Injector Upgrade Advice?

[Ihtisham Rauf]

Hi,

I have been told that with CGA3+CG10 gearbox, + fast inlet cam (its 250deg/9mm), and the simple GA16 + CAI mod, that the injectors will be on 100% which is dangerous.
So what recommendations have people got for injectors?
Matt recommended the K12 1.4's, but I know people have used Primera 1.6 ones as well, and some others.

The thing I am confused about is I have read on a few threads on MSC that stock injectors are good for up to 100-110bhp. Surely a CGA3 with just a better inlet cam and airbox mod is going to be around 90-95bhp (i hope!), so whats the problem?

Can someone clear this up for me please? Thanks!

PS - I know the full potential of the cams will not be released until some proper management is done - this will be done eventually!
Also, is it true that if injector upgrade is done, then remap is a MUST, because the stock ECU will not be able to run the upgraded injectors properly?

 

[Ihtisham Rauf]

Bump.

Anyone?

Forgive me if this has been covered before. I've searched the forum but can't find anything solid.

Thanks.

 

[fuzzy-hair-man]

I don't consider myself knowing the answer but here's a bit more info.
You generally don't want to run your injectors at thier capacity, because you'd like some in reserve (up to 80% is what I've heard) for fuel trims to adjust with as well it would seem more likely they fail as the injector cycle should be intermittent not on all the time allowing it to cool etc. High rpm makes high duty cycles worse as there's less time to inject fuel.
I have Ga15de injectors in my cg13de, but also have nistune so the ecu knows it's running larger injectors. If I remember correctly your cga3de rail has more options for injectors so may be better in this regard.
Without a tune the ecu will assume it still has the standard injectors in there and initially cycle the same, closed looping(feedback loop from the O2 sensor) should adjust to limit the fuel to what's appropriate if it is in it's window or ability to adjust, if you need that extra fuel then the chances fuel trims can make up for the rest are increased. You might be able to use a obd to monitor duty cycle to see if you really need bigger injectors, given the parts you've put in it seems a waste not to get it tuned, a nistune isn't that expensive comparatively. If you do put in larger injectors I'd use the smallest available that are larger than standard.

 

[Ihtisham Rauf]

I don't consider myself knowing the answer but here's a bit more info.
You generally don't want to run your injectors at thier capacity, because you'd like some in reserve (up to 80% is what I've heard) for fuel trims to adjust with as well it would seem more likely they fail as the injector cycle should be intermittent not on all the time allowing it to cool etc. High rpm makes high duty cycles worse as there's less time to inject fuel.
I have Ga15de injectors in my cg13de, but also have nistune so the ecu knows it's running larger injectors. If I remember correctly your cga3de rail has more options for injectors so may be better in this regard.
Without a tune the ecu will assume it still has the standard injectors in there and initially cycle the same, closed looping(feedback loop from the O2 sensor) should adjust to limit the fuel to what's appropriate if it is in it's window or ability to adjust, if you need that extra fuel then the chances fuel trims can make up for the rest are increased. You might be able to use a obd to monitor duty cycle to see if you really need bigger injectors, given the parts you've put in it seems a waste not to get it tuned, a nistune isn't that expensive comparatively. If you do put in larger injectors I'd use the smallest available that are larger than standard.

Hi, really appreciate all the info you’ve given me. Everything you’ve said makes sense.

I’ve seen on the forum two people used QG15 injectors no problem on CGA3 rails on cars that had roughly the same level of mods as me. So this may be the way to go from your info. It’s either these or K12 CR14DE’s - I ask Matt what may be better, if any one over the other.


In regards to mapping, Nistune isn’t an option for me as I have a coil pack, the only option is a remap from Tornado systems. But I’d rather do this at end, after all the mods are done. But in all fairness, I only have lightened flywheel left to do and possible exhaust, then will look at contacting Tornado.

Many thanks for your help!

One final question - what do people do for a better flowing exhaust side on a CGA3? I know a janspeed 421 will cause an engine management light, and is it even worth getting just a catback if a manifold is still the same old restrictive manifold? (Seems like the catback could only perform as good as the manifold before it?)

With everything done, including mapping, my target is 110-120bhp. I know Faisal on here got 105bhp from a cg13 with induction, full exhaust and injectors. So I want to do one better with a CGA3! And I know I’ll need to do so something on exhaust side, just unsure what’s the best option.

 

[Low Rider]

I'd speak to Mark at Tornado, he's a REALLY helpful guy and had done a lot of mapping on NA coilpack engines in various states of tune. So, he should have a well founded concept on what the injector duty cycles are and be able to advise you on what you need going forward.

Cams help some but the standard intake manifold holds their potential back by quite a bit unfortunately. I'm in the process of putting together a thread on CG cylinder head flow after playing with a few heads on the flowbench and comparing it will what the community has been achieving on the dyno, which some people may find interesting

 

[fuzzy-hair-man]

Well if you are going to a standalone ecu later the engine management light shouldn't be an issue, that said I have extractors and a aftermarket catalytic converter (cat) after this, it still passed emissions(Australia). It might mean you need to put in a new aftermarket cat further down and relocate the O2 sensors, I think the second sensor reports the health of the cat (can't remember if the CGA3DE has 2 cats). If I remember correctly the cat wiring is a shielded wire on mine so better if you can tease some more length out of the loom than cutting and extending.

 

[.Maarten]

See below

 

[.Maarten]

Qg18 (Primera 1.8) are a direct fit. Ecu Will compensate for iT so iT Will run (i swapped them in And car had No trouble) For more power get a remap.

Also a cga Will throw a code If you remove the cat. (only has 1 in the manifold) its a cat malfubction code And wont throw iT into limp mode. You can get a o2 faker to get around this.

 

[Ihtisham Rauf]

Thanks for all the help guys!

I have messaged Mark to get some advice on what injectors and if I really need them. Meanwhile, I have found QG15's for a real good price but struggling to find QG18's, only ones I can find are brand new £40 per injector. Any chance QG15 and 18 use same injectors?

Regardng exhaust, probs leave it for now, until I get injectors, lighetend flywheel and the CGA3 ecu in. But O2 faker seems like an easy getaround method, so thanks for that!

 

[.Maarten]

Not 100% sure but i think both engines (qg15 and qg18) use the same injectors.

 

[Ihtisham Rauf]

Ended up getting the QG15's , the deal was too good, and judging by google as well, they are in fact the same as you say.

Now to put this beast together!

 

[Ihtisham Rauf]

. EDIT