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Engines dont make power they applied force to connecting rod and piston at a variety of angles forcexlength. A lower peak pressure in the cylinder can result with higher output in terms of power with reduced peak stress on the piston with wider area under the curve of pressure.
^facepalm
This entire statement makes less than no sense
Sure, let's dig up ultraspecific examples of known overbuilt engines as a means to disprove a general statement.
Rock on, crouton.
Hmm. Overbuilt? Cast aluminum pistons, same as in truck engines from Chevrolet. Same lattice formation.
Everything is overbuilt. Its called safety factor. Engines, helicopters, bridges, buildings, are all overbuilt to withstand far more stress than they will experience. Bridges and buildings are cyclic loaded just like engines everyday, wind and traffic.
The covalent bonds between atoms either break, deform, or not at all. That is chemistry in engineering. If the engine or building or whatever is designed with specific stress in mind and overcompensated using general formula of safety factor, then it will cycle abuse stress indefinetely or until some limit as predetermined has been reached. What is the limit for buildings? bridges? Engines? An engine can go 1 million miles. If the engine suffers a failure before 1 million miles then it was because of use-error such as malmaintenance, improper tuning/setup, or failure to understand the limitations of safety factor in the original engineering.
You want a 'less overbuilt engine' example? Okay my sig contains one. I take a 200,000 miles 5.3L 2002 Tahoe engine and producing 600rwhp now for 5 years and 50,000 miles on original components. And I am the last person to do this- many have done similarly. Only they lack education surrounding PCV and tuning which interferes with reliability, knowledge which I posses. I will take this now 250,000 miles 600rwhp engine and take it to perhaps 300,000 miles then pull it apart for inspection and reveal near mint bearing and cylinder walls similar to the pictures taken when it had 200k only. Why, because I know what I am doing and how to apply stress to the engine properly.
^facepalm
This entire statement makes less than no sense
I don't expect you guys to have the PhD in mechancal engineering or the 25 years experience necessary to get these details. I am giving you heuristics and you can take this opportunity to increase your knowledge fundamentals. I've helped build and tune hundreds of vehicle which utilize stock engines that will outlast the original configurations because the most wear is caused by overlooked items as air filtration and PCV component features, which I developed a strict guidelines to overcompensate above and beyond OEM so the engine despite producing 2x to 3x original output will last longer than the original versions.
here is a visualconcept for what I described using words that you pretend makes no sense. Yet here it is in perfect sense.
The peak cylinder pressure is the peak stress to the piston lattice crystal. I don't have time to discuss application for 3D stress tensor in lattice formation but suffice to say the original engineers are well aware of directional forces associated with stress within the lattice and since 1988 for Toyota/Nissan and since 2001 for Chevolet all brittle fracture failure pistons (original style pistons with tight piston-wall) produced affect the modern production for directional lattice atomic structure resilience to applied stress. The similar technology in maingirdle and pan support derived from 3D computer modelling of stress in block design was necessary to bring the entire engine configuration safety factor approximately equal. In other words, the block, crankshaft, rods, pistons etc... are all engineered to fail around roughly the same internal parts stress ratios to one another. As evinced by the way we use these modern, original engines in racing applications,
A stock bottom end Gen4 engine 05-07 will do 1000rwhp reliably for 200,000 miles
So unless you want a 1200+hp setup, I stick with the factory parts. Guys are revving these things to 8400rpm and making 1400hp for multiple seasons when tuned correctly. Thats pretty impressive for a $300-500 long block IMO.
now lets briefly discuss piston stress and parts stress in terms of the picture I posted.
The connecting rod forms an angle with the crankshaft and from this is derived the vector force cross product applied to the crankshaft as a result of pressure over area applied to the piston in the Y-axis. That is, useful force applied to the crankshaft is only available during specific crankshaft angles. In particular, a piston at Top Dead Center, provides ZERO net force in a useful direction to the crankshaft. Now look at that picture of cylinder pressure- how much pressure is applied at TDC to the crankshaft? Quite a lot of pressure (STRESS) is applied at TDC yet none of it is doing useful work.
This example illustrates the simple fact that a massive stress may be applied to the engine internal components with absolutely no work being done to the crankshaft or tire. We can easily take a factory engine and rapidly advance the spark timing beyond safe limits and shatter a piston due to pressure/stress forces while actually reducing the engine power significantly. This again is showing us that, stress has little to do with power. Stress is not a component or feature of power production. We can over stress an engine without making any power at all. Once you understand this basic tenant and remove any connection in your mind of power with stress, you will begin to see why we can produce 2x or 3x the power of the factory engine without producing any significant extra stress to the engine internal components. Particularly look at the pressure in the cylinder after TDC- it begins to drop rapidly. Increasing the volume of the cylinder as piston descends and rapidly diminishing fuel molecules with oxygen to interact with results with a drop in pressure. In Forced induction applications, we can significantly increase the area under the curve of the post TDC pressure applied force to the crankshaft without increasing the peak. In other words, we can produce far more power than a factory engine without actually adding any stress to the piston or internal components whatsoever- because stress is unrelated to power. Stress is related to the pressure/area or force applied to the pistons so by virtue of extending the pressure without increasing the peak the force is applied for longer duration without increasing it's magnitude resulting with more power to the tires and no additional internal engine stress.
I do not have a PhD in mechanical engineering but I do have a bachelors in mechanical engineering and 20 years experience in manufacturing.
Sorry bro, but going on about lattice structures is pretty lame and it's obvious you are trying to sound smart and throw out engineering terms thinking I don't fully understand all the fundamentals of what you are saying.
I know enough to know when a guy is just is trying to overcompensate.
Not even going to bother going through your wall of text line by line to correct your out of context asssertions because I don't care enough
Just saying though, you are the guy who initially made reference to a STATIC structure with a STATIC load applied to it and used that in the context of stresses on a reciprocating assembly with hundreds and hundreds of moving parts
I do not have a PhD in mechanical engineering but I do have a bachelors in mechanical engineering and 20 years experience in manufacturing.
Sorry bro, but going on about lattice structures is pretty lame and it's obvious you are trying to sound smart and throw out engineering terms thinking I don't fully understand all the fundamentals of what you are saying.
I know enough to know when a guy is just is trying to overcompensate.
Not even going to bother going through your wall of text line by line to correct your out of context asssertions because I don't care enough
Just saying though, you are the guy who initially made reference to a STATIC structure with a STATIC load applied to it and used that in the context of stresses on a reciprocating assembly with hundreds and hundreds of moving parts
There is no such thing as a static structure. At all temperatures above absolute zero, everything is in motion.
Quote:
So unless you want a 1200+hp setup, I stick with the factory parts. Guys are revving these things to 8400rpm and making 1400hp for multiple seasons when tuned correctly. Thats pretty impressive for a $300-500 long block IMO.
That is your blind eye. The engine in my vehicle came factory 280bhp now has over 700bhp and it is the same reliability approaching 300,000 miles in the next 5 years. You are missing the data and evidence, ignore it, but it remains. Forced induction in and of itself does not reduce reliability. Properly setup, a turbo can increase reliability and power.
If you know, you know. I can't make this **** up or fool veterans.
Originally Posted by Tusc
For anyone who doesn't know, that is deep knowledge shared from a lot of experience. I actually screen shot it and saved the post.
I write alot because I write fast. Its a talent/ability reading and writing I make research papers and review papers rapidly for publication. What appears to you as a text wall is a 3 minute reading short couple of words to me. Try reading books to increase your reading speed and ability to gain knowledge from words instead of putting people down for writing and reading quickly on the internet.
Lets discuss some mods that kill reliability and how to get around them. This is the topic at hand and I've spent my life learning what to do , and what not to do. Outside of college, they don't teach this stuff in school. I just use school to work backwards through the experience and find out WHY what works and HOW it works, not WHAT works.
1. Any internal engine modifications. Anytime you open an engine it may bring in debris, dirt, pollen, fungus, anything from outside air is contamination. To get around this issue, setup a clean room before performing engine internal work if possible. A simple box with with an air filter taped to one side can be placed on the IN and OUT sections of a tarp enclosed space for example, $50 clean room effort, let it run overnight to clear the particulate from air.
=> Follow the FSM when performing engine internal work. Never dismantle the bottom end unless performing an FSM rebuild procedure in clean environment.
2. Touching parts with bare hands inside an engine
Always use fresh clean new disposable gloves on engine internal parts, including spark plugs. Never touch inside parts with bare hands no matter what you see or people tell you, its not okay. Plugs go in clean, they stay in. Never remove plugs to look at them. If you need to look at plugs to tune the engine, use cheap plugs, tune the engine fully, and then install the correct final plugs permanently and never remove them again. For example in 2018~ I dyno my vehicle, before the dyno I put fresh iridium plugs and never removed them since. The vehicle was already tuned prior to dyno day.
3. Tuning is rarely done properly
Dynometer is a tool but should not be used to fully tune a vehicle, never bring a build to a dyno with expectation to tune it there. Street cars get tuned on the street and then clean up on the dyno to remove timing and make it safer, not extract more power. This is the first big mistake 'tuners' make and why power starts to get a bad reputation when it is a TUNING issue not a POWER issue causing the damage. Use dynometer to find MINIMUM best timing, that is the secret and why I spend all this time to explain 'reliability' aspects. To make the LEAST engine internal stress you want the MINIMUM timing profile and LEAST amount of cylinder pressure possible, it may even be less than stock pressure peak with higher output to the tires. To gain power this way requires forced induction, you make as much power as you want with the least amount of timing for lowest peak pressure, gives the best survival and reliability rate for engine internals for a given fuel octane and temperature. Both temperature and fuel octane influence chemical reaction rate, you move one you move the other. chemical reaction of combustion is facilitated by collisions which is their collective normal distribution molecular velocity impact particularly outside of some relatable steric hindrance, which is why fuel octane is higher in more highly branched hydrocarbon chains despite the same number of carbons present. By moving timing on the dynometer at high output you can determine the timing 'window' availability of fuel octane and temperature of components to cover up future mistakes. In other words, when approaching a fuel octane limitation with respect to boost or compression, the timing available 'window' will be small and easily to detect on the dyno, as a warning that the fuel cannot support the power reliably in the future. This is an advanced tuning topic and while I don't have time to teach it here, the point is that everybody can understand that it is possible for a good tuner to determine the safety factor for a powerful, reliable engine, by using the dynometer, which isn't easily done on street or race track tuning situations. The dyno may reveal perturbations, oscillations in torque, spike behavior in the curve, and other graphing related abnormalities which need diagnosis and tuning efforts that go beyond what the engine is making to the tires. It could be in the suspension or the way the engine is attached to the chassis. Or it could be too much timing which caused cylinder pressure spikes resulting in excess stress and wavy/spiky graphs which show high peak power at the expense of engine life. This is common and anybody reading that want an example I can probably discuss this at length with example graphs.
So far we talked about the danger of contamination from opening the engine, touching parts with bare hands, and how tuning influence reliability despite or in the face of power output looking 'good' on paper.
Next lets talk a little more deeply about a particular internal engines mod which is typical or necessary even though we don't want to open the engine... the main thing all OEM engines need is a proper custom tailored camshaft profile and supporting spring effort. The discussion of cam profile is something that many people obsess about and want to discuss for years and years without end. I used to be like that. However there is a simple solution to this discussion and a very clean simple methodology to follow when it comes to reliability and engine output profile. The reason the cam is important is because it tailors the usable powerband in terms of engine frequency (just like clock frequency for a CPU), and this is done mostly via valve open duration. The reason duration influence powerband is because air is a fluid and just like any fluid such as water or oil, air has momentum flow, kinetic energy and acoustic wave property which can work with or against the frequency of valve opening/closing as air flows along some pathway. I said I would make this simple so here it is. The cam/spring/valvetrain profile for reliability needs 5 things.
1. Slow opening and closing ramps. This is essential to maintain lifespan of valvetrain components and to fully control the valve at high RPM, set it down gently and open it gently will give stock-like longevity for valve train parts as lifters and guides. Look at .006" and .050" lift to find longest interval or use cam profile software to determine longest interval of valve opening and closing, slowest ramp. Or ask for this specifically from a custom manufacturer. I will give an example of a off the shelf grind with slow ramps: TFS30602001 for example.
2. Low lift. This is one of the most overlooked ideaology behind camshaft 'upgrades'. Increasing the valve lift is not an upgrade, it is a downgrade to reliability and longevity. Select for lift near the OEM lift which will maintain OEM component longevity and allow you to use original valvetrain parts which last 200k 300k miles or more.
3. Long enough duration to meet peak engine RPM demand, near 6200rpm. Do not choose profiles for 7000rpm+ in daily driver applications with over 4L of displacement. 2L and 3L engine its fine to go 8000rpm some cases. But not necessary in V8 land. With any V8 it should be possible to make 1000rwhp or 800rwhp easily by 6000rpm~. By keeping a redline near 6k the engine reliability is maintained for many reasons, among them, oil flow character while using OEM style oil systems and limiter control dependability.
4. Valve springs as weak as possible to maintain 100,000 miles of reliability. Do not use a stiff valvespring as this will incur longevity issues and wear/tear. A good example for LS application is PAC1218, the spring is stiff enough to support 1200bhp and weak enough to support 100,000 miles or more reliability per spring change. High pressure springs often need to be changed every 12k to 30k miles for example. You do not want that in daily driver apps nor the wear and tear they cause.
5. As much OEM valvetrain components as possible. Use OEM lifters, valves, heads, guides, seals, timing chain, even oil pump. Upgrade pushrods is fine, perfect length if you dare. The big mistake people make is trying to 'upgrade' their heads or other parts in search of power. Ridiculous. Make more power than the engine can handle with a turbocharger and the stock head in almost any V8 engine in the world.
If you follow these, the camshaft will be an actual upgrade, produce similar reliability and support increased power. Remember not to touch it with bare human hands, use gloves, synthetic oil, cleanliness is the main key to everything.
Leave everything else alone. Do not put in new cam bearings or freeze plugs or send the engine to a machine shop, waste time. Which brings us to next rule:
Never machine the engine. If you need a new cam bearings or engine internals or find some issue, get a next used engine. Use a cheap engine platform, there are $500 engines such as LM7 which support 750bhp for 20 years. Make 1100bhp with a used gen4 05-07 engine for 10 to 20 years. Modern engines as gen4 LS are built like 2jz-gte engines using the same 3D modelling and stress analysis software for girdle and pan support, they are essentially Toyota engines after 2002.
What else- review my list from the first link above that I posted. That is how you make an engine survive with high output.
Nobody else knows these things. This is my cultivated theory from around 24 years building and tuning forced induction vehicles as daily drivers.
Turbochargers improve reliability for several reasons. The biggest is exhaust cushion which protects rod cap on exhaust stroke, allowing the use of OEM rodcap/hardware to support 3x 4x engine output for high RPM and high reliability. Superchargers at this level of output place tremendous stress on the crankshaft and bearing system and parasitic to the rotating assembly, reducing potential output maximum by around 100hp and causing extra wear/tear. A supercharger at roughly 1.65 (65% addl output) is generally considered safe and minimum impact on reliability. But 65% more power isn't going to get you from 300hp to 1000.
Want more. Ask any question I basically know everything, every wire every tuning strategy every nut and bolt and sequence. There is too much to list. For example injector timing and spray kinetic energy timed to the peak piston velocity is a discussion if you hang around tuning forums. You can add 100hp or more to a forced induction application V8 with proper injector timing at the mid-range RPM regions. It isn't a 'secret' but the knowledge is so far removed from basic intuition and typical forum car discussion that you won't even know it exists unless somebody happens to bring it up. PCV many do not realize is the key contributor to engine reliability and longevity. It must be done properly, superior to OEM. Air filtration is another one. You must pressure test the air intake pathway to ensure complete sealed and sealed crankcase. You must go above and beyond OEM filtration. It isn't well known and often overlooked but its plain to see once you think about it for a few years.
oof, careful there man. don't wanna pull a muscle patting yourself on the back!
before we die leave behind what you learned for future generations. It isn't (______name) patting himself on the back when he reveals deeper knowledge of the place we live. It is the nature of progression and discovery to reveal. If you want to publish some document about say, cancer research, you must become the expert which can publish such a paper. There is a long list of accomplishments necessary to get the job. If you don't say... nobody can guess... then you won't get the job and your efforts will be ignored.
Full disclosure - didn't read the engineering dossier posted above but still wanted to comment on OP's question.
Cars are designed to comply with emissions and fuel economy rules that will make it to the finish line of warranty period and that's it, any modification to increase performance will introduce compromises. The good news is that a mild cam upgrade with 16 proper hydraulic roller lifters to delete that crazy AFM contraption will net result in improved longevity of an LT1.
Completely different than a static beam with "x" weight hanging on it, in that case yes, if below yield stress it can hang there for 1000 years. Put that load on, then remove it, and repeat that 10,000x's per day and it will fail one day.
If we are talking about aluminum, I believe that is true. Steel is different - if you keep the load below a given threshold, steel can cycle pretty much indefinitely, at least in terms of human timeframes. How many loading cycles has the Brooklyn Bridge gone through in its 140 year life? Or a skyscraper dealing with ever changing wind loading...If steel fails on a bridge (or any other structure) it is because of a design deficiency, construction error, or corrosion reducing the section of the steel thereby weakening it to the point where it exceeds that yield point. At least that's how I remember it. Statics and Dynamics was a long time ago...
If we are talking about aluminum, I believe that is true.
Thank you for your post.
you are absolutely correct that when the covalent bonds of an aluminum or brittle material are stressed and broken, there is no going back. Bending a paper clip for example, at first the friction internal to the lattice creates microfractures and those cracks spread. However an aluminum table where you repeatedly set something on it for many years will never exhibit failure due to stress or cyclic loading because the covalent bonds have not been broken due to the stress applied.
Thus,
Depends how the aluminum is being loaded, how the aluminum is manufactured, and where the stress is being applied in terms of covalent bond angles of the material.
As engineering improved through the 80's and computer aided design became common, powerful, engineers are able to determine circumstances for material failure and creative means to counteract stress. They determine the angles and internal stresses and find a way to overcome or compensate for these type of stress in the lattice formation or direction of applied stress.
Example https://www.sciencedirect.com/topics...cyclic-loading
it can be seen that normal strain reaches its maximum values at angles 0∘ and 180∘ for a cyclic axial loading condition as shown in Fig. 10.4(a). On the other hand, the maximum shear strain is reached at angles of 45∘ and 135∘.
On the contrary, neither the cracking behavior nor the fatigue life of the tensile-dominant material will be influenced because the effect of compressive loading will be canceled by the hoop stress as shown in Fig. 10.3(h).
Any small crack is failure. The smallest crack is failed material. For example an aluminum piston which still looks perfect and has good compression is considered a failed material once it has some internal crack propagating and it won't be long before the crack spreads and the piston crumbles apart. It must never fail, it must never start to crack.
With this in mind, we can easily infer that the affect of cyclic loading a brittle piston is negligible. They will easily achieve 1 million miles if uncracked, unfailed.
Failure isn't a result of cyclic loading in the piston, if it was they would all fail in similar time frames or cycles. Its like an aluminum table you can set something on repeatedly forever if the object isn't heavy enough or sudden enough to damage the aluminum continuity of covalent bonds.
The reason cast or brittle pistons fail is because the stress exceeds a threshold for some reason, usually temperature or shock related.
For example take any stock engine and advance the timing more and more- causing larger and larger pressure spikes in the cylinder which hammer and stress the piston. Now the piston will break due to stress even though you did not add any power. The engine will make less power and the piston will break even with its brand new with very few cycles, cracked and falling apart. The lifespan of internal engine components is good for 1million miles at least. They do not fail from cycles of loading and they will not fail when stress is kept below some particular setting. The job of an (great) engine tuner is to setup and understand how the engine works to manage the stress applied to the internal engine parts and produce and schematic for preventing failure and understand the limitation of oem components where applicable. I've done it hundreds of times. I produce daily drivers with OEM pistons that last 200,000 miles at 3x factory output for applicable platforms. I've given the recipe for chevrolet, nissan, toyota on several forums and they remain the gold standard to this day have never been disproved or refuted.
The audience is performance enthusiasts seeking to better their understanding.
