Stock vs Mod motor

[Nickwillyhams]

As titled, can someone explain the difference to me

Cheers
Nick

[JohnM]

I could be wrong, but I think stock & mod is more a term from the past when you'd have a stock motor that was say a 27 turn & wasn't able to be taken fully apart for cleaning & skimming & modified motors that were of any wind & could be taken apart.

I think stock now refers to spec motors where you'll have a 13.5 limit for example, modifieds are no limit.

[mattr]

That's about right, stock were generally sealed can, "standardised" motors.
Mod were anything goes, dump the batteries 5 seconds after you finish your heat, rebuild/reskim weekly.

Basically.

Now we just have stock/blinky classes, where motor performance is essentially controlled by the ESC. (but you still have to have a standard motor and fixed timing endbell IIRC) and mod where you can either just turn the blinky off and go mad with your stock motor, or get a faster motor, no need for skims and rebuilds weekly.

If you are looking at the difference between mod and stock software on ESCs, AFAIK (and i've only looked at speed passion stuff), Mod software is designed for fast motors, so tends to have less adjustability, so you don't explode the motor, and stock has all the boost, turbo, timing and so on. So you can turn your "slow" motor into a rocket ship.
Think SP recommend a cut off at 8.5 turns.
FWIW, the 8.5 in my 410 gives away nothing noticeable on the straight (20+m long), but is far more driveable on the twisties than the 6.5 i had before.

The 5.5 i briefly put in was ferking insane, probably thanks to still having all the boost and timing turned up to 11 on my mentally unstable ESC........

[SlowOne]

Sort of...

Stock is a class where the motor specification is tightly controlled, and every eligible motor has to be checked for conformance to the Rules and have a wide availability. There are three types of Stock motor controlled in this way - 17.5, 13.5 and 10.5.

The timing on the motor is adjustable using the mechanism on the end plate to move the position of the sensors. This is allowed in Stock. All Stock classes now run with speed controllers where their timing is locked and set to 'zero'. The 12th Section run a list of these speedos that pass a test showing that their firing sequence follows the rules set out in EFRA and BRCA.

The idea of all this is that everyone can buy a motor to the same specification and race it against anyone else. As usual, the way a motor is designed within the Rules, and made, will give some differences in performance.

A Modified motor is a motor that conforms to a smaller set of design rules around its size and the way the sensors and wiring is laid out. However, there is no restriction on the wind, so Modified motors can be any wind at all. There is also no restriction on speedo timing, so many drivers running Mod use speedo timing instead of the end plate timing on the motor as it gives them more control over the motor performance.

In essence, Modified motors are in any wind from 10.5 down to 3.5. There are usually no winds between 10.5, 13.5 and 17.5 (so no 15.5 for example) as there is no point. In the US they also use 21.5 in F1 and 25.5 in USVTA - both as stock classes.

On Off-Road there is no Stock class at National level so drivers always use 'Mod' motors. Judging from advice on here, most people find something between 6.5 and 8.5 works depending on 2WD or 4WD.

Touring Car and 12th have Stock classes for their Nationals, as well as Modified classes. Things like GT12, F1 and GT10 have only one class using a stock motor - 13.5, 21.5 and 10.5 respectively - and there are other variations on those themes across the Clubs.

HTH

[mattr]

You've read the rules recently haven't you.......

[Col]

Originally Posted by mattr

You've read the rules recently haven't you.......

Nope... he helped write them!

[mattr]

Last time I raced stock, 27 turn silver cans IIRC, you had to send off an SAE to get a copy of the rules, which were probably Xeroxed in somebody's office after hours!

[Nickwillyhams]

Thanks for the explanation slowone! I thought there would be a clear cut difference like stock are non adjustable mod are etc obviously not

[SlowOne]

Thanks, Col!!

Nicky, it might seem like a good idea to lock Stock motors, but the reality is you can only then check them by taking them apart. Unlike the brushed motors of years ago, you cannot easily see where the sensors are for scrutineering.

With adjustable timing, everyone can experiment to find the sweet spot for their track and/or driving style. I know it sounds wrong, but on the track it does help to even up the motor performance. These days you are likely to get a performance advantage from the speedos as well - some 'blink' faster than others!

HTH

[Nickwillyhams]

What do you mean when you refer to 'blink' I've heard the reference to 'blinkey mode' lots

Nick

[SlowOne]

When the first brushless (BL) speedos came out it was assumed that they simply delivered the required firing for the three coils in the motor. As early as 2006 at major events speedo manufacturers were starting to play with adjustable timing in the speedo.

This 'playing' carried on behind the scenes until first Black Diamond and then Tekin came out with speedos that could be programmed to deliver timing adjustment on the fly. A DC electric motor's timing retards under load due to the interaction of the permanent magnet and the electromagnetic fields. If you were able to advance the timing as the motor accelerates then this would negate the loss of performance. That's exactly what Black Diamond and Tekin did, and so the programmable speedo was born.

This meant you had to have an in-depth knowledge of how motors work, as well as a laptop with the latest software and firmware for your speedo. People liked it at first, but it fell into disrepute because motors were going off like grenades in the hands of the inexperienced, and the cars became so fast they were almost undriveable by those below the top ten in a National.

In order to return some sanity to the situation, someone came up with the idea that speedos would be programmed to have zero timing advance to the motor and was locked into that mode to prevent fiddling at trackside. To signify that an LED blinks when the speedo is in neutral. Hence the term 'blinky mode'.

It has done wonders for participation at all levels. It means everyone can buy a speedo, set it in blinky mode, and then race with everyone else without worrying whether they have the latest software, the right timing setting to bring in their turbo or whether their boost profile is the right one for the track... or indeed whether their motor is going to last the whole five-minute race!

However, even with that fairly tight set of rules in place, it is possible to get more motor performance from other settings that are not in the rules, and indeed which are difficult, if not impossible to measure. Then there's the circuit board design, the quality of the FETs and the style of firing the FETs.

In short, different speedos deal with the 'blinky' mode differently, some better than others. It is a small difference, but for drivers with the right skills it is there to be felt. Hence the phrase "some speedos blink faster than others!" HTH