CA18ET bigger injectors?

**crouchie_b** · 17-05-2005, 16:50

Anybody successfully fitted bigger injectors to the CA18ET without changing the ECU or adding a 5th part fuel controller?

I'm running a nice big Cossie intercooler and have upped the boost and want to be able to shovel a bit more fuel in as well... the problem is I can't change the standard ECU as the regs i'm racing under don't allow it!

I think the standard injectors are 270cc(?) and I've read else where that 340cc injectors give problems with flooding the engine as the ECU can't back them off enough at starting.

So I'm thinking of some trying 300cc injectors (from a 300sx?).

I don't think a 10% rise in fuel should have the same issues as the 25% increase from the 340's?

As you can see from the question marks this is not really my area (no spanner involved!) so I'm looking for some help and advice please!

cheers

**Magnum** · 17-05-2005, 17:20

It will still over fuel.

**crouchie_b** · 17-05-2005, 17:23

Bugger - I take it you've tried?

**docwra** · 17-05-2005, 18:03

Does a fuel computer count as cheating??

If you get an AVC-R for instance, you could adjust the AFR the ECU sees

Alternatively, a switched fifth injector that only cuts in above 5k (for instance) might be the solution

**30psi** · 17-05-2005, 19:26

Don't ya mean S-AFC Doc?

**»» RichardK ««** · 18-05-2005, 08:11

I have the SAFC I got off Mart. Will be fitting it soon along with the bigger injectors. Also have a spare set of S13 injectors for sale.

**pukkaSILVIA** · 18-05-2005, 09:46

5th injectors are actually crap unless there controlled properly rather than just with a on/off boost switch. I had a microdynamics 5th injector contoller that came as a kit with a cosworth green injector, that worked well, ive also got the silvia engineering setupp that uses the cold start injector and a boost switch. I havnt found out if its gaining or losing me power but im starting to think the later as if the injector cuts in and then i back off the gas u can hear a slight misfire type noise as it cuts off. Its actually ghey.

**crouchie_b** · 18-05-2005, 10:31

The regs prohibit both a separate fuel controller or the use of a fifth injector

but allow the use of different injectors.

Question is will the standard ECU be able to manage the extra 10% fueling off boost and for starting?

**30psi** · 18-05-2005, 10:36

Can you change the fuel pressure regulator?

If not you could compress the standard one to up the pressure on the standard injectors.

**scimmy ben** · 18-05-2005, 11:04

Originally Posted by Magnum

It will still over fuel.

This is all about perspective...

It may overfuel, nah that's rubbish it WILL overfuel but you have to ask if it matters. Crouchie is racing the car where it is not tested for emissions so we should really consider whether this improves the driveability/power/torque of the car. I recognise that he will suffer from bore wash but for a race engine that will be rebuilt more often and the oil changed regularly does this matter.

One thing I would suggest doing is checking whether you need to change injectors. Clearly this depends on the other modifications you have embodied but I remember someone (Doc Maybe?) having a rolling road printout that showed a rich mix at the top end (180ish bhp).

**scimmy ben** · 18-05-2005, 11:07

Originally Posted by crouchie_b

The regs prohibit both a separate fuel controller or the use of a fifth injector

but allow the use of different injectors.

Question is will the standard ECU be able to manage the extra 10% fueling off boost and for starting?

Its whether the engine suffers it not the ECU. Someone (I'm not having a good day with names but may have been honest jim or Wacom) just threw a set of S13 370s in and it ran, just not very well.

**30psi** · 18-05-2005, 11:16

Best bet is to get it on the rollers...Who know what they're doing though.

If he uses the 300cc injectors he will have an 11% increase in fuel.

If we say the engine runs stoichiometric at 14.7:1. This increase will give a new a/f ratio of 13.2:1.

If on a tonk or cold start it gave 12.0:1 it would give 10.8:1 on the other injectors.

I think you will find if you kept 12psi and changed the injectors, the richness will be overpowering and you would find probably no power gain. However of course no normal person keeps it there, I would recommend you wack it up to over 15psi.

You may find that cold the engine starts pretty badly, missfiring etc. If it became a problem you could lean it out by fitting a resistor for the ECU water temp sensor so that the ECU thinks the engine is hot.

**scimmy ben** · 18-05-2005, 11:27

Originally Posted by 30PSI

Best bet is to get it on the rollers...Who know what they're doing though.

If he uses the 300cc injectors he will have an 11% increase in fuel.

If we say the engine runs stoichiometric at 14.7:1. This increase will give a new a/f ratio of 13.2:1.

If on a tonk or cold start it gave 12.0:1 it would give 10.8:1 on the other injectors.

I think you will find if you kept 12psi and changed the injectors, the richness will be overpowering and you would find probably no power gain. However of course no normal person keeps it there, I would recommend you wack it up to over 15psi.

You may find that cold the engine starts pretty badly, missfiring etc. If it became a problem you could lean it out by fitting a resistor for the ECU water temp sensor so that the ECU thinks the engine is hot.

Agree totally. I'm just not sure that he needs more fuel until its proved. The race series means you can't run more than a T2 other than super modified and race and then he'll be up against Craig in his Emerald managed, cammed up monster... Clearly the only way around this is to go for the race class, drop in a DET...

**30psi** · 18-05-2005, 11:31

Oh, can he run a hybrid of the T2...ie with a T25 housing?

I can't see anyone being able to get much more that 200bhp out of a T2.

**ratdat** · 18-05-2005, 12:19

Just one thought. If you increase the injector capacity by 11% then in theory, if you enlarged the Afm bores cross sectional area by the same amount it would compensate as the airflow would increase without the ECU knowing. This used to be how people fueled turbo'd KA24's. Fit bigger injectors and hack the AFM about.

**scimmy ben** · 18-05-2005, 12:46

Now that is ghetto tuning...

**docwra** · 18-05-2005, 12:58

Yes, I did mean S-AFC

My car runs slightly rich all the way through and its standard from start to finish - its actually one of the best AFR plots Ive seen

Originally Posted by ratdat

Just one thought. If you increase the injector capacity by 11% then in theory, if you enlarged the Afm bores cross sectional area by the same amount it would compensate as the airflow would increase without the ECU knowing. This used to be how people fueled turbo'd KA24's. Fit bigger injectors and hack the AFM about.

This is something we were talking about at Datmo the other day. I said it was too inexact, they said we should try anyway, I said its my bastard engine now piss off

**ratdat** · 18-05-2005, 12:59

Originally Posted by scimmy ben

Now that is ghetto tuning...

Yeah... but if it works it works...

**ratdat** · 18-05-2005, 13:01

I haven't seen anyone try to CA18DET ECCS on an ET yet? How come nobody has done that?

**30psi** · 18-05-2005, 13:11

Originally Posted by ratdat

I haven't seen anyone try to CA18DET ECCS on an ET yet? How come nobody has done that?

I guess it can be done. The only thought I have with this would be getting the CAS inside the dizzy to work with the S13 loom. I know they have the same disc internally ie the no. of slits etc, so i reckon it could be bodged.

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