trogdor
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| posted on 3/6/06 at 12:39 PM |
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sorry if this is a ditzy question to ask
hi, in the long term future i want to convert a car to bec power, i have looked into it and the car i am considering is viable as the torque of most
bike engines is as much as the oringinal engine but with at least twice the power which sound pretty good!
anyways i know that some cars have a chain diff transaxle thing but what do people do to enable them to run a propshaft and normal diff? i had a quick
search but couldn't easily find anything.
many thanks
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ChrisGamlin
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| posted on 3/6/06 at 12:50 PM |
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What are you thinking of converting?
To use a prop, we use a prop adapter such as one of these
This one's from Attitude Roadsters but you can get them from most
kit car manufacturers / suppliers such as MK, Stuart Taylor, Kit Car Workshop etc. They bolt on instead of the sprocket and then the prop in turn
bolts to that.
To be honest though engine torque is largely irrelevent and very low down the pecking order on things to look at when considering a conversion. To
start off with, the car weight is the most important thing. I dont know what you're thinking of converting but if you can't get it under
550kgs all up including the bike engine or 600kgs at the absolute maximum, then its not worth considering.
cheers
Chris
[Edited on 3/6/06 by ChrisGamlin]
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trogdor
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| posted on 3/6/06 at 01:01 PM |
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well its prob going to be a saab 96, if i ever finish the one i am modifing now! i have seen a midget with an R1 engine and an midget is a similar
weight to an 96, well they feel about the same when pushing them around the garden. the engine i was thinking of was the truimph triple, prinicpally
of cheapness and the high torqueness of it.
is this a viable proposition?
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ChrisGamlin
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| posted on 3/6/06 at 01:02 PM |
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I don't know, when I think SAAB I think large family car 
How heavy is it with the current engine?
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ChrisGamlin
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| posted on 3/6/06 at 01:09 PM |
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A quick Google reveals it's one of these?
This site says the unladen weight is 950 kgs(2094 lbs) so sorry to be the bearer of bad news
but if that's correct, I'd say you're going to struggle to shed something like 500kgs out of that (including current engine) in
order to allow a BEC engine to be installed and stay around ~550kgs
Chris
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trogdor
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| posted on 3/6/06 at 01:17 PM |
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yep thats the one, is it really that heavy? its a pretty small car! but i guess it is a saab and they build them like tanks. i was expecting about
750kg which would be ok with the engine removed. oh well its gonna be hard to remove 500 kgs.
can u tell me why its such an issue? the original engine has is 65hp and 85 lb/ft engine and the truimph triple stats i found say 140bhp and 105
lb/ft that seems to me that it would be ok on this car? i guess i am missing something really obvious! hence the title.
EDIT - i also found that site, but thats the early two stroke slightly smaller car, so its prob gonna be heavier than that! oh well its a long term
thing anyway. i am currently putting an zetec in my current one!
[Edited on 3/6/06 by trogdor]
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dmottaway
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| posted on 3/6/06 at 01:22 PM |
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I think the problem is WHERE the engine produces the power. to get the car rolling, you need a fair amount of power down low in the rpm's else
you end up burning your clutch and not moving at all.
dave
Somewhere, in Texas, a village is missing its idiot.
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ChrisGamlin
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| posted on 3/6/06 at 01:23 PM |
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No probs. Basically it would still fundamentally move under its own steam, but bike engines / gearboxes / clutches are designed to drag along maybe
300kgs of bike and rider. In a car the overall gearing is lower so a car and driver say around the 500kg mark put more stress on the mechanicals, but
maybe not as much as you'd initially think considering its twice the weight. Add another 300kgs though (say 750kg car + 75kg driver), and
you're going to be pushing it beyond its limits and will have lots of reliability issues. It also won't be that quick, quicker than the
standard engine no doubt, but something like a 1.6 Vauxhall 16v engine or a Zetec with similar power to the bike engine will give you better
performance and far better reliability.
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trogdor
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| posted on 3/6/06 at 01:25 PM |
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ah yeah of course, that would be a good reason! hadn't thought about the rpm/power range.
ah well its was an idle thought/plan really. i should stop daydreaming about other plans when my first project needs doing.
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DIY Si
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| posted on 3/6/06 at 01:27 PM |
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You could always fit a pair of bike engines. You'd be suprised just how much cars can weigh. I was a little shocked to discover a focus weighs
in at nearly 1500kg! Bike engines will struggle due not so much due to their power, but that the clutch/gearbox is designed for a 200kg bike.
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ChrisGamlin
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| posted on 3/6/06 at 01:31 PM |
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Yep its where the power / torque is produced, and also the gearing that matters, as well as the strength of the clutch.
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ChrisGamlin
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| posted on 3/6/06 at 01:36 PM |
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Don't get started on a twin BEC conversion hehe. Apart from anything else (like the huge costs involved!) I very much doubt there would be room
for two bike engines inside that SAAB, you might even struggle with one to be honest beause the engine needs to be pushed over to one side of the
engine bay so the prop can be attached, and with a lot of saloon cars is you have a fairly narrow engine bay with the inner wings getting in the way
of where the bike engine and exhaust needs to go.
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trogdor
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| posted on 3/6/06 at 01:59 PM |
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yeah two would not fit in the engine bay, though there would be space in the back..... but it sounds like a non starter as it would be very expensive
to do. the engine bay is quite narrow but u can cut back the arches a fair way if needed.
i am now thinking of a v long term project involing a space frame and a 96, much like the PPC mag's space frame escort. that would prob work,
especially with fibreglass wings and doors!
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JoelP
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| posted on 3/6/06 at 04:33 PM |
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you could strip the life out of the inside of the saab, reduce a fair bit of weight. Since you're thinking of putting a bike engine in one, its
not like you need the rest to look original! Id completely gut it to a shell and start from there. Fibreglass doors and bonnet/boot arent easy, but
certainly possible. Even carbon 
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trogdor
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| posted on 3/6/06 at 05:06 PM |
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well fibreglass wings exist, and i think bonnets do too! so thats a good possibility. so what is the max sort of weight that a bec can be? do some
bikes have a stronger clutch and gearbox?
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JoelP
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| posted on 3/6/06 at 05:44 PM |
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if you choose a touring engine rather than a sportsbike engine, you will find more torque and probably a stronger clutch to match. But that also
defeats the point somewhat, as they usually have less power. 
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Coose
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| posted on 4/6/06 at 11:01 AM |
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Why not two bike engines in the back? Have a look at the twin engine grass trackers....
I know a bloke near me who builds them - the last one I saw was a Fiat Cinquecento with two VTR1000 engines in the back. He had a Sierra diff and each
motor was driving a drive-shaft!
Spin 'er off Well...
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trogdor
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| posted on 4/6/06 at 06:28 PM |
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two in the back does sound good but it would need alot of modification as the saab is front wheel drive, there would be enough space in the front for
the bike engine and diff, since there is a transaxle and car enigine in there.
since there is nothing on the back i would have to cut a lot of metal out and fabricate aload of stuff and move the fuel tank etc.
would be better if i did that, to make a space frame saab. which would be cool and unusual!
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ChrisGamlin
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| posted on 4/6/06 at 06:31 PM |
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Were you planning on keeping it front wheel drive? 
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trogdor
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| posted on 4/6/06 at 06:32 PM |
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would that be a problem?
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ChrisGamlin
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| posted on 4/6/06 at 06:35 PM |
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Unless you've got about 3ft of engine bay in front of the front wheel line to fit the engine and diff in, I think it will be a struggle. Even if
you have got room though, having the engine that far forward wont be great for weight distribution I wouldnt think
[Edited on 4/6/06 by ChrisGamlin]
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trogdor
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| posted on 4/6/06 at 06:37 PM |
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well the car currently has a 100kg v4 engine infront of the wheels, and an zetec will fit in the space, just. so a bike engine will be no prob. as far
as i can tell anyway. weight won't be a prob as if anything it will be too light at the front with no car engine or gearbox.
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ChrisGamlin
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| posted on 4/6/06 at 06:42 PM |
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Do you put the Zetec in with a transaxle then, or is it a transverse engine? Also dont forget that a V4 engine will be a lot shorter than a striaght 4
bike engine, and I suspect the transaxle is underslung below the engine somewhat, in order to line up with the front axle line? If you use a BEC you
need the "length" of the engine plus a small prop, plus the length of the diff as they'll all be inline with each other.
Sorry, don't take this as me being negative, just thinking aloud
Chris
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trogdor
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| posted on 4/6/06 at 06:49 PM |
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the zetec will mount straight to the orginal gearbox, hopefully it will take the power and torque, have been told it will by other saabers!
it will be longditionally mounted, the orginal setup is like that, like the audi setup in their cars. i guess it depnds on how long the engine is, but
an zetec and transaxle will fit in there.
does it sound possible to fit the bike engined setup?
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ChrisGamlin
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| posted on 4/6/06 at 07:38 PM |
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I think the difference might be that the transaxle will be designed to hang slightly under the engine, so the drive shafts will come out more under
the back of the engine than behind.
Looking at this pic, I reckon if you put the bike engine in touching the radiator with a diff behind, the driveshafts would run along a line somewhere
through the middle of the battery and under the heater fan.
About....................................................................................................... | Here |
[Edited on 4/6/06 by ChrisGamlin]
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