Whats Your fueling preference.

[AshG]

easier than my bloody brakes were lol.

[davidimurray]

Being as I value your advice mate ..... Do you think that I will be aiming a bit high by doing the following....... 1.8 115bhp Zetec, 2 litre cams, 2 litre throttle body , 4 - 2 - 1 exhaust & modded inlet manifold .... All on the stock ecu

I have not got a clue if the Ford ECU is tweakable ( Somehow doubt it though )

Hi Ronnie

Apologises in advance if you know this lot already - hopefully it may be of interest to some of the members on here.Generally, most modern cars have either a narrow band lambda system and they are open loop. As open loop suggest - there is a defined fuel and ignition map in the ECU and the engine runs to those settings. A narrow band lambda system has a narrow band lambda sensor built into the exhaust to measure the air fuel ratio. In the event that there are small changes to the lean/rich mixture of the exhaust gases then the ECU can make a small adjustment to the fuel map to correct for this. (For info on lambda see - http://www.motec.com.au/aboutlambda/lambdaoverview/)

Sorry if I'm teaching people to suck eggs here - but I always find it useful to go back to basics. Engines require 3 things to work - enough air to fill the cylinder, enough fuel to mix with that air, a spark to ignite the mixture at the right time.

Now when you change the intake/exhaust sytem, you change the amount of air you can get into the cylinder - either becaue you have a better intake with less fricitional losses, or with a better exhaust you can expel more of the exhaust gas from the cylinder leaving more space for fresh air - or both. The efficiency of the intake system is typically now as the volumetric efficiency (VE). When you port a cylinder head, you are reducing the airflow losses to increase the VE

Now that you have more air in the cylinder, to maintain the same mixture of air and fuel (AFR or lambda) you now need more fuel. But how can you achieve that. The first method is to modify the map in the ECU - and this is what everyone thinks off when we say mapping. A 'fudged' method of doing this is to increase the fuel pressure - the map works by turning the injectors on for a period of time - the ECU is dumb and doesn't actually know how much fuel it is squirting in, only the time it is open for. So by turning the fuel pressure up you can inject more fuel across the whole map, but this still won't be ideal.

The last part of the equation is the spark, or more importantly the timing of that spark. Becuase it takes a certain amount of time for a given volume of the air fuel mix to burn, the change of mixture may require a change to the ignition timing.

To tune an engine properly you need to run through every load site and adjust the fuel, ignition then back to fuel until you make maximum power. The skill that good mappers have is that from their experience they can often predict where the engine is going and what settings will be required. There is also another question to ask here - do you tune for max power or driveablity. You would immediately think max power - but it is surprising how unnerving it can be to drive a car round a tight twisty circuit that tries to rip your eyeballs out everytime you touch the throttle. Surprising how much quicker a car can be when it is mapped throughout the range properly.

There are two dangerous things in engine terms - knock, effectively when you ignite the air fuel mix too early and try and push the piston down while it is still on the way up. The other is running lean - i.e. not having enough fule in the mixture. This leads to excessive gas temperatures and is why things like piston crowns melt.

So, in answer to your question Ronnie - you should be able to run your engine safely on the mods proposed without any great risk of damage. However, what you will probably find is that it will actually make your car less driveable and you may even make less power Personally, If you've got the money, I would go down the Aftermarket/Megasquirt route - but remember to include in your costs a rolling road session or two. For any EFI installation the quality of wiring is so so important. Use good connectors, with the correct cable and crimps. It's amazing how may people will tell you that there £1K+ ECU is a pile of rubbish and good for nothing - when you actually look at their installation you will find that they have thrown a few wires together. You wouldn't use a bit of garden hose, a jubilee clip and gaffa tape on your brakes - so why would you do the equivalent for your ECU.

If you don't want to go down the EFI route then carbs are a good alternative, you will still need to set them up, but once done properly they are self-metering so will adjust to the airflow going into the cylinder within reason. However, carbs tend to have a few distinct bands of operating points, e.g. idle, part throttle, wide open throttle - whereas efi will have settings say every 10% from closed to open throttle. The result - carbs can make almost as much max power as EFI, but they will suffer across the range - comes back to driveability again.

Right that's quite an essay for tonight - bed time for me - I got a car to build tomo!!

[Tatey]

I have to say David that was a really good read. You really seem to know your stuff there.

How many will a rolling road session normally cost to get carbs setup? I've seen the figure of £200+ floating around before.

[dogwood]

Originally Posted by AshG

easier than my bloody brakes were lol.

Yea, I'll give you that one..

[flyerncle]

Cheeky bu**er Ronnie your birth certificate has symbols on it !!

Brake's sorted David ?

[gingea1pom]

I think Ash’s rolling road session was around £200, But get a recommendation. From my experience there are rolling road sessions and rolling road sessions if you know what I mean. I used to work for Middlesex Tuning Centre (over ten years ago). As has already be mentioned it is not just a case of all out power.

When we got Ash’s done I was amazed the time and effort that went into the set up, the needles where in and out about 5 times with a run up on the rollers after each adjustment then they did a few more tweaking the MJ.

He stopped one run because it was to lean. I will defiantly be running me car over to
Atspeed Racing.

Cheers Ginge

[dogwood]

Originally Posted by flyerncle

Brake's sorted David ?

I think/hope so yea,
I'll see later today.
Defo think we are on the home straight..

[Bonzo]

Originally Posted by Tatey

I have to say David that was a really good read. You really seem to know your stuff there.

I'll second that

That has really been helpfull ........ Thanks David

[flyerncle]

Sounds good David,Good luck Ash,another one for the road so to speak.

[Land Locked]

Originally Posted by dogwood

Hey Ronnie.
Don't you just hate it when people dismiss wiring as the easy bit !!!

But wiring is the easy bit. Bring your car and I'll show you