Emerald on a X/Flow?

[MJ]

To improve low-mid range pick-up / driveability, and dare I say, improve fuel consumption, I am considering the fitment of an Emerald ECU to my 1700 X/F.

 

Does anybody have any experience of such a mod, and if so, is it positive? Am I wasting my money (though I presume I could swap it over if / when I upgrade to a K)?

 

Any other comment from those in the know would be appreciated.

[martinwhitcher]

".....upgrade to a K"

 

😬

 

Martin

 

MW 51 CAT

Superlight No.171

[Paul McKenzie]

Clay Head has a 3D ignition mappable DTA unit on his x-flow and it's marvellous, I also have it on a VX with carbs.

 

What you require for this is a throttle pot, harness and ECU. You could use an Emerald if you wanted, but it wouldn't do anything more.

 

The real interest in Emerald has come from their widespread usage in injected tuned K's and from the mapping skills of Dave (whatever his name is) and Karl.

 

Now if you are also considering injection on the X-flow then an Emerald might be a good idea especially if you're eventually going to go to a K-series, but again other after market ECU's can proably map the fuelling just as well.

 

Paul

[MJ]

Exuse my ignorance, but is DTA the make or is it a type of mapable ignition?

 

Likewise, which type of ECU would you recommend if not the Emerald?

 

Any idea on approx costs?

[V7 SLR]

I had an ingition-only Emerald on my XF but as I bought it that way I can't say how it had changed.

 

However a chap on Cam7 has just showed us a lovely set of throttle bodies destined for his XF. I haven't heard an injected XF for a while. I think it sounds like a top project.

 

Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours

 

[Paul McKenzie]

DTA is the make of mappable ECU.

Cost is around £350 ECU

£50 for throttle pot

£100 for loom

plus rolling road time for mapping

An injected cross-flow is a great project, since older engine designs gain more from correct control of fuelling and ignition.

Paul

Also of course you're into a lot more expense if you're going to injection

throttle bodies, fuel rail, tank or swirl pot, hp pump etc etc

 

Edited by - Paul McKenzie on 17 Oct 2003 16:21:21

[oilyhands]

There is an article on my website about EMSs that contains a section on upgrading from a clockwork distributor to mapped ignition and another section on upgrading from carbs to injection, all the various parts and procedures are detailed, it's available here, it's also reprinted on Emeralds website.

 

Here is a section from the article comparing 2D woth 3D systems

 

After-market mapped ignition systems are now quite common, you may wonder what advantages they offer over a conventional ignition system. A conventional ignition system is a 2D system that only takes into account engine speed and not load on the engine; it gives a constant timing that is dependent on engine RPM only. At full throttle this is acceptable, however on part throttle economy and driveability are seriously affected. In another vein with some performance engines the required advance may not alter in a linear manner, there may be places in the engines speed range where required advance can fall even though RPM is rising.

 

Some 2D systems go part of the way towards varying the ignition timing for load by fitting a vacuum advance device which advances the ignition when vacuum in the inlet manifold is high, E.G. when load on the engine is low but this will be crude at best. A mapped system can give precisely the right ignition advance whatever the engine speed or load. This improves the tractability of the engine dramatically as well as giving far better economy.

 

To appreciate the difference between a 2D and a 3D mapped ignition system you have to understand a little about combustion within your engine. When a fuel and air mixture ignites within the combustion chamber, the burning of the charge starts at the sparking plug and spreads throughout the mixture from that point. It takes a given amount of time for the whole charge in the chamber to burn, expand, and hence force the piston down the bore. This is why we have to start the ignition process before the piston reaches top dead centre. This lead-time is called "ignition advance".

 

It follows that as engine revs rise and the engine turns faster there is less time for the charge in the chamber to burn hence the need to increase the ignition advance with increasing engine speed. Before the age of sophisticated electronics the ignition advance was always controlled mechanically, in the very early days by a lever, mounted on the steering wheel or handlebars of the machine. The driver, or rider, altered the advance according to his best guess, going on the feel of the engine - not always too successfully

 

What followed was a mechanical advance system based on a centrifugal system of weights located in a distributor. As engine speed increased the centrifugal force acting on the weights increased and caused them to move outwards, against the resistance of a couple of clockwork springs and in doing so advancing the ignition. The springs pulled the weights back as the engine slowed again reducing the advance. A series of stops and different tension springs allowed the ignition advance progress to be controlled, or altered from one engine to another, dependent on engine speed.

 

But there is another factor effecting advance that needs to be taken into account - cylinder filling. The speed at which the mixture in the combustion chamber burns varies with the amount of compression that the charge is under. This in turn depends on how full the cylinder is before compression takes place. For example: on a small throttle opening at higher rpm, the cylinder will only partially fill, compared to wide-open throttle at the same engine speed. It follows that you need different ignition timings for the same engine speed, but dependent on throttle position or engine load.

 

With the centrifugal distributor advance systems manufacturers often fit a vacuum advance unit. This pulls the timing to more advance when there was a high vacuum present in the inlet manifold (throttle closed or nearly so). The problem with these mechanical systems was that they were crude in operation and movement of the distributor base plate at high rpm caused timing scatter. For this reason most performance engines had the vacuum advance removed and the base plates welded up.

 

An EMS can control the ignition with very few moving parts; all it needs is a trigger and a load sensor of some kind. The EMS knows the load on the engine as well as the engine RPM. Since the ignition timing is mapped for each engine speed and load the timing is at the optimum for the engine for each load condition including part throttle. This gives the best possible performance and economy whatever the throttle position. In addition since the triggering systems invariably have no physical wear points the timing stays set correctly more or less indefinitely and is maintenance free. There are other spin-offs such as rev-limiting, shift light, accurate tacho driving and telltale as well as the certainty that the timing is never likely to ‘go off’.

 

The benefits from a mapped system have to be experienced to be appreciated, throttle response is razor sharp, economy is improved and tractability (especially with more radical cams) is amazing. In my own experience an engine converted from a centrifugal advance type of system to a mapped system undergoes a transformation.

 

 

 

Oily

 

Edited by - oilyhands on 17 Oct 2003 17:25:16

[Mcalvert]

Emerald is well known on K series, managing both ignition and injection.

 

For Xflows where only the ingition timing is in question, the Weber Alpha system is very popular. I have fitted one to my Xflow with 234 cam and the results were excellent. The basic view is the more wild the cam, the better the imporvements from the 3D system.

 

Regards,

 

Michael.

[MJ]

Cheers guys - very interesting. Looks like a mapable 3D system is on the cards.

 

Speaking as technical imbicile, does anybody happen to know of a reputable spannerman & roling road where I might be able to have these mods done???

[frog-one]

A question for Mcalvert; ref Alpha.

 

Did it come with a stock ignition map or did you have to have one made up on a rolling road?

 

Tkx