Engine Reliability Once Chipped

[Gioseppe]

No one. I would bet my last dollar that every single one of these companies would sidestep liability by blaming the problem on the way you drive.

could maybe take them to small claims court if you had a current AFR readout on a dyno proving those lean conditions, but then they could argue that you knew about it and did nothing.

hmmm.

[USMC850T]

could maybe take them to small claims court if you had a current AFR readout on a dyno proving those lean conditions, but then they could argue that you knew about it and did nothing.

hmmm.

Yep. About all you could do is slander their name enough so that no one on the forums would consider buying their products. That said I'm still getting a chip

OOOOOO Got my new custom exhaust yesterday!!!! New free flow cat to 2.5" piping into flow through muffler! Sounds really ballsy and when I go WOT and the turbo spools, I can hear a mad rush of exhaust gasses as they rip through the cat! It's a really cool noise hearing all the gasses leaving. At first I though it was my fan for the climate control going ape stuff, but no...this is the sound of less restriction!

[Slater]

I've never heard of any chip running lean.

Ever seen an A/F readout on a ST 17psi chip?

[PorBleemo]

Ever seen an A/F readout on a ST 17psi chip?

If you have an image I would be interested to see it. I thought most of them run enough fuel for 21Psi but there have been some flukes.

[Slater]

If you have an image I would be interested to see it. I thought most of them run enough fuel for 21Psi but there have been some flukes.

It has been posted here before during long discussions about the ST chips.

I will try and do a search and find it.

[Guest 300+_T5R_855]

If you have an image I would be interested to see it. I thought most of them run enough fuel for 21Psi but there have been some flukes.

There is a local with an S70 that has a Speedtuning chip and his runs much leaner between 4200 and 6000 RPM than the IPD and Upsolute chips that were there that day. Dangerously lean, no, but leaner nonetheless.

I have the IPD ECU. I would like it better if I could tune it in to my fuel, mod combinations etc...but for an out of the box chip I am quite pleased. Go with the company or chip you feel most comfortable with and enjoy. There is plenty of people that have chimed in that their ECU upgrade has not harmed there car.

Good Luck, Enjoy!

[matt1122]

Don, this is the kind of bullsh*t that got you banned from there in the first place. So grow up and stop spreading shite on the net. One day you may be held accountable for the rubbish you quote!

ADAM - This is not the place to whine and complain about people or support or put down Volvot5.co.uk, make a thread in OT if it's that important to you so we can close it without ruining this lovely thread. Thank you.

[Slater]

It has been posted here before during long discussions about the ST chips.

I will try and do a search and find it.

Here ya go:

http://volvospeed.com/vs_forum/index.php?showtopic=20279&hl=

I would not exactly call that AFR safe...

[Guest 300+_T5R_855]

I would not exactly call that AFR safe...

I would agree on that one. the one I saw was in the 11.5 range. That brings up an interesting issue. How consistant are ST chips?

[Johann]

You simply can't say a Darn thing about it with all the "home improvement" going on.

If you stick to the rules set by the chip 9 out of 10 will perform well and within range, the known brands I mean.

[tknutson]

So does this mean that ST is dangerous or what????

And also what is the safe AFR for our turbo cars, Someone have told me 14.5 is where it should be all the time ???

Is this correct?????

Thor

[dreddj]

So does this mean that ST is dangerous or what????

And also what is the safe AFR for our turbo cars, Someone have told me 14.5 is where it should be all the time ???

Is this correct?????

Thor

see article by Marco on AFR-

Air - Fuel Ratios By Marco Alsterfalk

Who am I?

I am a Volvo enthusiast, and have a sound education together with many years of experience as a professional in the field of Internal Combustion engines (intercooler engines), and Engine Management Systems (EMS). I hold two masters (M.Sc.) degrees in these fields - one from the Royal Institute of Technology, Stockholm, Sweden (Vehicle dynamics & Internal Combustion engines), and one from the University of

Michigan, USA. (Internal Combustion engine & advanced control systems) I have worked within the field of Internal combustion engines for about 15 years and have experience from several vehicle manufacturers including Volvo, Saab Automobile, Porsche AG,and Ford Motor Company, to name a few.

Why Am I Contributing To The Web?

I want to help performance enthusiasts make sound choices of performance products. I am well versed with this field of science and, hence, can shed some light on some common, but important topics.

I do believe that enthusiasts, who may not always have the same level of in-depth knowledge in this specific field of intercooler engines and Engine

management systems, are often misled by profit searching parties who

themselves may have limited knowledge in the field. This may possibly occur because the majority of enthusiasts do not have the ability to

professionally judge the information given and merely take it on the

assurances of the party giving the information.

In many cases, with the best intentions, enthusiasts share what they heard from someone, who in turn heard from someone, who knows a guy at "the manufacturer" etc.. Information is easily distorted and misinterpreted when passed on this way. There are also inevitably those who will purport to be "the one who knows" though unfortunately in some cases they may not, and this leads to further confusion. Naturally, I do not know everything in the field of intercooler engines, but as they say, the more you learn the more one realizes how little one knows. I am setting out to lay the bare facts, so anything I come to contribute will be well grounded. I do own a business that develops software for the vehicle industry and specializes in performance oriented applications, and have been involved in the tuning of Volvos for about 10 years. I simply want to help raise the common knowledge among fellow enthusiasts, by helping them make sound decisions when refining their cars, and possibly be able to better judge statements made by other people. Unfortunately my time for this cause is limited, but I will try my best to clarify some of the pertinent issues.

Fuel Enrichment Effect On High Load Operating Points

The lambda for maximum power (actually imep - indicated mean effective pressure) given a fix ignition angle and fix engine speed will vary slightly from application to application but occurs in the range lambda 1 to slightly rich of 0.9 (Air Fuel Ratio - AFR 14.7 to 13.2). Normally imep peaks slightly lean of lambda 0.9. Above Lambda = 1 (AFR 14.7) imep will decay quickly as lambda increases, below 0.9 it will decay slightly as lambda decreases. To make a sound choice of which lambda to run one has to consider thermal limits of the combustion chamber- and exhaust components, as well as knock limits. If the operating point is not critical with respect to knock,or with respect to excessive thermal stress on exposed components the lambda to run is close to 0.9 as mentioned before. This is because at this lambda the maximum number of oxygen molecules will take part in combustion. Adding more fuel than this portion at the given conditions will not give more power because there are no more oxygen molecules available. Any additional fuel added will flow through the engine unburned, and as it then stays a liquid it will have a cooling effect on the combustion process.

The Definition of Knock

Knock is defined as detonation of the fuel-air mixture and is a very rapid process (almost instantaneous - the flame front spreads at roughly 1800 m/s). During normal operation, the fuel-air mixture in a Spark Ignition (SI)intercooler engine burns progressively (the flame front is propagating at about 25 m/s) rather than detonates. If the fuel-air mixture detonates the dissipated heat is so intense that no material used in intercooler engines today can withstand it. This is the reason for knock being dangerous. Had there been materials that could withstand such heat, then a detonating engine would be the ideal engine from an efficiency point of view. But that is a completely different issue which is far too detailed to be discussed in sufficient depth at this point in time.

The Fundamentals of Knock (Detonation)

The scenario an SI intercooler engine goes through as it is pinging (detonating) is normally as follows: as the air-fuel mixture is ignited at the spark of the sparkplug a flame front starts to propagate through the combustion chamber like a growing ball of fire. Naturally, behind the flame front there will be burned gases and in front there will be unburned gases. As the fuel-air mixture burns heat is released. As the gas temperature increases, so will the pressure. The laws of physics dictate that the pressure spreads

instantly. Hence the unburned fuel will be exposed to the same pressure as the burned, and as the pressure of the unburned gases increase so will its temperature. If the temperature becomes too high the unburned gases will self ignite and this results in combustion occurring with one instantaneous bang - this is detonation a.k.a. knock.

So whether an engine knocks or not is dependent on whether the flame front consumes the last of the unburned gases before it self ignites. If it doesn't the knock limit is exceeded.The knock sensitivity naturally will increase if there are sharp edges in the combustion chamber that becomes hotter than the average combustion chamber surface. If the knock limit of the application is reached what needs to be done is find a way to cool the unburned air-fuel mixture to give the flame front the time it needs to reach the last of the unburned gases. Examples are to add extra fuel, or add some other liquid (e.g. water, as in water injection), retard ignition to decrease the effect of the piston's upward movement on pressure and hence temperature etc. Any way to cool the unburned gases in

front of the flame front will decrease knock sensitivity.

Some Facts

I would like to introduce 3 important facts at this juncture:

1. The knock limit at high load with respect to ignition advance in

practice lies at an ignition angle much later (retarded) than the optimum ignition angle for the engine speed and application at hand. By optimum, I refer to the ignition angle that would produce maximum imep / torque, if knock did not exist.

2. The torque (imep) of an engine doesn't decrease much as lambda is

decreased beyond 0.9 (within reason of course, say above 0.7).

3. In addition, the knock limit of an air-fuel mixture increases

significantly as lambda decreases.

These three facts collectively imply that there is power to be gained by richening the mixture beyond lambda 0.9 and then utilizing part of the increased knock limit to advance spark and in this way produce more power.

So What is The Optimum Lambda Then?

Well, it depends on what you are optimizing for - power, durability (thermal component protection) or fuel economy or a compromise thereof. In real life this should to be judged from application to application, and it also depends on which of the limits is reached first: thermal stress, knock limit, or the mechanical stress limit? Which of these bad things is the most important to avoid? For private persons increasing the performance of their cars, the most devastating thing that can happen is usually a breakdown of the engine internals because of the expense it implies. Therefore the sound decision is often "better safe than sorry", so with the knowledge above one realizes that when optimizing for power it is, in some cases, possible to make a safer and yet more powerful approach than blindly going on the said to be perfect lambda of 0.9 or 0.85 or what ever. The sound path is the one that takes into account the complete application at hand and optimizes it for its purpose.

[turbobrick]

Here ya go:

http://volvospeed.com/vs_forum/index.php?showtopic=20279&hl=

I would not exactly call that AFR safe...

i still dont believe it.. and neither do the people who see my massive fuel cloud when they're behind me..