Lancia Integrale injector impedance & selection

[Evodelta]

Hello all,

I am looking for some help!

The story so far:

I have uprated many of the components on my Delta integrale 16v (Evo2)engine mainly to let it breathe more efficiently and it is ready for the ECU re-mapping, because of the expected increase in power I am going to need some larger injectors and have set my sights on some Bosch 0 280 150 403 'Greys' as they should suit my expected power output.

The problem:

The existing system on my car uses 'High impedance' (high resistance or high ohms) injectors and any readily available injectors are of the 'Low impedance' type. The two are not interchangeable. I have heard it said that you can swap one for the other if you use 'ballast resistors' in the wiring loom, can anyone confirm this and advise on how to do it or someone who can do it for me?

Some theory and a picture:

Injectors fall into two broad classes in terms of their coil resistance - "low" and "high". Low resistance injectors have 2-3 ohm coils, while high resistance injectors are up around 14-16 ohms. If you are upgrading a car to larger injectors, the new injectors should be of the same resistance class as those being replaced.

A pic below showing how to check the resistance of the original injector, the proposed injector has a rating of .5ohms.

Any help appreciated,
Thankyou.

[djaychela]

You should be able to do this by using a resistor in series with the injector, of a value which makes up the resistance to the original value - around 12 Ohms would look to be right. I have seen this done before with Megasquirt systems (and indeed used them myself for a short while on one MS installation), and it worked fine, but it will depend on your ECU. Power rating wise, I would think you would be looking at a current of about 1 amp (12 volt feed across 14 ohms), so you'd need at least a 12 W resistor, and probably 25W to be on the safe side. This would mean the gold-bodied power resistors like the one I've shown below. You'd just need to insert them into the current injector wiring, one one side or the other (the side shouldn't really matter - whichever you can break into most easily to make for a neat wiring job), or you could make a separate loom which would plug into the existing one and then connect to the injectors.

[SteveNZ]

There is no problem using a resistor. Some manufacturers even use them.

What ecu do you have?

[NickRP]

Hello!

Maybe I could help you :). If you are inserting ballast resistors, they should be 7-8 ohm ones, as we want a bit more voltage to appear at injector terminals. Of course, with such a mod (ballast resistors in series with low impedance injectors) will give laggy injector response no matter what (how many milliseconds do you expect to have at idle)?

Furthermore, there is a curve in the ECU for injection pulsewidth correction vs. battery volgate. This should be revisited, as now you have different combo.

Better solution would be to use ECU that already has peak-and-hold injector drivers (you most probably knew that, which control unit are you using at the moment?), or to use separate peak-and-hold injector driver box (can be purchased through many suppliers).

In the case you are using IAW control unit, it has built in current limiters in injector driver circuits. I've seen people using low impedance injectors connected directly to high impedance suited IAW outputs. However, the downside is extreme heat disipation in IAW injector driver stage - so I wouldn't recommend this to anyone. Much better alternative is to use IAW control unit suited for low impedance injectors, such as from Delta 8v. Of course, an expert would need to configure it to run with 16v software.

Please let me know if I can assist you any further.

Best regards,
Nikola

[Evodelta]

Thanks all for your answers, It seems this isn't going to be easy....

I'm using the original Evo 2 IAW 4WG ECU. the people that are going to be remapping it are the UK outlet for your products Nikola.

<<how many milliseconds do you expect to have at idle?>>

No idea! Although to help further I'm expecting a power output of 330 - 350 bhp and the 403 (503cc) injectors are rated at around 400bhp on 3 bar of fuel pressure. I know that more advanced ECUs (MoTeC) can handle huge injectors on small power outputs, but not sure how the Webber-Marelli sytem will cope with what I have.

On doing some more research I have just found that someone sells injectors labelled as "Ford EEC compatible High Imp Saturated injector (Up to 400bhp) " Would I be better off investing in these? They are well over twice the price of the 403s I have seen, although this seems like the ideal solution to me.

Or would I be better off stretching the original injectors to cope? As they are fitted to a 200bhp engine and I am hoping for a 150bhp increase you would think not as they could be running at max duty cycle. I have enclosed a spec sheet for them below.

I am struggling from my own (uneducated in these matters) point of view as to how (seemingly) downgrading to a 8v ECU will help, isn't the later Evo 2 ECU a lot more advanced with it's 32 bit chip and capacity to drive the existing twin coils and wasted spark?

Nikola - If you think you can modify the ECU to suit then please feel free to Pmail me your proposals, although remember I must balance the cost of this against the possibility of buying some High imp injectors (If this is possible!)

Where would I find a "separate peak-and-hold injector driver box" ?

Really I am just after the best solution, I don't want any of the aforementioned injector lag or anything prone to breaking, cost is of secondary importance, as someone once said:

"Quality remains long after price is forgotten"

And the whole idea behind the modifications I have made so far is to make a car which is powerfull, entertaining, comfortable and easy to drive while being as reliable as it has been up till now.

Thanks,
Martin.

[NickRP]

Hello Martin,

I've sent you a PM with the link to one aftermarket low impedance injector driver. There are many manufacturers, and I am sure there are such units available on the UK market. There is no rocket science behind such a unit, basically one with some knowledge of electronics and some spare time could easily build one.

I am quite sure you could have success with high impedance high flow injectors for your setup, as it is not that radical to create extreme difference between idle and high revs full boost fuel demand. You should stay above 2ms at idle with saturated injectors to avoid any trouble, and this should be easily achievable.

I don't expect stock injectors to be able to cope with 350bhp, so don't bother keeping them, you'll just waste your money on mapping (as you would have to have it done again).

As for IAW ECU mod, I was unaware that you're using the P8 unit (actually, now I remember that you told me once). Just to make small correction, P8 unit has 32 kilobytes of EPROM memory, while older units (also known as L8 or P7) have 16 kilobytes of EPROM. Both are using 8 bit wide data bus. L8 can also drive two or four coils in wasted spark mode, so this is not a limitation. Delta 8V has peak and hold injector drivers, so I mentioned it as a solution to overcome injector resistance problem you were facing. But let's presume you want to stay with P8 ECU. Do you know that Escort Cosworth has also the P8 ECU, but with peak and hold injector drive circuitry? The same goes for the last generation of Dedra Integrale. So this might be an option, too.

If I were you, I would shop for prices on this low impedance injector adapter box, as this seems to be the most cost effective option, still giving full advantage of peak and hold technology.

Best regards,
Nikola

[Evodelta]

Hello Nikola,

Many thanks for your reply, just out of interest, would an Escrote ECU work on an integrale, presumably it would need a lot of work doing to it?

I am leaning towards using some high imp higher flowing injectors, wouldn't these just be a straightforward swap? (and then onto remapping of course) What do you mean when you talk about a 'saturated injector'?

I haven't managed to find anyone in the UK who lists a low impedance injector driver.

Martin.

[NickRP]

Hello Martin

The only problem I could think of when using Escort P8 control unit would be the cam trigger (Escort has inductive vs. Hall on Integrale Evo2) and one pull-up resistor (vs pull-down on Evo2).

Low impedance injectors are also called 'peak and hold', while high impedance injectors are called 'saturated'.

Hope this helps,
Nikola

[SteveNZ]

What about "Ford racing" green injectors, 280 150 558.

These are very common, easy to get and cheap. Rated at 42lb which is about 440cc. Bosch ratings are usually at 80% so you could get over 500cc out of them if you need it.

[G&G Motorsport]

Hello there,
There are a number of high impedance units avalible that will suit your application.
I spec/supply a Bosch unit that delivers 440cc/min with good results, I've used these in various applications.

If you would like more info on these units drop me a e mail to maps@ggmotorsport.co.uk

I also just did some quick calculations using a Brake Specific Fuel Consumption value of 0.6 and for 360 fly wheel horse power it came out at 550cc/min running 3.5 bar fuel pressure. This is for a 4 cylinder engine with a max duty of 85%

I hope this is helpful.

Phill

[Guy Croft]

Thanks for taking 'time out' Phil,

GC

[Acki]

Hmm why you think the engine has a BSFC of 0.6?

[G&G Motorsport]

I Use 0.6 as an estimate for forced induction units that I don't know the correct value.
If anyone can give me the correct value I will re-calculate.


Phill

[Guy Croft]

I'm afraid I don't know bsfc turbo units need either, but if it's any help I published a number of bsfc results for Nik - for normally apirated units at:

http://guy-croft.com/viewtopic.php?t=451&highlight=bsfc

The trouble is that whilst you need to know the injector flow capacity so few people use fuel flow as a means of calibrating engines these days, so I don't get the feedback to tell you.

Careful study of the information on this site will probably get to it, can't fault it, this firm does aircraft engines etc and it's one of the best I have read:

http://www.epi-eng.com/ET-VolEff.htm

GC

[Evodelta]

Calculating what injectors to use is a very tricky business it seems.


I used this on line calculator here: http://www.rceng.com/technical.htm

To do the calculations for something which I know the answer to, I.E:

An integrale 16v uses 384cc/min (tested at 3 bar) injectors at a lower 2.5 bar fuel pressure to provide 200bhp (for injector spec see my earlier post).

The calculator tells me that using .6 BSFC the injectors are running at over max (90%) duty cycle on a standard car! This can't be correct, using this calculator seems to suggest a far larger injector than currently used. The standard injector can only be used at 90% max.

So It was out with the calculator, paper and pen and use another formula:

Where:

HP = Max horsepower
C = No. of cylinders
K = 5.6 (for forced induction engines, I don't know where this Figure comes from!)

And:

HP x K / C

200 x 5.6 / 4 = 280. This is 'theoretical flow'

Now use this TF number here where:

N= No. of injectors per cylinder
M= Duty cycle

TF x 100 / N x M

SO:

280 x 100 / 1 x 73 = 383.56

This is pointing us in the direction of our standard injector being used at a max of 73%, I say 'pointing us in the direction of' because I have had to use the 3bar fuel pressure = 384cc figure, whereas in reality it only uses 2.5 bar which of course lowers the output of the injector (to what I don't know without plotting a graph), so the figure will be nearer the optimum recommended 60%.
It is of course, all relevant and does give us something which is 'ballpark' and believable.

Ok, lets back back to my car and a hoped for figure of 350bhp.

The RC site calculator says I need a 694 cc injector

The formula above says I need a 612cc injector

Phill suggests 550cc

I proposed a 500cc!

Confused? Yes sir!