Out of injector? I didn't think I would be. I mean, 30# SVO on a 355. The old 383 did fine, but these are Vortec heads. I shouldn't run out of steam on the 355.

Anyways, guess I'll do some calcs on the duty cycle and see. Anyone have a good source for some 42# or 55# high-impedance?

 

Watch the Turbo Buick boards, guys are always updating their small injectors for larger ones.

 

What is the largest size injector you can run and still have good idle quality?

 

I'm pretty sure Ford Lightning Green Top Bosch injectors are 42 pph. Idling in closed loop could be an issue. What intake manifold are you running that can flow enough air for them? How much power and what RPM are you running out at? If it's marginal, just up the fuel pressure.

 

Bruce is running 60#'s on his Buick and I have 60#'s for my TTA when the motor finally gets done :-)

Ask him if it works or not :-)
later
JEremy

 

I can attest to a 383 AFR 195 to run out of the stock fuel pump at about 3500-4000rpm..... but not run out of Accel 30lb injectors...

My 355 ran out of 24lbers pretty easy though....

I'd be intersted to know if you really ran out with the 30lbers because that's what I was planning on getting here shortly.

 

They seem OK
Might check with RBob, Provst, Ken, Bill, and Saturn 5, they've seen, heard, felt it.

One side issue with big injectors is having enough fuel pump. I use two 340 LPH pumps, with the second one coming on at 3 PSI.

 

It's like mechanical Viagra..

 

PS to the above :-)

Im running Ford SVO 30#'s on my 91 Formula, with hotcam/vortec setup and no fueling issues thus far.....


The 24#'s covered it as well just wanted more breathing room for future enhancements
later
JEremy

 

I just picked my injectors on ebay 3 weeks ago 42#svo
Idle is good run great with the $60 code from bruce. They were fairly well priced at $289 delv. I believe they would be good for 575 hp at 43.5 psi on a N/A application.


ED89

 

The only real way to tell if you are running out of pump, is to hook a hose up and take it for a hard drive. If you have a long enough hose, you can run it through the inner fender well on the passenger side and come through the antenna cable hole behind the kick panel. Of course you will have to pop the rubber plug out of the way until your test is over.

A buddy to hold onto the gauge and watch it for you would be a very good thing. This allows for a shorter hose and you to keep your eyes on the road. As far as running out of injector, the Accel DFI manual (IIRC) says that 24# injectors are only good for 325HP.

If you have the ability to check your O2 on the fly, that should tell you if you are running out of injector. You should start running lean because the injectors can't keep up. If you have the capability to change your programming (Just ordered a prominator!!) you can enrich your fuel settings to make sure its not a program problem before spending the bucks on a pump.

Some racing buddies have said that bigger fuel pumps have made their "stock" 350's be more responsive and run faster. They were running Mustang (sic, Ford yuk) fuel pumps (280H?). I have a TPIS in tank fuel pump sitting in the garage that I'm contemplating installing. This thing is a monster supposedly capable of handling 550 HP and I'm afraid it may overload my system. This is a Bosch unit Part #300-178 on TPIS website. Do any of you guys have any experience with this pump in a daily driver??

 

The correct (at least pretty darn good enough) way to measure a pump is to pour the return line (after pressure regulator) into a bucket and stopwatch it with the pump on (engine off) and measure the flowrate. The regulator is keeping the pressure at whatever it needs (unless supercharged), and the bypass has to be enough to fuel the engine at about max horsepower plus a factor of safety. Another empirical method is to watch a fuel pressure gauge at WOT all the way to redline, and see if the pressure stays high enough (keeping in mind that any intake vacuum caused by say a restrictive TB, or air cleaner will lower the pressure a psi or so).
A pump is NOT too big, unless the regulator and lines themselves won't allow the pressure to get low enough. There are drawbacks to putting on a realy big pump, in that it'll heat up the fuel in the tank from recirculating more fuel through the engine bay, which'll cause more evap, and hotter fuel, and lower pump life. The bigger pumps sometimes take more current to power too which is bad.

 

In the case of high HP systems, guages are about useless. The pulsations, and fuel demand are so fast, that they get lost on a mechanical guage.

It's another item that needs datalogged at a pretty high sampling rate if you really want to see what's going on.

Sampling the return line is better, IMO, then the pressure side.

A Volt Booster is a worth while investment. A search at Turbobuicks.com will supply the specific data, as done by PT+E in that reguard. Motors/solenoids (fuel injectors), operate increasing well with even minor voltage increases. Not to mention increasing the ignition systems reserve capacity.

 

Well I just picked up an AutoMeter FP gauge (electric full-sweep) along with a new set of Racetronix 42# disc-type. Don't know how they'll do compared to the pintle type, but worth a shot for learning if nothing else. Of course I'll measure pressure on the return side at the backpressure regulator (Aeromotive @ 45psig). Pump is Walbro 255 in-tank. Stock lines.

I'll go ahead and see what the calculated duty cycle ends up being. My darn WideBand sensor (L1H1) seems to have coughed up a bone. Reads 20+ all the time now, even though it goes through proper warm-up cycle. Gotta install the spare ;^). Last one though :^(.

 

I saw several different ones mentioned.

I ran across voltage boosters while searching for something else a while back, but can't remember where. Seems there wasn't one available for my truck.

Grumpy, is there any particular brand you recommend, and why?

 

Where was it mounted?.
Can Doc have it?. He autopies them. Ya, I know, weird.....

 

It was back behind the Y-pipe. Sure, I'd like to know what went wrong.

I did have it in the exhaust stream for a little while (a few 10-20 miles) without being energized, but it worked ok for a while after all that. Could be moisture damage I guess, or carbon buildup.

 

Careful examination, by a seasoned Pro like Doc, can be revealing. Think of it as kinda like reading spark plugs.

Besides, the lil guys like throwing them at the squirrels.

 

And in the decades that I've know them, the squirrels have never incured an injury from the antics of the lil guys. Matter of fact if one was to get injured, it'd probably live the life of Riley, with their constant care, and attention.

 

Yeah, we've got a few rogue squirrels around here as well. They chew off Christmas lights and bury them.

My cats are not so forgiving to the little critters. They've brought down at least 4 that we know of this year, as evidenced by 'gifting' of partial squirrels, sometimes the front half, other times the rear. What are you going to do? Instinct is a powerful thing.

One time they brought one in the house, still alive and very active but woefully injured. It was a bloodbath, took the better part of a day to clean up the mess.

 

That's EXACTLY why Mity Cat stays in the house.....

 

OK,

Strange enough. Went with 42# injectors and added the FP gauge. Target AFR is in line with what it should be, and I'm assuming the PW being called for is in agreement with that. Pressure is fine.

So the ECM calls for 12.5 AFR and only achieves 14.5, not good. Can't be saturated, injectors are too big for that, doesn't even warrant inspection. Unless there's a disconnect between commanded AFR and PW.

Hmm, most strange. Running S_AUJP in a 6-cylinder-sourced 749. Could it be that the injectors aren't being driven like they need to be? Hmm. I've got a spare box of the same ilk, could put it back on and try. Hope I didn't fubar the harness wiring during a recent intake swap. No, because it ran fine after that with the 165/maf setup.

Weird...

Is there like a max PW setting somewhere?

Cant run the car like this obviously. Also, it has a strange 'lean stumble' periodically, like at 1/4 throttle while cruising. Lasts all of 1 second, and then recovers. Periodic like every minute or so around town.

Wonder if it's a wiring issue? Everything else seems rock solid though.

Any suggestions welcomed.

 

Complements of The $60 hack


APLH: FDB 30 ;Min Base Pulse Hyst. Value
; 1.068 mSec

APLL: FDB 10 ;15 ;Min Base Pulse
; 0.793 mSec

APMAX: FDB 393 ;Max Asynchronous Pulse
; 5.997 mSec

APMIN: FDB 52 ;Min Asynchronous Pulse
; 0.793 mSec

 

Are you sure there's not a mechanical issue?.
What do the plugs indicate?.
No the injectors drivers are pretty much a given. Using a 749 you do have it wired up like the syclone don't you. The Sunbird uses P+H instead of the saturated strategy. That really shouldn't matter but is worth looking at.

I have a stock 749 running 60 PPH injectors for my 6 cylinder.