hey i just bought an s5 BNR stage 4 turbo and i was wondering if my 720cc secondaries will be enought to handle about 13-15 psi of boost? i also have an safc, walbro 255, and will have freshly rebuilt 550 primaries. if this isnt enough what do you think i will be able to run psi wise with this setup? oh other mods include 3" turbo back exhaust, oldschool trust fmic, streetported motor, and tid, tb mod, and all emissions removed with block off plates.

thanks for your help!

David

 

No they won't be enough.

Jrat here has a stage 4 and is running bigger injectors.

I think he's running 720's and 8XX somethings in secondaries.

He's also running a hlatech and alcohol injection so the tuning may be off compared to you.
He may wander into this thread or you can pm him.

 

im gonna go ahead and say what alot of people are gonna say.... the stock computer is not gonna cut it.

you went out and got a big boy turbo... time to step it up. start looking for a used e6k.... there out there for $500 or so.

 

ill trade you my bnr stage1 for your stage4 you'll have enough to push it then.

8-)

 

ha i might consider it if it was a stage 2.

what kind of boost could i run safely with this setup til i can afford a stand alone? 10 psi?

 

I think 10 psi is still way too much.....i wonder how much you would be able to run with a stage 2 and your setup....

 

That sig pic is ******* awesome. I've seen plenty of TII's before, but at that angle, that type of paint, and just the way it looks, its ******* sweet! If you have a full size pic, please PM me or post it

 

10PSI is way too much?

wtf? that's like, 4PSI over stock. BFD.

I'm currently running something pretty similar to a stage 4 BNR, 11PSI midrange , and it drops to 8 at redline

10PSI is MORE than safe, I have stock ECU+ safc + 720 injectors and have the car tuned SO stupidly rich that it shoots fire every time I shift (10.8:1 AFR's). And you've got a front mount!

you should be able to run 12-13PSI safely, I'd bet, especially with the front mount and etc.

 

^ what did you dyno at?

 

i did a little searching on the topic of injector sizes and what they will support.

"ECU Controlled Max Duty Cycle is the maximum injector duty your reprogrammed computer uses. For reprogrammed ECUs, please contact your ECU programmer for specs. If unsure, use 80%. The Stock ECU is approximately 58-63%."

"You can go higher than 85% duty cycle but it is really starting to work the injectors too hard and you risk getting one stuck open."

at 85% duty cycle 4x550s is good to about 269Bhp.

at 85% duty cycle 2x550s and 2x720s combo will max out at: 311.1 flywheel hp.

at 85% duty cycle 4x720s is maxed at 352.7Bhp

so you got a 350rwhp turbo and 311Bhp worth of fuel.

these values were calculated on http://rx7.com/calculators.html

do you can run what you want... id listen to the math, and not to anyone on here. There has been lots of false info given out lately. Id say fuel suppily is pretty important.


Im not even going to get into the topic of making 350rwhp on the stock tii timing map.

 

^ thanks for the info man. thats what i needed. ill just buy 2 more 720's and put em in the primary spots. then ill take it to be dyno tuned. im gonna turn to mbc all the way down so i dont boost to much on the way there.


oh and about the sig pic. the paint is the original black that came on the car from the factory, i had just waxed it the day we took the pics and i would have more but i got a new computer now and lost the pics. ill see if i can talk to the guy that had em hosted to see if he still has em. but thanks for the complimant

 

so whats your power goal?

with 4x720s and a safc you might have a flooding problem at start up. could install a inline switch to cut off the fuel pump to make crankings easier.

 

he made 244rwhp. thats not a stage 4. your injectors are good to 311Bhp turn up the boost just a few psi and you wont have the fuel. The bnr stage 4 is gonna make more that 244rwhp at 10psi. My stage 1 did 247 at 11psi.

 

im running 750s and 860s.. my car starts when i ask it too.... i have an safc2 and datalogging wideband for tuning(zt-2). im also running a stage 3 12lbs. dont run your car on just 720s in the secondaries or your car is toast.. its better to overbuild a fuel sys and turn it down than to run lean....... lean equals very fast for 5 minutes.....

 

well my goal now is like 325, that is after seeing the chart in the previous post. ill run 4 720's and just tune it down.

 

you have everything else to support 325?

list out your mods to the detail so we can check it out and make sure you didnt miss anything.

you need to start searching for people making 325whp on the stock ecu... and what problems they have had. Im sure there they have had some problems.

 

mods:

3" tid
3" turbo back exhaust (corksport)
large Streetported motor
emissions removed using block off plates
hks fmic
walbro 255 fuel pump
will have 4 720cc injectors
S-afc
boost and a/f gauges

umm i think thats it. if i missed something ill remember if you point it out

 

I'll trade you my stage 3 for your stage 4 I've got a stage III running 550cc primaries and 890cc secondaries witch supports the same hp as 4x720cc injectors.

 

thats ok but thanks for the offer

 

look into a egt gauge... and a wide band if you can.

if the WG of that turbo is not ported... do it... go big.

get ready spend some time on the dyno to get your a/f right.

 

the previous owner said that bnr ported the wg as large as i would need it so im assuming its good. ill double check b4 putting it on, and ill def look into getting those gauges

 

ok so im goin 4x720's and im putting it on this sat. this will be enough fuel?

 

Like someone else said, it'd probably be *smarter* to leave some head-room and tune some bigger injectors down, instead of taking the risk of maxing out smaller injectors...

I know there are some larger injectors out there (1000cc?) that will fit the stock fuel rail. Maybe some 890cc's like hondahater will be big enough for you, though.

In all seriousness, you got a stage 4, I wouldn't risk skimping on the fuel.

Let us know what you decide on, and if everything works out.

edit: If you've already got the 720cc's, you should simply get the car dyno tuned and make sure you aren't pushing the car like crazy.

Good luck,

 

Here is my .02 since i have been running a stage 4 for a bit:

In my opinion, you should go larger then the fuel calculators say. Not by much, but those calculators are just educated guesses. They do not take into account the changes in BSFC, and this is an ever dynamic number.

Now having said that, my duty cycles at 17 PSI are around 75-78%, but DONT FORGET, I am also injecting an additional 600cc of alcohol above 7 PSI. That is with 720 Primaries, and 890 secondaries. Without alcohol, I bet that number would be pretty close to the magic 90%.

So lets address some things:

Maybe 15 or so on a stocker, but not on an Stage 5 BNR.

In case you dont know, 10 PSI on a stock turbo and 10 PSI on a HI FI are two very different things.

Umm.. Hailers all but debunked this rumor.. So take that for what its worth.

Enough fuel for what? 325? Sure, with very little headroom. Not too mention you are going to be on an SAFC.. The driveability will be outstanding (sarcasm). IMHO, you would be better off with stock primaries and larger secondaries. But in my EVEN MORE HONEST OPINION, you should light that SAFC on fire, then stomp on it, then **** on it..

But if you insist on the SAFC (and I did it too for a while so I am as guilty as the next), then those 720 primaries may cause you some problems. You should really lean towards 550s and like 1000cc secs. I did have 720 primaries on my SAFC, and they sure caused me some flooding headaches..

Rat

 

so if using an safc to tune a larger turbo whatever the case may be you should really only upgrade secondaries for ease of use/tune? If using an SAFC of course