Oval racing

[waxer52]

This is my first post so first things first and hello to everyone. I live in Ireland about 10miles from an oval track in a place they call Rosegreen Co. Tipperary.
Everyone around me is building toyota starlet 1.0 litre cars for racing on this track, but I have decided to be different and use a Nissan Micra.

The rules state that I cannot modify manifolds or do any major head work so I am quite limited. To gain a few bhp the alternator is removed and we run from a battery to power the ignition coil, (all the starlets have electronic distributors from 1.3 litre engines installed).

Suspension can be hardened and different poundage springs can be used in each corner but no coilovers. The front can be cambered but not too much.

These are the rules to the best I know and im looking for all the help and advice to squeeze as much power and handling out of the little k10 1.0litre as possible without killing it.

I have read a lot of threads over the last few days but a lot of these are all out tuning manifolds and bike carbs as such. Subtle mods that are not really noticed would help also.

Thanks for any help.

 

[frank]

hi waxer (Y)
i used to do stockrods and senior ministox (and bangers) and i think a 1.0 k11 could compete with the starlets (because they have the same mani,s, throttlebodys heads, valvesize etc as a 1.3), but i think you will have your work cut out competing with a stock-ish k10 tho (tamac oval i presume ?)

 

[getawaycar]

If the specs are the same in Ireland as here you can get away with drilling or changing the carb jets, lightening the flywheel and bottom end (as long as they are original), skimming the head and changing the camshaft profile.
because you have chosen something different there aren't really set combinations of cam profile/jet sizes to work from but finding out what the Starlet guys are using.

Are the 1.0 and 1.2 manifolds the same? If they are different would the scrutineers know if there aren't any other Micras to compare them to?

Might be worth disconnecting the coolant pipes from the manifold? or modifying the throttle and choke butterfly to open together?

I think your decision to use the Micra is a brave one but I'm pretty sure the K10 is slightly lighter than the Starlet, so it could be quite a good one!

Good luck!

 

[waxer52]

Good info thanks. Yes you can modify the jets on the carb and open the butterflys fully. Lightening the flywheel can also be done. As for a cam regrind and would i get away with it, i dont know. It will probably idle a little lumpy but would it be noticeable just by looking at it?.

Whats the best way to lighten the bottom end?

Is there much difference between the 1.2 and 1.0 litre inlet manifold?

Thanks People for all replies.

 

[markbognor]

Is there any scope for building a 1.0 block up with a 1.2 crank and boring out to use the largest stock oversize pistons available?

 

[waxer52]

I think you have to use stock pistons, I dont know if you can get oversize standard pistons.

If I fit a 1.2 crank will it increase the stroke or do I need the 1.2 rods. What is the difference visually between the cranks? Not many people know the micra mechanically so I might get way with more.

 

[frank]

the 1.2 has a taller block i believe (and a longer belt) some CG internals might fit eh :grinning: (superls would know)

 

[waxer52]

I cant use a 1.2 block as they will know what it is.

 

[RTLkyuubi]

if your allowed fit some k11 arbs for the handling

 

[getawaycar]

if my memory serves me correctly (which it sometimes doesn't! Ex 2 litre saloonstox racer!) you are allowed to lighten and balance the crankshaft by drilling only.
But if you have it drilled as much as possible maintaining the balance you will be ok. You can take a good bit off any crankshaft just by drilling it without losing too much strength.
I remember reading somewhere, for every kilo you can take off rotating parts in the engine its the same as losing 4 kilos off non rotating parts! (Frank, a kilogram is about 2 lbs, LOL!)

You can take material off the pistons and con rods to balance them only, in the saloons we used to take as much off them as we could without blowing the engine up. You can justify it by saying you built the engine from 2 previously prepared ones, each time you had to remove metal to balance the parts!

In UK rules you are allowed to run the engine at the maximum overbore too, so many people would just go straight to that providing you use original (oversize) pistons.

Another thing to think about is the ratios in the gearbox. Anyone got a list of available ratios?

Are you allowed to use different sizes of control tyre? Road tyres? Or does everyone have to use the same size? If you can't get decent gear/diff ratios it is worth remembering the original K10s had 12" wheels.

 

[superls]

yes as above the ma12 is taller than the ma10, not sure of any cg bits that would swap, nothing performance enhancing jumps to mind.

 

[john-jones]

Well waxer52 did you have any luck with the micra, what mods did you do? Did you try putting 1.2 pistons in to it i think they are bigger 71mm instead of 68mm. What about porting and polsihing. Also what gearbox are you using the 4 speed or 5 speed. the 4 speed would be better for weight. did you think about changing the carb to gain a extra bit?

 

[getawaycar]

Hey, Waxer! Get some pics posted!