Knock Configuration

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In decimal 303 * 1.1 = 333 which converts to 14D in hex
307 * 1.2 = 368 which converts to 170 in hex...

I think I'd better use the convention of using 0x to preceed the hex value:

303*1.1=333 = 0x14D
307*1.2=368 = 0x170

Use windows calculator to convert hex to decimal and back again.

The value used in Manmttg99cXX we recommend starting at 0F (0x0F) as its the mid point between 0x00 and 0x1F, shift the value down and up to see the effect on the difference between R & D

[dnb]

People have said the same about the ancient Rover too...  It just means you need to do more signal processing...

Electrical noise can be dealt with - I assume you're working from your own scratch built loom (A series minis not being known for EFI) and you don't have points etc for the ignition.  And you'll have used shielded cable as appropriate.  So as far as signals go, things should be as clean as they can be.

All that leaves is mechanical noise from the engine.  Most of these should surely be proportional to RPM, so you should have some knowledge of what this will be at any given moment.   

Record what a knock sensor "hears" on a PC and run it through a spectrum analyser and compare it with the RPM of the engine at those instants.   Do a few tests at different revs and plot a graph of the main noise frequency peaks vs RPM. 

Now compare these to your 1st harmonic knock frequency to see if they sit "in the way" at any RPM.  If not, then you'll be able to do some good VEMS has a nice digital bandpass filter built in to the knock detection which can remove the noise.

If the knock frequency and the engine noise happen at the same frequency, then there's little you can do at this particular RPM with VEMS (remember the knock frequency is approximately constant, but your engine noise changes in frequency with RPM).  With luck, this won't happen at high revs + high load where knock is most damaging.

There's a few games to play, but essentially once a signal is buried within noise that's similar in spectral characteristics it's the devils own job to get it out again. 

[Agriv8]

dnb,

Are you saying rover v8s are noisy and rattly 

I am running rhods anti pump lifters and yup as warned they are erm - ticky ( unfortunatly the same ticky as a sticky valve  ).

Anyway where have you mounted your knock sensor / sensors ? as a future plan is to deck the block to up the CR and would like to add the knock sensoring.

Kind regards

Agriv8

[dnb]

I'm using the thinner tin head gasket to up the compression on mine.  From 10:1 to 10.78:1

My block has all the bosses etc for cross bolting.  However TVR never took advantage of this   But it does mean I got the knock sensor bosses that are used on the later GEMS etc Range Rovers - one per side of the block. 

If you don't have these, there's a handy bolt hole where a set of (now redundant) earth wires went to on my block, behind where the dizzy bracket sits on my Serp front end.

[Agriv8]

Thanks dnb.

Also running the Tin gasgets and skimmed heads CR is arround 9.5 on my 4.2. looked at the altenator mounting points as the heads can be run on either bank

but thinking that a central point on either bank wound be better will have a look at my block there maybe somthing there that needs drilling /tapping any chance of a photo if you get time.

many thanks

agriv8

[dnb]

This bolt hole was on the block - not the head.

I'll get some pics sorted as soon as I can.  (I need to find my camera or make my phone talk to my computer properly...)

[se7ensport]

I now understand Hex which makes it a lot easier!

A couple of the figures I got while reving it on the drive (couldn't take it out as it was pissing down and I have no roof):

D F1=241
R B5=181

&

D DB=218
R D8=216

Next plan is to get some actual data from driving, I understand that Manmttg99cXX moves the ratio between D & R. two questions:

1. Is the target to get R to 303-307 and then get D to read /1.1-1.2 of the value i.e. 275, or D to 303-307 and R to read 333-368?

2. How do you get R (or D) to be 303-307 if Manmttg99cXX only changes the value between D&R (okay, you could adjust it up or down but then the ratio between D&R would be wrong)?

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All the values will increase with higher gain.

Remember these are rule of thumb numbers if you need to concentrate more on getting the ratio between R & D right than the actual values - not all engines are as noisey as each other.

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I merged these two topics because they're both along the same sort of lines.