[JohnKing6]

David,

I think you're basically saying the same as Mikko and I argued thru the thread - the rotational weight doesn't make enough difference to worry about much at all. Things like driver performance (in most cases), driver/kart weight (in cases where it's above the minimum), aerodynamics (although perhaps only for the faster karts on bigger tracks) and actual braking performance will have a much bigger chance of improving lap times than shaving a few grams off the disk or axle weight.

The bottom line is that anyone who thinks that taking weight off the disk will improve top speed by anything measurable is kidding themselves and wasting a whole bunch of time/money.

[DMmotorsport]

OOOWWLIIII SH...... !!!!

I did not followed this discussion anymore... cause for this reason...
Theoritic this, theoretic that...
Ofcourse of the talking you guys to protect your own brand.... (no discussion for that,
i do this myself)...

the difference is the provement on the track and Bench, do not lie...
at same surcomstances... (or how you see it in englisch)....

For sure, there will always be people coming up with their theoretic etcetc...
So one more thig; to make it clear to normal people who are not intrested in cheated engines,
theoretic bullshit etcetc...

A heavier mass takes more energy to bring in movement... so that's it...

[RocK]

as a driver, we only care about lap time..

[DMmotorsport]

Yes ofcourse,

And the driver is always ok it's always the chassis or engine which is bad, when bad laptimes come up haha

greatz, Kristof
DMmotorsport

[David Goldman]

To be honest i think that the driver usually is always ok.. When bad laptimes come up the driver needs to change what needs to be changed, you dont see marco ardigo blaming tony kart for a bad chassis or vortex for a bad engine, he and his team does what needs to be done and its done.

[DMmotorsport]

Yes ofcourse !

But indeed you have to know that not everyone can handle a steering wheel...
so thats 1 fact!
2nd fact is; the chassis has to be build for the type of tyres you use...
most people don't know that... cause in homologation fiches you see a chassis... but between tolerances you can change the tube's possition, etcetc...
so thats a fact too...

Than there is the 3 fact: the team has to setup the material for the driver... as you said... but thats experience !

and than there is the Engine... but thats a story appart... i can tell you, its my work for living

Ciao, Kristof

[David Goldman]

But those tolerances that you talk about are so small that they really wouldnt make too much of a difference, if you look a bunch of karts use different length wheelbases and yet theyre all on podium, in fact tonykart and crg are 10mm apart in wheelbase and yet they are both at the top so those tolerances really wouldnt change too much. And theyre engines are all within reason the same, a vortex rok engine and another vortex rok engine and only be changed so much, and everything is checked so its not like they can sneak anything.

[DMmotorsport]

Nonono,

the tolerances are a lot bigger than you think.
the longest FIA-chassis is about 3cm longer than the shortest...
EVEN, inside 1 brand....

And for example, the backbehind you seat (the non demountable one) is placesd on the homologations-form... and from that measurement you can change it and move it 100mm to the front or even to the back, meaured from the original, welded, positition.

To be clear: there is a Vortex engine in the top 3 all the time, there is a Maxter engine in the top 3 all the time... but pleas do never buy one of those two... PLEAS!
Cause you'll never have the same engine.
I personally know the hometuner of the Thonon's Maxters.. and he totaly rebuilds the engines...

this story is the same for chassis...

[David Goldman]

I see what youre saying. But my point is that even if you can move that bar behind your seat, the point is that almost every single chassis has that bar no matter where its placed. The only radical new design is the latest maranello kart, I believe the rs9.

[DMmotorsport]

Yes indeed, the bar is always there!
But you know there is a big differance iff you replace it:

For example here in the BeNeLux we use our Jesolo JP1 evo and JP2 chassis.
=> for KF2: in from the chassis is smaller and very flaxible, the rear bar is 90° (right to right)
=> because we use the Hard type of there, by rgulations for this class

=> For KZ2: Its also flexible, but les... cuase we use medium/soft tyres for this class... and in KZ you corner speed is lower, but you take less meters around the corner (shorter turning).

=> for KZcross (motorcross6speed engine): we mate the chassis longer, this one is Called the JEsolo JP2, why? becaus, a longer chassis drives easier.. and this class drives on very hard type of tyres.. so you drift more... and when your chassis is longer, you can control it easier in a drift of a long turn...


... so you see it's a lot to do.. and for sure i did not mentioned that we use the 32mm chassis
but our competition model (the JP1evo) is a mix of 30 and 32m tubes....
... and than there is the rim-types
... and than there is the axle hardness


And so on....

[Mikko Nassi]

Theoritic this, theoretic that...

I hope that as an engine builder you believe in theory at least a little bit.

the difference is the provement on the track and Bench, do not lie...

Unless of course your testing methods are inaccurate and the changes were brought about by some other change such as weather conditions, then they can very easily be misleading.

A heavier mass takes more energy to bring in movement... so that's it...

And i showed (yes, in theory) how much of an effect this has in the rotational sense on a brake disc (negligible). And I also provided anecdotal evidence (not theory) which proves that the effect is extremely negligible (adding ~7 brake discs made no measurable difference to laptime, top speed, or anything else). The amount of time taken between running the same kart with a different brake disc leaves a lot of time for changes to take place (more rubber on the track, cooler/hotter track, different wind strength and direction, etc. etc.). The fuel level in the kart and the amount of water the driver had to drink between runs would likely have a greater effect.

Would I run a ~50% lighter brake disc while all else remains equal if I could? Yes. Would I spend more money to do so? No I'd probably spend it on something that would bring me more benefit.

[DMmotorsport]

So there it is!!
You do not have to spent more... cause on our chassis, the Brembo system is already there! at, AT LEAST, the same price.. Ow and than it is wurth it !

Nobody talking about buyng other braking system... but its obvious the Brembo system is the most 'normal', as we know from race-cars and road-cars.. with the normal 'nipple' system.

Something else, our measurements have always been proven on a bench... where wheater etcetcetc.. are no matter.

Indeed as an enginebuilder, yo have to believe in Theory.. BUT again, only the HP's and NM's on the bench is what counts... NEXT to ofcourse the feeling of the driver...

An other tests around the brakes: we used in total 7 systems at 7 of the same chassis.
Brembo was the winner is this, the other 6 i will not mention... cause some people will attack me...
what did we do...=> we bought the system... like a normal person would buy a chassis and go to the track...
and start running al 7 togehter, all the same time, ...

After day 1: already 2 systems fell of... (no choice in brakepads)

After day 2: We allready knew with 2 it would be; the Brembo MQ, or the Brembo-Made VEN's from CRG: but why the Brembo-Made iff we good have a good relationship with Brembo themselfs... so choice was made...
BUT in the meanwhile we kept on driving all those systems tegether.. whithout looking at them... no maintainance, only changing pads and run the chassis...
Now after 2 seasons, only 2 systems still alive (the 2 brembo-mades: the Brembo and the VEN)


So it is not only about the cost when you buy a new chassis or systems, it's all ather things around
Especially here, we testing at the track near our Workshop. we have a very diff. weather , very difficult, very hard, in summer 30degrees, sometimes more, in winter snow, and Minus-5

So the systems had to bestrong, reliable, and easy to maintain...
AND it's the lightest!! OVERALL: not only the discs, but also the calipre...

[Mikko Nassi]

Kristof I haven't been debating 1 brake system vs another. I quite liked the CRG VEN brakes (without the lighter disc). I'm saying that the simple fact is that a bit of extra rotational mass does not make a measurable difference. That's all I'm saying. If you found a difference in lap time or especially in top speed it was because of variations or the driver being able to use the brakes better because of feel.

[DMmotorsport]

No it's not.. we know what we measure... the bench never lies...

[Mikko Nassi]

Care to share some numbers?