Car Cannot Take Timing

[scotty nm35]

And what would you expect the plugs to look like on ethanol anyway? The shit would evaporate before you got the plug out. It's hard enough to read plugs on petrol since all the lead was removed.

Plugs looked fine, and were not causing misfire. No melting, or signs of DET damage.

The DET was picked up with a knockbox setup that Trent has been proficient with for 5+ years, I am sure he has heard more knock than any of us... Amplified 100 times over.

[MagicMikeZ32]

So plugs show no sign of knock but knock is heard?

Pinging or pre-ignition?

[scotty nm35]

Slight pinging isn't going to show on the plugs after a few runs, some of you run higher knock levels without even knowing.

Can you tell the difference on the headphones Mike?

[MagicMikeZ32]

I can't, but they are caused by different conditions, and we are trying to work out what is causing it right?

[scotty nm35]

Very hard to prove without climbing into the cylinder at full noise. Considering the engine is brand new, I doubt there is any carbon buildup causing pre ignition, sharp edges in the quench perhaps, but I don't think Tony wants to rip the head off unless all other avenues are exhausted. (Plus we need to give the engine builder the benefit of the doubt, I am sure he knows what he is doing.)

What other causes of pre-ignition can be ruled out with the head on? Remember, this is happening on ethanol and 98...

[Chris32]

Has a different intercooler been trialed yet? Inlet temps measured?

[Ben C34]

Has a different intercooler been trialed yet? Inlet temps measured?

previous page mentioned next Monday is dyno day.

[SiR_RB]

Curious to know results !

[r33_racer]

More often then not its something stupidly simple....

How about the water temp sensor? Could that play a role in perhaps a timing correction table based on what temps or something??

[Dose Pipe Sutututu]

More often then not its something stupidly simple....

How about the water temp sensor? Could that play a role in perhaps a timing correction table based on what temps or something??

highly doubt that is, Trent will know straight away.. you will see it in Nistune if the temp correction table is used as it lights up green.

I would recommend plugging up an EGT into each runner (one at a time I guess to keep cost down) and data log the EGT per cylinder for the same run/conditions 6x times - this would still be cheaper than pulling a head off

[r33_racer]

Yeh it was a wild guess. But I suppose Trent would be onto it if it was a problem.

Hopefully it is just the CAS that is playing up and it all comes good when its run with the replacement.

[AngryRB]

would the pistons having the valve cut outs have a tendency for hotspots combined with the comp ratio?

[scotty nm35]

From the comparison shots I saw, the aftermarket pistons looked nearly identical to the stockies at a glance.

[AngryRB]

In his build thread , the pistons have a large flat dome with cut outs, isn't a stock piston a bowl shape?

Edited February 7, 2014 by AngryRB

[scotty nm35]

Not the neo pistons from what I could find on google. I am sure there would be some pictures on SAU somewhere but I couldn't find them.

[AngryRB]

what about the effect of having a polished ported intake side, apparently this can be a bad thing and cause knock?

"The carburetor or the fuel injectors spray fuel droplets into the air in the manifold. Due to electrostatic forces some of the fuel will form into pools along the walls of the manifold, or may converge into larger droplets in the air. Both actions are undesirable because they create inconsistencies in the air-fuel ratio. Turbulence in the intake causes forces of uneven proportions in varying vectors to be applied to the fuel, aiding in atomization. Better atomization allows for a more complete burn of all the fuel and helps reduce engine knock by enlarging the flame front. To achieve this turbulence it is a common practice to leave the surfaces of the intake and intake ports in the cylinder head rough and unpolished."

picture of the droplets in my manifold i saw when removed

Edited February 8, 2014 by AngryRB

[GTRPSI]

I would start back at basics.

Throw in another set of injectors or get the old ones flow tested, one lazy one and its DET city.

Make sure none of the injector wiring is a issue, right back to the ECU plug, one injector not opening enough or long enough will lean out the engine on one cylinder, enough to cause det so check wiring and plugs.

Run a test with 1 or 2 heat ranges cooler spark plugs, see what it does after the injectors have been tested, dont just test with another set of plugs of the same heat range, issue could be cylinder temps, im guessing there is no EGT probe.

[scotty nm35]

Injectors have been flow tested professionally and came up fine.

No egt probe unfortunately.

[89CAL]

Neo pistons have the valve reliefs, non neo dont.

[ido09s]

Piston slap? Wouldnt be the first time i have seen knock sensors picking it up