Aftermarket Engine Knock Control (F3 Engine Content)

The J&S stuff looks like a good bit of kit.

The only input I have is that a few years back, Rayhoop on here built a 2.0 overbore 8v on k-jet which was suffering from knocking and could only run very little advance. He retro-fitted a knock control unit from another vag engine which transformed his car. It would pull like a train after.

Gurds

 

Cheers Gurds

This is an aera which i think will be a great interest for everyone that's the reason for the main question.

 

Note the type of engine he is using, and the implicit budget.

A 14:1 compression ratio is serious indeed, but ballpark then for F3, although I believe it's higher even now. He can afford to break that and replace it, and hence he is looking to max out what he has.

I would be interested to see the pistons from a J&S knock controlled on-the-edge motor, to see how good it is at protecting the componentry. Also to see how many sensors are being used.

I would assume there are implcit gains throughout a rev range from this sort of set up, but wonder how it affects engines of differing/lesser specifications.

 

there is a place for knock sensors and a good reason why bosch have chosen to use them on their engines these past few years.. It allows the engine to adapt and optimise all the time, and to dial out settings when it hears knock.

Its a clever system... but not "The Safeguard" to all things headgasket..

My own ibiza, as those who witnessed its cloudy demise @ Combe, had no knock audioble via knock sensors, and ran a lot of advance........ cylinder pressures were extreme and lifted the head.. Not s sign of det on the piston crowns.

Worth looking at as another gizmo tho.. It could help things on standalone side.

 

Cheers Gents

So we have found an interesting topic that from all aspects will protect but also optimise performance without sacrifice.

 

This is true ^^

It's effectively a recipe for giving control over to a box, and potentially luring a fairly costly investment into a false sense of security. There is a hidden uknown in the set up phase, which could be quick, or could be very time consuming on the rollers.

As an aside, there was talk of 'damped' Digifant 8v knock sensors in the Mk2 Golf race cars, just to blind the ECU a bit, to keep its OEM meddling failsafes at bay.

 

Any info if the VW Kit Cars used control of this type Mr Eyre .

 

It woudn't be a case of needing to insulate OEM sensors like with the Golf racers - they'd reprogram the lot if they still ran them in Group A.

I've never checked the kit cars - give the Mk3 Group A vs Kit Car kitcar manual a frisk for sensors/number of sensors. See VWM.info.

 

BTW, I want to add to my previous post that despite how it might have sounded, I'm definitely not knocking (boom boom!) the idea of using knock detection; in fact it's something I've spent lots of time looking into and I got as far as doing some modeling and testing of various filter circuits, etc. We went out in the car and made lots of recordings and analysed them. I even finished the hardware layout for a DSP-based knock detector which was supposed to have been a joint project with some guy in the US, but that project has stalled for the time being :-(

Very high up on the list of stuff I find very interesting but never have the time to properly do...

 

Spot the Knock Sensor

Photo's from FSI Thread.

Some actual pics of an F3 FSI:




Courtesy HPR:

 

I can see just one sensor, compared with the 4 on the BTCC motor. These are a decade++ apart.

I assume the FSI has 1 or 2 standard?

 

F3 Engine Dyno Graph here -

Bottom of page

http://www.jandssafeguard.com/VampirePage/J&S_Vampire.html

 

Put one of those things on and the sacrifice will be your engine

If it was as easy as they make out, they'd surely be supplying those to OEM's who obviously waste months calibrating their knock systems

 

Well that's an interesting point of view

The person who put me to the J&S link was tuning MK1's with 16v's before most of the people on her were born.

i wouldn't want an engine to go the same way Bill's 20v went and NigeP's 16v

 

As long as you set your spark safely or even on the very edge of detonation you can hear with a set of cans you will be fine.....Bills by the sound of it was non knock related anyhow.

I would much rather know my spark was where I left it than give control over to that J&S thing and potentially have it retarding 20 degrees for what it thinks is knock.........i can already picture my poor exhaust valve heads dropping off[:^(]

 

Hopefully Bill might invest in one and show us some good results.

 

*cough*
mine did not let go becuase of det brooky... it had no det at all, just a lot of cylinder pressure which the head studs did'nt contain = lifted head and lots of steam doh!

zero evidence of det on the pistons, and none on the dyno when it was being listened to with det cans.

I am interested in getting my own det measurement system for when I am on badgerwagen tuning next.. on my own dyno..
I wont be running as much ign advance tho - lol

26 degree's at 35psi seemed too much for the Raceware studs!

 

I though that NigeP's engine failure at the Ring last August was due to an ingested bolt that danced around on the piston?

Before that, he had an engine die to his K-Jet running very lean?

Gurds

 

Knock detection is a massive engineering challenge, it really is akin to looking for a needle in a haystack. I recon a large proportion of OEM ECU's use the knock sensors for ignition map self-learning over the long-term, rather than instant retardation at the instant knock is detected.

 

from playing about on the dyno at work, my 16v made little or no response to ignition only changes, stock engine though.

Chris, i'm wondering if the 4 knock sensors are there for dyno cell mapping purposes?? I haven't seen any STW pics with the engine in and wired up?


My understanding was modern vehicles were run at the limit, i.e max advance for best torque etc, and the knock system kept everything optimised???