detonation/pinging??

[mark '87 930]

I noticed today that under WOT, I can hear pinging in the engine. After reading about detonation, I think this is what it is. I installed a GHL header and B&B exhaust, and running .9 bar boost... Would that be detonation? I'm about to put the car away for the winter and was going to take it to the dyno in the spring to check the A/F mixture and make sure it is tuned as optimally as possible. Is that detonation.. ? Should I reduce the boost? Could it be the gas I run (91 octane)?

[briankeithsmith]

Probably the fuel. But if you can hear it, its probably detonation.

[William930t]

The 930 I now own, on initial test drive, had a tank of cheap gas and detonated at wide open throttle. I was worried about the damage, but filling up with a tank of quality Chevron super unleaded cured the problem.

[mark '87 930]

Would reconnecting my o2 sensor do anything to help?

Thanks for the tips so far.. the onyl thing I can get better than 91 is 94.. and that's only at Sunoco.. So I'll have to find them around my place.

[hobieboy]

Originally posted by mark '87 930
Would reconnecting my o2 sensor do anything to help?

Thanks for the tips so far.. the onyl thing I can get better than 91 is 94.. and that's only at Sunoco.. So I'll have to find them around my place.

I only use 94's on the 930... rather be safe than sorry for the little inconvenience. But then, having an excuse to drive around looking for one is not so bad eh

[WydRyd]

I've *ONLY* ever used 98RON (equal to your 94 PON) in my turbo Carrera. Won't use anything less than that. Better to have peace of mind IMO

[mark '87 930]

I'm impressed that a few octane levels makes such a difference! I will try that.

[dean]

Originally posted by mark '87 930
I noticed today that under WOT, I can hear pinging in the engine. After reading about detonation, I think this is what it is.

I installed a GHL header and B&B exhaust, and running .9 bar boost... Would that be detonation? I'm about to put the car away for the winter and was going to take it to the dyno in the spring to check the A/F mixture and make sure it is tuned as optimally as possible.

Is that detonation.. ? Should I reduce the boost? Could it be the gas I run (91 octane)?

You could also retard the timing a hair.

If it was a cold day that you noticed it pinging, then it is probably due to your air/fuel being too lean. The cold air is denser and so you get more air in the motor but not more fuel.

Dean

[mark '87 930]

Dean

It was a cool day (55 degrees or so).. that being said, would the octane level have made a difference if it was a touch lean?

[dean]

I believe every thing you can do helps but I am not sure.

I went EFI and solved the problem

[garibaldi]

Ive pulled a bunch of 930 motors apart and had the ring packages fall on the ground in numerous peices when I slid the cylinders off due to detonation. It doesnt take much

[mark '87 930]

Now that's encouraging news!

[garibaldi]

I know right? Well, when theres severe detonation, and the rings get busted up, you will obv feel a loss in power, but there will be tremendous blowby in most cases. I had a customer who ran a heavily modified 930 on the track and came in wondering why there was oil mist all over the back of his car, it was puking out of everywhere, the breathers, the filter, the rear seal had pushed out, and after pulling the motor apart, we found out why.....he was running the 47 piece ring package on his Mahles

[mark '87 930]

47 piece... that must be the lightweight package with a 'some assembly required' insignia on the box!

Well, I'm going to pay close attention to it early in the spring next year and get it on a dyno to see what is happening..Also it's 94 octane from here on in.

[38D]

Detonation in a turbo is a serious problem. It takes only a few seconds to do major damage. I would do a leakdown to see if the engine is ok.

Higher octane fuel can help to prevent some detonation, bnut not all. If you have crazy high temps with bad timing, even 110 leaded will detonate.

[WydRyd]

Originally posted by garibaldi
I know right? Well, when theres severe detonation, and the rings get busted up, you will obv feel a loss in power, but there will be tremendous blowby in most cases. I had a customer who ran a heavily modified 930 on the track and came in wondering why there was oil mist all over the back of his car, it was puking out of everywhere, the breathers, the filter, the rear seal had pushed out, and after pulling the motor apart, we found out why.....he was running the 47 piece ring package on his Mahles

I take it this car was also blowing out a blanket of blue-ish white smoke out the exhaust and idling like crap?

BTDT! Few years back, I got a bit TOO cocky with my EBC and pushed the boost past the limit of what the motor could handle at the C/R. It only took a 5 second burst to crack a big chunk of piston ring land off the #1 piston

THAT, my friend, was an expensive mistake. Was a perfect opportunity to rebuild it with much better go-fast bits though

[garibaldi]

yeah, it smoked a little, but the best part was that when we went to go tanning, all we had to do was rub our male-thong clad bodies all over the rear to get all oiled up

[WydRyd]

Originally posted by garibaldi
yeah, it smoked a little, but the best part was that when we went to go tanning, all we had to do was rub our male-thong clad bodies all over the rear to get all oiled up

Aarrgghh! I dunno what's scarier, an engine rebuild, or seeing your oily male-thong clad bodies

I think I'll take the engine rebuild ANY day

[mark '87 930]

wow.. that gives a new definition to pinging and detonantion I guess.

No thongs for me thanks..

[mark '87 930]

Dean, You mentioned retarding the timing.. how is that accomplished in these cars. The distributer cap is notched into place. the only other vehicle I timed was a '79 buick, and that was accomplished by turning the distributor cap with a timing light check the pulley! REALLY, I'm not that old!