UkLockCompany
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| posted on 29/2/08 at 08:57 PM |
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SR20 rear engined locost
Hi Guys,
Well here is another newbie with a dream to build a rear engined home build locost.
I have a Nissan Primera P10 eGT that has a low secondhand value. So, my plan is to use her as a donor for a rear engined SR20DE Locost. For those of
you that are not familiar with the SR20DE engine it has 150 hp and 132 ft Lb of torque as standard. I am fitting a supercharger to increase the output
to approximately 205 horses and 185 ft lbs of torque (figures to be realised after installation).
I would like her to look like a standard locost but with the engine behind me.
I have some skills in engineering and welding and am not afraid to practice and practice until I get what I want.
The knowledge I need from you guys is:
How do I mount an engine that is designed for front wheel drive ot th rear of the car?
Making the chassis etc has to wait until I know how to mount the engine as this will be a strssed part of the car ( I hope).
Other considerations include gearbox linkage fabrication. I haven't got to grips with this yet.
If anyone has some ideas I would be grateful for your input so I can get the plans together for the build.
Cheers
Ian
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speedyxjs
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| posted on 29/2/08 at 09:02 PM |
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Welcome to the madhouse 
Thats a very interesting project but i can already see two problems.
1) how are you going to fit an engine into the tiny space in the back
2) the car, as i understand, will be rear engined and in a car as light as a locost, you will struggle to go round corners without sliding in the dry
let alone when it is wet 
ps where abouts in sussex are you?
[Edited on 29-2-08 by speedyxjs]
How long can i resist the temptation to drop a V8 in?
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big_wasa
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| posted on 29/2/08 at 09:07 PM |
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Have a look on the net for the sylva mojo and riot -se for a few ideas 
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UkLockCompany
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| posted on 29/2/08 at 09:10 PM |
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Hi Speedy,
I'm in the same town as you Actually, I'm in Langney.
I understand your thoughts and plan to counter the problem by moving the seating position forward and moving anything that isn't connected to
the engine to the front to give a better weight distribution.
Please let me know your feelings so I can find all the problems prior to getting to grips with the design.
Cheers
Ian
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kb58
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| posted on 29/2/08 at 09:23 PM |
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Buy the book in my sig. It shows how to install a FWD drivetrain in a mid-engine configuration.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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r1_pete
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| posted on 29/2/08 at 09:24 PM |
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By Locost do you mean a 7 esq design? if so I'd fear you have nowhere near enough weight over the front wheels, understeer would be a big
problem.
As per Wasa, look for something designed for mid / rear engine.
Gearchange is going to be your big headache, I've seen a sliding tube arrangement, and rose jointed paralellogram designs, keeping it light and
precise is the biggest issue.
Regards.
Pete.
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UkLockCompany
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| posted on 29/2/08 at 09:36 PM |
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Thanks guys for your input.
Hey Kimini, nice punt for the book....... I might take you up on the offer. Any knowledge is good.
I can see the understeer issue as being the biggest problem. Gear linkage as the next.
No good having a car that wants to go straight on.
I have a feeling that a complete redesign is in order. Start from a clean slate, calculate weight position then get to the design.
Some of you may say..... 'why use the SR20'.... well all I can say is it is a great lump. I'm a primera eGT fanatic and don't
want ot waste the engine. I sold my last Primera (Tasha) for a silly price and am still missing her. I have this attachment to my vehicles that some
may say is not right.... All i can say is that it's not just metal and plastic, she has a heart and soul that needs to be cared for. Weird huh?
lol
Some of you out there will know here I'm coming from.
Yeah I could go out and buy a car for 5K, 10K, 15K but would it be mine?..... I think not.
Wow...... I'm blabbing on. sorry!!!
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UkLockCompany
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| posted on 29/2/08 at 09:43 PM |
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What I will do is as I get to grips with my project and realise the design I'll post the progress here.
I'm on a mission to do this. Might take me a while but we'll get there. It'll all be in the public domain to copy and improve.
Cheers
Ian
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speedyxjs
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| posted on 29/2/08 at 09:51 PM |
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quote:
Originally posted by UkLockCompany
Some of you may say..... 'why use the SR20'.... well all I can say is it is a great lump. I'm a primera eGT fanatic and don't
want ot waste the engine. I sold my last Primera (Tasha) for a silly price and am still missing her. I have this attachment to my vehicles that some
may say is not right.... All i can say is that it's not just metal and plastic, she has a heart and soul that needs to be cared for. Weird huh?
lol
I know the feeling. I am the same with my jags
Unfortunatly, you will struggle to have the seating position further forward and have it still look like a seven. That said nothing is impossible. Im
planning to fit a jag V12 post SVA
If you need any help or borrow tools etc, send me a u2u
How long can i resist the temptation to drop a V8 in?
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UkLockCompany
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| posted on 29/2/08 at 10:23 PM |
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Thanks Speedy,
You might regret saying that lol )
I know what u mean about Jag engines. Love em myself too. one day I will get myself a 420G
[Edited on 29/2/08 by UkLockCompany]
[Edited on 29/2/08 by UkLockCompany]
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kb58
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| posted on 1/3/08 at 01:47 AM |
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quote:
Originally posted by UkLockCompany
I can see the understeer issue as being the biggest problem. Gear linkage as the next.
No good having a car that wants to go straight on.
Understeer is not a problem on my mid-engine Mini - and neither is oversteer. Check out the videos on my site.
About the shift linkage, it's not a big deal, really.
[Edited on 3/1/08 by kb58]
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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RazMan
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| posted on 1/3/08 at 09:38 AM |
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Your design will be guided by the practical needs of plonking your engine behind the driver, so weight distribution will probably naturally follow.
Just look at any middy and the engine bay size is dictated by the dimensions of the FWD engine and drivetrain (you literally transplant the whole lot
so it is not as involved as you might think) A transverse engine can be squeezed in much easier but a 'north south' engine will require
much more length.
The biggest challenge with your engine might be the height, making the bodywork more of an issue.
Another point to watch is the height of the driveshafts in relation to the gearbox and sump - can you get the car low enough without heavily modifying
things?
hth
[Edited on 1-3-08 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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CaptainJosh
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| posted on 1/3/08 at 11:06 AM |
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I've also seen SR20DE engines in a north and south orientation, im guessing nissan do a RWD gearbox for it ( i.e. 200NSX or Silvia? ).
That may you could just build a standard chassis.
Checkout this:
http://www.locostusa.com/forums/viewtopic.php?t=2664
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RazMan
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| posted on 1/3/08 at 11:12 AM |
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The 200SX uses this engine in a RWD form but the Primera is a FWD iirc
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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britishtrident
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| posted on 1/3/08 at 02:49 PM |
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Using the engine as a stressed member isn't on for transverse layout.
Weight distribution won't be major problem but you will need to use wider wheels & tyres on the rear and take care to get the roll centres
and the roll couple distribution right to avoid snap oversteer.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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zilspeed
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| posted on 1/3/08 at 03:04 PM |
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I'm starting to think - after listening to far more knowledgable people than I - that transverse is all very well, but proper racing cars will
always have longitudinal engines because of the far better weight distribution.
Yes, the car might have a longer wheelbase or a cabin forward design, but that gives the front end a fair share of the weight distribution. Cars like
the elise may have a transverse engine, but that's because the supplier (Rover / Toyota) already makes these a million at a time.
It's no accident that the transverse engined Elise has big wide rear tyres and relatively skinny fronts. That's becuase Lotus are the
masters of handling balance and they know that this combination is what gives that balance.
When at Autosport, I noticed that all of the pukka racing cars with mid engines, such as Sports 2000, Le Mans Prototypes and V de V all had
lonigtudinal engines and the gearbox behind. Not because they have to, but because it's just better that way.
Not mocking transverse, just an observation. That and the fact that a friend is currently trying to flog me a zetec friendly Audi box and paddle
clutch. :-)
(Yes Graham, I really was listening).
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RazMan
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| posted on 1/3/08 at 03:38 PM |
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Having already built a transverse V6 middy, I am now determined to make a 'proper' one next with a longtudinal V8 - namely the Audi 4.2
As Zil says, almost ideal weight distribution but with a longer chassis as a small penalty. The Audi engine is quite short for a V8 so I reckon an
extra 150mm should do it.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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kb58
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| posted on 1/3/08 at 06:57 PM |
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I think "proper weight distribution" depends on your goals. For best acceleration you want the weight toward the rear. Same for braking.
For cornering, set tire width equal to static weight distribution and presto, it will corner as well as any 50/50 car.
My mid-engine Mini is 41/59 and have no issues with oversteer. In fact, I had a very hard time trying to get the car to spin on the skidpad. I'm
not sure where "mid-engine" ended up meaning "will spin like a top". It simply isn't true.
[Edited on 3/1/08 by kb58]
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Lippoman
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| posted on 1/3/08 at 08:12 PM |
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It's not "will spin like a top", more "will spin like a top, when it spins".
Traditionally midengine layout gives better cornering traction but when it loses it, it's quick to spin due to the lower inertia.
The transverse layout has one big drawback in my opinion, different length or shorter driveshafts than a longitudinal, causing short A-arms.
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kb58
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| posted on 1/3/08 at 10:16 PM |
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True, if true A-arms are used. If lateral and trailing links are used however, the suspension geometry can be as desired.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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