This is just mostly a curiosity thing , as to what happens if you keep driving the hell out of a car that is losing or has lost alot of compression say a car with about 75 PSI compression . has trouble starting , BUt still starts you know its got its days numbered

BUT why ? What will happen if you keep racing , and abusing said motor? will the compression simply get so low that it just wont start ? Or will the lowered compression cause some kind of catastrophic failure? and how ?

 

Depends on the miles the engine has.

If it is a high mileage engine, the side seals have ate a groove around both rotor housings. If it is in fact a high mileage engine when you rebuild, you'll need new rotor housings.

Hah, speaking of...

I drove my car until it had only 75 psi compression for over a year back and forth to work. It was hard to start sometimes, but it moved the car just fine. The engine had 169k miles on it. It was hard to start but yet it was incredibly reliable.

When the engine came apart, the front iron was cracked in 3 places allowing exhaust gas into the cooling system, and the apex seals where worn down to the wire. Also, my housings where trashed, F word trashed. The corner seals where so worn they made a 1/4 dig all the way around the housings. On top of that, I had a spark plug electrode insulator break off and the engine ingested it and chucked it out the exhaust.

It still ran.

At the time, I knew my engine needed help the day before yesterday, but I got it to pull through until I got the funds to rebuild. When I finally had the money to properly fix it, it STILL ran. It didn't like the cold nor did it like the hot but the thing would still start and move the car.

Long story short, It will live less something you cannot see causes a problem. It will be sluggish, be a hoe to start but still run. You can still beat the **** out of it but that will just lower its life span.

In my journey, I ended up getting new housings and all new irons only keeping the rotors and eccentric shaft (which where fine).

 

If it is still running,then it will keep running!,until it ***** itself all over the freeway!
If you know it's got low compression then you can save the money on parts that you would need for a rebuild..that is if you don't explode the engine by letting it kill itself before hand!

I always thought you would hear a crunch or scrape or some kind of warning before they decide to give up.
One sunny day..just nice ..cruise to downshift...BAM!!....pukka,pukka,pukka...(WTF?)..

 

Haha, that last post...lmao

 

My vert which I dont drive any more had 60psi on the rear rotor and 64psi on the front. It still started hot(with a switch to cut the start signal to the ecu) and cold, it was sooooo slow but it just kept going. I even drove it to a few drift events like that too(110mi one way). one of these days I will pull it apart to see how bad it is.

 

The stupid 3 piece seals are the real danger when driving a worn out engine. They beat the hell out of the rotor apex seal groove and once the top piece wears past a threshold, it will roll out of the groove damaging both the rotor and housing.

 

The low compression is a symptom of a problem. So, no, low compression won't cause a failure.

But, depending on whats wrong causing the low compression, That could certainly lead to a catastrophic failure.


It's like, It's not the headache that kills you, it's the brain tumor that caused the headache!