22 replies to this topic

[dave]

In one of the interviews this week an engineer was talking about a soft rev limiter and a hard rev limiter. I know what a rev limiter does, but what is meant by a hard and soft limiter and how are they applied to engine revs? I'm sure someone in here knows.

Thanks in advance.

Dave

[desmo]

Found this brief explanation on the web from:

http://www.indyracin...hp?story_id=316

“The IRL limiter is called a hard limiter because when it is activated, it shuts down the entire ignition system," explained GM Racing Engineer Ned Baker, the group's electronics specialist. “It's like an on-off switch. When it determines that the engine has exceeded 10,700 rpm, it effectively shuts off the ignition until the rpm falls below the specified speed. When
the limiter is activated, engine output drops to zero. The limiter doesn't restore current to the ignition system until it has determined that the engine is below the rpm limit, so there is a period when the car is essentially without power.”

This stand-alone rev limiter that is supplied, maintained and inspected by IRL officials is the policeman that enforces the league’s rpm rule. It calculates engine speed by measuring the intervals as four teeth on the flywheel pass a block-mounted sensor. The circuitry can measure engine speed with remarkable accuracy. At 10,000 rpm, for example, there are 666 pulses per second, permitting the limiter to detect changes in engine rpm continuously.

"The IRL limiter also has a powerful data-logging capability,” Baker said. “It records engine rpm in real time, so officials can examine engine speed at any point during an event -- in practice, qualifying and the race.

“The IRL hard limiter is extremely harsh, so there is a second rpm limiter incorporated in the engine control module (ECM). This limiter is set just below the threshold of the IRL limit. The ECM calculates engine speed just as the IRL limiter does, but uses its own sensors and its own logic. When it is activated, the internal ECU limiter shuts off the signal to the ignition module. The interruption may last only a thousandth of a second, but it is usually enough to keep the engine speed below the point where the IRL limiter intervenes.

"The third limiter, which is also contained in the ECU software, is called a 'soft' limiter because it is reduces engine power progressively by cutting the spark to selected cylinders. Instead of shutting down all eight cylinders like a hard limiter does, it drops one, two or more cylinders per revolution. When the ‘soft’ limiter is engaged, the engine can still produce a significant percentage of its potential power instead of going to zero as it does when either of the hard limiters is activated.

“With the ‘hard’ limiter, it's all or nothing; with a ‘soft’ limiter, you might still have 90 percent of engine power available to drive the car. There is still the absolute boundary of 10,700 rpm that you can't cross, but the ‘soft’ limiter allows you to walk a little closer to the line while
maintaining a relatively high performance level.”

It is instantly apparent when a driver steps over the line because the engine's exhaust note changes abruptly. When the ignition system is shut down, fuel still is injected into the cylinders. The unburned methanol goes out the exhaust system, where it is ignited by subsequent firings. The result is a distinctive sound that can be heard in the grandstands.

[dave]

Thanks Desmo. That's a good explanation. I understand now, and it makes good sense.
Thanks!!!!

Dave

[RTH]

Sealed FIA electronic limiters have now worked very successfully in F3000 and British Touring cars for nearly 20 years and make very good sense to me as a good cost saving measure if applied to all forms of FIA championship racing . Its revs that cost real money - if instead of 19500 rpm current F1 engines , - a 12000 rpm limited was mandatory life,exotic materials,r&d and rebuilds could be drastically cut and no doubt new car makers could be tempted in.

[desmo]

Recycled post, but on topic here:

I had a chat with an F1 engineer about potential rpm limits in F1, just to gauge his reaction to the idea. His feeling is that profound scrutineering issues would be raised- analagous to the problems encountered in the TC morass. Apparently the Monk limiter employed in F3000 prior to the spec powertrains being mandated was fairly easily outwitted by some of the entrants. In his opinion the only workable way to implement rpm limits in F1 with any certainty of compliance would be to use a single system supplier- a solution that the manufacturers would likely never agree to.

[Ben]

I think the Le Mans have shown that inlet air restrictors are a much better (if still outwitted) way of limiting an engine. There are certainly less ways to bypass it than a mechanical rev or fuel flow limiter.

Ben

[RTH]

I think if it was made abundantly clear that ANY transgression of the technical rules in order to gain a performance advantage would result in the whole team being disqualified for the whole year with immediate effect and no appeal , that right or wrong the FIA's decision was final - as it should be anyway. The punishment would be so bad - that the team principal would think twice before cheating.

Surely audio equipment is good enough now to determine whether an engine is turning in excess of 12000 rpm. Actually for a number of reasons a standard ECU might well be a good idea now anyway - and yes they will always try to blackmail the governing body by threatening to pull out , but sensible ideas that are the same for everyone and could save tens of millions of unnecessary expenditure are in the end taken on board.

Something has to be done, - the spectacle is rubbish, - there is a tiny field of 20 cars - only 10 of which are even remotely competitive, - by the end of this year the field may get smaller yet . Once the TV audience goes the whole thing will fall apart overnight , - it really is that serious.

[Ben]

The talk of stock ECUs ignores one fundamental fact; electrical systems. The only area where a modern F1 car and a high spec road car share similar systems is in engine and chassis control. BMW Motorsport electronics are in the same department as the road car stuff for a reason.

You only have to look at the outcry from the race teams in F3 when they had to go to a stock ECU to realise that the OEMs will leave or massively reduce their financial input if forced to do the same in F1.

Ben

[desmo]

It seems likely to me that a fuel quantity limit could effectively put an end to the rpm race, while at the same time increasing the technical relevance of the powertrain development expenses to production vehicles. Furthermore it could accomplish this without continuing F1's evolution towards a spec racing formula, a process that threatens the unique historic identity of GP/F1 as a relative showcase of technical innovation. All this without the thorny scrutineering issues raised by a mandated rpm limit too. Fresh thinking may be in order here.

[Greg Locock]

RTH, I think all your suggestion would do is line the lawyer's pockets.

[Ben]

Originally posted by desmo
It seems likely to me that a fuel quantity limit could effectively put an end to the rpm race, while at the same time increasing the technical relevance of the powertrain development expenses to production vehicles. Furthermore it could accomplish this without continuing F1's evolution towards a spec racing formula, a process that threatens the unique historic identity of GP/F1 as a relative showcase of technical innovation. All this without the thorny scrutineering issues raised by a mandated rpm limit too. Fresh thinking may be in order here.

The idea that F1 is evolving into a spec series is odd. In the 50s we had a de facto spec of Maserati 250Fs due to a lot of privateer entrants. In the 60s Cooper and Lotus both ran Climax engines, and many privateers ran Lotus chassis'. Into the 70s most of the grid ran Cosworth DFVs.

At the moment we have more bespoke engineered components on the grid than at any time in F1's history. While I agree that the regs make the cars look similar, this shouldn't be confused with spec motorsport.

Ben

[desmo]

Originally posted by Ben


The idea that F1 is evolving into a spec series is odd. In the 50s we had a de facto spec of Maserati 250Fs due to a lot of privateer entrants. In the 60s Cooper and Lotus both ran Climax engines, and many privateers ran Lotus chassis'. Into the 70s most of the grid ran Cosworth DFVs.

At the moment we have more bespoke engineered components on the grid than at any time in F1's history. While I agree that the regs make the cars look similar, this shouldn't be confused with spec motorsport.

Ben

Point taken and I cannot remember the '50s and '60s, but just take a look at the diversity of technical approaches to chassis design in the '70s compared to today. The examples of obvious innovative differing engineering approaches are too numerous to mention. In spite of the fact that most of the grid were running DFVs, there was a lot more diversity in design philosophies than exists today. As the technical regs accrete and the design parameters are ever narrowed, the cars on the grid are defined into greater and greater similarity. This trend line, if followed or even accelerated by the mandating of spec ECUs, is leading to a set of regulations so restrictive that only essentially one design solution will be viable, and no matter how much bespoke engineering is uindependantly done it will essentially be just different roads to the same place.

In the '50, '60s and '70s, substantial innovation still existed or was at least theoretically possible. If current F1 fans no longer care about such things, then fair enough, but the passing into liveries and detail engineering being the largest differences between the cars on the grid IMO merits at least thoughtful acknowledgement. It may perhaps be that such an outcome isn't an inevitability or even in the best long-term interests of the sport. I think it's approaching the point where looking at a comprehensive redefinition of the formula is in order. The current regs are hardly more than a haphazard collection of rules reflecting the history of the battles fought between the sanctioning bodies to restrict the speeds and the entrants to work around the restrictions. There is no real underlying unity or philosophical focus evident. I find it impossible to believe that a much more tightly focused and succinct set of rules couldn't be formulated that would do a far better job from any possible perspective.

[Ben]

Interesting thoughts desmo.

This is sadly inevitable though. If we draw an analogy with evolution, yes there were a lot of differing approaches to design in the 60s and 70s. However many of them were crap. Chapman defined the standard with the T79 whereby the car took the form of (referencing Wright);

Front Axle - Driver - Fuel Tank - Engine - Gearbox - Rear Axle (radiators in sidepods)

In an evolutionary process of elimination, everyone realised he had got it spot on and followed suit.

I suppose I'm sort of agreeing with you in that the only way to stop this decent into homogeny is to allow all the technical innovations you can think of. This has always been my position and why I feel that advocating banning TC, etc and complaining about the cars looking the same is an untenable position (despite the number who appear to take it).

As an aside it is worth pointing out that the job of a modern F1 engineers to optimise within a very small box rather than to think outside it (most of the time anyway). This leads to the bizarre sight of Williams' new nose being called innovative (it is not BTW) while the real achievements of modern CAE and design optimisation go unheralded because they cannot be simplified for the average Autosport reader, and those who obssess about rev limits and whether Renault are 500hp down or not.

Ben

[RDV]

I will repeat what I have stated before, yes the rules are limiting, and we will end up with very similar looking cars the same way aircraft are very similarly shaped.

This is because , as form follows function, once you define a dimensional tolerance in the case of cars, or you are aiming at a particular mission profile for aircraft, they will end up with an optimised shape , form and weight. As a corollary they will have very similar performances, if the project is well executed. Given that Ferrari have the biggest budget and a stable design team, and stable and settled drivers there is not much that will disturb the equation.

As chosen materials used for construction will be the proven ones for any period , performance will be very similar. No aircraft manufacturer will go out on a limb of unproven technology or materials any commercial craft has to pay its way, and nowadays projects are so big you are literally betting the company on it.

Likewise for a F1 team, there are no new concepts being developed, and the refinement of simulation an wind tunnel testing by the leading teams leave little margin for diversity. The call for diversity, as experienced in the 70*s ignores the fact that it was a great era for new ideas, but most of them were wrong, and wouldn't get past the initial research stage.

Diversity was rife , because most racing teams had cars that were correctly designed as far as engineering procedures go , but aerodynamics were rudimentary (wind tunnel time was expensive, moving belts were rare, damping was a black art (well it still is , but seven poster rigs and massive computing power make it a bit better), tire design was of a suck it and see type, and the number of people and money involved was two orders of magnitude less. Steering racks were not bespoke, they were modified Triumph Herald units, transaxles were derived from VW beetle cases (its legacy was seen up to transverse boxes), and so on down the line.

I will say it again, diversity was a result of lack of knowledge, not a golden era of innovation. Trust me I was there.

As Ben says, I also found it ludicrous to have all the media having orgasms over the shape of FW23 wing brackets for crissake , the number of mag covers and column inches over a minor aerodynamic appendage just points to the fact that most coverage today is of a very superficial manner, and that the engineering work under the skin is ignored.

Filament wound carbon units, metal matrix castings, electron beam welding and laser or water-cut items are just not sexy enough for the dumbed-down approach.

Cater for the masses, the emphasis will be on the lowest common denominator.

This statement is in no way elitist, engineering is a trade like any other, but the arcana is not sexy to outsiders to the craft. and decidedly boring to the couch athletes, whose interest is in competition, one man (or woman) against another.

Electronics might inspire some awe, but lets not make it too complex, people accept as matter of fact that you can pick up your mobile phone and speak with auntie Mabel on the other side of the world without wondering in the least how its done, and what marvels of electronic, aerospace and manufacturing has bought them an affordable and now ubiquitously necessary mobile phone.

Motor racing has been evolving over a century now, but the WDC was configured in the 50:s and like politics has not kept up with the times. Absolutely free regulations will change the competition, but the cost issue would still be there, those who have more to spend will , if correctly managed , overwhelm the unfunded.

By the same token strangling engineering does not bring costs down, we have been hearing this sirens song for over three decades and it has not happened yet, and probably will never happen until market forces make it so. Given that the worlds gnp increases, sometimes faster , sometimes slower, but the numbers of cars on the grid are frozen, unit costs , or income available for it, will continue to increase.

And desmo, absolutely correct, but as in most things , the world is not logical, so the convoluted , twisted affair that is the Concorde agreement , and all that will follow it , is in the hands of people that have vested interests, and will not relinquish it for an equitable or different form from the one that gives them/it power.... the only way to have a change is to completely remove all participants and sporting authorities and start afresh... again , as F1 has eclipsed all other forms of motor racing in a world perspective (Nascar might be bigger financially, but it is a niche racing class, and spec to boot..), we are left with the crown princes manufacturers consortium...... puhlease!!
IRL?..... snigger.... Premier formula? where art thou?

Face up to it , you cant win, you cant break even , but it is the only game in town...... rant over.... lets go watch some tractor pulls or curling...

no takers? OK roll on Imola .... and if we are still worried about the red tide, suffice to say that this too will pass, MS will stop one day, the team behind him will disband and we will go on to the next cycle of hand wringing about team Mandarin dominating boring , no overtaking F1 racing, and how good we had it in the start of the century with those mythical gods, the iceman, the red baron and the fiery Colombian....

[Ben]

Originally posted by RDV
Filament wound carbon units, metal matrix castings, electron beam welding and laser or water-cut items are just not sexy enough for the dumbed-down approach.

Cater for the masses, the emphasis will be on the lowest common denominator.

This statement is in no way elitist, engineering is a trade like any other, but the arcana is not sexy to outsiders to the craft. and decidedly boring to the couch athletes, whose interest is in competition, one man (or woman) against another.

Excellent words as ever from someone who knows.

RDV makes the point I have often made on this board that motor racing is not a sport where man competes against man on a level playing field. No such level playing field exists, never has, never will. As an engineer, I will continue to follow F1 from a technical standpoint but for sporting excellence I will look to the roads of France in July (see the sig) and the track in Athens come September.

In the same way Peter Wright talks about reading Pomeroy's books as a boy, I read Len Terry's and however outmoded the technology in it now is, one thing stuck in my mind; "To understand a racing car, you must understand what has gone before and the engineering constraints behind it". Obvious paraphrasing, but you get the idea.

Having used filament wound composites (F1 driveshafts made this way are coming BTW), MMC, beam welding and laser cutting in a race car I would venture that BAR's gearbox is the most interesting development this year. A reliable composite transmission in a reliable and quick car. They appear to have balanced the technical innovation with systems integration brilliantly. It suffers from a number of problems as far as the general public goes though, It's not a barge board and/or wing, and you can't draw attention to it with a facile TV graphic.

Ben

P.S. On the sport thing, go Justin Rose. The Tiger is 3 over!!

[kos]

RDV, Ben Excellent and very interesting posts

[RDV]

ben-No such level playing field exists, never has, never will.

quote:
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ben-No such level playing field exists, never has, never will.
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Fairness is a civilized concept, motorsport has never been a civilized pursuit, it just goes back to beating the opposition in the most expeditious way possible, you do this by de-stabilizing the opposition, whether by influencing rules changes to suit you, stealing the drivers girlfriend even if not interested, offering a job to the key personnel of other team, stealing their sponsors, leaking scurrilous gossip about opositions problems/moral habits/personal higiene/inteligence/difficult financial position/morals or haircut style... check press for current examples...

Machiavelli is required reading for team management... and all this is obscured by personal ambition/hidden agendas/incompetence ..... mmmm, sounds a lot like politics, nest ce pas? again human nature forged over millennia of evolution, where the winners survived. The recent CEO behaviour disclosures in the recently deceased dotcom boom a field guide for alpha male behavior....

The veneer of "fairness" is due to nobody wanting to appear ruthless in the achieving of his goals, we have to delve into deep Jungian archetipes to better explain this, but dear deiety , not in a tech forum... see alexbikers comments in the "cheating" thread.

back to the subject, I think the problem is that there is a whole diverse phyla of people all watching "GP racing" with different expectations.... there are the techno heads, there are the celebrity chasers ( celebrities earn a lot of money and are on TV), the vicarious " I can do that , but don't so I wont" ex scalextric owners and arcade f1 drivers, there are the chauvinist follow my country ( attach one from selection= driver, engine , car , team), there are people leading surrogate lives by being fans of this or that driver with an almost religious tinge to their fandom and as religion is a mild form of insanity not rational engineering oriented, even , presumably , a fair leavening of the same people that make up the 7% that always seems to answer " don't know" in polls, and what it boils down to , is that apart from died in the wool techies, the vast majority of them are not interested in the finer points of technology, but really want to see at least two men fighting it out ( you cant beat the genes guv.) , and all we have in the name of rules is to try to even the playing field

However , nature has never been "fair" , and as D.Gurney (I presume, or was it J.Hall?) once say "the only way you will beat cubic inches is with cubic money"... the sad thing is that sometimes there are quite good tussles in the midfield , but (genes again guv.) it doesn't seem as important as n#1... ...lets just accept that any sport that depends on equipment will be subject to budgetary capacity... this is of course assuming F1 racing is a sport...
(mmm....just checked my settings and found them on- rant and- extreme....)

[BRIAN GLOVER]

'No substitute for cubic inches except square money'. Don't know who coined that.

May I make a suggestion, RDV. No, not that one. You know the one about doing some rather awkward things to yourself. Not that one at all, but:

How about you and McGuire collaborating on a book. A hilarious account of autoracing behind the scenes with obscure anecdotes embellished with your sophisticated humor. Perhaps cartoon like drawings amongst the pictures. It's got to have pictures. I cant read a book without pictures.
A funny technical book. With quotes from famous characters in motor sport.
Submit a story to Autoweek, the most humorous Auto magazine with a very sophisticated readership.
Dutch Mandel- Editor Autoweek-1155 Gratiot Ave-Detroit MI 48207-2997

Heck, it may become a regular column marying the past with the present.$$$$$$

I'm grateful that you and others share your literary talents with us, but have you thought of capitalizing on these talents other than your obvious engineering acumen and fabrication skills. Just a thought.
We already have some famous scribes on this BB.

Originally posted by RDV


quote:

Fairness is a civilized concept, nature has never been "fair" , and as D.Gurney (I presume, or was it J.Hall?) once say "the only way you will beat cubic inches is with cubic money"... the sad thing is that sometimes there are quite good tussles in the midfield , but (genes again guv.) it doesn't seem as important as n#1... ...lets just accept that any sport that depends on equipment will be subject to budgetary capacity... this is of course assuming F1 racing is a sport...
(mmm....just checked my settings and found them on- rant and- extreme....)

[McGuire]

Originally posted by BRIAN GLOVER
How about you and McGuire collaborating on a book.

I'll contribute the scurrilous lies.

[Croaky]

It strikes me that the whole rulebook for modern F1 is nothing to do with racing or competition or cheating. It's almost entirely down to safety- reducing speeds in particular. Since everyone has to be constrained for safety reasons (real or imaginary) they have to try and make sure everyone is similarly constrained, nobody's allowed to go too fast. A wise man once told me of the phrase "reductio ad absurdum" meaning something is taken to its illogical conclusion. F1 seems that way, the supposed pinnacle of motorsport is turning into a spec series because every single thing is regulated.
As for the issues of traction control, automatic gearboxes and the like, the World Rally Championship has all sorts of technology, right up to active diffs, but it getting more and more popular. Why? Because the cars are exciting to watch, they appear to be on the verge of a massive accident on nearly every corner. A car on the limit is a car on the limit, no matter how it got there, and your granny bloody well couldn't drive it!

[Ben]

The FIA goes on about regs changes for safety yet refuses to limit engine performance. If you reduce downforce by cutting numbers of wing elements, etc all that the engineers will do is recover the downforce but less efficiently and increase engine power to maintain top speeds.

The FIA has the people (Peter Wright, etc) but they are so emasculated, as engineers, by the politics of it that they might as well not be there.

Ben

[nicholasc]

Originally posted by BRIAN GLOVER
'No substitute for cubic inches except square money'. Don't know who coined that.

May I make a suggestion, RDV. No, not that one. You know the one about doing some rather awkward things to yourself. Not that one at all, but:

How about you and McGuire collaborating on a book. A hilarious account of autoracing behind the scenes with obscure anecdotes embellished with your sophisticated humor. Perhaps cartoon like drawings amongst the pictures. It's got to have pictures. I cant read a book without pictures.
A funny technical book. With quotes from famous characters in motor sport.
Submit a story to Autoweek, the most humorous Auto magazine with a very sophisticated readership.
Dutch Mandel- Editor Autoweek-1155 Gratiot Ave-Detroit MI 48207-2997

Heck, it may become a regular column marying the past with the present.$$$$$$

I'm grateful that you and others share your literary talents with us, but have you thought of capitalizing on these talents other than your obvious engineering acumen and fabrication skills. Just a thought.
We already have some famous scribes on this BB.

agreed
At the very least I'd be happy to organise lessons for new F1 fans in 'common sense' if you'd agree to speak. While the budgets of f1 teams rise ( I most definitley agree with your gnp theorum) so the quality of F1 writing falls....

[Christiaan]

We have had great debate on this forum about policing rev limits in F1. I am convinced that it is possible through dual use of harmonics and a "mechanical" system described by Desmo (great post Desmo). How are they currently providing those rpm counters on TV?