Adaptronic - 4 injectors vs 8 injector.

[Jessop]

Alrite chaps.

Just thought i'd post up on here as i know there are some knowledgeable chaps who can give me some good advice on this subject.

As some of you know im building a turbo VTS motor, and now looking to use adaptronic management. However after speaking to big jim, he reccomends using an 8 injector setup over a 4 injector setup with a custom inlet i'm looking at having made up.

Assuming the adaptronic is ideal for running 8 injectors, What are the pro's / con's of running 8 instead of 4?

Would it cost more to have 8 mapped up ?

Thanks for advice in advance =]

[Jessop]

Would i also be right in saying that independant control over each of the 8 injectors isnt possibly with the adaptronic ? Would need something like a DTA S80 to achieve this?

ie - adaptronic jsut runs two banks of injectors (2 at the same time) rather than having the ability to have 1 rail firing and the second rail in use as and when required [ie - WOT]

Correct me if im wrong, but doesnt that sort of rule out the benefits of spending the extra on a second rail/row of injectors ?

The adaptronic e1280s 'super ecu' seems to have support for everything on earth though, up to 12 injectors. It is a lot more expensive on the other hand though.

Maybe scoff can shed some light on this :D

Cheers =]

[Scoff]

Hi jessop, while there's certainly advantages to having 8 injectors staged like that, the gains are not going to be radical so you need to weigh that against the cost of fabrication of such a manifold & rail. I'm sure jim could do a better job of explaining the benefits than I could.

it actually makes mapping easier in some sences, it's easier to tune smaller injectors. the only mildy complex part is achieving the staged injection. I say mildly because even that's pretty easy. You configure a spare output to activate at whatever MAP value you wish to engage the 2nd set of injectors, while at the same time you switch to a second fuel map tuned with the additional injectors activated. There isn't much you can't do with the ECU's inbuilt modular logic.

[Jessop]

So running the 8 injectors on the adaptronic on your site is fine then ?

I may need to pick your brain about injector choice which ever way i choose to go upon getting the inlet made up :D

As long as running 8 is fine on that chosen ecu.

[Rob@Backyardracing]

Can i ask why 8 over 4, whats the plan with the car?

[Scoff]

You need to just choose whatever ECU you prefer. I think you're asking me to "sell" the ECU, but really I'm not comfortable pushing anything on anyone. You need to read up on your chosen finalists and decide for yourself.

The Adaptronic or a high-spec DTA like the S80 will work fine with 8 injectors. The methods of effecting 2 stage injection will differ between units, the result will be the same though. Adaptronic has 4 x high current injector ouputs, so it can deal with 2 high impedance injectors per output. We need some external FET switching (not difficult or expensive) with an Adaptronic to activate the secondary set of injectors. The software and functions for the staged injection are already in place inside the ECU.

[Jessop]

Thanks for the reply again Scoff. Will check it out more.


Can i ask why 8 over 4, whats the plan with the car?

This is why im asking the question regarding benefits of running 8 over 4.

I notice a few of the guys in the saxo scene are running 8 injectors now, some only running a DTA S40 though. I just wanted to see what the fuss was about really. Fabrication/fuelling wise i dont think its that much more expensive to set up. big expensive Injectors dont seem to be neccesary. Could run a row of standard injectors and a row of another cheap additional injectors which are readily available.


Plan is mainly trackdays, although i will of course be overcome with the temptation to see what it can at at the Pod, hopefully not breaking anything mind. :laugh:



While im here, i'll post this up too. Talk about motivation :devil:
http://www.youtube.com/watch?v=qCwD_Rzx4qY&feature=related

http://www.youtube.com/watch?v=8_iqucJKUO4&feature=channel

[Woznaldo]

I think the main reason for running 8 injectors is to maintain drivability at low engine speeds using the first small set of 4 injectors and then having the second set come in at a certain engine rpm and/or MAP, as it is sometimes difficult to have the best of both worlds when running some older type 'big' injectors.

[andyrg]

On a personal front the advantages from running a 8 set up is not really worth the money and time and effort, unless your filthy rich and can throw the doller away 2) need exta cooling from the fuel ( use bigger injectors ) or 3) want to say too the lads at the pub " i run 8 injectors"

The costs outweight the advanages if your using the car for fast road/track :)

[Rob@Backyardracing]

I think the main reason for running 8 injectors is to maintain drivability at low engine speeds using the first small set of 4 injectors and then having the second set come in at a certain engine rpm and/or MAP, as it is sometimes difficult to have the best of both worlds when running some older type 'big' injectors.

Well yes i know the purpose for it, but how many peeps have trouble with 4 big injectors, i run 750`s on my d16 and its fine on low rpm :confused:

[Jessop]

Well i've mailed Jim @ big jim racing and i'll post up the reply if its of any help to anybody on here in the future whether i do or dont go for 8 injectors.

[Big Jim]

Guess as I'm here I may as well post summat... Two injectors will always be better than one IF the setup is engineered and mapped right. Of course one injector can do the job, especially with more modern injectors that still atomise well at low durations, but there is no getting away from the fact that low speed running and economy is best served by injectors as close to the cylinder as possible, whereas peak power is better with injectors further away.
I always say run two if the budget allows it, but if it doesn't then get four big ones and you'll be 90% of the way there. The ECU doesn't matter as long as it can turn the injectors on and off at the right times. All credit to Scoff for not bigging up the Adaptronic massive, but ECU choice comes down to who you know/want to work with and what they can get the best out of. I tend to be a bit of a purist and I like what is technically best. The trouble is the real world gets in the way and you have to make the best of what is practical and affordable. I think I've said before..... You pay your money and take your choice.

[Rob@Backyardracing]

:agree:

[Woznaldo]

I remember Dave Walker, of CCC/Practical Performance/Emerald fame, who set up a Pug 205 GTI 1.9 8v with a two injector setup and, like Big Jim has said, one close to the cylinder as per std and the other injecting at the mouth of some very long trumpets.

From memory the second set didn't kick in until 5000rpm. The result was a top end increase of about 15bhp bringing power to about 212bhp.

[MFaulks]

Jim, totally agree with the available time for atomisation - 2 over 1, but assume you are referring only to short duration injection events close to the head (and those that don't flood the port wall), to yield economic running i.e. high thermal efficiency? As soon as you get wet flow the thermodynamic efficiency falls, and the proximity to the head is no longer benefit. The in cylinder direct injection by Merc et al for LeMan etc required significant atomization development to yield fuel efficiency benefits, the majority was improvement in torque, benefits of piston crown cooling, and throttle response. Airflow performance was deliberately sacrificed to achieve greater in cylinder turbulence to assist in achieving a homogeneous mixture.

You know, if it wasn’t for the restriction of the carb venturi, it really does an incredible job. You could always heat the fuel, and not worry about the second set of injectors… just a thought :)

[Big Jim]

Absolutely, the problem always used to be that big injectors (I'm talking about cossie's running "grey" injectors) just dribbled fuel in at low durations giving terrible atomisation and mixing. The result was you had to run massively rich low down and on road cars this damaged engines from oil dilution.
The economy benefits do indeed come from accurately phased sequential injection and good atomisation. The early direct injection mercs from the '50s used modified diesel injection pumps to get the timing, pressures and atomisation necessary to work properly.
I know what you mean about carbs; they did, after all, do the job for a hundred years but they really are just too compromised in all sorts of ways. Heating the fuel? I'm assuming you mean to get rid of the primary injectors, but surely you'd lose some of the charge cooling benefit?

[MFaulks]

Yes you do, but then relying on fuel atomisation as charge air-cooling is really a kludge to another problem. But agree it depends where the benefits and payoffs lie, and dyno testing would be the only way to know those points really, but yes heated fuel to achieve better atomisation ala Porsche end of the turbo years. Getting back to topic, given the choice and spending the money on custom anyway, surely you are not going to lose anything by trying anyway, have more room to experiment, and could start off fitting bigger injectors in both positions running only one set and get baseline figures for both positions independently. Then split to smaller sizes and would give you real information to play with and possibly adjust ratio between each bank, admit extra cost but great learning opportunity. But then I’m probably perverse like that, laugh :laugh:

[Big Jim]

I'd never heard of the heated fuel thing, learn something new every day....

[Rob@Backyardracing]

Sorry to jack thread....Which porsche was this out of interest??

[Rob@Backyardracing]

http://www.youtube.com/watch?v=OIxdRqcIEKY

this is the latest in n/a tuning, highlights jims point r.e injectors further away making power :)

[Andrew Cooke]

I'd never heard of the heated fuel thing, learn something new every day....

we've only tested on a N/A, but cooler fuel = more power, not much, but something.

[MFaulks]

The heated fuel was in Porsche F1 engine if my recollection is correct, and the aim was fuel economy through improved fuel atomisation, think it was very experimental at the time, dates back to Cossie DFX days.