akira_onboost

Hey guys any input greatly appreciated.

Ok so my mods are:

Full Stock except - Fujitsubo Power Getter Cat back , Apexi filters , PFC, Took out stock BOV and running 14psi on base map and its a series 8.

Max knock readings on these mods was about 50.

So at this moment i decided to put the stock air box with K&N back in as i think i was hitting boost cut and also the motor didnt like the hot air from the open intakes it would drive like a pig.

So on the weekend finally got the chance to drop the airbox with the K&N back in, cleaned all the intake pipes and re installed the stock BOV.

Took it for a drive and it drove perfect, boosted fine and it actually feels fast again
But the problem is my Knock Readings on the PFC has shot up to about 120 and its starting to worry me.

So thats the story, any input will be great.

Thanks

cewrx7r1

iTrader: (2)

S1: Ok so my mods are:
Full Stock except - Fujitsubo Power Getter Cat back , Apexi filters , PFC, Took out stock BOV and running 14psi on base map and its a series 8.
Max knock readings on these mods was about 50.
A1: Knock could be caused by being too lean as 14psi is high for a stock map even with almost stock engine. Or it could be noise.

S2: So at this moment i decided to put the stock air box with K&N back in as i think i was hitting boost cut and also the motor didnt like the hot air from the open intakes it would drive like a pig. So on the weekend finally got the chance to drop the airbox with the K&N back in, cleaned all the intake pipes and re installed the stock BOV. Took it for a drive and it drove perfect, boosted fine and it actually feels fast again. But the problem is my Knock Readings on the PFC has shot up to about 120 and its starting to worry me.
A2: So it runs better and thus makes more power and the knock is higher and is most likely even leaner.

akira_onboost

when i had the apexi filters/catback/pfc/no bov on it was running more boost (14.5psi) with less knock readings making less power (max 50)

and now with the stock air box/catback/pfc/oem bov its running less boost just hitting 14 psi on colder nights with higher knock readings making more power ( 120 )

So it does'nt necessarily means that running more boost will increase knock readings coz atm im running less boost but making more power with higher knock readings.

these readings are off my DEFI boost gauge.

But on my stock boost gauge it hits 100kpa regardless and this is on the stock gauge.

and if ive done the conversion correctly 100kpa should be 14.5psi?

Well anyways this is a pic of my stock boost gauge for reference.

So that means im actually running 100kpa/14.5psi in full stock trim. Is'nt that too much for the standard twins and i believe boost cut is at 14.5psi.

Im gonna try and tighten up everything that got involved with the OEM air box installation just to make sure nothing is loose that can be making noise.

cewrx7r1

iTrader: (2)

More boost mean higher air temps out of a stock small IC which can produce higher knock in during warm weather.

Colder air produces more power which can also cause more knock. Thus you could make more power with less boost when the weather is cold.

You really nees to do some learning about engine dynamics and log your PFC with a DATALOGIT and wide band. Or get a professional to tune your engine befreo you blow it.

mdpalmer

iTrader: (24)

FWIW, I have logged (Datalogit) knocks over 100 when I'm cruising/off-boost. My knocks drop to no more than 50-60 when I'm on the gas/max effort. Peak knock need not necessarily occur during a boost run. Car runs just fine under both conditions, so I'm assuming the low load knocking may be noise.

arghx

iTrader: (3)

I don't understand why people mess with their engine like this without a wideband, especially one that is notorious for blowing up. We can all sit here and speculate what the engine may or may not be doing under certain conditions but nobody knows for sure. Once again, what costs more, a $350 (US) wideband or thousands of dollars on a motor???

and i never knew a series 8 FD had a stock boost gauge

fd3s7007

just get a wideband. hooked it up on your datalogit and start map watching. Start with af (get chucks notes on how best to do this) once done map watch knock. there should be corelation on particular cells where knock occurs. cross reference to other parameters then adjust. Keep doing this until knock is reduced. Without the wideband you're pretty much blind and will cause serious engine damage.

akira_onboost

Ill be looking into a datalogit and wideband very soon.

And ive just noticed that the knock readings are not consistent.

arghx

iTrader: (3)

you don't even need the datalogit right now. obviously it's not ideal, but if you get a wideband with a gauge you can just eyeball the thing while doing pulls and do some guesswork on the commander. it's better than nothing.

Smitter

your engine can still knock under full boost with good a/f ratios.
if your knocking under boost u better back off the throttle and go see a tuner. wideband or no wideband