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

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]

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?

I don't know, when I think SAAB I think large family car

How heavy is it with the current engine?

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

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]

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

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.

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.

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.

Yep its where the power / torque is produced, and also the gearing that matters, as well as the strength of the clutch.

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.

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!

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

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?

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.

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!

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!

Were you planning on keeping it front wheel drive?

would that be a problem?

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]

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.

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

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?

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]

A bit more googling shows what I mean...




You can see that for starters the engine is going to be shorter than a bike engine because its only 2/3 cylinders wide so even if this transaxle would fit the bike, you'd already need to find more room up front to get the driveshafts back in line with the wheels.
On top of that the driveshafts come out immediately behind the clutch (which is roughly where your bike engine output shaft would be. If you imagine a normal diff in place of the transaxle, the driveshafts will come out near the back of the casing, not the front, so you'd probably have to move the engine a good 30-50cm further forward than the current engine to claw back the space needed to get the driveshafts in line.

Chris

[Edited on 4/6/06 by ChrisGamlin]

where u say the driveshafts will need to be if the bike engine is touching the radiator is about where they are on the saab, there is not much in it. deffo room if i move the radiator.

with the zetec installation i am doing the engine will be right up against the front panel. meaning i have to move the radiator behind the engine, this has been done before with v6 conversions.

if needed would a radiator be ok behind the bike engine? how much cooling do bike engines need? more than a ford essex v6? there will plenty of space.

[Edited on 4/6/06 by trogdor]

Must be an optical illusion or something then because looking at the car from the side, the front wheels seem quite close to the front of the car, and I can't imagine the current driveshafts being that far back!

Just thought though, you said you were using the Triple so ignore some of my comments from above about the length of 4 pot engines. At the end of the day though without some measurements its impossible to say, but I strongly suspect that any bike engine with diff hung off the back will be longer overall than the current setup with transaxle, so it will need some measuring up to see if its feasbile. Also you'll need to look at the height of the gearbox output on the bike because as well as too far back, it might also position the diff too high making the driveshafts run at silly angles downwards

cheers

Chris

shoot, i just got what u meant about the driveshafts coming out further back along the diff. is going to be a tight squeeze, how long is a bike engine and gearbox? a typical installation at least?

am trying to remember how long the zetec was? if the bike installation is the same or shorter than a zetec then it will fit, if not then prob not.

yeah it is strange how far back they are, they aren't angled up or down by much, will have a look for the triumph triple engine, does anyone have a decent pic of an installation? like u said u really need to measure it to make sure.

Ive not measured it personally but an R1 is evidently about 55cm wide overall, ie front to back in the way we mount them. Guessing at how long a Sierra diff is to the centreline of the driveshafts, about 25cm or so. On top of that you'll need some kind of small prop or cush between the engine and diff to join them up, so overall you're not far off needing a metre from the front of the engine bay back to the front axle line.

A triple will probably be shorter than the R1, but not by a huge amount.

[Edited on 4/6/06 by ChrisGamlin]

i can't recall how long it is from the driveshafts to the front of the car but a metre is definatly pushing it, i think gonna be a prob to fit in the space, not suprising really.

oh well will have to dream about it some more!

many thanks for ur help chris

No probs, don't just take my word for it though cos all those measurements above are only guesstimates and in addition to that, Ive never seen inside the engine bay so get your tape measure out, you might be suprised!

i would of got it out and measured if i was living with the car, its at my parents house at the mo and i am at uni! i am in southampton and i come from runcorn, its the town next to liverpool. if someone could tell me how long the truimph triple engine with gearbox is that would be great!

have been thinking about when i offered up the zetec, measuring from the gearbox to the front of the car it was 54 inches. i think i am right, will have to get it confirmed but that is over a metre! 1.3 metres or so. so it looks like it could be possible after all!

[Edited on 4/6/06 by trogdor]

I assume thats to the back of the transaxle though, as opposed to the front axle line?

its from the front of the gearbox, i measured it from there as i was offering up the zetec, it will be mounted to the orginal transaxle. so if anything i could add a few inches to that.