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Chassis ideas and plans
TurboLocost - 23/1/21 at 05:17 PM

Still hoping to build a locost or something at some point, but have a new engine to use.....

Bit mad, heavy and big for a standard Locost type chassis though

A Cummins 6BT 5.9L 6 cylinder turbo diesel....

What I'm thinking about building is a rwd off road buggy sort of vehicle with this engine!

Has anyone done a off road buggy? Or know of some chassis plans?


ianhurley20 - 24/1/21 at 09:45 AM

'A Cummins 6BT 5.9L 6 cylinder turbo diesel....'

Most self built cars rely on agility, added lightness, easy hard cornering and braking - I think your engine would be more suitable in a replica tank than an agile self build. That engine gives 230bhp and massive torque but that kind of power is available from much lighter engines. The ST170 on TB's gave 225bhp on the rolling road. Good luck with whatever you try to do.

Oh - forgot 450kg ish dry, then ther is 24 pints oil and cooling water ....



[Edited on 24/1/21 by ianhurley20]


TurboLocost - 24/1/21 at 10:43 AM

Yeah its a heavy beast and big, but I have a good jap axle with diff lock as well, so was fancying an off road buggy type vehicle

I know generally with locosts it's lightweight is aim of the build

But I am thinking of a rwd buggy with massive torque, 500lbft plus......


Charlie_Zetec - 24/1/21 at 11:41 AM

The Cummins engine is a popular swap for the Land Rover boys 'n' gals who want something a bit different. As such, I think your best bet is to get something like a Discovery chassis (I'd say Defender, but they're lot more money for an almost identical chassis) and bobtail it. Whilst it won't be the lightweight space frame you want, it is a tried & tested route, and LR parts are generally easily available and not too difficult to service and maintain.

The only downside will be if you want to IVA it and get it on the road, as I'm sure a "significantly altered chassis" would need this - and there's virtually no rounded edges on a Land (except the wheels).

Maybe look at buying a Disco/Defender, engine swap, advise the DVLA of the new engine, then look to modify the chassis? Whilst not ideal (and potentially not quite within the rules), it might be a quicker/easier route.


TurboLocost - 24/1/21 at 01:02 PM

I have considered that route using a discovery chassis, and to keep within guidelines, not bobtail it and build a space frame on that

Just thinking of alternative options as with a pre existing chassis I have got to check for rust already etc

And I have a good jap axle with diff lock I can use already

I just fancied something different to the norm, a cummins engine, rwd buggy type thing but I somehow doubt a locost chassis is the best starting point as not sure it would cope with 500lbft plus of torque without major redesign

Basically the build sheet Iwant is:
Cummins 6bt
Rwd or 4wd
Space frame
4 seats or 5


jacko - 24/1/21 at 04:30 PM

So that’s where my Ford pinto went about the same weight some would say
Hehe
Jacko


ettore bugatti - 24/1/21 at 05:22 PM

Have a look on Youtube, there are tons of American builders doing similar things what you want to do.

Just look for baja truck, Ultra4, prerunner, trophy truck, rock crawlers and sand rails builds.

https://youtu.be/FlUq-mPlTFA
https://youtu.be/OwMj3ZtnbH8
https://youtu.be/oMubVjguqJw

Also worth looking at race-dezert.com


russbost - 25/1/21 at 09:06 AM

It depends what you mean by "off road buggy", a lot of off road stuff spends a fair bit of time flying over bumps & jumps, sometimes from quite a height. With an engine that by the time it's full of oil & water with all its bits like radiator, exhaust etc hung on it is going to weigh probs around 550Kg you are going to need a very, very sturdy chassis if it's going to get airborne or it will simply fold up when it hits the ground.
If you mean off road more like as in Land rover type off road then I can see some merit in it, but assuming it's only going to have 2 wheel drive, I would think it would be limited even then.

There are reasons why some stuff gets built the way it is & although I like to push the envelope somewhat myself, I would be asking whether it's going to do what I want it to do b4 I started


sheepish0001 - 26/1/21 at 07:39 PM

How about something like the rally fighter, it was all open source design so all the CAD is out there for looking at free and its an offroad thing to look at


James - 26/1/21 at 09:33 PM

Nothing about 6L diesel engine makes me think of 'fun car'!

Replica tank maybe...

But doesn't the fun come about from stuff being small and light-weight?

I know not everyone is the same- my BiL likes model trains for example and unlike me, not everyone chooses to be kicked in the face for fun but...

Just seems like months or years of work for something that might not be that fun at the end.


Sorry to a stick-in-the-mud!


TurboLocost - 26/1/21 at 10:42 PM

I will keep researching chassis designs i think, that rally fighter looks a bit like what I'm aiming for, although flat panel basic body is more my aim I think!

I've seen the ultra 4s etc before, it's just finding decent enough parts for a build like that over here without costing £10000 just for axles!

And there are different types of fun really

Locosts, Caterham etc always have appealed to me, small, lightweight cars, not needing mass amounts of power to be quick etc

But at other end of scale, big torque laden monster engine like a cummins, in a fairly lightweight tube chassis, realistically around the 1000kg mark? Approx 200hp, 500lbft plus all through the rear wheels, and a chassis that would allow the fun to be on road, off road, wherever the mood takes? Drive to work, drive to the shops, drive across fields or the beach, greenlanes, or even do a hill climb!


Same as rock crawlers and rock bouncers...
Rock crawlers are fun in the way of climbing seemingly impossible terrain, rock bouncers for the mad 'let's climb this muddy rough hill as fast as possible....


ettore bugatti - 27/1/21 at 06:43 PM

What Jap axle do you have? I guess you could use the front axle of that car as well?

Another idea is to get the Dodge Ram with the 6bt shortening it and put a rotax/dakar body on.

Another donor could be an ex army Daf 45 (150) 4x4 bit heavy, but the axles, gearbox are all there (and are strong). Plus some beefy wheels.

Laying out the design would not be to hard, just position the axles, drivetrain, seats and design the frame around it. A bit of research would make clear what materials to use, for street use more things need to be considered.

I think Colin Chapman used in the early days of Lotus a factor of 5 to the engine weight to get the target weight for the whole car.
https://www.researchgate.net/publication/316375697_Colin_Chapman_and_Automotive_Mass_Properties/link/58fc10b34585152eded1321d/download
That would be over 2000kg.

Pirate4x4.com is another forum to browse for ideas and builds.

[Edited on 27/1/21 by ettore bugatti]


johnH20 - 28/1/21 at 06:37 PM

I am with Russ Bost - part of the lightweight crew, but full on respect your ambitions. Certainly different to most on here but go for it!