I am building a poor man's ZZ4 this spring and need to round up a pair of injectors. I believe I will be close to the same torque and HP as a ZZ4 crate engine.

Those of you that are successfully running BBC injectors on a 350, what I want to know is what size and what PSI are you using? Also how many HP you are supporting?

Thanks for your input.

 

well in not sure what psi but i would say atleast #65 injectors , atleast your fuel pump is ok

 

ttt

 

Where did you get your 65# injectors from? Also, where did you get your fuel pump as well?

Sorry, I have no clue as to your question.

 

With 65's as suggested I think it'll take a lot of pressure to keep up with a ZZ4's needs. JPrevost has the 350HO which has somewhat similar power with a ZZ4 and I believe last I've seen he was running a constant 28psi. That should be a really good setup, do you have a 2" bore TBI? I'd say you'll need a 2" bore and use the BBC injectors if you get a 454 unit or go for the Holley unit with the 85pph injectors, I think either of those options should be well suited for your application.

 

I bought the pair of injectors here on the clasified board. Do a internet search and you will find several sites that sell the walbro pump, I dont remember which site I used.

I am thinking I might want to go with larger injectors and run less pressure to achieve the same end results. Just woundering what size / pressure combinations were working well.

 

Well, I'm running 80# injectors with the VAFPR. Pressure varies between 11-15, obviously depending on vacuum.

HP? Dunno. Best 1/4 time is 15.50 with most around 15.60. All times with street tires, stock converter, mostly stock suspension. First 1/8 mile usually feels good, second 1/8 seems to fall flat. This spring is addition of Performer RPM and BB throttle body. The falling flat situation existed before the BB injectors. I was hoping to correct a top end fuel starvation problem with the big injectors.

I know this in not the best nor most technical method of improving performance. I'm not that good with the ECM tuning procedures. This was more of a result of steps taken as a result of observations and best guesstimates.

Hope this is the info you were looking for. FWIW, I didn't pick up any power with 80# injectors compared to the 65#'s. Yes, injector constant was changed but not much more tuning was done. No data logging, etc. Perhaps better results could have been had.

 

Any other 350's out there?

 

I'm runnin 75 pph injectors at 22 psi and have plenty of room left for more power. I'm only making around 300-330 hp. I ran a best of 8.9 at 78 in the 1/8 with the carb on it last summer, thats high 13's at 98 in the quarter. I through in a slightly larger cam this winter at the same time I put the TBI on so I may run a little faster now. I have my PW around 4 MS at 6000 rpm. TBI injectos crap out around 5 ms at 6000. I'm kinda pushin it at idle with only 1 MS pw. Much lower than that and you start loosing resolution. If you use 65 pph you'll need at least 25-28 psi of fuel pressure. I believe with 85 pph injectors at 28 psi you could feed 400-425 hp. Thats my best guess. I'm using an external pump off of a 89 ford truck with dual tanks, with no problems.

There's a lot of tuning involved with big injectors. I'm using alot of the 454 settings in my chip and it took me a while to get a handle on the beast with the big TB and injectors. Then again I was starting from scratch with unknown everything.

 

350 cid. 90 lbs injectors at 9 lbs FP. 222 rear wheel HP 268 TQ. 12.1/1 A/F at 5100 rpms. www.gmpartsdirect.com for injectors new.

 

thanks

 

All last year I ran stock 55#'s @ around 32 psi, ran good, but I seemed to have a stumble at low rpm's under quick accel. I believe this was caused by my vac ref regulator. How? well, my pressure would spike really quick when vac was removed quickly from the regulator, It was hard to tell on the gauge, but it seemed to go to about 40 psi for a split second.

Anyway, I found a 454 tb unit with 90# injectors at a swap meet for $70 canadian. So this spring I'm gonna try running those with no vac ref @ about 15 psi. Should have pulse witdh problems down low as I idle at 900 rpm.

 

my idle is smooth with 90 lbs at 9 lbs. provides enough fuel to run 12.1/1 all the way to 6000 rpms per WB on dyno. another member (DOM) suggested i run 9 lbs.

 

Im going from the stock (45ish?) injectors to 80 pph injectors in a few weeks with the installiation of my 454 tbi. I want to make roughly 250 hp, what pressure am I looking at?

 

Heres a nice little calcaulator for injecotr flow. I always jsut use the the old saying " one pound of injector flow supports 2 hp".

http://www.csgnetwork.com/fiflowcalc.html

So to support 250 hp, you would want 62.5 # pounds of injector. (x 2 hp per #) x2 injectors = 250 hp

 

Cool site, thanks man

 

9-10 lbs. no less than 9. i was ok at 6000 rpms at 9 lbs 12/1 A/F on wide band dyno