Herblenny

iTrader: (13)

Sounds like a newbie questions..

But i was curious and wanted to make sure if someone could explain to me how.. NOT! just "when you run too lean"..

A friend of mine blew his engine tonight..

I've also heard bad spark plug could cause apex seals to go.. Wondering how??

Want a good explaination..

Thanks!

PHIL

twinturborx7pete

iTrader: (3)

um too lean...

coolant ring failure

oil starvation

fuel starvation from g cornering forces

too hot of a plug..

skunks

with a bad sparkplug, it might have detonated at teh wrong time

rpm_pwr

A few ways to kill a rotary:

1) Too lean (knock)
2) Too hot (knock, water seals)
3) Wrong / Bad fuel (knock)
4) Plugs too hot (knock)

There's heaps of rarer ones but there's the main ones.

-pete

rpm_pwr

There's a good time to detonate?

89Turbo944

Downshifting from 5th to second usualy blows the engine And tranny, and everythign else.

Dont do that. i saw a new integra Type- R do that on the highway. I rolled up next to him and he decided he wanted to go. I pounch it in 4 th and hes in 5th so i guess he wanted to downshift to 4th but instead gets 2nd. And WAAAAAM. It looked like he slamed on his breaks on the highway, except there was black smoke, and a few parts coming out the back. Was intresting to watcht tho. Always wondered what would happen when you do that, now i know

Herblenny

iTrader: (13)

I guess I should of better phrase my question..

I have heard and know some what why bad knock, bad fuel, running lean, etc blowing rotaries..

But no one so far explained WHY?

If someone could explain in detail to why.. running lean cause Apex seals to go.. Is it because too much compression when leaned out or other reasons..

Herblenny

iTrader: (13)

Can you tell me why detonation at the wrong time will blow apex??

I'm sure others will like to know exactly how this might cause this..

Damn, I sound like a newbie.. which I'm might be.. since I'm asking this kind of question.. but I have an idea... but want to make sure before telling others..

HDP

iTrader: (2)

Well, you should see when someone accidentally drops it in reverse...

huffner

Ask gordon monsen he is good at breaking motors.

paw140

Knocking = uncontrolled explosion = extreme combustion chamber pressure = broken apex seal.

Herblenny

iTrader: (13)

Now we are talking..

Can we take this and break it down to more detail??

I would like to know "uncontrolled explosion" in more detail, ie: how chamber gets this extreme pressure (is it the timing of the ignition being retarded, and position of the rotor when it ignite cause this detonation??)

I've heard the advancing timing too foward could produce power but also cause engines to blow.. how??

XSTransAm

Detonation:
Detonation is the spontaneous combustion of the end-gas (remaining fuel/air mixture) in the chamber. It always occurs after normal combustion is initiated by the spark plug. The initial combustion at the spark plug is followed by a normal combustion burn. For some reason, likely heat and pressure, the end gas in the chamber spontaneously combusts. The key point here is that detonation occurs after you have initiated the normal combustion with the spark plug.


Pre-ignition:
Pre-ignition is defined as the ignition of the mixture prior to the spark plug firing. Anytime something causes the mixture in the chamber to ignite prior to the spark plug event it is classified as pre-ignition. The two are completely different and abnormal phenomenon.



More on Detonation:
Unburned end gas, under increasing pressure and heat (from the normal progressive burning process and hot combustion chamber metals) spontaneously combusts, ignited solely by the intense heat and pressure. The remaining fuel in the end gas simply lacks sufficient octane rating to withstand this combination of heat and pressure.

Detonation causes a very high, very sharp pressure spike in the combustion chamber but it is of a very short duration. If you look at a pressure trace of the combustion chamber process, you would see the normal burn as a normal pressure rise, then all of a sudden you would see a very sharp spike when the detonation occurred. That spike always occurs after the spark plug fires. The sharp spike in pressure creates a force in the combustion chamber. It causes the structure of the engine to ring, or resonate, much as if it were hit by a hammer. Resonance, which is characteristic of combustion detonation, occurs at about 6400 Hertz. So the pinging you hear is actually the structure of the engine reacting to the pressure spikes. This noise of detonation is commonly called spark knock. This noise changes only slightly between iron and aluminum. This noise or vibration is what a knock sensor picks up. The knock sensors are tuned to 6400 hertz and they will pick up that spark knock. Incidentally, the knocking or pinging sound is not the result of "two flame fronts meeting" as is often stated. Although this clash does generate a spike the noise you sense comes from the vibration of the engine structure reacting to the pressure spike.

One thing to understand is that detonation is not necessarily destructive. Many engines run under light levels of detonation, even moderate levels. Some engines can sustain very long periods of heavy detonation without incurring any damage. If you've driven a car that has a lot of spark advance on the freeway, you'll hear it pinging. It can run that way for thousands and thousands of miles. Detonation is not necessarily destructive. It's not an optimum situation but it is not a guaranteed instant failure. The higher the specific output (HP/in3) of the engine, the greater the sensitivity to detonation. An engine that is making 0.5 HP/in3 or less can sustain moderate levels of detonation without any damage; but an engine that is making 1.5 HP/in3, if it detonates, it will probably be damaged fairly quickly, here I mean within minutes.

Herblenny

iTrader: (13)

WOW.. now thats kind of answer I was looking for.. thank you!!