Viper Is Dying! Oh NO!

[LeonOfTheDead]

My 1.6 litre petrol Nissan B13, as I speak, has over 260,000 miles or 418,429 Km. This is reliable for a petrol engine and I am going to rough handle the car this evening for fun, as I enjoy driving it.

Now, if you placed the amount of torque and horsepower generated by a diesel engine of equal engine size as my petrol engine, on my current engine, It is doubtful that my petrol engine car would have made it this far or have been as reliable as a diesel engine. Simply, the amount of heat generated in a diesel engine with the amount of work it does, will be a challenge for a petrol engine to reasonably sustain, over an extended period of time.

That's why diesels are heavier: the whole engine has thinker parts, so to sustain the higher pressure and temperature.
If you give a look at the "security coefficient" (translation from Italian, meaning the ratio between the maximum sustainable stress and the actual one) of the same parts of the two engines , a diesel and a petrol one, they will be pretty similar. Maybe a bit higher for the diesel, or at least it used to be so, in the pre common rail era.

This is true. But it does not change the fact that a similar sized diesel engine as my petrol car, is in theory, more reliable, given the amount of work the diesel engine does, compared to my petrol powered car.

In engine design, more work and power output, simply means, less reliability.

the output has little to do with the stress. A powerful engine isn't more stressed than a smaller one. It's not about bhp and lb-ft, but the force acting on each component second per second, which depends on the weight of the component and the acceleration it is sustaining.
So an engine running at a certain rpm because of the combustion is as stressed as an engine running at the same value because actually connected to a real engine, without any combustion taking place.

[G35COUPE]

The correct stoichiometric ratio (which isn't the one provided by chemistry as a combustion chamber isn't the perfect and ideal volume on which those reactions should take place) can be maintained even by a naturally aspirated engine.
Each cylinder would divide the quantity of air that just entered, divide it per 14,8 (iirc) and introduce that quantity of fuel. This is done by both engines, just the turbocharged engine can "contain" much more air, thanks to the turbine, and accordingly, it will enter more fuel, but still 1/14,8 times the quantity of air in the cylinder. Actually, as I mentioned, engines don't work at the stoichiometric ratio, as that's the theoretical value for having the perfect combustion, which never happens. So a lean or rich mixture of air and fuel is to be adopted, also to help to cut the emissions on the exhaust line.
But this is a different story, still, the stoichiometric ratio has nothing to do with the turbocharging. It just changes the quantities, not the ratio.



That's my point, so there s no reason to think the SHO's engine won't work properly



That's not physics, it's statistics.
By that, everything could fall apart, but there are things so common that they are now considerable as a safe and reliable component. Even a connectin rod could collapse under the stress of the combustion cycle, but it doesn't happen, because it's a common component and there aren't secrets about its design. So it's for turbos. The can fail, that's why warranty exists, but statistically they won't.
Superchargers used to be a bit less reliable, especially the scroll ones, but they are fine since quite some time now.



I mentioned Tata only for as regards who owns Jag, don't say I meant it to have an engineering meaning.



How are Lexus'? Cars full of stuff, especially the hybrid ones. Mercedes', BMWs? All the same. Are they reliable? Yes. they are also more expensive, that's for sure.
The I6 twin turbo from BMW is available also on the 1 Series coupe, which should have (I think) an after all similar price in the States as that of the SHO.
The BMW's is a good engine, and reliable. I can't see a given reason for the SHO's to be different.
As I said above, turbos are a common element, designed and redesigned for years, I'd say they know how to build them by now. Also, we are not talking about a 300 bhp/liter engine, it's a 100 bhp/liter one, a pretty common and "safe" value for a turbocharged engine.

1. The practical reality of tuning still remains an attempt to get to the stoichiometric combustion value at all rpm ranges and in changing conditions of pressure and temperature. For an N/A car, getting to this value can technically be easier than for a forced induction application as in a turbo or a supercharger. In a turbo charged system or supercharged system, YOUR MAIN CONCERN, is to maintain a theoretical and practical stiochiometric ratio or combustion value, regardless of volume of air and fuel being drawn into the system. Its easier to control ratios than actual volumes. Ratios dictate actual volumes in the final combustion process.

A wrong stoichiometric ratio is what leads to more air than required going into the combustion process, thus leaning out the exhaust effluents, or too much fuel being used in the combustion process, thus, enriching the exhaust effluent. Stoichiometric ratio IS everything in a combustion process, regardless of application---NA, Turbo, or Super chargers. Whether you beleive it is theoretical or not, makes no difference to a tuning shop which tries hard to ensure that they achieve the desired stoichiometric ratios in the combustion process. As you well know, its safer to run rich and foul up the spark plugs and valves and loose some power, than to run lean and raise the risk of pinging and engine destruction (detonation).

2. If you beleive things falling apart is statistics, fine. However, my physics tells me otherwise. I only used statistics to help in describing the situation or explainign the condition.

3. Lexus is a Toyota product and Toyota uses a technique called "kaizen" in its manufacturing processes, and so, they have less quality problems than most cars since "kaizen" aids in their quality procedures. As for Mercedes Benz and BMW, there are lots of horror stories in the US as to their reliability. I beleive the 3.35i BMW once had fuel pump issues that has carried itself over to the 1 - series. And the 3.35i in some models, lacked intercoolers which caused power output to decline, when it got too hot. I understand they have fixed this problem by installing intercoolers. As for Mercedez Benz, their issues are even more numerous since after their foray with Chrysler. Their design and reliability in the US is now very questionable.

4. I have no doubt that turbos have improved over the years. However, they are still governed by moving parts which add to the existing moving parts in the car. Moving parts break and the more of them you have around, the more likely that they might break. Again, my use of statistics to describe a physics phenomenon.

[G35COUPE]

That's why diesels are heavier: the whole engine has thinker parts, so to sustain the higher pressure and temperature.
If you give a look at the "security coefficient" (translation from Italian, meaning the ratio between the maximum sustainable stress and the actual one) of the same parts of the two engines , a diesel and a petrol one, they will be pretty similar. Maybe a bit higher for the diesel, or at least it used to be so, in the pre common rail era.



the output has little to do with the stress. A powerful engine isn't more stressed than a smaller one. It's not about bhp and lb-ft, but the force acting on each component second per second, which depends on the weight of the component and the acceleration it is sustaining.
So an engine running at a certain rpm because of the combustion is as stressed as an engine running at the same value because actually connected to a real engine, without any combustion taking place.

Perhaps, what I was trying to explain to you here is that a 3.5L V-6 engine putting out 200 bhp will do less work than a 3.5L V-6 engine putting out 400 hp, even at the same stoichiometric ratios. The more work the 400 hp engine does, the more stressed the engine. Why do you think engines that have turbos or superchargers installed, which increase engine output, have bigger engine studs, thicker rods, and other re-inforcements such as stiffer springs and gaskets, etc, in order to handle the additional stress that comes from forcing more volume of air per square inch into the same combustion space, under the same stoichiometric ratios???? There is a reason why an engine that produces more output, is more re-inforced than one that does not produce the same ouput. If you have an after-market turbo or supercharger and you go beyond a certain output ona stock engine, my advice to you is to rebuild the engine by fortifying it. Just an advice. I would ahte to see a friend blow their engine with white and blue smoke flying everywhere on the highway, or having a bent rod and valves, because they installed a turbo or supercharger on their car, without tuning the engine properly or without re-inforcing the internal components to handle output beyond the stock engine's design limits.

[LeonOfTheDead]

1. The practical reality of tuning still remains an attempt to get to the stoichiometric combustion value at all rpm ranges and in changing conditions of pressure and temperature. For an N/A car, getting to this value can technically be easier than for a forced induction application as in a turbo or a supercharger. In a turbo charged system or supercharged system, YOUR MAIN CONCERN, is to maintain a theoretical and practical stiochiometric ratio or combustion value, regardless of volume of air and fuel being drawn into the system. Its easier to control ratios than actual volumes. Ratios dictate actual volumes in the final combustion process.

A wrong stoichiometric ratio is what leads to more air than required going into the combustion process, thus leaning out the exhaust effluents, or too much fuel being used in the combustion process, thus, enriching the exhaust effluent. Stoichiometric ratio IS everything in a combustion process, regardless of application---NA, Turbo, or Super chargers. Whether you beleive it is theoretical or not, makes no difference to a tuning shop which tries hard to ensure that they achieve the desired stoichiometric ratios in the combustion process. As you well know, its safer to run rich and foul up the spark plugs and valves and loose some power, than to run lean and raise the risk of pinging and engine destruction.

Sorry but you are wrong.
You don't have to use the stoichiometric ratio all the time, as it would only need to more emissions, as the combustion is never perfect, not matter if you used the stoichiometric ratio. The catalysts, depending on their type, could need an excess of oxygens or of CO2 to work, that's why I don't use it.
Also, in oder two measure a ratio, you have to measure the quantity.
It's actually easier to calculate (you can't really measure it) how much air entered the cylinder in a turbocharged/supercharged engine, as the system is working with the parameters (let's assume it's only a matter of boost, which it isn't) you decided, while in a naturally aspirated engine, the flux of air in the intake manifold is only supposed to be so considering the tests and tuning done during the development of the engine, but properties of air can change a lot, and you caculations can't work perfectly for every situation. On a forced engine, you can "avoid" bothering about measuring the temperature and pressure of the air as during the compression in the compressor they reach a basically standard level.
That's why NA engines are more sensible to be run during the night or ona mountain road than forced one.

3. Lexus is a Toyota product and Toyota uses a technique called "kaizen" in its manufacturing processes, and so, they have less problems than most cars since "kaizen" aids in their quality procedures. As for Mercedes Benz and BMW, there are lots of horror stories in the US as to their reliability. I beleive the 3.35i BMW once had fuel pump issues that has carried itself over to the 1 - series. And the 3.35i in some models, lacked intercoolers which caused power output to decline, when it got too hot. I understand they have fixed this problem by installing intercoolers. As for Mercedez Benz, their issues are even more numerous since after their foray with Chrysler. Their design and reliability in the US is now very questionable.

Are you saying MB used Chrysler parts, really?!
MB got issues about electronics mainly, uo to 6 years ago, and now solved.
Still, any news of a failing turbo? No.

4. I have no doubt that turbos have improved over the years. However, they are still governed by moving parts which add to the existing moving parts in the car. Moving parts break and the more of them you have around, the more likely that they might break. Again, my use of statistics to describe a physics phenomenon.

A moving part: the crank shaft. They break down all the time right?
Cams, valves, chains? Yes if tuned improperly or not taken care of they break down as everything in the known world, but otherwise, they just work fine because they are a common and well known feature, with good safety coefficients and...how can I explain this again without repeating myself?!

Whatever.

[G35COUPE]

Sorry but you are wrong.
You don't have to use the stoichiometric ratio all the time, as it would only need to more emissions, as the combustion is never perfect, not matter if you used the stoichiometric ratio. The catalysts, depending on their type, could need an excess of oxygens or of CO2 to work, that's why I don't use it.
Also, in oder two measure a ratio, you have to measure the quantity.
It's actually easier to calculate (you can't really measure it) how much air entered the cylinder in a turbocharged/supercharged engine, as the system is working with the parameters (let's assume it's only a matter of boost, which it isn't) you decided, while in a naturally aspirated engine, the flux of air in the intake manifold is only supposed to be so considering the tests and tuning done during the development of the engine, but properties of air can change a lot, and you caculations can't work perfectly for every situation. On a forced engine, you can "avoid" bothering about measuring the temperature and pressure of the air as during the compression in the compressor they reach a basically standard level.
That's why NA engines are more sensible to be run during the night or ona mountain road than forced one.



Are you saying MB used Chrysler parts, really?!
MB got issues about electronics mainly, uo to 6 years ago, and now solved.
Still, any news of a failing turbo? No.




A moving part: the crank shaft. They break down all the time right?
Cams, valves, chains? Yes if tuned improperly or not taken care of they break down as everything in the known world, but otherwise, they just work fine because they are a common and well known feature, with good safety coefficients and...how can I explain this again without repeating myself?!

Whatever.

1. Have you ever been to a tuning shop? They actually have computers that monitor the stoichimetric ratios, and they try so hard to get it to line up at all rpms ranges. Certainly, if you have a turbo installed, you are going to have more air going into the combustion process. Now, is that necessarily a good thing???? NO!!!!!!!! So, what do you do??? You start controlling the ratio of air goining into the combustion chamber using the computer connected to your ECU for modern cars or manipulating the AAC valve for older cars, while measuring your exhaust gas levels for changes in stoichiometry. The air you are controlling is simply to control the stoichiometric values at all rpms. Who cares about emissions if you install a turbo that won't blow your engine up??? Much cheaper to fix emission issues than buy a new engine.

Certainly a turbo will force more air into the system, irrespective of stoichiometric ratio, and thus, you are likely going to fail emissions, except your catalytic converter was designed to handle the increased volume of effluents that the car's engine will produce as a result of the forced induction application. if your OEM catalytic converter is able to make the car pass emission tests, then it is not going to last for its intended design limits---it will have a short life span. And the increased effluents as a result of the turbo application is why a turbo engine sounds awesome and beautiful, under WOT (Wide Open Throttle) than a naturally aspirated system. In fact, a turbo requires as free flowing exhaust channel as possible or even bigger exhaust pipes, or else, the back pressure of gases unable to escape, can go back and damage your exhaust valves, thus, causing the car to over rev beyond the engines limits. In addition to that, the stoichiometry ratio sometimes requires increasing the size of the fuel pump of the car by buying a bigger fuel pump or increasing the size of the fuel injectors, and requiring the installation of spark plugs that are one step colder ( to help control burn rate in the combustion chamber) than the OEM spark plugs. Only the stoichiometric ratio, as determined by a professional auto tuner, is capable of making these increased equipment demands in a forced induction application (Turbo or Supercharger). Simply controlling only air volume, will not give you this information.

And properties of air don't change by a huge margin depending on elevation, temperature, and atmospheric pressure. Air continues to generally be a mixture of oxygen (20%) and Nitrogen (78%) and other inert gases (2%). If not, some of us would have evolved into three-legged creatures as a result of any significant change in the properties of air, while some of us maintain our legs and hands.

Mercedez Benz is still living its nightmare with its previous merger with Chrysler, till this day. Go online and read about the horror stories of their electronic systems.

The more the number of moving parts you introduce into a system, the likelihood a moving part will fail. My beleif is that, if it can be avoided, then do so. A system with 100 moving parts producing 100 KW of energy is less likely to have as many parts breaking than a system with 200 parts producing the same 100 KW of energy. Parts will break, no doubt, but one system will be more prone to breakage than the other.

[LeonOfTheDead]

Have you ever studied what you are talking about?
have a nice day.