Confused on pinging?

[Guest firebern]

What do you guys mean when saying pinging?

Is it the pistons that clash with the valves?

 

So I was reading the following statement from

http://www.geocities.com/MotorCity/2824/engine.html

 

"

N42s, and N47s WILL INCREASE COMPRESSION ON FLATTOPS TO WELL BEYOND 10, WHY NOT USE THESE?

 

I won't pretend to know everything about those heads, but I posed that question to the Z Doc who I trust. He said those 2 heads are widely used, but can ping easily on flattop motors as their low quench chambers are designed for dished pistons. This shape lets the flame kernal spread away from the spark plug and ignite. For a good budget racer, probably not a bad idea, just be ready to use some octane booster

BTW, the Doc races an E31 with larger 280 valves on a flattop motor and says it runs "right on the edge of pinging".

"

 

So I have a N47 head and want to get a flat piston block which should increase my power by 20 HP. But I don't know what pinging means?

 

And then as anybody ever tried this.

Thanks,

Fire.

[Mikelly]

1st of all Tell Z Dr. that Mike Kelly says hi and ask him about the time I beat him at the airstrip... He has a sweet Carmel colored 240 with power steering and all the trick suspension parts on it. And yes he has an E31 with a lot of time spent at Malvern Racing Machine Shop in Charlottesville... Doc hasn't spared any expenses on that machine...

 

Through Z Dr. I learned a great deal about heads and getting the right combo of stock parts to work together to make decent HP. Detonation or Pinging is cause by a lean condition in the combusion chamber, more air than fuel... One of the most common situations with an L series motor is to much timing advance or a faulity vacuum advance unit. I was running an N42 head with 82ZX flat top pistons in a standard block once and was able to achieve good tuning with a 10:1 compression ratio and 12 degrees of initial timing... only with NGK plugs and 92 octane gas. N42 heads are OK, I'm not fond of the N47. I'd look for a P79 or P90 mechanical head and get it shaved accordingly and get the cam towers shimmed up properly. That will be a much better head that has better chambers and ports.

Z Dr. can help you with all that...

Mike

 

------------------

 

"I will not be a spectator in the sport of life!"

mjk

 

[This message has been edited by Mikelly (edited November 19, 2000).]

[BLKMGK]

Detonation - one thing you didn't mention Mike and that's preignition. Sometimes the compression is so high that the mixture detonates before the spark pluf fires it. This can also occur due to a hotspot in the chamber - carbon or overheated plug electrode for instance. When this occures the piston will often try to compress a mixture that's already expanding. This uncontrolled explosion sounds like popcorn under the hood and can flatten bearings as easily as it can break pistons!

 

Diesel motors use this sort of preignition to run - no spark plugs. Their compression ratios are quite high for just this reason. On the gas available at the pump you want to be careful you don't run too high a compression ratio. Note: higher octane gas actually ignites LESS easily! It is LESS explosive and if you run "race gas" in a low compression motor it will actually lose power. You only need enough octane in the gas to prevent preignition - more is not always better.

 

My .02

[Guest Anonymous]

As BLKMGK said (and its rather a good analogy) it sounds like popcorn hitting the top of a metal saucepan lid. You'll know it cause if you back your foot out of it, it'll stop. Pistons kissing the valves make a WHOLE other noise. It usually sounds like ChaChing (cash register noise) followed by silence and alot of coasting to the side of the road, usually its preceeded by overheating, shaking, smoking and later it often causes the driver to want to vomit.

 

Regards,

 

Lone

[Guest firebern]

That is great, I learn new stuff every day.

That is exactly the information I needed to understand this a little more.

 

I thank everybody who replied. I really appreciate my Z because of all this knowledge I gain through other Z owners.

 

Cheers ,

Fire.

[Guest firebern]

Holly smoke guys,

 

you will never believe this one. I was dismantling my exhaust manifold yesterday with my friend Jief. I was telling him about putting a F54 SB under my N47 to increase HP.

I bougth my 78 280Z this summer from a guy who had a weird story about its past. Anyways, I look down on the SB(which a connectiong rod cracked through ) and found out it was a F54!!! It gave me the freaks. I looked at Jief as if I couldn't believe it and I went around the car to look at the head and there it was, a freaking N42 head with the square exhaust ports! I couldn't sleep all nigth. I had the good combination.

 

I had my engine gaskets replaced when I bougth the car, It cost me 650$US and the stupid mechanic never told me about it and he was supposedly a import specialist what a joke . He never told me about this. And even though, we could imagine that he doesn't know about datsuns, I had bougth the exhaust gasket for a 78 z because I thougth I could do it on my own so I gave him but I had the wrong part, why? Because I thougth I had an original 78 Z engine which has round exhaust ports. So that mechanic had to know about it, 'cause he had to order a square port type gasket for a 75-76 Z.

 

I am not going to refer him to anybody,

he can forget about it He cost me probably

200$ canadian more just because he is sippose to be the import specialist and an excellent mechanic. But what about customer service?

 

 

Cheers ,

Fire.