Fuel system.... how far can you take the standard injectors?

[hairyhoover]

I am/was looking to upgrade my secondary fuel system, to go on my new rebuilt engine, it has a decent sized street port and ill be using a t04s with a 1.00 A/R on the exhaust side.
I currently have a standard primary’s and secondary with braided lines from the bulkhead with apexi GTR fuel pump
I have spoken to a few vendors about upgrading my secondary fuel system but every one Ive spoken to (re:worx – rxmotors – WGT) have suggested I get my injectors flowed and tested and rewire the pump and just up the fuel pressure
This all sounds great(nice and cheap) but has any one got any concerns about the setup before I go down this route?
cheers

[BlitzBoy]

With your setup I would run 850s all round Primary and secondaries, get a decent FPR so you raise the fuel pressure (Aeromotive or SARD not that FSE rubbish) and have the injectors flow tested and pump rewired as suggested . That should easily supply fuel for 400rwhp, which is what your tubby is capable of at around 1.1 to 1.2 BAR

[hairyhoover]

Hi Mark, what would you say the limit of the 550cc + 850cc would be? as i am happy to stick with 1bar for now.

[clive]

I agree with Mark, you can just about getaway with 850\'s all round providing your on a smallish turbo and no crazy porting.

You can modify the stock rail to get rid of the stock regulator to fit an aftermarket regulator which you will need to up your fuel pressure

You ask what the 550/850 limit is, well to run these you need to put the twins back on.

Hope this helps

[Prof]

This thread has some info about what injectors sizes will support what HP:
 
http://www.mazdarotaryclub.com/forums/showthread.php?t=30430

[hairyhoover]

I was running a single turbo previouly on this fuel system and it made 321 hp at the wheels duty maxed at about 80% on stock fuel pressure.
 
Reading the links above this doesnt sound possible, any idea?

[BlitzBoy]

The problem with those calculators they do not take into account when you up the fuel pressure.

The most hp at the wheels I have seen with with 550/850s is 330 ish, if you up the fuel pressure maybe a little more.

If dont want to upgrade the primaries coz of fear of idle issues then go for the 1600 kit if your goal is 400whp

Whats your HP goal?

[hairyhoover]

Mark, i would be happy with 360rwhp for now, as the car fund is tight at the mo, long term ( 1year hopefully) i want a gt* turbo with 1600 injectors.

[BlitzBoy]

Then yes 850s all round and rewire the pump and with an aeromotive fpr and up the fuel pressure will defo do 360 rwhp. Seen a few FDs with these mods do 400rwhp

[Mims]

Sorry for hijack - Can stock primaries & 1680 secondaries support 380rwhp without a fpr or uprated pump?

Regards

Mims

[BlitzBoy]

no, an uprated Pump should always be the first on the list of fuel mods

[Speedline Imports]

My car made 325rwhp with Standard Primary/Secondaries with a FPR and uprated GTR fuel pump.  Was only running at 0.7 bar.  
 
850s all round should do the job if your not upping the boost too high.  Probably the cheapest upgrade to do too.

[hairyhoover]

I was trying to avoid using 4 * 850cc\'s because of the issues people have lighted about the problems with idle low speed fuel cosumtion etc.
 
Is it really something i need to worry about?

[strange_days_uk]

no mate, that is what I had, 850\'s all round, sweet...

but get fpr defo

[hairyhoover]

this looks like a good kits, what do you guys think?
 
http://cgi.ebay.com/Aeromotive-Style-Fuel-Pressure-Regulator-SKYLINE-GTST_W0QQitemZ170184100200QQihZ007QQcategoryZ72205QQrdZ1QQssPageNameZWD2VQQcmdZViewItem?_trksid=p1638.m122