Jump to content
SAU Community

Recommended Posts

what about the internals used - forged internals will read higher knock - yes ?

this is especially so when the engine is cold.

I get readings in the 40-55 range on my R32 GTR - but dyno testing show no ping (thank god!!)

I've spoken to guys that have built and raced GTRs for many years - and the answer to this question depends on many factors. So I guess - the correct answer is - it depends

Get your car on a dyno – that's the only way to tell for sure (AFAIK)

Forged internals won't read higher.. Maybe if they are running super sloppy clearances, if that were the case the motor wouldn't last much longer than 25,000km's.

The knock sensor works off various frequency's..

I have forged pistons in the 3ltr that run on the sloppy side, to Wiseco's 24+psi/race spec. They see a max of 10 on start up, once idling and you can hear the pistons slapping away, knock is 1.

When reading knock levels I think the trick is to watch the graph, under acceleration it will rise up and hold fairly even, ping or detonation is when you see sharp little spikes. If yours is rising to 45-55 and those values are consistent, i.e no spikes then there's no need to worry.

Also remember a little spike here and there won't hurt a fairly stock motor, push 300rwkw+ through it and its a different story.

Edited by Cubes
  blk180 said:
yer my car will idle at 3-7 but a WOT can get up to 25-30 and have seen it get to 42 max when backing off mainly was tuned on a dyno

you'll find that what you have just stated is pretty damn spot on

  Cubes said:
Forged internals won't read higher.. Maybe if they are running super sloppy clearances, if that were the case the motor wouldn't last much longer than 25,000km's.

The knock sensor works off various frequency's..

I have forged pistons in the 3ltr that run on the sloppy side, to Wiseco's 24+psi/race spec. They see a max of 10 on start up, once idling and you can hear the pistons slapping away, knock is 1.

I have wiseco's too - not sure on the clearance - but it's VERY niosy @ start up, and I get higher knock readings (still under 50 tho)

  Quote
When reading knock levels I think the trick is to watch the graph, under acceleration it will rise up and hold fairly even, ping or detonation is when you see sharp little spikes. If yours is rising to 45-55 and those values are consistent, i.e no spikes then there's no need to worry.

good advice - I have not looked for this - but I think I'm OK

  Quote
Also remember a little spike here and there won't hurt a fairly stock motor, push 300rwkw+ through it and its a different story.

well - I am pulling 300awkw - so why is that different (knochk is knock - right) ?

  itbmils said:
I have wiseco's too - not sure on the clearance - but it's VERY niosy @ start up, and I get higher knock readings (still under 50 tho)

good advice - I have not looked for this - but I think I'm OK

well - I am pulling 300awkw - so why is that different (knochk is knock - right) ?

Its interestering you get high knock readings on start up, I know of an other R32 that on startup spikes to 50 or so. Why it does this I don't know, it shouldn't but it does.

I have heard some VT Commodores ping on start up.

Probably just a bad ignition timing and rich cold start afr mixture causing a rapid uneven burn.

Detonation is detonation but when you make more power you have higher combustion pressures, as a result a little detonation is much more likely to damage something. Exactly why those little old ford lasers can rattle along for many years without cracking a piston. :D

mine registers about 30-40 on startup

I reckon its something to do with the starter motor on the flywheel

Engage that while the motor is going, I see about 40 knock if I do that

OK

let's take this thread in slightly different direction

is what the PFC reads as knock actually detonation ?

WAIT !! before you answer ....

I have just had a power run done this morning - and one of the things I asked them to look at was knock. My PFC will sit @ ~40 all day - even under light load and low boost, but I have no signs of detonation (or so I'm told). This has been checked and rechecked by three different workshops on three different dynos and three different days.

if the man with the head phones on says – no ping – then I happy with that :(

My understanding is that the knock sensors will pick up ANY noise – and translate that into a reading on the PFC hand controller. This supports my understanding that if you have forged internals with large clearances – you'll get what the PFC picks up as knock – but it's not actually detonation – it's just a noisy engine.

I had an old 323 BMW that had the same thing once.

I have weisco pistons – and I do no know what clearances where used – but I do know that I can hear the forged internals – even once the engine is warm. So if I can hear them – so can the PFC.

This is all just my opinion, and opinions can be changed – so I'm happy to hear evidence to the contrary.

I have wisecos @ 87mm.. i don't really hear the piston slap, and the motor doesn't sound any different once warmed up. My knock gauge on the pfc floats around 0-25 while just driving around normally. No abormal knock value upon startup.. my guess is around 0-10 on the start. haven't gunned it yet on the new motor (no tune)

so - I'm guessing I have a loose motor

clearance was set by Marty White from John White Racing up here in Bribane. They also did the hone and deck of the block and a port and polish (reco) of the head.

He does the work for Theo W - so that was good enough for me (yes I spoke to Theo before going to him)

Might just be an 'over active' knock sensor. Picking up frequency's it shouldn't or something?!? :P

On that note now the warmer weather is here I can't actually here any knock. I had a listen this morning.. No Slap, water temp was 24degree's before I had started the car first thing this morning.

Last winter some mornings I saw water temps of 2degree's. :D

Edited by Cubes

i havent noticed much more knock since air temp's have increased. if anything they are a little better. i dont get any knock on startup. i think knock of over 100 ish is "detonating" as ive never heard mine ping on the road. only time ive ever heard my car ping was stock everything and i ran 1 bar (bypassed the actuator by accident) and then it pinged its ass off

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

    • just an update to this, poor man pays twice  Tried sanding down the pulleys but it didnt do the trick. Chucked another second hand alternator in the na car which I got for free off my mate and its fixed the squelling. Must have been unlucky with the bearings.    As for my turbo car, I managed to pick up a cwc rb alternator conversion bracket + LS alternator for 250 off marketplace, looked to be in really good nick. Installed it , started the car and its not charging the battery.... ( Im not good with auto elec stuff so im not sure if this was all I needed to do but I verified such by using a multimeter on the battery when the engine was running and I was only getting 12.2v )   I had to modify the earth strap for the new LS alternator , factory earth strap was a 10mm bolt which did not fit the bolt on the LS alternator which was double the size so I cut it off , went to repco bought some ring terminals that fit, crimped it onto the old earth strap and bolted it up to the alternator , started the car and same issue. Ran like shit and was reading 12.2 at the battery.  For a "plug and play" advertised kit thats not very plug and play but alas.  My question is , am I missing something ? Ive been reading that some people recommend upgrading the stock 80 amp alternator fuse to a 140 amp but I dont see how that would stop the alternator charging especially at idle not under load.  Regardless ive pulled it out and am going to get it bench tested by an auto elec tomorrow but it would be handy to know if ive missed something silly or have done something wrong.   
    • My wild guess is that you have popped off an intake pipe....check all of the hoses between the turbo and the throttle for splits or loose clamps.
    • Awesome, thanks for sharing!
    • To provide more specific help, more information is needed. What Android screen? What is its wiring diagram? Does the car's wiring have power at any required BAT and ACC wires, and is the loom's earth good?
    • So, now all you need to do is connect the 2 or 3x 12v feeds into the unit to permanent 12v, ACC 12V and IGN 12V that you can find in the spot behind the stereo, and the earth, and then it will switch on with the car.
×
×
  • Create New...