Jump to content
SAU Community

Recommended Posts

Hi, I have a problem with my car overboosting and causing it to knock

here is my set up

GCG HF/BB

555 HKS injectors

Pro spec B2 B/C

FMIC

it was set to 15psi high boost and 10psi low boost on the dyno

on the road high boost climbs to 17.7 psi and low to 12.2psi low

my boost controller on high is set at

gain 15%

set gain at 50

the over boost cause to knock after 6000rpm

any ideas why

cheers

joe

Link to comment
https://www.sau.com.au/forums/topic/192179-overboosting-knocking/
Share on other sites

when my m8s car was on high boost it started knocking at high revs... then at most revs... then at all revs... the knocking getting worse and worse... turned out he had done a big end bearing. probly nothing this major in your car just a thought thats all

running power FC

had a knock reading of 94

on the dyno it showed a nice straight line at 15psi at peak getting 252rwkw

Take it to your tuner and get him to adjust the tune - it's not a matter of adjusting the boost controller, esp considering on a freezing night you'd be likely to get a spike again anyway... rather you should try to ensure the tune is better...

So speak to your tuner :ninja:

Take it to your tuner and get him to adjust the tune - it's not a matter of adjusting the boost controller, esp considering on a freezing night you'd be likely to get a spike again anyway... rather you should try to ensure the tune is better...

So speak to your tuner :ninja:

this is been an ongoing problem on dyno its sweet on the road in spikes even with the boost contoller of it boosts to 12psi

even with a perfect EBC it'll still spike a bit - I'm surprised your tune is so close to the limit that a tad more boost causes knocking. Why not richen up the tune (or take out a tad of timing) a little so at least you can drive the thing properly whilst identifying your issue :ninja:

Edited by TommO

Thanks everyone, its really fustraiting me I had the spike problem with it before, i was informed that the OP6 housing will fix it. but im back to square 1

I'm to the tuner 2moro

if i get them to tune

13psi high boost do on the road i should get 15psi

8 psi low road 10psi

maybe that will work

why don't you just have one tune at one set boost, and control the power with your foot?

I have one tune running 300rwkw and 18psi of boost.

When I want half power, I use half throttle?

Edited by The Mafia
why don't you just have one tune at one set boost, and control the power with your foot?

I have one tune running 300rwkw and 18psi of boost.

When I want half power, I use half throttle?

how do you do that when its on man.. all you wanna do full throttle and punch the gears,

how do you get 300 stock engine no knock

how do you do that when its on man.. all you wanna do full throttle and punch the gears,

how do you get 300 stock engine no knock

a decent tune.

I ran 370rwkw, no spike, no knock.

Its a combination of things.

Plus your running a PFC - so you cant have two maps unless your running a datalogit and change it everytime you change boost setting.

Power/boost is controlled by the right foot. I ran 24psi daily without issue

a decent tune.

I ran 370rwkw, no spike, no knock.

Its a combination of things.

Plus your running a PFC - so you cant have two maps unless your running a datalogit and change it everytime you change boost setting.

Power/boost is controlled by the right foot. I ran 24psi daily without issue

370rwkw with the RB25?

Sounds like a handful lol

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • I neglected to respond to this previously. Get it up to 100 psi, and then you'll be OK.
    • I agree with everything else, except (and I'm rethinking this as it wasn't setup how my brain first though) if the sensor is at the end of a hose which is how it has been recommended to isolate it from vibrations, then if that line had a small hole in, I could foresee potentially (not a fluid dynamic specialist) the ability for it to see a lower pressure at the sensor. But thinking through, said sensor was in the actual block, HOWEVER it was also the sensor itself that broke, so oil pressure may not have been fully reaching the sensor still. So I'm still in my same theory.   However, I 100% would be saying COOL THE OIL DOWN if it's at 125c. That would be an epic concern of mine.   Im now thinking as you did Brad that the knock detection is likely due to the bearings giving a bit more noise as pressure dropped away. Kinkstah, drop your oil, and get a sample of it (as you're draining it) and send it off for analysis.
    • I myself AM TOTALLY UNPREPARED TO BELIEVE that the load is higher on the track than on the dyno. If it is not happening on the dyno, I cannot see it happening on the track. The difference you are seeing is because it is hot on the track, and I am pretty sure your tuner is not belting the crap out of it on teh dyno when it starts to get hot. The only way that being hot on the track can lead to real ping, that I can think of, is if you are getting more oil (from mist in the inlet tract, or going up past the oil control rings) reducing the effective octane rating of the fuel and causing ping that way. Yeah, nah. Look at this graph which I will helpfully show you zoomed back in. As an engineer, I look at the difference in viscocity at (in your case, 125°C) and say "they're all the same number". Even though those lines are not completely collapsed down onto each other, the oil grades you are talking about (40, 50 and 60) are teh top three lines (150, 220 and 320) and as far as I am concerned, there is not enough difference between them at that temperature to be meaningful. The viscosity of 60 at 125°C is teh same as 40 at 100°C. You should not operate it under high load at high temperature. That is purely because the only way they can achieve their emissions numbers is with thin-arse oil in it, so they have to tell you to put thin oil in it for the street. They know that no-one can drive the car & engine hard enough on the street to reach the operating regime that demands the actual correct oil that the engine needs on the track. And so they tell you to put that oil in for the track. Find a way to get more air into it, or, more likely, out of it. Or add a water spray for when it's hot. Or something.   As to the leak --- a small leak that cannot cause near catastrophic volume loss in a few seconds cannot cause a low pressure condition in the engine. If the leak is large enough to drop oil pressure, then you will only get one or two shots at it before the sump is drained.
    • So..... it's going to be a heater hose or other coolant hose at the rear of the head/plenum. Or it's going to be one of the welch plugs on the back of the motor, which is a motor out thing to fix.
    • The oil pressure sensor for logging, does it happen to be the one that was slowly breaking out of the oil block? If it is,I would be ignoring your logs. You had a leak at the sensor which would mean it can't read accurately. It's a small hole at the sensor, and you had a small hole just before it, meaning you could have lost significant pressure reading.   As for brakes, if it's just fluid getting old, you won't necessarily end up with air sitting in the line. Bleed a shit tonne of fluid through so you effectively replace it and go again. Oh and, pay close attention to the pressure gauge while on track!
×
×
  • Create New...