Clipse3GT

iTrader: (10)

I have been doing some data logging on the car. I am peaking boost about 24.5-24.9PSI and tapers to about 20PSI. I record a knock retard amount of 0.5 to 0.7. I know the ideal amount is to have 0.0 throughout the powerband. However, for the EVO X what is considered a really significant amount about 1.0?

I can always turn back the boost level a little bit to get closer to 24psi and taper to about 19psi.

Thanks for any information. I am using the COBB AP to do my measurements.

sbdemon

What octane are you running and what flash? You can always use a custom or lower octane flash or use a "reliable" octane booster to help with the knock.

Clipse3GT

iTrader: (10)

I use Shell 93 Octane. COBB STG.1 + COBB SF Intake (their map).

I was think about turning the wastegate eyelet out one more turn. To help lower the boost just a tad, until I get it protuned. Just waiting on my exhaust and have to buy a new intercooler then go for a tune.

sbdemon

The Stage 1 + Cobb SF 91 octane flash would slightly lower your peak boost .5-1 psi and taper it approximately 1 psi lower than the 93 octane tune that may help. If you still have knock you could use the Cali gas tune ... The wastegate preload adjustement may help too.

bravo-x

Suggest you check out the forum on the Cobb website. I was reading some posts out there about a week ago, and remember one of the techs had indicated that a knock of less than 1.0 was not signficant. But there could be some mitigating points to consider.

Clipse3GT

iTrader: (10)

Thanks for all the info guys. I will definitely look into what is a significant reading.

dcpatters

iTrader: (8)

You have the Forge WGA and AMS downpipe too? Stock cat? As an alternative, you could use the COBB ATR and adjust the waste gate duty cycles to achieve the desired boost. However, .35 - .70 of knock is not an issue. Usually occurs during boost transitioning.

Clipse3GT

iTrader: (10)

Right now I have the stock exhaust system. I am waiting for my T1R TP & CBE to come in so I can install the DP and the rest of the system.

I will just turn back the wastegate eyelet to to take a bit more boost. However, I have no issues with boost or knock really with the tune I am using now. The car will be protuned once I install a FMIC and 3 port boost control system. To get the best control over the setup.

Rands

Hey everyone, sorry to bump and old thread, but I have a question relating to this topic as well.

I have the Harman Motive intake on my car and running the Cobb Stage 1 91 Octane map for the Cobb SF intake. I know I know, I shouldn't be running map that isn't designed for my intake, but I'm just planning on a custom tune in a couple months. This is just a temporary solution for now, if it is safe to do so of course.

I'm seeing the 0.35 and 0.70 counts of knock retard in my logs in the low RPMs and from transitioning every once in a while, which seems to be normal from what I've read on this thread. But after logging some data yesterday I saw a couple logged samples where the knock retard count went to 1.05 and 1.41. I'm looking at the samples and nothing really popped out at me, boost pressure was only at about 6 lbs, and WGDC was at about 4%. But this only happened to me a couple times in the entire log. I did another log yesterday and did a couple pulls on 2'nd and 3'rd gear and didn't see any knock retard at all. Boost was at about 20 lbs, and WGDC was at about 100%. Should I be concerned about those couple samples of knock retard?

Thanks in advance everyone!

tephra

iTrader: (6)

1.41 knock retard = 4 knocksum.

which is totally acceptable...

however you are right you shouldn't run that intake with that tune...

knock isn't the only thing that kills engines..

Rands

Okay cool thanks for the info!

Can you tell me what other things I should be looking for in my data logs that could be problematic? I'm a total noob to this stuff, so any info would be greatly appreciated!

tephra

iTrader: (6)

when changing parts the biggest worry is AFR, so u need a wideband to make sure its still ok...

Rands

Well I figure doing mods like an intake you are scared of your AFR being too lean. And I thought too lean of an AFR would cause engine knocks. Or am I way left field here?

tephra

iTrader: (6)

too lean = bad

1) the timing is tuned for a certain AFR, running leaner might require less timing
2) running leaner (closer to stoich) means hotter

so yeah its not good, if your not tuned for it

Rands

Ah okay good to know, thanks for the info!

On a side note, the evos throw a CEL if you ever run too lean right?