BillRed85

Some of you might have read that I melted my 383 due to over fueling. I was running it NA with :cough: 48# injectors :cough:

To make a long story short, The motor ran for about 3 hours total and then developed a rap.

I drained the oil to look for carnage and while I didnt find any metal, the oil smelt more like 94 octane then oil.


So here I am now, the motor should be back from the shop soon and I am left with the question.

What size injectors should I use this time?!?

I bought the 48lb injectors for use with a Blower, so I'm gonna hang on to them, and install them when I upgrade to the Blower.

Here are all the specs I can remember:

383 Stroker
Eagle Steel Crank
Eagle H-Beam Rods ARP Hardware
SRP Forged Pistons (8.5:1 comp. or so)
AFR 190 Heads
Comp. Cams Roller Rockers
Roller Lifters

Crane Hyd. Roller Cam PART# 119831
.509 IN
.528 EX
112* Lobe Sep
http://www.cranecams.com/motorsports...ler/119831.htm


SuperRam Intake manifold Runners and Plenum

Ling. 58mm Throttle Body

All MSD Ignition

Accel DFI ECM


I think thats all the relevant Info.

So, 30# injectors? Yes/No?

Thanks!

Bill

qkvette

I use the FMS 30#s on my 383 and everything seems okay. I previously had the accels but had problems wiht 4 of the 8 injectors :eek: . Here's the formula you can use to estimate the injector size :

inj size = (max HP x BSFC) / (# of inj x duty cycle)

where BSFC for NA engines = .45 and duty cycle=.80

hope this helps.
joel

J Z06

I have 26# injectors on a bread and butter LPE-383. Seems to be fine. Beach Bum is a die hard 1/4 miler on the left coast with a similar 383 and I believe it also sports 26 pound injectors. 30's are only a 4 pound difference. I am sure if you backed the fuel pressure or the pulse width they'd do fine.

jburnett

30's are generally perfect for a n/a 383 but it does depend on how much power you're producing. Use the above formula to determine what you need. I suspect your 48's washed your rings out... Pretty common actually on a new motor with WAAAYYY too much fuel. Sucks though!!
-Jeb Burnett

ZylaRace

jburnett
ditto


Who progged the injection? Too much fuel, way too much. What were you using for tuning tools? (NB/WB O2 sensor? anything else?)


BTW Too much fuel won't melt you engine. Too little fuel, melts piston's. In your case, the unburned fuel leaked down into the crankcase.


[Modified by ZylaRace, 1:54 PM 5/7/2002]

BillRed85

I did a quick search on the forums. Seems like people arent liking the accel fuel injectors?!? Am I better off with the FMS Injectors? They are cheaper, but I'm reading that they are rated diff.

What size FMS Injector can you guys recommend?

As far as melting my motor, yeah I know I didnt melt the pistons, when I said I melted the motor it was a general term. I bet my bearings were melting though! heh ::sigh::

I'd rather not say who helped me with the inj. programming, it was in NO way his fault, this whole thing was my bad. I gave him all my specs and he sent me a startup file with the DFI Unit. Which is what I was using to "tune" it Calmap

Bill

qkvette

FMS 30#s for $209 at scoggin dickey :yesnod:

LPDesRoche

Just use the FMS 30# injectors. If you are running DFI you could actually run the 48's if it was tuned right. You may get a crappy spray pattern with them but they would work if set up right.

You are better off with the 30's though.

jmr302

I'm actually using FMS 24# injectors but I haven't gotten the whole thing sorted out yet. Still some funky Code 33's. I'm a little worried these things will be too small. I'll find out eventually.

SPD DMN

I am running 30#'eers in my 396 and they are not even getting close to being maxed based on my calculations.

vader86

run something like 26 or 30lb injectors

ralph

i know of plenty of 383/SR engine running 24# injectors. Since the SR limits the rpms, the 24# injectors are fine. I'm pretty sure you could also tune into 30s and have some room for growth if you ever moved to a higher reving intake.

BillRed85

ok, I'm sold on either 24# or 30#

From what I have read, The Accel Injectors arent getting very good reviews? So is the choice the Ford Injectors?

Is it true Ford Injectors are rated Differently and the Ford 24# Injectors are closer to 30# Accel Injectors??

Will I have more resolution tuning my DFI with 24# Ford Injectors, or will the 30# injectors be just as easy to tune?

Thanks for all the help guys!

Bill

95BLKVette

I believe the Fords injectors are rated for 30 #/hr at a fuel pressure of 39 psi. Since a TPI LT-1 Vette typically averages a 42 psi fuel pressure, these woould actually deliver 42/39 x 30#/hr = 32 #/hr. I have my 30# Ford injectors programmed at a size of 32#/hr using LT1 Edit and my 383 runs great :D

AquaMetallic94LT1

I am running FMS 30# units on my setup without any issues. I had Accel 36#s but they seemed to dribble when they got hot and the engine was shut off.

The main problem you face with large injectors is that the minimum amount of fuel the injectos can discharge is still too rich when the engine is at idle. You will still have this problem with a blower.

I don't know if 48# units are too large for a 383 because Shalin had 50# units on his 350 blower motor. They may have been added as separate units that only worked under boost or used as the main ones.

jburnett

I run FMS 36's in my DFI'd 396... If I were you I'd go with the 30's, they may be a little on the large side if your combo if fairly mild but I'd rather pull pulsewidth out of the 30's than risk going into too much duty cycle if the 24's are marginal. You will be able to knock down the pulsewidth pretty good with the DFI, but don't go under about 1.9mV or you'll start getting flow problems.
-Jeb Burnett

SPD DMN

Jeb,

My injector pulse width at idle is usually about 1.4-1.7 ms and i have seen it at 1.0 at times. Are you saying that I have flow problems? At WOT they are generally between 9.4 and 9.8 ms (used to be closer to 10.2-10.7 with a different program).

Chris


[Modified by Vette92, 10:57 AM 5/8/2002]

ZylaRace

FMS injectors are rated at 39 psi. Also, the Ford injectors are slower than the GM ones. To fine tune them, you should change the Inj. Offset vs. Battery
Voltage to a higher value.

The advertised Flow Rate is for 100% duty cycle (full ON).
Useage of the injector should not exceed 80% duty cycle.

FMS injectors are rated at 39psi, GM injectors are rated at 43psi.
Inj. Size = sqrt(Your_Fuel_PSI/Rated PSI) * rated Inj. Size

jburnett

Most of the major DFI tuners don't recommend going under 1.7-1.9mV on base pulsewidth... It has something to do with the injectors "fluttering" below this amount. I've been working with DFI for about 10 years +/- and have never experienced it myself but I've spoken with Craig Railsback of BDS about it as well as Lance (lastname slips my mind, but he designed the DFI and FAST systems) and they confirmed what I read. I'll see if I can find the hard copy of this discussion and forward it to you.
-Jeb Burnett

yoslambo1@cs.com

after reading this post im getting a little nervous. :eek: im finally getting my car back this week with a new 383 stroker. i went with a edelbrock air gap intake & a holly 750 carb. will i have this type of problem(too much fuel)? i just got a air fuel ratio guage....where should it run? will i have to change the jets? i dont want to blow up my new engine! :eek: :confused: