Turning off one engine

[imperialdata]

Mainly aimed at TimD this one:

In another post, Tim mentioned turning off an engine. How easy is that, in other words, what controller is used to ‘deselect’ an engine and can it be done while driving?

[TimD]

Hiya,
Really easy – you just make sure it’s in neutral and hit the kill switch. Can be done whilst driving or stationary. Unfortunatly due to a wiring problem I can’t restart an engine while driving without powering the whole car down and up again
The 2 engines are completely seperate in everything apart from their cooling circuits which are twinned together with Y connectors. The car has seperate wiring looms, controls, displays, and gear selectors for each engine.
All that happens if only one engine is being used is that you go slower! and the other engine has it’s gearbox output shaft spun back via the transfer box – hence the need to be in neutral. If the other engine is in ger it is possible to bumps start it from the running engine – or just strip the teeth out of both gearboxes (which has been done on the yellow car in the forum title picture!)
In practice I never really bother driving on one engine apart from just shunting it about in car parks or similar..
Cheers,
Tim.

[imperialdata]

Wow, that sounds so weird, “Just make sure it’s in neutral and hit the kill switch”.
If it isn’t in neutral what happens? And speaking of neutral, do you ever get false neutral as often happens on motorbikes?

[TimD]

If you’re not in neutral at the time, and you bring the clutch up you’ll end up driving one engine off the other through the transfer box and the engine’s gearbox. At anything much over 20mph this would be enough drag to strip teeth from gearboxes. At low speeds (ie pulling away from lights) if you stall one engine only you can just bump it back into life from the running one which can be kinda handy!

Yep, false neutrals do happen, usually only on one engine at a time, and normally only because you don’t push the levers far enough. It’s not such a problem in a single engine BEC as it is with the twins. A bigger problem is missed shifts where onlty one engine changes gear and the other stays put. This is the only thing stopping me from bolting the gearlevers together, and is quite a frequent problem on track expecially.

[Anonymous]

@TimD
Tim, how do you drive these cars, is it usually with both gearlevers moving at the same time?
Is it still one down and four/five up but done with your hand?

[TimD]

Yup, you change both at the same time, it’s like a split “T” shape – see pic:

You need to have the levers split in case of missed shifts etc. (the other, shorter, lever further forward is for reverse – the transfer box can also reverse the drive giving 6 reverse gears if required! [])
Yes, it’s one forward, and five back same as on the bike. All you have is a load of linkages joining the gearlevers in the cockpit to the gear selector wotsits that you’d normally use with your foot. [^]

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