybe?
A Mini weighs (say) 700kg, and I presume there's relatively little torque, so do you always need to use LOTS of revs? What about rev-matching given that the engine has such light rotating mass? A bit lurchy? Clutches wear out very quickly? Are you stuck with a screamer when cruising (6000rpm at 70mph)? Can add overdrive, maybe?
Mine is lighter than said Mini at 500kg or so so it may be different but fundamentally, it drives sort of like a normal car in as much as you recalibrate your brain to the revs. What I mean is, the gearing may be twice as short as a normal car but the redline is twice as high too so while pulling away sedately at 4000rpm or cruising at 7000rpm to do 70mph sounds mental, it doesn't feel like you're straining it and you're still "in the midrange".
It has an R1 engine and it's surprisingly tractable and torquey low down, due again to the incredibly low gearing. The actual engine torque output is obviously low but torque at the wheels is, I guess, similar to what a similarly powerful car engine would provide.
Pulling away is somewhat harder than with a car engine due to lack of flywheel effect and a grabby clutch but not too bad really.
Overall for a very light car bike engines work fantastically. Love the gearbox too and the ratios are so close you're never in the wrong gear on a trackday. The gear change is so quick and slick you can bang it up and down the gears midcorner without upsetting the car at all.
It has an R1 engine and it's surprisingly tractable and torquey low down, due again to the incredibly low gearing. The actual engine torque output is obviously low but torque at the wheels is, I guess, similar to what a similarly powerful car engine would provide.
Pulling away is somewhat harder than with a car engine due to lack of flywheel effect and a grabby clutch but not too bad really.
Overall for a very light car bike engines work fantastically. Love the gearbox too and the ratios are so close you're never in the wrong gear on a trackday. The gear change is so quick and slick you can bang it up and down the gears midcorner without upsetting the car at all.
I stuck a GPZ900R into a Fiat 500 in the eighties (mid engined). With a solid rear axle, dodgy brakes and questionable steering, the last things on your mind were reverse gears, overdrives and other such fripperies.
Good weekend project, all veering slightly towards the lethal side of things. My friend's Guzzi powered 2CV was much more sensible.
Good weekend project, all veering slightly towards the lethal side of things. My friend's Guzzi powered 2CV was much more sensible.
apotts said:
I stuck a GPZ900R into a Fiat 500 in the eighties (mid engined). With a solid rear axle, dodgy brakes and questionable steering, the last things on your mind were reverse gears, overdrives and other such fripperies.
Good weekend project, all veering slightly towards the lethal side of things. My friend's Guzzi powered 2CV was much more sensible.
Mate of mine did something similar back in the 80s - he built a Kawasaki 1000 powered Fiat 500. Engine was mounted longitudinally facing the passenger side with a propshaft off the gearbox back to a diff from an Isuzu (IRS) bolted into the back. Went like stink but was very tight for the passenger who's nose was almost pressed into the windscreen. Not a real issue as it was primarily a hillclimb racer.Good weekend project, all veering slightly towards the lethal side of things. My friend's Guzzi powered 2CV was much more sensible.
He followed that with a Kawasaki 1300 powered Suzuki Fronte (like the Whizz but slightly smaller and predecessor to the Whizz). That was blindingly fast and would regularly trouble big V8 track cars of the time (think Bathurst).
A real giant killer.
As mentioned it was difficult to get either away from the line without lots of revs but once moving it was positively evil with the amount of power and lack of weight.
R1 Indy said:
I had a 500KG kitcar with a R1 engine.
It was surprisingly easy to drive once your used to it.
The low torque was not an issue when cruising, top gear from 30mph + it just went. Obviously 10K rpm+ is went really well
The main thing that put me off was constantly dealing with this!
What sort of problems did you have with it? Mine's been pretty good so far, only trip on a recovery truck was due to a snapped throttle cable.It was surprisingly easy to drive once your used to it.
The low torque was not an issue when cruising, top gear from 30mph + it just went. Obviously 10K rpm+ is went really well
The main thing that put me off was constantly dealing with this!
lostkiwi said:
Mate of mine did something similar back in the 80s - he built a Kawasaki 1000 powered Fiat 500. Engine was mounted longitudinally facing the passenger side with a propshaft off the gearbox back to a diff from an Isuzu (IRS) bolted into the back.
Excellent! The Kwak was mounted transversely in the passenger seat area, so the chain could go straight on to the solid axle. Trailing links at the same point as the engine sprocket. 2CV disk on the rear axle (because it has a parking brake built in).A little after it was retired, I filmed a friend having a go..
https://youtu.be/6-_Hmjgjn7c
apotts said:
lostkiwi said:
Mate of mine did something similar back in the 80s - he built a Kawasaki 1000 powered Fiat 500. Engine was mounted longitudinally facing the passenger side with a propshaft off the gearbox back to a diff from an Isuzu (IRS) bolted into the back.
Excellent! The Kwak was mounted transversely in the passenger seat area, so the chain could go straight on to the solid axle. Trailing links at the same point as the engine sprocket. 2CV disk on the rear axle (because it has a parking brake built in).A little after it was retired, I filmed a friend having a go..
https://youtu.be/6-_Hmjgjn7c
There are so many myths about bike engines in cars - let me try to debunk a few of them:
1. Bike engines have low torque - well yes, the engine does, but the gearbox has a 2x reduction gear just before the output, so by the time the torque is at the wheels, it is similar to a small car engine.
2. Bike engines are lurchy and hard to drive in traffic - neither of mine have been. Get the throttle and clutch adjustment right, so that they are not just on/off switches. My car will happily sit in traffic, and do hill starts all day long. I very rarely stall it, or need to pull away with galactic revs. Equally, I have never regretted removing the reverse box when I built the car. It makes you think before you park, but I have never had to get out and push!
3. Bike engines chew through clutches - sure, if you use a small bike engine (sub 900cc) then expect the clutch and gearbox to wear prematurely, but the super bikes that we typically use tend to have beefier gearboxes and clutches. I have not worn out a clutch yet (two different engines, and I have never had to replace a clutch plate), despite 5000 miles, including 8 trackdays and 2 hill climbs. If they do fail, a clutch on a bike engine is a 30 minute job even for the untrained, so not like in a car engine.
4. On the motorway, I will be doing 18000rpm and my ears will bleed - well only if you take no care over matching your engine to your final drive choice. If you are going to build a Mini, I assume chain drive? If so, no excuse for not getting the sprockets just right to give you the ratio you need. My car cruises on the motorway at ~5000rpm, and maxes out at 135+mph at 12000rpm. It returns 35+mpg if I am not on it (although that drops to mid-teens if I am on it!). Just watch out, as the Busa tends to need a low final drive (i.e. a 3.14 not a 3.92) or you will run out of revs. this is because the Busa has a modest rev limit, and the ratios are not ideal (but the power delivery and reliability is!).
5. Bike engined cars are unreliable - any car is unreliable if you build it badly and/or dont maintain it adequately. Lots of bike engined cars do regular European jaunts without worry. My longest drive in a day is around 400 miles, and she didn't miss a beat. All of my breakdowns have been due to my wiring (frayed ignition feed, loose earth strap etc.), not the engine or gearbox.
So in summary, don't listen to all of the horror stories. Your mini will be awesome if you do some reading, and go into the project with your eyes (and ears) open! I would suggest you get on Locostbuilders.co.uk as there is wealth of knowledge, and they love a good project. Good luck!
1. Bike engines have low torque - well yes, the engine does, but the gearbox has a 2x reduction gear just before the output, so by the time the torque is at the wheels, it is similar to a small car engine.
2. Bike engines are lurchy and hard to drive in traffic - neither of mine have been. Get the throttle and clutch adjustment right, so that they are not just on/off switches. My car will happily sit in traffic, and do hill starts all day long. I very rarely stall it, or need to pull away with galactic revs. Equally, I have never regretted removing the reverse box when I built the car. It makes you think before you park, but I have never had to get out and push!
3. Bike engines chew through clutches - sure, if you use a small bike engine (sub 900cc) then expect the clutch and gearbox to wear prematurely, but the super bikes that we typically use tend to have beefier gearboxes and clutches. I have not worn out a clutch yet (two different engines, and I have never had to replace a clutch plate), despite 5000 miles, including 8 trackdays and 2 hill climbs. If they do fail, a clutch on a bike engine is a 30 minute job even for the untrained, so not like in a car engine.
4. On the motorway, I will be doing 18000rpm and my ears will bleed - well only if you take no care over matching your engine to your final drive choice. If you are going to build a Mini, I assume chain drive? If so, no excuse for not getting the sprockets just right to give you the ratio you need. My car cruises on the motorway at ~5000rpm, and maxes out at 135+mph at 12000rpm. It returns 35+mpg if I am not on it (although that drops to mid-teens if I am on it!). Just watch out, as the Busa tends to need a low final drive (i.e. a 3.14 not a 3.92) or you will run out of revs. this is because the Busa has a modest rev limit, and the ratios are not ideal (but the power delivery and reliability is!).
5. Bike engined cars are unreliable - any car is unreliable if you build it badly and/or dont maintain it adequately. Lots of bike engined cars do regular European jaunts without worry. My longest drive in a day is around 400 miles, and she didn't miss a beat. All of my breakdowns have been due to my wiring (frayed ignition feed, loose earth strap etc.), not the engine or gearbox.
So in summary, don't listen to all of the horror stories. Your mini will be awesome if you do some reading, and go into the project with your eyes (and ears) open! I would suggest you get on Locostbuilders.co.uk as there is wealth of knowledge, and they love a good project. Good luck!
T0MMY said:
What sort of problems did you have with it? Mine's been pretty good so far, only trip on a recovery truck was due to a snapped throttle cable.
In 2 years and 10K (hard) miles:3 clutches, 2 clutch cables, 1 accelerator cable, 1 gear shift cable, 1 sump, 1 radiator, 1 diff, 1 reverse motor and 2 SP30's.
However the engine actually survived which was my biggest worry item!
R1 Indy said:
In 2 years and 10K (hard) miles:
3 clutches, 2 clutch cables, 1 accelerator cable, 1 gear shift cable, 1 sump, 1 radiator, 1 diff, 1 reverse motor and 2 SP30's.
However the engine actually survived which was my biggest worry item!
3 clutches in 10,000 miles!? Mine was on the car when I got it so no idea the total mileage (although the car itself is 10 years old) but I've done about 5000 miles without an issue. I was also going to say (hard) miles but then I thought that there are no "soft" miles in a BEC3 clutches, 2 clutch cables, 1 accelerator cable, 1 gear shift cable, 1 sump, 1 radiator, 1 diff, 1 reverse motor and 2 SP30's.
However the engine actually survived which was my biggest worry item!
I said all this in a previous thread about kitcars but to my mind, at the low end of the price range, a bike engine seems far and away the best option for a track or fast road car that's going to be driven very hard. The alternatives on a sub-10k budget are either pintos and xflows or k-series/zetecs/redtops etc. and I think a bike engine is far more exciting and definitely faster, at the expense of some reliability and usability. If you can afford a swanky new 200+bhp Duratec or S2000 engined car, perhaps even with a sequential box, then to me that's better as you have the manic performance without the downsides but it's a different league cost wise.
Rich1973 said:
You only think low torque is a problem if you have never driven a bike engined car!
I helped a mate build a Stuart Taylor locost some years ago using a fireblade engine and it was nuts. 0-100 in about 8 seconds and 440kg total weight. The rawness and speed was breathtaking.
No offence but I think your mate was pulling your leg with that 0-100 time! BECs are very quick to 60 and not bad to 100 but nowhere near 8 seconds, not with an n/a fireblade engine anyway.I helped a mate build a Stuart Taylor locost some years ago using a fireblade engine and it was nuts. 0-100 in about 8 seconds and 440kg total weight. The rawness and speed was breathtaking.
You're right about the torque though, I can trundle around at low revs just fine and in fact I rarely go anywhere near the redline on the road, even when making brisk progress . Makes it feel all the more mental when you do redline it too.
Edited by T0MMY on Wednesday 28th October 22:42
A seven is going to be a totally different proposition to a full bodied car as the mini puts the engine right behind your ears .
I ran bike engines I'm my reliant for a few years and enjoyed it but the constant chain maintainence get old quick and being in a closed box the noise and smells at cruising speed are a pita too. Since going to a car engine I can cruise comfortably and go backwards without making horrendous noises and jerking .
if I had spent a day in a bike engined mini before building my car I would have gone car engine straight away . The whole sequential shift bike rev range is pretty special especially for track use but for me too many drawbacks for a road car for any distance driving
I ran bike engines I'm my reliant for a few years and enjoyed it but the constant chain maintainence get old quick and being in a closed box the noise and smells at cruising speed are a pita too. Since going to a car engine I can cruise comfortably and go backwards without making horrendous noises and jerking .
if I had spent a day in a bike engined mini before building my car I would have gone car engine straight away . The whole sequential shift bike rev range is pretty special especially for track use but for me too many drawbacks for a road car for any distance driving
Wow - thanks all for sharing your thoughts, and explaining the myths. I'll have a look at that lowcost forum.
What got me started was a complicated but smart Honda N600 project in the USA. Documented fully somewhere, but this was the result: http://www.speedhunters.com/2015/09/a-homebuilt-ho...
What got me started was a complicated but smart Honda N600 project in the USA. Documented fully somewhere, but this was the result: http://www.speedhunters.com/2015/09/a-homebuilt-ho...
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