Northstar rebuild: Will style (Page 59/119)
Will JUL 26, 02:06 PM
Haven't tried yet... going to pick up the injectors at the end of this week and put both in at the same time.
Will JUL 29, 02:07 PM
Picking up the injectors tomorrow.
Will JUL 31, 11:58 PM
Injector pickup didn't go as planned. The shop hadn't received them back from the shop he sent them to. He had expected them back as well. He called and was told that only 3 of the injectors worked correctly, 3 were dead and 2 were intermittent. He sent me this info via email. I haven't spoken to him directly about it yet.

I KNOW my dad and I had all 8 of those working on the bench last year. I also know that there's no way the engine had a dead miss on three cylinders when I had it running. We blew out the varnish when I got it running last year, and it sat all year with race gas in the fuel rail, so the injector shouldn't be *that* gunked up... but maybe they could.
It almost sounds like the injectors are stuck and the guy checked them by hitting them with +12 once and didn't try anything else. Now I didn't check their operation pressurized, so there may be problems I didn't find, but I *KNOW* they all operated.

Anyway... won't solve anything until I get my shop on the phone Monday. In the mean time I left another set of injectors on his doorstep.

[This message has been edited by Will (edited 07-31-2010).]

IXSLR8 AUG 01, 01:24 AM
Are your injectors stock or are you using a higher flow injector?
Will AUG 01, 01:44 AM
Stock until I get tunable engine management.
IXSLR8 AUG 01, 01:12 PM
I was talking with CHRF and Alan mentioned that the stock injectors would not handle the 272 cams I have. I understand that he uses Ford racing injectors for his configurations. He did also say that I could use the stock injectors if I turned the fuel pump pressure up to 65 lbs. But he noted that option would need to be monitored to confirm that the injectors are keep up with the required flow at WOT.

I'm going to go that route first, if I ever get this thing running right.
AJxtcman AUG 01, 03:33 PM
65 PSI will hydrolock the injectors and or lean out the engine. I ran a bunch of testing on the OE injectors
aaron88 AUG 01, 09:25 PM
I don't know about 65 psi because the O&M has this big thing in it telling you to make sure your fuel rail pressure never goes above 60 psi. However I can say that I ran my motor (1998) with stock injectors and the fuel rail at 60 psi for almost 12 000 km.

I'll also say this. I don't know what the spray patern of the injectors looked like but from the O2 sensor readings I know that now that I'm adding power I better increase the injectors, because the stocks were at max duty cycle (80+%)WOT & .6 volts at 6500rpm.

[This message has been edited by aaron88 (edited 08-01-2010).]

Will AUG 02, 12:19 PM
Wow... injectors are so damn cheap that there's no excuse risking your engine trying to run them at 90+% DC or higher than rated fuel pressures. I could get a set of 19# Ford injectors for $50 on ebay. I didn't check 30's and 36's, but those sizes are common as dirt as well and will support nearly double the stock horsepower.

You guys have done Northstar swaps... don't cheap out on the injectors.

The only reason for not upgrading now is that I want to drive the car before I upgrade to tunable engine management.
Will AUG 08, 01:34 PM
2nd set of injectors had 7% variation across the set. That should be 2% for high performance use.

Of course I didn't think to ask what the actual measured flow rates were. So now I need to get that info (maybe Monday) before I can get replacements.