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Mid engined locost?
Slimy38 - 9/11/12 at 08:53 AM

Can anyone point me in the direction of a mid engined locost build diary? The type of build where the engine is behind the driver and the builder has simply used a front wheel drive set up? I just want to have a bit of a look on what sort of things happened and how they were worked round compared to the more traditional front engined cars?

I'm particularly interested in any that started life as a Haynes Roadster rather than a modified commercial kit for instance.

Thanks

hughpinder - 9/11/12 at 08:58 AM

I'd be surprised if any midi's had actually been a normal 7 first. There isnt a lot of space for the engine behind the driver.
The sylva riot can be built with a zetec SE engine/box/driveshafts etc as standard, rather than as a bec.

Regards
Hugh

mcerd1 - 9/11/12 at 09:20 AM

someone did start doing it with a dax chassis, but they effectivly just made a new chassis with some assemblies cut out of the old one... it looked like it would have been easier to start from scratch IMHO



[Edited on 9/11/2012 by mcerd1]

balidey - 9/11/12 at 10:55 AM

Google Midlana for some ideas

coyoteboy - 9/11/12 at 01:15 PM

Locosts are mid engined already, strictly speaking!

Slimy38 - 9/11/12 at 02:10 PM

quote:
Originally posted by coyoteboy
Locosts are mid engined already, strictly speaking!


Yeah, I've never fully understood how cars are classified, to me a mid engined car would have the engine sat on the drivers lap!!

But essentially I'm looking for a car that has it's engine where a standard Haynes car would have it's rear axle and petrol tank.

Balidey, thanks for the Midlana suggestion, looks like quite a lot of info on there.

mcerd1 - 9/11/12 at 02:41 PM

quote:
Originally posted by Slimy38
quote:
Originally posted by coyoteboy
Locosts are mid engined already, strictly speaking!

Yeah, I've never fully understood how cars are classified, to me a mid engined car would have the engine sat on the drivers lap!!

mid engine just means its inbetween the 2 axles instead of in line with one axle or hanging over the front/back



there are quite a few interesting midi projects on this forum (in the midi section)

Slimy38 - 9/11/12 at 02:46 PM

quote:
Originally posted by mcerd1
quote:
Originally posted by Slimy38
quote:
Originally posted by coyoteboy
Locosts are mid engined already, strictly speaking!

Yeah, I've never fully understood how cars are classified, to me a mid engined car would have the engine sat on the drivers lap!!

mid engine just means its inbetween the 2 axles instead of in line with one axle or hanging over the front/back



there are quite a few interesting midi projects on this forum (in the midi section)


So actually what I'm thinking of should really be a rear engined (the engine is likely to be above the rear axle), whereas the current Haynes designed is mid engined?

I'll have a look in the midi section, thanks.

mark chandler - 9/11/12 at 03:34 PM

Also have a look at VAG setups in larger cars such as passat's, some of these have transaxles so much more akin to a single seater race car, driver<>engine<>gearbox

The V6's and turbo 4 pots as donors are very cheap an old thirsty passat's is not a desirable car.

jacko - 9/11/12 at 03:44 PM

http://www.mkengineering.co.uk/
have a look at the MK Midi
Jacko

[Edited on 9/11/12 by jacko]

mcerd1 - 9/11/12 at 03:48 PM

quote:
Originally posted by Slimy38
So actually what I'm thinking of should really be a rear engined (the engine is likely to be above the rear axle), whereas the current Haynes designed is mid engined?

^^ depending on exactly where the engine ends up it could be called rear engined (although most people seem to wait untill its hanging over the back like a 911 before they call it that....)

when most folk design a midi (with the engine at the back) they end up moving the driver forwards a bit and the engine ends up between the driver and the rear axle (even if its only a few inches from the axle)

when your looking at typical 'front engined' se7ens there can be quite a big difference in the engine position
e.g. lots of them have the engine is quite far forward when you open the bonnet and need extensions on the gear lever because of this, but a dax has it as far back as possible (at the expence of some leg/foot room) needs no gearlever extension and has a very short prop



the ideal position (that you might never achive in real life for practical reasons) will depend on the weight distribution you want to achive
the further back you put the weight the more grip you'll have off the line, but the more it swing around behind you when you try and corner
ultimatly how close you can get to your idea weight disrtibution will depend on the engine and drivetrain that you use...

[Edited on 9/11/2012 by mcerd1]

Slimy38 - 9/11/12 at 04:10 PM

quote:
Originally posted by mark chandler
Also have a look at VAG setups in larger cars such as passat's, some of these have transaxles so much more akin to a single seater race car, driver<>engine<>gearbox

The V6's and turbo 4 pots as donors are very cheap an old thirsty passat's is not a desirable car.


It's actually the turbo 4 pot I have in mind, having got the VR5 in my car I'm quite impressed with VAG engines! Although I'm more after the transverse fit, I believe older Passats went for a longitudinal fit but still a FWD box?

I'm imagining the engine being directly above the rear axle, again in my tintop it's pretty much a straight vertical line from driveshafts to spark plugs. The MEV cars that use Focus's as a donor also seem to have it sat right on the rear axle.

I have noticed one very pretty car that keeps popping up, the Sylva J15...





Which brings me back to Cyana sports cars...

Sports kit 5
Sports kit 5

I wonder if I could get an engine squeezed in the back of that somehow...

mcerd1 - 9/11/12 at 04:30 PM

quote:
Originally posted by Slimy38
Although I'm more after the transverse fit, I believe older Passats went for a longitudinal fit but still a FWD box?

yeah, they hang the engine out infront of the front axle (dates back to at least the first quatro's

the latest RS5 still has a similar setup (although they have moved it back a bit)


a diesel passat box makes a great transaxle for an AUDI V8

[Edited on 9/11/2012 by mcerd1]

iank - 9/11/12 at 06:08 PM

quote:
Originally posted by Slimy38
...

So actually what I'm thinking of should really be a rear engined (the engine is likely to be above the rear axle), whereas the current Haynes designed is mid engined?

I'll have a look in the midi section, thanks.


99% of FWD are layed out like this with the engine mass well in front of the driveshafts/contact patch, so will be properly mid engined if stick in the back.

coyoteboy - 9/11/12 at 07:29 PM

Indeed, they're pretty good when stuck mid-rear, unless they come from a particularly sporty background because then they tend to have been leant over to get them as far back as possible in the original, which would then make them more rear-biased in a mid-rear, which is a shame and part of the reason I didn't bother going 3S-GTE in my current build.

PSpirine - 9/11/12 at 07:37 PM

Passat transaxle and engine would be brilliant if you can package it - 1.8T engine is the same as in the A3/TT etc. and can be boosted to 400hp if you wanted. I wouldn't use the V5 or V6 engines as they're heavy, less revvy and not as tunable.

The passat you want is B5 (1998-2003). Audi A4 from the same era offers exactly the same powertrain

Slimy38 - 10/11/12 at 11:16 AM

quote:
Originally posted by PSpirine. I wouldn't use the V5 or V6 engines as they're heavy, less revvy and not as tunable.


True, but they sound SOOOO nice! The 1.8t is probably more realistic though, and it's been used in so many cars in various forms. Even the bottom of the range 180bhp set up will be more engine than I could cope with!

Madinventions - 10/11/12 at 11:58 AM

I know you said that you were after Locost-style chassis, but there may be some useful information in my Mojo build for you (link). Essentially it's a very similar mid-engined layout to the J15/Riot, and uses Fiesta/Focus/Puma running gear in pretty much stock form.

Ed.

hughpinder - 12/11/12 at 10:04 AM

I think you may have a weight distribution problem if you place the engine mass over the rear axle (plus height at the back). On my design, using a zetec E engine/box the COG is about 250mm in front of the axle line. This will give an approximately 62% rear/38% front weight distribution. That is with a 40l fuel tank and the battery at the front, and everything moved forwards to make space for the engine (e.g driver/seats/... all 250mm futher forwards). When the tank is empty it will be more like 68/32. Just something to think about.
Regards
Hugh

JoelP - 14/11/12 at 07:25 PM

Ive been quite tempted by the v8 out of the S6, 340bhp as standard. No turbos so not as tunable, but youd be spending BIG money to get a 1.8t up to that power. Plus if a tuned engine blows, its big money again, whereas you can get a whole S6 for 2 grand and sell most of it to get your money back.

b14wrc - 19/11/12 at 12:32 PM

The 1.8turbo actually comes in a 150bhp model as the base. My mate stuck one in his A3 out of a golf GTi, with a few different bits on it that can be boosted up a lot.

Check out my drive train, it is well forward of the axel line!

////

coyoteboy - 19/11/12 at 01:20 PM

quote:

I think you may have a weight distribution problem if you place the engine mass over the rear axle (plus height at the back). On my design, using a zetec E engine/box the COG is about 250mm in front of the axle line. This will give an approximately 62% rear/38% front weight distribution. That is with a 40l fuel tank and the battery at the front, and everything moved forwards to make space for the engine (e.g driver/seats/... all 250mm futher forwards). When the tank is empty it will be more like 68/32. Just something to think about. Regards


This is precisely the reason I opted for an all-alloy V8 in proper longitudinal arrangement, over a more compact I4 transverse. I plugged a few numbers into a simple model and found the rearward dryinsh weight bias was vast with a FWD drivetrain arrangement. The V8 comes in around 50kg heavier than the VAG I4 turbo with it's ancils (if you take an average of the usual quoted values and account for some missing/additional parts), but sits further forward and lower down. It does mean my wheelbase will be at least 2400mm but that's not a bad thing with 300hp behind you.

[Edited on 19/11/12 by coyoteboy]

rick q - 20/11/12 at 03:05 AM

This might be of interest :- http://diysportscar.blogspot.com.au/

Nickp - 20/11/12 at 06:35 AM

quote:
Originally posted by hughpinder This will give an approximately 62% rear/38% front weight distribution.


Similar to an MR2 then? They don't handle bad and make a great track car

hughpinder - 20/11/12 at 10:03 AM

# quote:
# --------------------------------------------------------------------------------
# Originally posted by hughpinder This will give an approximately 62% rear/38% front weight distribution.
# --------------------------------------------------------------------------------


# Similar to an MR2 then? They don't handle bad and make a great track car


Yep, I hope so! My thoughts were that this was about as far as I would want to go, and if the engine was over the rear axle as proposed by the OP, rather than offset to the front as in mine, you be more like 70/30 with a full tank of fuel - the front will be seriously light at speed!
Regards
Hugh