Mapping

[iigodiix]

Any of you geniuses do hard cut limiters on mapping? Mines been done by pro Steve. At hdi tuning in Bristol.
Cheers

[E_KEL95]

jammapic on here does them, mapped my car and put one on it pm him he's based in manchester though i think

[iigodiix]

Well that's a bit far! Lol I'm based in Kent lol

[E_KEL95]

No idea of the distances between the 2 am from ireland lol if you read your ecu and send it to him he's fit to do it that way, thats how i did mines took and it took about an hour maybe less

[iigodiix]

4 hour drive lol and I would like it to be dyno'd at the same time as well.

[Tom]

Have you asked Steve to do it?

[Slam Wagon]

Its either steve, whippy or jammapic. All are going to be a few hours away im afraid. Thats if you want someone who really knows hdis.

[Mr Whippy]

Does anyone know the resonant frequency of the drive-train and engine in various states, like 1st gear, 2nd gear, clutch up vs clutch down in them all, or at intermediate points, vs the torque flipping frequency of the on/off fuel limiter?

Given every car has different weight wheels, different clutches, and can be driven in a range of ways, I wouldn't like the idea of having a customer get a gearbox spitting out it's bits under certain rare but possibly attainable conditions.

You could probably work it out with some decent maths, but I haven't. This is why most diesels will stall by design rather than struggle and resonate under certain low frequency conditions (generally under 600rpm or so), and have DMF to avoid resonant frequencies destroying the engine/gearbox/drive-train etc.

Also just the rapid and variable frequency at which the fudge operates is gonna add weird loads through the crank, into the camshaft and so on... all at high engine speeds and so on.
Lets put it this way, I wouldn't want a solid lower engine pulley, 4800rpm and a hard cut rev limiter fudge doing it's thing

Maybe I'm worrying too much.


I've always talked my customers out of doing this because I just think it's silly hehe.


I know people fit dump valves because they think they are cool, and they kinda are. But they do NOTHING useful on a diesel, so it's actually a bit silly.

Hard cut rev limiters on a diesel just seem like they have never been done probably because it's not good for the diesel engine. Maybe if you had uprated rods/bearings/bolts and a good crank (HDi110 one perhaps?) then I'd be ok with it, but doesn't anyone else cringe at the idea of throwing ALL that extra stress on a HDi90 crank/rods/bolts at high rpm, likely already running torque way beyond the OEM design specs?


Dave

[Slam Wagon]

But everyone wants a diesel that sound and goes like a petrol race car, but with low down torque, epic boost, good mpg and reliability. Why cant you guys just make a map that does that already!

Ps, the internet doesnt translate sarcasm well.

[pro_steve]

Exactly that Dave!

[jammapic]

If people want hard cut limiters, then who are we to say otherwise? I will always advise, but ultimately map anything people want. If someone wants a map that smokes it's bollocks off because they think it's cool - I'll do it.

At the end of the day, I've never had a problem with a hard cut - and I've had diesels with it mapped in for 60,000 miles. My Golf for example, had nearly 200k on the clock when I got rid and it had a hard cut on most of the time I owned it (and I bought it with 110,000 on the clock!)

If you want me to map a hardcut for you, drop me a PM.

JP

[Ruan]

Meh, newer high torque DI petrols sit there using Launch Control etc which is still fuel/spark cut limiting... They also sit there at 6000rpm battering off a bouncing limiter, it's just that until recently with Petrols you've not been able to cut the engine torque back cleanly, but look at fly-by-wire MED7, they cut the throttle back to stop a bouncing limiter... Tailing off to a governed speed is preferable in the world of engine calibration, but does just feel shite...

I wouldn't be too concerned about it, and especially seeing the quantities going in, it's hardly like you're putting in 80mm^3 and cutting it in and out... You see the TDi guys with proper "popcorn" limiters injecting that sorta quantity straight again afterwards to get the "pop" noise you get as it hits the limiter, it's probably not good for it, but at the same time, you see petrols running anti-lag and "pops and bangs" remaps regularly and all sorts of wierd timing adjustments on the limiter and at transient throttle changes to make cool noises... I think that yes, there's a bit much worrying there, don't get me wrong, I don't think it should be a "standard" thing on a map - but for a customer who clearly is into extracting the maximum performance whilst knowing there's the potential for sacrificing reliability - is it that bad!?

[jammapic]

Agreed Ruan.

[Mr Whippy]

Different strokes for different folks as always

Petrols are completely different engines. They generally spin 50% faster so are much stronger by original design.

Remember the bulk of bottom end forces in a diesel engine are torque related at normal operating speeds, with not much expectation for high inertial loads from high rpm. Usually after 4000rpm the torque is much much lower in a diesel.
Throw in high rpm AND higher torque via tuning, AND some age, AND then also some resonance. Hmmmm.

It might be fine on 90% of cars, but then another customer might have a solid lower engine mount and get a resonant feedback loop and smash their gearbox, or split their crank?!


For me it's not something you can easily test for, and it's potentially a complete show-stopper... all for a novelty effect that has no performance benefits that I've heard.

At that point it's not really tuning for performance any more, and that is where my interest ends.

Dave