Technical Rotax Fiche

[mandelbug]

As you may have seen from other posts, my son races in a '22 spec Mini Max aka Restricted Junior Rotax. Our focus so far in his karting journey has been him, his ability, improving him. I believe we have (or very soon will) hit the point where the metal bits become as important or more important.

I think I understand what the different builds are:

Rotax design the engine, as an example an inlet port might be specified as 28mm diameter. Manufacturing tolerance might be 1mm meaning that port could be anywhere between 27 and 29mm and be 'within tolerance'.

Blueprinting would mean that an engine builder made sure that port was 28mm exactly.
Fiching would mean the engine builder made it 29mm.

Yes that's a very simplistic view, and I have read through the MSUK fiche document specifying the components involved.

When we moved to Rotax, everyone talks about Fiching the engine, getting it Fiched when it's about 15 hours runtime. Our engine is a Next Karting engine which I believe will be as it came out of the Rotax factory (i.e. within manufacturing tolerance).

Would fiching make that much of a difference for a Mini Max, given it's so heavily restricted compared to the less restricted junior? I have been giving it some thought and think it would make more sense to get this done at the end of the year as we move in to Juniors and take off the restrictors. i.e. now the engine can only run at 70% performance, without the restrictors it might be 90% but with fiche it would be 100%.

I am considering hiring a 'built' engine for an event to see if it makes any difference to his times, and a 'top end' rebuild on our engine.

 

[LE#99]

How long has your pilot been driving and what sort of position is he running at on the grid?
I never had a top engine until I'd been driving for a good while and TBH it forced me to get used to making overtakes that otherwise I would never have tried. If I couldn't keep up on the straights I had to do it on the brakes and in the corners...... when I got a good engine it just made everything much easiser and allows the driver to think more about what they are going to do and the racecraft while in the seat.
A hire engine would be a good idea but never let the driver use it until the end of testing and the racing. We wouldnt put our best engines on sometimes except for the TQ & Final to save them.

I'd say there are a couple of routes you could take;

1 - Get the engine dynoed by a tier 1 tuner like Time. If it's good then get it fiched and up to speed. Then you need to think about a spare/wet/backup engine.

2 - Invest in a decent new engine that you can see should be good from Time Racing etc as if it's anything like Iame, you can't make a bad or average engine good. Then you can keep your current unit for Wet or as a spare. Then get that fiched if it's somewhere near good.

If you're ever at the same tracks as us, come into the awning and say Hi and my dad will usually try to give some advice if asked a question

 

[mandelbug]

Been driving nearly 2 years, in 22 was Honda Cadets, only doing Rotax for 23 (tested at the end of 22). I am leaning more towards not bothering with a fiche until the jump to junior, given we're restricted heavily, I don't see the benefit at this time. Will look to get it dyno'd and a top end rebuild (was thinking GMS as we see them at Bayford).

Oh and thank you for the offer, will keep an eye out for you when we're out and about