Hello,

I´m pretty much new here, I´ve been reading about the locost scene for the last few months and trying to get a picture of my future car. I´ve already selected an engine, the M50 from BMW. This will give me something like 200 hp, sufficient for my use. Secondly, I like to use a E34 525i, because they are cheaper than a E36 325i.
Because the M50 is a pretty long and wide engine, I´ll use the McSorley 7+442 design as a basis. But the next thing I'm trying to figure out is: what rear suspension configuration is the best choice?
Obviously, BMW has engineered a very good rear suspension on the E34, I know Aerosam is reusing it. But I think it isn't the best option, because the 525i weighed nearly 1600kg. Using the BMW rear suspension would be a bit overkill for a 650kg car. Could I adapt the rear axle to make a double wishbone suspension set up?
Or should I use the BMW setup?

quote:

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Originally posted by Broekens
Hello,

I´m pretty much new here, I´ve been reading about the locost scene for the last few months and trying to get a picture of my future car. I´ve already selected an engine, the M50 from BMW. This will give me something like 200 hp, sufficient for my use. Secondly, I like to use a E34 525i, because they are cheaper than a E36 325i.
Because the M50 is a pretty long and wide engine, I´ll use the McSorley 7+442 design as a basis. But the next thing I'm trying to figure out is: what rear suspension configuration is the best choice?
Obviously, BMW has engineered a very good rear suspension on the E34, I know Aerosam is reusing it. But I think it isn't the best option, because the 525i weighed nearly 1600kg. Using the BMW rear suspension would be a bit overkill for a 650kg car. Could I adapt the rear axle to make a double wishbone suspension set up?
Or should I use the BMW setup?

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Yeah, a mid engined one will be very cool car, but probably too much of a racecar for me. But using the BMW engine and a Sierra(Cosworth?) rear axle could be another option..

Zil's advice is spot on. I will add a piece of my own, and that is that the BMW engine is too big and far too heavy for the power that you can get out of it. It's OK in a heavy saloon, but inappropriate in a light weight se7en

John

And if I may add.

All that weight up fron has got to mean understeer.
(All Rover V8 users can stop jumping up and down, I know they're light 'for what they are'.)

When it comes to engine choice, the first thought of a heavy engine makes me think of hairpins where all the nimble cars with light engines will get into the corners better.
I know plenty of throttle will get the back end out and sort of balance it out, but it's not fast. The guy with the K series / Zetec SE / tuned xflow or bike engine will gain 2 or 3 car lengths at this point.

Mid engined V8 is a different ball game here IMHO. I look forward to seeing V8Kid's car proving this theory at events this year.

Ive used an E36 donor, ok im only using a 1.6 so not as much weight up front as yours would be (or power for that matter)

But im re using the rear end, well partly. Im reusing the diff, drivehafts and hubs, with fabricated uprights and using the roadsters rear setup and bones.

I dont know how effective itll be but its saved me having to get new diffs etc

The BMW M50 is weighing 195kg , but it kicks out nearly twice the power of the pinto. I couldn't find the weight of a Pinto engine, but a crate zetec 2.0 is 168 kg. I'm not sure, but 25 kg isn't that much for 40 horses extra?
And besides that, I ain't going on the track, so a bike engine is a no go for me. The BMW engines are one of the smoothest running engines that I know.
About the Rover V8, I think it is a bit old fashioned, the design is dating from the 50s.. Also I'm affraid of a high fuel consumption when using a V8.. And besides that, there are many people (especially in the US) who fitted a Small Block Chevy.. Or are they all driving a uncontrollable understeered lump of metal?
I 'm trying to get about 200 horses from under the bonnet without emptying my bankaccount. Do you people know an alternative to this engine?


[Edited on 23/3/09 by Broekens]

You will be fine with the engine, otherwise throw some bricks in the back

You might consider a deDion setup, easy to manufacture. The suspension geometry is also understandable for a novice designer (compared to double wishbones)

Yeah, your namesake did put straight 8s in his racecar, so a straight 6 should work

With the suspension, I think I'll stick to the IRS design of the roadster, maybe with some adjustments.. Does anyone know a book where suspension design is comprehensively adressed?

Try Staniforth or Milliken.(Bol.com)

Also a member called Rorty made drawings of a IRS and deDion for a locost. There are somewhere here...

Thanks, I'm certainly gonna buy one of these books.. Which one do you advise? Miliken is twice as expensive, but if it is the better book, why not?

[Edited on 25/3/09 by Broekens]

LOL, I cannot advise you since I dont own any of these books

Ok thanks for your help.
I like your design, it reminds me of the Alfa Romeo RZ/SZ fron the early ninetees

But does anyone know which book is best when designing a suspension for a roadster?

quote:

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Originally posted by Broekens


But does anyone know which book is best when designing a suspension for a roadster?

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Yes, I'm still sticking to the BMW engine. I'm going to correct the understeer with my foot..
But has anyone used the BMW E34 hubs before?