Motorcycle Engine Swap

[kingfloopy]

I have been thinking a lot lately about swapping a motorcycle engine into a car. I think it may be a viable alternative to get a mix between performance and fuel efficiency (especially if gas prices keep rising). The problem is that I cannot find a lot of information about the swaps. I was thinking of a Hayabusa engine and that you would probably need a light chassis. How is the drivetrain typically set up? Is the bike transmission used or the car transmission? Any information or website links about these types of swaps would be appreciated.

J.D.

[RobC]

What sort of car are you thinking, because of the lack of torque a bike engine has the lighter the chassis the better.

Some links to get you started -

http://www.750mc.co.uk/racing/formulae/rgb.htm
http://p081.ezboard.com/bdsrforum

[Dauntless]

JD, the Hayabusa can be an excellent basis for such a project. I say 'can be' because I don't know just what you have in mind. If it is dropping an engine into a Datsun 1200 or other similar small car, then I'd say no, but if you plan to build say, a Locost then yes. In any case, the Busa can be mounted longitudinally with a prop shaft to a conventional rear end, or mid-mounted with a chain drive to a rear diff - with or without reverse. In nearly all cases the bike trans is retained, with a converted starter motor or bespoke reversing diff (such as from Quaife) used where a reverse gear is required. Heavy duty clutch springs are recommended, but that's about it.

For mid engine (race car oriented but lots of info in any case) installations, check out the Sports Racer Forum at http://p081.ezboard.com/bdsrforum

For Locost ideas, do on internet search on 'locost hayabusa'. There are some very good photos here: http://www.gulp.org/gallery/Locost-Chassis

For economy, buy a VW TDI...

[richard_sykes]

Hayabusa are very popular choice for this.

[graham bahr]

Originally Posted by kingfloopy

. How is the drivetrain typically set up? Is the bike transmission used or the car transmission?
J.D.

although i did see one bike engine which was fitted to a bespoke crank case which was bolted to a hewland in the back of a single seater (the owner said it wasn't worth the hassle) every otherone i've seen or heard of uses the bike transmission with a seperate reversing box if required.

what do you plan to do with it, they are great on track where you can keep the engine buzzing, but not so good for road use, without any real torque they still need to be reved even when going fairly slowly and and its tiresome going up and down the gearbox all the time.

if you want to put it in a car weighing much more than 500kgs forget it due to the lack of torque and high engine speed at which the powers developed, oh and a clutch that isn't big enough to cope with the kind of abuse that would be needed to get a heavyish car off the line

[imull]

the sport bikes arent that much better on teh economy either. we were talking to a customer today who said his only does 32 per gallon...

it is an expensive and complicated thing to do (properly) as you will be in for about 5K ion the transmission alone from memory

[Gore]

Possibly I'm being naive, but I always presumed the reason bikes are so fuel economical (right now I'd kill for 32mpg!) was that there is so much less mass to accelerate, and so much less drag to push against. In which case you'd lose most of the former and all of the latter advantage by sticking it in a car chassis, and be pretty much back at the car's initial fuel economy.

But I have been known to be wrong about these kind of things in the past.

[RobC]

Originally Posted by Gore

Possibly I'm being naive, but I always presumed the reason bikes are so fuel economical (right now I'd kill for 32mpg!) was that there is so much less mass to accelerate, and so much less drag to push against. In which case you'd lose most of the former and all of the latter advantage by sticking it in a car chassis, and be pretty much back at the car's initial fuel economy.

But I have been known to be wrong about these kind of things in the past.

Yup, also the harder you push it the quicker the mpg falls. Example being my 600, on a long steady trip it would do 45-50mpg, on a sprited ride it would do 26mpg

[graham bahr]

the trouble is bike aren't economical, they are built to give lots of power at a zillion revs, very small bikes are fairly i once had a 200cc twin which would regulary achive 80mpg, but then it only had about 20bhp and didn't rev, that wouldn't be much use in your car,
i also had a 650cc twin which on a steady motorway run at 60mph would do over 50mpg, but normal usage was more like 43mpg, and that still only had 65bhp,
i've had lots of big 4 cyl 750-1200cc bikes and they all averaged between 32-38 mpg, my current GSXR does about 35mpg so i guess in a car weighing 3 times my bike you'd get mid 20's to the gallon, when driving sensably.

i've nothing against putting bike engines in light cars, but i think its a non starter ecomomy wise, a lightly tuned torquey car engine will give far better ecomomy.

if i want ecomomy i drive my diesel car, otherwise i use my bike, which is incredably effecient compaired to my race car which does 4mpg!

[greenamex2]

My 1200cc 185mph BMW does about 50mpg. It's even got a catalytic convertor!

Weird.

[graham bahr]

Originally Posted by Denis Bassom

My 1200cc 185mph BMW does about 50mpg. It's even got a catalytic convertor!

Weird.

thats good, but whats it going to do in a car 30mpg??

[greenamex2]

Shove it in a normal weight hatchback and I reckon less than 20mpg coupled with new clutches every 5000 miles, a new gearbox every 10000 and a complete rebuild every 20000. Double these for a Caterfield type car.

I find the whole bike versus car engine debate highly amusing. Having clocked up over a 1/4 of a million miles on a variety of Japanese and German sports bikes, and numerous miles in kit and race cars I am in a better position to comment than most.

The reason bike engines produce so much power is because they are highly tuned. The reason bikes can get away with these highly tuned engines is because they weigh nothing compared to a car and they don't need much torque. The only reason bike engines last any length of time is because the average mileage of a motorcycle is around 3500 miles per year and they are so light you can't push the engine as hard (however big a hero you think you are).

If you want a car engine to match a bike one (assuming we are talking proper multivalve engines) then just tune it the same, it's just an engine after all.

The only advantages that bike engines offer are they come 'pretuned' cheaply due to mass production and they are light, because they don't have to take the same sort of abuse or mileage.

Finally, are bike engined cars faster than normal ones. On a budget AND assuming it is able to capitalise on weight, obviously yes. Remove those constraints and the answer is probably not, just look at a race involving a properly driven Jade, Stealth or LM3000 which also involves a minimally tuned bike engined Radical, the car engined car always wins.

[graham bahr]

Originally Posted by Denis Bassom

Finally, are bike engined cars faster than normal ones. On a budget AND assuming it is able to capitalise on weight, obviously yes. Remove those constraints and the answer is probably not, just look at a race involving a properly driven Jade, Stealth or LM3000 which also involves a minimally tuned bike engined Radical, the car engined car always wins.

i certainly noticed that in hillclimb and sprint circles, a bike engined verses a V8 or multi valve engine that they all stand an equil chance of winning.

i've entered sports and saloon car races in my 950kg car and beaten bike engined kit cars, although last time i had to settle for second against one, infact we had similar power to weight ratio's, although i had a far better torque to weight ratio and could make ground up on the bike engined car on the straights, the real disadvantage i had wasn't in the engine dept but that i had so much more weight to stop and corner on a very tight stop start circuit, although with a bit more weight loss and theres lots more that could come out my car, i dont recon, said mentioned kit car would of stood a chance against my wall of torque

[greenamex2]

Torque to weight ratio can certainly make a car easier to drive.

Says the guy with no torque and loads of weight up against 205's with the opposite! Ever tried driving a car with a 1500 RPM power band and 1200 RPM between gears?

[graham bahr]

Originally Posted by Denis Bassom

Says the guy with no torque and loads of weight up against 205's with the opposite! Ever tried driving a car with a 1500 RPM power band and 1200 RPM between gears?

could be worse.. 1200 power band 1500 between gears!

lost 3rd gear at lydden earlier in the year (only used 3rd + 4th there in the first place) the turbo lag coming out of the elbow and up the hill was something else altogether!

[phoenix]

All normally aspirated 4 stroke IC engines use more or less the same fuel ratio to produce power and most engines are very similar in there thermo dynamic efficiency for a given compression ratio (increases in power usually coming from improved volumetric efficiency)

Therefore all normally aspirated 4 stroke IC engines of whatever capacity require about the same amount of fuel to produce the same power, which results in little improvement in fuel economy from a lighter engine - assuming racing conditions - although improved performance over a heavier car/engine combination would of course be expected due to the increase in power to weight ratio.

On the road a lighter car would require less power to achieve the same performance as a heavier car, so improved fuel economy could be expected - but not in flat-out racing conditions. Also on the road the lean-burn characteristics of modern standard engines and management systems can be used to improve economy whereas most modified race engines will be run richer rather than leaner because of the risks to the engine in running too lean.

[kingfloopy]

Thanks for the information. Does anyone know how much a Westfield Megabusa weighs? I found one when I was looking through a copy of Top Gear magazine I bought, but there isn't a lot of chassis information. Maybe something similar to one of those might work.

J.D.

[graham bahr]

how about a diesel engined westfield if economy is your thing? there lots of fairly lightweight all alloy diesel engines out there these days