Ok, I have been boosting 15-18psi on 91 octane. I have no clue how to know when to stop increasing boost on pump gas. What I mean is I have 23 deg advance in timing at 15-18psi, A/F is at 98v-1.02v at WOT and full boost, EGTs get around 1400 in the top of 4th gear at around 100MPH/full boost, fuel pressure is fine 42psi at WOT and full boost. (625cc inj.)

How do I know when to stop before stuff breaks???

what would safe numbers look like for 20psi on pump gas 91 octane?

A/F:
EGT:
Spark Advance:


tia

thats what the guages are for (yes I know you already know that), maybe pick up one of those knock sensors that mounts in the car, I think kiku has one. But if all guages are okay, hmmm boost it. You might just snap axels first before doing any damage to the engine, or bust the tranny

When you get too much knock is when enough is enough. As long as you do not have knock you are still good. Thow it on a dyno and you will see exact a/f and can see what your knock looks like. Oh for a Stage IV, 18psi is just fine. :) Not sure of the reaction of 20. Have run it but never really datalogged it or did a lot of hard driving at 20. Nothing has broken on mine yet if that makes you feel a little better. Of course, I guess I would have to drive it more often eh?

Hmmm, I'm not sure if running 18 psi on 91 octane is a good practice. Even at 8-10 psi, most turbo kit manufacturers recommend at least a 92-93 octane. But then all your gauge readings look fine though. I'd be careful not to push it too much until you can datalog your car, just like Murix stated.


Kon Chittavong
Boosted by HRC: Stage IV | http://laoracer.homestead.com/mainpage.html

All I can get is 91. There are a few places that I can get HIGH octane from but that shit is expensive. I put 7 gallons in and it coast me like $32.

I have a data logger and that is why I posted this question. My a/f is at .98-1.+ v at WOT w/ the power controler set at 0. My EGT's are 1400 at WOT at the top of 4th gear, on the street boosting around they are 1300ish.

Data logger says that my spark advance is 20-23 deg WOT full boost.

The only thing I dont know about is knock. We dont have any way of counting knock so I dont know how that is?

As far as I can see things look good...I think?

Just wish I could count knock like the 4g guys

Someone on here has a knock light. I thought its either kiku or armond

Only 1g 4g guys can count knock. 2g 4g guys go by timing as well. Yes, they have knock sensors, and so do you. However, that information isn't readable through the dataport and therefore won't show up on your datalogger. Gotta love OBDII :)

Can someone explain to me (cause I am new to all this turbo stuff) what knock is?

Knock is detonation. When the piston is on the upward stroke (compression), it gets so hot that the air/fuel mixture ignites before the spark plug goes off. (sometimes there are more than one explosion during this time). This means that the piston and rod are forcing UP as the explosion forces them DOWN. You have two very strong forces going head to head, and something will eventually give. (usually piston rings or a rod).

A knock sensor reads strong vibrations in the block and reports to the ECU. When the ECU reads the knock counts, it retards the timing so the plugs fire later. This reduces knock, but also kills performance.

Knock is bad, mmkay?

eh. I missed the 91octane part. I hate the Socialist Republic of Kalifornia. :-/ All your readings DO sound good, but you have shitty gas. The reason I like dynos is because it is actually a lighter load than the street and gives you a chance to save something as you see it in real time. Tracks work as well once you know exactly what you are looking for.

Oh, and it is Armond with a knock LED. It is from MSD. Keep in mind, a slight amount of knock is tolerably and it seems - with the 4G guys at least - that they get faster times with a little knock vs no knock as no knock means they are running rich. On good forged pistons, a little knock should not kill you either.

About turbo kit manufacturers recommending premium fuel on 8-10 psi. Remember, this is on stock 9.6:1 compression. With that compression ratio, plus 8psi, you NEED at least 91 to resist detonation. JustOne has lowered compression, therefore the need for higher octane wont become a problem till 18+psi. If he lowered his compression further, he could boost even more before he would need higher octane to resist detonation.