750cc's too big for stock ign timing???

[6boltscooter]

I have been told my various people that running 750cc injectors with a MAF-T will give too advance of timing. Seeing that the ECU is thinking only 60% (i.e. 450/750) of the air is really getting to the engine, the ignition timing will be more advanced than it really should be. Driving around at 15 psi, the car pulls ridiculously hard (relatively). I can even feel it advancing towards the top end. There is no oddness or wierd dips in the power, just lots of it. I would like to keep this setup just the way it is but I want to be certain that my headgasket is not going to bust or chip a ring land. I run 93 octane gas with a nice big FMIC so I would think I have some safety room for more boost. I'm pretty good at determining when a engine is knocking and pulling timing. If I can't feel or tell that the knock sensor is pulling timing, is there any real reason why I can't run like this? The knock sensor should have the final say shouldn't it? Can I blow an engine with simply too advanced timing if there is no knock?

Thanks!

 

[blownturbotsi]

Too much timing will cause knock. Do you have a logger?

 

[JeffGST]

You won't be able to feel when the ECU is retarding timing due to knock. When you are knocking around 3-10 counts you won't notice.

IF you do actually feel the car bog down from knock retard, that means the ECU is really pulling a TON of timing away because there was serious knock.

You need some sort datalogger to view knock retard by the ECU. No way around it, unless you like tuning blind and aimlessly.

 

[6boltscooter]

^and that's my issue...I can't feel ANY timing being pulled. It just feels fast and smooth. I'm pretty good at detecting when timing is being pulled and it really isn't there. I have not data logged it yet but I will soon.

What I contend is the knock sensor has the final say and it 'should' pull timing if knock is detected so what would be the harm in running advanced timing is the knock sensor is still safeguarding the engine from knock. Is it possible to due damage by too advanced timing without having any knock?

 

[JeffGST]

^and that's my issue...I can't feel ANY timing being pulled. It just feels fast and smooth. I'm pretty good at detecting when timing is being pulled and it really isn't there. I have not data logged it yet but I will soon.

What I contend is the knock sensor has the final say and it 'should' pull timing if knock is detected so what would be the harm in running advanced timing is the knock sensor is still safeguarding the engine from knock. Is it possible to due damage by too advanced timing without having any knock?

That is false logic.

The ECU pulls timing away because of the detention that the knock sensor hears. While it is retarding timing, it is continuously hearing more knock so it continues to steadily retard. Just because the timing is retarded does NOT mean the knock has been avoided. The knock retard is there so that the knock does not get any worse.

So in essence, the knock sensor is not there to avoid knock, but it is there so that the knock does not continue at it's current pace.

And yes, it is possible to damage a motor with quality fuel by having too far timing advance. Just ask me and my Carrillo Rods.

 

[cjridert1]

Spend 80 bucks off the classifieds and get a logger. If you arent getting knock, who cares? If you are getting knock this will make you aware of it (and take care of your trims too).

 

[JayRolla]

Or go larger and run e85. Then the timing wont be an issue.

 

[6boltscooter]

Or go larger and run e85. Then the timing wont be an issue.

Ok, off I go to log it. I'll get back and tell you the results. E85 might not be a bad idea really. I already have 750's so they should be plenty large enough for 15 psi on a 16g with E85. That would be a pretty elegant solution to my problem is just switch fuels and take full advantage of the already advanced timing. It's not my daily driver so I don't really care about the MPG. In the long run I'd probably just get an Eprom, socket it, flash it and call it good.