CB Blackbox Programmable Ignition

Richard RRC

New Member
Has anyone used one of these ignitions on the Rover v8.
I have one on my 1988 Range Rover v8 3.9 litre, just having a bit of trouble working out the correct timing map for it.
 
I have an EDIS system run by megasquirt, so do have a spark map. I haven't heard of the CB Blackbox though, got any piccies of the system and the map?
 
Hi.
I use another brands Ignition unit.

Are you needing help in obtaining a suitable timing map for a Range Rover 3.9 engine?
If you are wanting a map, I sure someone here has a std map from a workshop manual.
or
Are you needing help with programming the CB Blackbox with a timing map you have, I.e. getting a Map into the correct format for the Blackbox?
I had a quick look at their sample Map Files and the format is not obvious; there are a lot lines and numbers. You'll probably need to contact CB for that.
 
I think I should clarify what I require.

I have just done some work on my engine and drove it for the first time yesterday.

The engine is a 3.9 litre with new high compression pistons, 30 thou off the block, 20 thou off the heads, composite head gaskets. Heads had valves reseated were ported and the inlet manifold matched to the intake ports.

I now have around 9.8:1 compression I believe, better than the 8.0:1 compression I had before given the deck height I had. I run the car on LPG with a BLOS mixer.

I have no problem putting the MAP file into the Blackbox unit. Now I need to come up with a MAP to suit the new setup on LPG. A copy of the previous MAP I was using is attached.
 

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I am thinking of using 16-18 degrees initial timing plus 12 degrees vacuum advance and 12 degrees mechanical advance. So,

Idle (with vacuum advance disconnected) 16-18 degrees
Cruising at 100km/h 40-42 degrees
Full load 28-30 degrees

Does anyone have any other values they think may be better than these for LPG in the 3.9 litre?
 
That's a fair bit different to mine. I have no idea what the top line is but am thinking the second line down is air pressure or vacuum.

I can't really see why there are so mine lines on there, as the last eleven are all the same, and quite a few of the columns are as well.?

All I can suggest is to read up on what LPG and a higher compression ratio requires of your spark map, and apply that to it, then take it for a run and see how it feels. Does the blackbox have any way of logging?

When I put mine together, I just followed Des Hamills book on the Rover V8 to get the base line, then added the vacuum amounts to fill the map. This made up my base map, then I did the fuel map with the help of logging and an afr gauge, and the feel of the car.

Where did you get the map you currently use?
 
The ignition came with a few example maps. The current one I am using is a modified one from the example map I got with the ignition for a single carb v8 on petrol.
 
If you still have the vacuum advance connected and the mechanical advance active no map is going to be replicated in the engine. Are you converting a distributor ignition or some other type? The map needs a base TDC point from which to alter the timing. The Two distributor advance mechanisms will keep altering that point so the black box will be altering the timing on a variable zero point.

Advance is normally dictated by the combustion chamber shape. The RV8 uses an open chamber which is also quite shallow. Generally 34 - 36 degrees is the max on petrol and it should be there before 2500 rpm. LPG will require less total timing but more down low in RPM.

Reallistically it would be best for you to take the car to a Dyno where they can adjust the map specifically for your engine and fuel given you have made some pretty radical changes (no factory map is going to fit properly).
M
 
I have removed the vacuum and mechanical advance and locked the distributor.
You can use the software and lock in a timing figure, I locked 20 degrees and checked with timing light and there was 20 degrees advance. I then did it again for 40 degrees and that showed 40 degrees on the harmonic balancer as well. So, the advance I have is set by the ignition unit.
I think you are correct, and it needs to go on a dyno.
 
It sounds like you've got the system working correctly, it is just a matter now of perfecting the MAP.
t would be best for you to take the car to a Dyno where they can adjust the map specifically for your engine
I'd second that.
If you have fitted LPG for economy reasons then you want to get the timing correct to maximise the energy from the LPG.
One of the advantages of a programmable ignition is there will be outliers in the timing MAP, I.e. not a smooth curve, and these can be programmed into the MAP.
Be warned: An engine can quickly and easily damaged when playing with the tiiming. Don't ask how I know.
A dyno or rolling road is needed to find the sweet spots. Once you have a safe base MAP, spend your time getting the timing right around the conditions you will be using the engine to gain the overall fuel economy. I.e. if you spend hours crusing at half throttle at 3500rpm, then spend the time on a dyno perfecting these conditions.
Or if it only gets used on a drag strip, only do the wide open throttle conditions!
 
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