Effects on running fuel pressure at 43.5psi....

[WHYTRYZ06]

ok here is the deal...


im gonna run a dry kit roughly 350rwhp total... im gonna use efilive cos5 for fueling.

question is....

I wanna run the racetronix 79# high imp.injectors, but i wanna run them at 43.5psi (what they are rated at), so hopefully it would be easier to tune... can it be done. w/o any issues??.. If I scale em at 58psi they act like a 91# injector. remember its a nitrous car, 2001 corvette

Fuel system will consist of....

racetronix 255lph intank w/ hotwire harness
a&a return style front mount FP regulator w/ 97 vette fuel filter
KB boost a pump

according to my math its gonna take 331lph to support the hp I wanna make, according to KB the boost a pump boost's the fuel pump's out by 50%, so if there is any truth to that combine my pump w/a boost a pump it and it should flow 382lph...

so pros to running a lower FP
1. makes a larger injector easier to tune
2. allows the pump to flow more volume.
3. the injector flows what it is suppost

cons...
1.will the motor function properly....

cant think of anymore...

[johnv]

Can't see why it shouldn't work, you will have to re-do your VE table to suit though as it will be off at the lower FP.
Your running a pretty big injector for your power goals, but at least you have plenty of head room to grow:hihi:

I will probably have a go at this with 60 # injectors and boost ref, easier on pump and lower fuel line and rail preasure under boost:)

[TAQuickness]

Assuming your VE table is dialed in correctly, changing the IFR table, correctly, there should be no need to redo the VE table.

VE table = airflow
IFR = fuel flow

[WHYTRYZ06]

Assuming your VE table is dialed in correctly, changing the IFR table, correctly, there should be no need to redo the VE table.

VE table = airflow
IFR = fuel flow

My VE is spot on... I just talked to mike @ KB and he said w/ my racetronix pump & harness, and the BAP the system will pump 380lph... which meets my requirements... still need to test it tho.

now lets see how the 79#ers are to tune at idle...

Ill keep u guy posted...

thanks

[WHYTRYZ06]

Guys what do I need to log as far as PID's when I get these new 79#hr injectors.. I want to get them perfect, as best as i can... hopefully they will idle and cruise at stoich w/o too many issues..

I can make the maps in the scan tool, I just need to know that to log.

thanks..

[Chuck L.]

Just my $.02.. I doubt one Walbro will support a RWHP of base HP, + a 380[rw]shot dry....380 shot at the wheels, is at least 430 at the FW.
That, plus the FW of the engine, [400??]
Looking for a reliable system at over 800FW, is alot to expect of that pump.
Like I said... Just my $.02..

[WHYTRYZ06]

Just my $.02.. I doubt one Walbro will support a RWHP of base HP, + a 380[rw]shot dry....380 shot at the wheels, is at least 430 at the FW.
That, plus the FW of the engine, [400??]
Looking for a reliable system at over 800FW, is alot to expect of that pump.
Like I said... Just my $.02..

we will see...:grin:

[vatman02]

Thats just what I have 79's @ 43.5.

[WHYTRYZ06]

Thats just what I have 79's @ 43.5.

How's it idle??? A/F wise.... What tables did u adjust besides, injector flow rate..??

thx

[vatman02]

Iv'e been playing with the voltage correction table. It Idles really well, but I am useing E-85 so I would flow more fuel than a gas motor. With my altitude I need 20% less fuel and the E-85 needs 30% more. I figure compared to sea level I use about 4% more. I am having other issues not related to the injectors so I may have made some unneccsary changes.

[WHYTRYZ06]

Iv'e been playing with the voltage correction table. It Idles really well, but I am useing E-85 so I would flow more fuel than a gas motor. With my altitude I need 20% less fuel and the E-85 needs 30% more. I figure compared to sea level I use about 4% more. I am having other issues not related to the injectors so I may have made some unneccsary changes.

did u make a MAP for the voltage correction table?? if so, could you please post it,id like to see what you put for data, and also what PID's you logged to make the MAP work. im gonna run the racetronix 79# injectors too..i wanna be ready when I get em'

[eurospec1]

did u make a MAP for the voltage correction table?? if so, could you please post it,id like to see what you put for data, and also what PID's you logged to make the MAP work. im gonna run the racetronix 79# injectors too..i wanna be ready when I get em'

I guess i dont understand why you want to lower the fuel pressure, those injectors are not hard to tune at 58psi, is there another reason that is going over my head?

[eboggs_jkvl]

The only reason that I can think of is to run the pump at a cooler temperature and not kick it up with the BAP until you need the pressure?

I run at 52 PSI and when the Aeromotive pump controller sees 0 vac/0 boost it activates to the higher voltage and the PSI slaps to 58 and then rises 1 PSI of fuel pressure for every 1 PSI of boost. I end up at 72.5 PSI of fuel pressure at full boost.

I can't really see a reason to run at lower fuel pressure unless you are strapped for the pump being able to handle the full load or you are running small fuel lines?




Elmer

[joecar]

Some people run the lower pressure so they can better control their big injectors at idle...

the larger injectors are more prone to physical (mass/inertia) effects... they have a "minimum" on time.

[eurospec1]

Some people run the lower pressure so they can better control their big injectors at idle...

the larger injectors are more prone to physical (mass/inertia) effects... they have a "minimum" on time.

We did a 440TT c5 a few days ago with the 79# racetronix's injectors, just a base tune for idle so he could run it for a 30 minute break in period, it settled right into idle at 800RPM with a few tweaks of desired airflow and VE once we input the correct IFR table and accounted for the extra cylinder volume, it was really easier then i had expected it to be, although the RR plays a huge part in that.

I see the logic in your statement Joecar, im just assuming from my experience that this is not neccesary with the racetronix 79's

[WHYTRYZ06]

We did a 440TT c5 a few days ago with the 79# racetronix's injectors, just a base tune for idle so he could run it for a 30 minute break in period, it settled right into idle at 800RPM with a few tweaks of desired airflow and VE once we input the correct IFR table and accounted for the extra cylinder volume, it was really easier then i had expected it to be, although the RR plays a huge part in that.

I see the logic in your statement Joecar, im just assuming from my experience that this is not neccesary with the racetronix 79's

So what you are are saying is that they (79#ers) are easy to tune, w/ the correct IFR table??

[joecar]

Oh, the Racetronix 79'ers must be well behaved (high quality)... cool... :cheers:

AJ/WHYTRYZ06, you should able able to calculate your IFR table using your measured rail pressure and you should be good to go.

[WHYTRYZ06]

Oh, the Racetronix 79'ers must be well behaved (high quality)... cool... :cheers:

AJ/WHYTRYZ06, you should able able to calculate your IFR table using your measured rail pressure and you should be good to go.

Heck, I hope so...

[vatman02]

did u make a MAP for the voltage correction table?? if so, could you please post it,id like to see what you put for data, and also what PID's you logged to make the MAP work. im gonna run the racetronix 79# injectors too..i wanna be ready when I get em'

I can't seem to be able to post the map but it is DATA= XXX.BEN COLUMN=GM.VOLTS ROW=GM.MANVAC
These are what you will need to log as well.

[WHYTRYZ06]

I can't seem to be able to post the map but it is DATA= XXX.BEN COLUMN=GM.VOLTS ROW=GM.MANVAC
These are what you will need to log as well.

ok got it.