Max HP (reliable) on stock 440cc injectors?

[SuprA70]

I'm upgrading to 550s soon but was just wondering what the most HP people have hit safely with just the stock injectors.

I dyno'd at 324rwhp, 342rwtq @ 16psi, upgraded ct, stock 440s, FCON + VPC. Dyno shows as running a bit lean. I currently have no way to tune other than the limited settings on the VPC.

Is low 300s pretty much the limit of the stock injectors? Curious to know, thanks guys.

 

[psycho]

I think that they would be maxed out by the high 300's.

This guy on 7mpower made more the 435whp. Eventhough his compression is a little higher than the stock, its a lot of power.

click here

 

[psycho]

by the way, did you change the fuel pump and install an afpr yet? that should make a BIG difference in fuel delivery.

 

[SuprA70]

by the way, did you change the fuel pump and install an afpr yet? that should make a BIG difference in fuel delivery.

Still on stock. 550s, mk4tt fuel pump, SAFC-2 next up. Is an AFPR necessary? Thanks.

 

[SuprAng]

400-440 is possible, i would run them that high duty though. Most sets actually flow 460cc or more.

 

[psycho]

am pretty sure that it is necessary. If i were you i would get these mods in the following order: fuel pump, afpr, 550's with lex afm, afc.

 

[SuprA70]

am pretty sure that it is necessary. If i were you i would get these mods in the following order: fuel pump, afpr, 550's with lex afm, afc.

Most certainly. I'm still undecided on the whole VPC or MAFT or Lex AFM. Not looking to go standalone as big unstreetable power isn't my goal. Looking for just about 400-450. Motor is a fresh rebuild and the numbers are just a little lower than I expected. It certainly feels strong, even at above or near stock boost so I'm not worried. I'm just a little anxious to start putting down some decent numbers :icon_bigg

 

[Disco Stu]

Kickass fuel injector worksheet:
http://www.rceng.com/technical.htm#WORKSHEET

(RC recommends 80% max duty cycle, many people use 85% w/o problems, and some crazies actually go all the way to 100% to max out an injector)

JBLMK3 has put down over 400 to the ground on 440's with TWO different cars, one with high compression and one stock.
http://www.jblmk3.com/id126.htm

 

[aye mate]

I would say definately get a bigger fuel pump. That will richen up the mixture quite a bit.

 

[Disco Stu]

The fuel pump will NOT richen the mixture. The regulator pressure and injector pulse width/static flow rate are the olny things that will affect the amount of fuel. Replacing the factory pump is only required if pressures and flow rate of the stock unit is exceeded, which just happens to be very soon w/ the MK3.

 

[aye mate]

The fuel pump will NOT richen the mixture. The regulator pressure and injector pulse width/static flow rate are the olny things that will affect the amount of fuel. Replacing the factory pump is only required if pressures and flow rate of the stock unit is exceeded, which just happens to be very soon w/ the MK3.

I stand corrected. So if I got a Walbro pump w/o bigger injectors or an AFPR it would be pointless?

 

[moorman]

I stand corrected. So if I got a Walbro pump w/o bigger injectors or an AFPR it would be pointless?

It wouldn't be pointless as it paves the way for future additions, but it won't make any immediate changes in and of itself. Inadequate fuel flow due to a weak pump isn't something I have an interest testing, so the FP has always been among my first 'mods'.

I'm running 348rwhp (370rwtq) on 440's & Lex, but in my case it required a pretty high base fuel pressure to get the Vf's happy during cruise. The base FP that John Lunsford uses wasn't enough for my application, so I'm seeing 55psi base FP to keep Vf right at 2.5v. The AFCII is set to pull -16% at WOT for the meat of the powerband with AFR's at ~11.3:1.

 

[shaeff]

if you get a wally, make sure you drill out the J pipe, or remove it, or cut it off and run a custom return line.

having a j pipe and a wally pump is not recommended too much pressure.

-shaeff

 

[aye mate]

Thanks Moorman,

if you get a wally, make sure you drill out the J pipe, or remove it, or cut it off and run a custom return line.

having a j pipe and a wally pump is not recommended too much pressure.

-shaeff

^ answered my next question.

 

[shaeff]

nice!

-shaeff

 

[Disco Stu]

That small block chevy blockoff plate works great for the J-tube spot. You can prolly find it @ Autozone or PepBoys for ~$10. Then you would need a line. I bought a S.S. Fuel Pulsation Dampener removal kit from JBLMK3 when I did mine