Is it possible that the 3rd gen street port motor would ping and not show any changes on the AF off a wideband?

 

Absolutely. The wideband monitors air/fuel ratio. It does not monitor engine ping/knock. You need a PFC or a J&S Safeguard to do that.

Sonny

 

but I don't think an engine will knock/ping if its running at good AFR. someone correct me if I'm wrong...

 

That is wrong. AFR alone does not determine if an engine will ping/knock. It's ignition timing and amount of fuel that are the main ingredients. If your timing is too far advanced for a given load (or your gas is not good enough), it doesn't matter how much fuel you run (unless it's so rich that it won't ignite), the engine will knock.

You can have engine destroying knock at 10:1 AFR's if the timing is too far advanced. Similary, you could run as lean as 13:1 (not recommended), but if your timing is pulled far enough back, you won't hurt anything.

Sonny

 

Ahhhh.... I see.....

That is why I won't attempt tune my own car....

 

EGT's will give you a good idea if you have timing issues, BTW. If you have solid AFR's but sky-high EGT's, time to pull out some timing.

Dale

 

Dont forget about intake air temps and combustion chamber wall temps (rotor face, carbon deposits, etc.).

 

Good to know. Putting race fuel in and remap the timing on PFC and we'll see what happens. Thanks guys.

 

If you are pinging, you would know it. Unless you are running ceramics, it's called cracked apex seals. Also, Dale is on target......an accurate EGT gauge is invaluable.

 

I'm running 3mil. So are you saying the first sign of pinging means your seals are gone?

 

Rotaries usually do NOT tolerate pings well...I'd say more than 4-5 hard ping runs and any rotary would be just about done. The thing is, the rotary is so loud (exhaust, and internally) that by the time you hear a ping audibly, it's a pretty bad one internally. The small ones that you'd say would probably not be so severe, can't even be heard over the engine itself.

 

ive heard light load pinging, while tuning, and the engine is ok

 

Well the race gas didn't help. But the 2 stroke oil helped.... wierd.

 

You must have good ears

 

what makes you say that?

 

The 2 stroke oil should have hurt the efforts. Oil in gas lowers octane rating, to my knowledge.

 

Yep, oil in your gas effectively reduces the octane. That's why it's so common for PCV systems to get ditched in "performance" car applications. The PCV system that I had in my old car essentially piggybacked the stock PCV system but forced the oil vapors to go upwards through a series of baffles. This pretty much eliminated oil going back into the intake.

Sonny

 

We have just given owners of tired stock twins new motivation to get them rebuilt, I believe

 

So this brings me to a conclusion that it was not pinging but rather something else inside the engine that is making this noise that might have thought to be detonation?

 

exhaust leak? but as was said before a 11.5 afr with 85 octane will ping under boost where a 93 will not

 

That shouldn't be an issue for the FD you can't even adjust the timing. The only thing that would influence detonation in the fd is AFR's, temperature, and octane.

 

It's a loud knocking sound coming from the engine compartment. The exhaust system is mostly new.dp, magnaflow mp, hks ti. I'm now running 113 unleaded race gas. This noise occurs around 3000-3500 rpm with 0-3 lb boost.

 

jupiter is running a PFC, so he can (and has) adjusted the timing.

Sonny

 

The timming is set at 14-20 degrees on the PFC.

 

jupiter: Is the datalog on the PFC showing any knock?

Sonny