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zx12r DIY sump and baffle mods, experience. Lotus 24 monocoque
rodoe - 25/2/16 at 01:33 AM

Hi there,
this is my first post so please be gentle (I've done a fair bit of searching but to no specific avail)
I'm building a 1960's Lotus 24/ Elfin Mono monocoque style single seater track day car. Already have a ZX12R engine for it.
This is a true budget build with estimated cost to build at $5k using mostly second hand parts and all diy where possible.
Anyway, exchange rates (Australia, basically double what you pay in pounds) prohibit me from buying a billet sump from AB or Nova:- ,, so hoping someone has drawn a sump mod and baffle for this. I could stump up for the swivel , which i would like to use.
Can others tell me of there experience , tricks and 'watch out for' using the ZX12R please.

SPYDER - 25/2/16 at 01:07 PM

I picked up this print of the Lotus 24 on Sunday at Stoneleigh...

twybrow - 25/2/16 at 06:10 PM

I have a homemade baffle, shortened sump and an accusump on my ZX12. I still suffer surge especially under sustained braking. I don't think my baffle is perfect, so I have bought one from AB Performance which along with a tweak to my Accusump setup I expect to sort it. I have done quite a few track days and more than 1500 road miles with the current setup, and the engine still sounds as good as it ever did...m

rodoe - 25/2/16 at 10:24 PM

Thanks for your comments Twybrow. May I ask how you shortened the sump and how deep it is now (any photos on hand?)? Do you think a swivel pick up would work any better?
Thankyou

twybrow - 25/2/16 at 10:43 PM

U2U me your email address and I will send you some I have to hand. I had mine cut and welded my a fellow LCB member - you just need to find someone you trust to do some tig work on the sump. It meant cutting the bulge from the sump, and welding a plate on, as well as relocating the drain plug. A swivel pick up (could) would be good, but I didnt have the funds for one, so went accusump instead.

Sam_68 - 25/2/16 at 11:01 PM

I can't help you with the sump baffling, but having looked at similar ideas myself, I think you might struggle to fit a 4-cylinder bike engine within the width of a monocoque chassis if you use the same approach as the early Lotus, of using twin 'booms' projecting out behind the driver:



Ideally you need an engine that's no wider than the driver's backside (max. 400mm). If you make it wide enough between the booms to fit a transverse 4-cylinder bike engine, the tub starts to look very wide and bloated. I went in the direction of a V-twin, which is just about narrow enough, but if you're definite about using the ZX12R, maybe think about a tubular spaceframe from the roll bar bulkhead rearwards?

Surely a monocoque Lotus 24 would make it a Lotus 25, by the way?

Jeano - 26/2/16 at 12:33 PM

quote:
Originally posted by twybrow
I still suffer surge especially under sustained braking. I don't think my baffle is perfect


how do you know your suffering from surging?

twybrow - 26/2/16 at 05:12 PM

quote:
Originally posted by Jeano
quote:
Originally posted by twybrow
I still suffer surge especially under sustained braking. I don't think my baffle is perfect


how do you know your suffering from surging?


I have a manual pressure gauge teed into the low pressure sensor.

rodoe - 26/2/16 at 05:23 PM

Hi Sam68, you are correct, Lotus 25 and 27. I'm more aquainted with the Elfin mono.
Did you actually build a monocoque with the v~twin? Do you have photos?The Suzuki TLR1000 was going to be my choice but the zx12r came up extremely cheap and complete, so grabbed it.
Yes i know it is too wide for the standard size Lotus 25 rear chassis pontoons. I am considering the rear to be made with tube. Not too sure yet. The aim is not so much speed as looks, that veing said, the ZX12R will be quick .

Sam_68 - 26/2/16 at 08:01 PM

quote:
Originally posted by rodoe
Did you actually build a monocoque with the v~twin?


No the designs are on a sort of second back burner, at the moment!

We're at the prototype construction stage with a more conventional (spaceframe, front-engined, 2-seater) car that I've designed for a company who're aiming at production next year. Then my 'traditional' (Lotus 27-esque) road-legal single-seater concept developed into a 'contemporary' version - sort of an ultra-light, small-capacity BAC Mono - that uses a much rationalised and updated monocoque structural concept, which I want to build first. I've done a certain amount of practical development work and testing on the tub fabrication concepts for that, but it's been set aside at the moment in favour of the commercial project. I may hopefully get back onto the traditional '27' design at some later stage, but the way things are going with other pressures, it seems increasingly likely to be a retirement project!

For both single-seaters I am/was looking at the Aprilia V-twin, which has the advantage of being dry-sumped as standard (so no baffling mods to worry about there!!), but I understand that Aprilias are regarded as somewhat rare and exotic Down Under?

You need more rain (ideally mixed with the traditional British blend of mud, cowsh*t, white lines and potholes)... we have a limitless supply of crashed superbikes over here!