I decided I’d start a thread to deal with the issue of STRESS, as it seems most people who ‘THINK’ they know all they need to know to challenge me on this subject, need a THOROUGH LESSON to show how LITTLE THEY REALLY ‘KNOW’.
SIMPLE FACT 1;
It is OBVIOUSLY TRUE that adding nitrous oxide to an engine via an incorrectly designed kit, that has been fitted incorrectly and/or is used incorrectly and/or has NOT been setup/tuned correctly WILL ADD STRESS to an engine.
SIMPLE FACT 2;
I have 100s of thousands of customers using MY systems and NOT A SINGLE customer who has followed my instructions correctly, has ever damaged a single engine component, DESPITE A LARGE PERCENTAGE OF THEM having increased the power by as much as 100%.
SIMPLE QUESTION 1;
If nitrous oxide is supplied to an engine by a CORRECTLY designed system, that has been fitted correct, which is then set up/tuned correctly and is then used correctly, adds stress to the engine in the magnitude such ill informed people believe it does, then how come the 100s of thousands of customers using MY systems DO NOT BREAK ANY PARTS!?!?!?!?
SIMPLE ANSWER 1;
MY systems do NOT increase stress AT ALL or at very least to anywhere near the magnitude, such ill informed people expect.
SIMPLE QUESTIONS 2;
What happens to power and therefore the load and stress, if the timing is retarded on a NA engine?
SIMPLE ANSWER 1;
If you retard the timing on a NA engine the power falls and therefore so does the load and stress on the engine.
MORE SIMPLE FACTS;
1) Adding nitrous to an engine increases the combustion speed, therefore without retarding the timing by an appropriate amount, the PEAK LOAD on the engine WILL increase but that does not necessarily mean the stress will also increase.
2) By RETARDING the timing, it is possible to reduce the PEAK load on the engine and therefore any increase in stress.
3) UNLIKE a NA engine, a UNIQUE quality of a nitrous injection engine, is that excessively retarding the timing, DOES NOT CAUSE a total loss of performance.
4) By EXCESSIVELY retarding the timing, IT IS POSSIBLE with a nitrous engine to actually REDUCE the PEAK load/stress on the engine components (even below that of NA), whilst still making MORE MEAN POWER.
5) For anyone who doesn’t understand how this is possible, allow me to explain; i) Combustion chamber pressure rises are EXPONENTIAL in the extreme and as a consequence, PEAK combustion pressure ONLY occurs for a fraction of a second ii) The value it reaches depends on a number of factors, the amount of combustion charge, engine speed, ignition timing. iii) Overly advanced timing results in extreme, undesirable PEAK pressures iv) The pressure AFTER PEAK pressure is always in decline v) By filling the combustion chamber with more charge and then firing it later than optimum, such high PEAK pressures can be AVOIDED but because there is much more expanding exhaust gases, the MEAN pressure is HIGHER, which results in a higher pressure from the point of PEAK pressure onwards, despite that pressure being in DECLINE. The result is an increased push on the piston for a longer period of time, before they exit the exhaust valve.
6) Whilst we are making more power it is NOT AN UNAVOIDABLE CONSEQUENCE that more stress is generated, DUE TO the way that increased force is generated/applied.
7) Even without the timing corrected the engine is subjected to less stress than normal (or at worst ONLY MARGINALLY more), as a consequence of the difference between the combustion process NA and how it’s changed by adding nitrous.
8) Without nitrous the NA combustion process is akin to hitting the piston with a sharp blow from a hammer, because there is minimal charge in the cylinder (compared to a nitrous charge) and therefore the combustion process is short and sharp, like a hammer blow.
9) However, although the burn rate is quicker when nitrous is added, there is much more to burn, so the process takes longer overall and so it acts more like a SUSTAINED PUSH on the piston, rather than a blow from a hammer.
10) Surprising for most people, without nitrous the cycle of pressure/force changes within the engine are extreme in comparison with those when nitrous is added. Rather than the sharp rises and falls in pressures/forces within a NA engine, a nitrous engine sees more SUSTAINED and more prolonged changes, which is MUCH KINDER to the engine components than NA.
11) The best example I witnessed of that was on a motorcycle I was dyno testing some years ago. The bike had a very long chain run and when doing a full power run NA the chain was whipping about like something deranged. However, when the same power run was carried out USING NITROUS, the chain stayed PERFECTLY STRAIGHT WITH NOT A SINGLE IRREGULARITY!!!!
12) This PROVED to me that the NA combustion process was like the piston being BRIEFLY HIT by a hammer, while the nitrous combustion was more like a MORE SUSTAINED PUSH on the piston
13) The load/stress on engine components rises EXPONENTIALLY as rpm rises, for anyone who doesn’t understand what ‘exponential’ means, here is an example of an exponential rise rate; 1 – 2 – 4 – 8 – 16 – 32 – 64 etc. etc. The load on the engine (in particular the piston/con rod) might be as follows; At 1,000 rpm = 1 unit of load/stress At 2,000 rpm = 2 units At 3,000 rpm = 4 units At 4,000 rpm = 8 units At 5,000 rpm = 16 units Etc.
14) This means that you could increase the power by say 50 hp at say 1,000 rpm and it could create less load/stress than the same engine running at say 2,000 rpm WITHOUT the 50 hp increase.
15) When tuning NA to achieve substantial power increases it is UNAVOIDABLE to do so without increasing the peak rpm of the engine, which INEVITABLY results in HUGE increases in load/stress.
16) With nitrous you DO NOT NEED to use even ONE rpm more to increase the power of the engine, therefore for an equivalent increase in power (say 50 hp), a NA engine will be subjected to MUCH HIGHER loads and stresses than a nitrous engine.
17) Furthermore it is ACTUALLY ADVISABLE to use nitrous over the LOWER rpm range, because it is more effective then, as each induction cycle is longer and therefore more nitrous gets in to the cylinder per stroke, which results in a HUGE increase in torque.
18) Even using the normal peak rpm shift point is unadvisable, as using a lower rpm shift point results in quicker acceleration, because more time is spent using the higher torque output generated at the lower rpm, that the engine drops to after a lower peak rpm shift.
19) As RPM rises, less and less nitrous enters the engine per cycle, therefore reducing the load on the engine when inertia loadings are naturally increasing
20) Inertia loadings are the main cause of component failure
21) The combination of maximum effect (torque) being generated at the lowest rpm and the fact that inertial loadings rise exponentially as rpm rises, in conjunction with short shifting (as I always recommend), means that it’s not only possible NOT to increase the load on an engine when adding 50 hp of nitrous but it’s also possible to REDUCE the load below that on a NA engine whilst still achieving an increase in performance.
22) The perfect example of that is the latest Audi V8 engines which started suffering component failure due to excessive inertia loadings just before they were released on the market. To overcome the problem, they lowered the rev limiter by a few 100 rpm but this still left them close to the limits of what was reliable. However, despite that being the case, we have added in excess of 100 hp worth of nitrous and by advising customers to cut the nitrous off or shift 500 to 1,000 rpm earlier than normal peak rpm, those customers continue to have TOTAL RELIABILITY.
23) The more intake charge you feed to an engine, the more effort it takes to compress it and this effort acts as a damper/limiter to rising inertia loadings, so it’s actually safer to run with nitrous than without it.
24) MOST engine failures occur when the power is REMOVED, therefore if we just use a ‘simple’ law of physics that ‘APPEARS’ to state, that adding more power unavoidably results in more stress and therefore less power should create less stress, that should not be the case BUT IT IS A FACT.
25) It is also a FACT that THE REVERSE of what causes such failures, is responsible for why nitrous can make such HUGE power increases WITHOUT breaking anything due to increased ‘stress’.
26) The reason parts brake when you remove the power is as follows; i) When the pistons move upwards they generate HUGE inertia loading, which as stated previously, rise exponentially as rpm rises and the ONLY THING that stops the piston crashing in to the head, is NOT the con rod BUT THE VOLUME OF CHARGE BEING COMPRESSED AND FIRED on top of the piston. ii) If you rev your engine up to max and then throttle off instantly, the cushion of gases vanish (as does the start of the combustion process) and is replaced with a VACUUM and guess what happens to the con rod and big end bolts in the process. iii) If you haven’t guessed it or don’t know, the answer is that THEY STRETCH and in so doing they weaken and will eventually break. So THE WORST THING YOU CAN DO to an engine is NOT to add more power but TO TAKE IT AWAY. iv) As stated above, removing the gases that the engine is pumping leads to component failure, it therefore follows that INCREASING THEM WILL REDUCE COMPONENT FAILURE.
27) Conrods and conrod bolts are NOT as capable at handling stretching forces, as they are at handling compression forces, therefore the last points made above are EXTREMELY IMPORTANT.
Anyone who relies on the laws of physics and/or thinks such laws are ‘simple’ to apply and understand, should first make sure that the law itself is appropriate and being applied not only correctly but also with a full understanding of not only the law but also the subject it’s being applied to – THAT’S A BIG ASK for even the MOST QUALIFIED people let alone the simpletons on most forums who probably don’t even have an ‘A’ level in Physics.
There are no "simple" laws of physics and to think so will inhibit your understanding of many things in life. I'm always being told I'm wrong because of this law or that law but the FACT IS MY RESULTS PROVE I'M RIGHT!!!
More often than not, those that rely on those 'simple' laws of physics are either not applying them correctly or don't understand the full extent of the principles involved.
CLOSING STATEMENT; Whilst adding nitrous from a badly designed nitrous kit (as ALL others are), in an incorrect manner and under certain conditions, will most certainly increase stress, just like most things, if the job is done correctly, the reverse can be the case and as I stated previously, IT IS POSSIBLE to run a nitrous engine which will deliver improved performance, WITHOUT increasing the risk of engine failure, when you KNOW WHAT YOU ARE DOING!!!
_________________ Regards
Trev (The WIZARD of NOS)
30 years of nitrous experience and counting!!!!
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