720cc injector upgrade question.
 

I have a BNR Stage II turbo and a boost controller installed. I want to turn up the boost. Can I put 720cc injectors in the secondaries with the stock ECU?

You can but the car will probably run rich and the AFRs will be less than ideal. If you don't care about power and gas mileage you can keep it that way but an SAFC or RTEK 1.7 will help a lot.

Rtek 1.7 is so inexpensive for how simple they are and what you get out of it.

^ second that.. do it or lose it..

+1 for the 1.7 , especially since they've had the stumble elimination fix for a while now

So you guys are saying the stock ECU is no good with this set up?

it'll work, but your AFR's will be rich under load. I compared back-to-back running the stock ECU with 720's and running 720's with the Rtek 1.7, no SAFC correction for either setup. The Rtek had AFR's in the mid 11's under boost and the stock ECU had it in the mid 10's, which is rich enough to make your car smoke under boost. The Rtek also has retards the timing for safety and will stage the secondary injectors better (less likely to stumble).

If you really wanna upgrade then I think the stock ecu needs to be ditched (like everyone else). Other people say go for Rtech 1.7 but I say go for a haltech standalone. It's the road that I took and I would do it again.

550/720 is pushing it for a BNR stage 2, I'll agree. You may consider an Rtek 1.8 or 2.1 with 720/720 and a rewired fuel pump. I don't think you need a standalone. A standalone is a big investment, and people have dyno'd in the mid 300's on the Rtek.

10 psi on the 550/550 with the stock ECU would be trouble then.

yes it is probably leaning it out under the long 3rd 4th 5th pulls..that stock inj combo isnt meant to run with the bnr2..when you run lean with the rotory it will go pop believe me i did it..stock turbo running 11ish psi on 550/550..it went pop 3 weeks after i was running it like that. bnr2 you can run set of cleaned 550/720 inj combo with the rtek 1.7 and only @ 10psi no more saftly..might want to make sure you have a reliable boost gauge that you can see how much you are really running too.. digitaltuning.com for the rtek reflashes less than $150 for your app..

Thanks.
That's the setup I am gonna go with.
Rtek 1.7 and 550/720 injectors.

You could always put in some 720's (or GSL-SE 680's) for secondaries and "Firehose" them with the stock ecu for extra insurance against leaning out. I can't say I condone increasing boost on a motor if you can't afford an ecu upgrade, or even a safc to support it safely. An Rtek is a lot cheaper than a shortblock...

I got 720's from TLFperformance before reading the thread on Venom injectors. I sent them out to KGParts to be tested. The results showed 700cc. I called TLF and he told me to call Bobby at venom which I did. I am sending them to him to be checked.

I was not expecting that. Epic thread.

It all depends on your setup.. stock exhaust or straight through?

it will actually run very well if you run those injectors on the stock ECU stock ecu with 3" exhaust and intake mods.. it will actually put you back in decent AFRs, if not still run too lean. I would not run anymore than 10psi or so until you have a decent fuel controller though

the stock 550s are rated at 38psi fuel pressure. your 720s are rated at 43.5psi, which means only about 15% more fuel over stock, which is not enough to make much of a difference when running a hybrid turbo running more than stock boost. if youre still running stock exhaust, it is probably choking out the turbo enough to keep your AFRs still in the safe zone though

i got 3" downpipe and straight through exhaust and i got a walbro pump.

so is a bnr Stage2 and rtek 1.8 good for 300 hp?? safely without a safc?

br7boi
Do you have a SAFC? if not use the money that you where going to spend on one and get the rtek2.1. Gives you ALOT of flexibility You can run 550s 720s hell even 1000s on them and just tune it acordingly

It should be, but you're still going to want to monitor the AFRs, then slowly up the boost until you know it's not leaning out.