Need your Help
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Need your Help
Hey guys i am new to the site, hope you can help me out....I have a 91 bronco with the EFI 351w stroked to 408 cid, 9.5 compression, edelbrock 3782 cam (you can get specs from the edelbrock site http://www.edelbrock.com/automotive/index.html), edelbrock 3881 manifold, edelbrock twin 61mm throttle body, ford oem heads that have been ported exhaust only valves are 1.94 int and 160 exh., shorty headers and 3 inch exh...fuel pressure is good with stock injectors.
The motor pings pretty bad....does anybody know what lbs. per hr. the stock injectors are and should i go bigger....and how much bigger.....I did order custom chip from jet that doesnt change anything it runs the same with or without the chip so know i am going to try injectors....any help would be appreciated.
by the way I had a real bad experience with Jet and dont reccommend them has anybody else had a bad or good experience with them?
The motor pings pretty bad....does anybody know what lbs. per hr. the stock injectors are and should i go bigger....and how much bigger.....I did order custom chip from jet that doesnt change anything it runs the same with or without the chip so know i am going to try injectors....any help would be appreciated.
by the way I had a real bad experience with Jet and dont reccommend them has anybody else had a bad or good experience with them?
Elder User
Joined: Oct 2002
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From: Medina, Tn.
Almost sounds like your stock injectors are not supplying the fuel needed to keep the beast running smothly. Check out this link, it's pretty informative and you could call them and speak to a teck. I have heard they are very helpful. http://www.horsepowerfreaks.com/default.asp?Meta=FLEX
Good luck,
Good luck,
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From: Loveland, CO.
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From: Corinth, TX
the stock injectors on a 351 are 19#. the size you need depends on what power output your engine *should* have with your upgrades. Here is the formula for calculating injector size:
Injector # = est. horsepower x (BFSC/number of cylinders)
BFSC is the amount of fuel required to produce one horsepower. Use a BFSC of .45 for n/a applications, and .55 with a blower. so if you are not running a blower (and you have a v8), you multiply estimated horsepower by .05625; with a blower you multiply by .06875
If you plan on making 350HP with no blower, you will be fine with the stock 19# injectors: 350 x .05625 = 19.6875. if you plan on making more like 425HP, you will need to upgrade to 24#: 425 x .05625 = 23.9
for grins, here's what a 600HP blown motor would need: 600 x .06875 = 41.25 or 42# injectors. Keep in mind that it's better to have too large injectors than too small. Ford put 24# injectors in my '97 Cobra, but it only made an estimated 305HP stock.
Let me know if I can povide any more information
-Josh
Injector # = est. horsepower x (BFSC/number of cylinders)
BFSC is the amount of fuel required to produce one horsepower. Use a BFSC of .45 for n/a applications, and .55 with a blower. so if you are not running a blower (and you have a v8), you multiply estimated horsepower by .05625; with a blower you multiply by .06875
If you plan on making 350HP with no blower, you will be fine with the stock 19# injectors: 350 x .05625 = 19.6875. if you plan on making more like 425HP, you will need to upgrade to 24#: 425 x .05625 = 23.9
for grins, here's what a 600HP blown motor would need: 600 x .06875 = 41.25 or 42# injectors. Keep in mind that it's better to have too large injectors than too small. Ford put 24# injectors in my '97 Cobra, but it only made an estimated 305HP stock.
Let me know if I can povide any more information
-Josh
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thanks for the info...I am estimating between 300 and 350 hp...so my stock injectors should be fine, I will need to get another custom chip to open the injectors longer....
I am now having another problem.....I am going through distributor gears this is my third cam and 5th dist. gear this last time i went with an edelbrock cam instead of comp, new rebuilt dist. with new iron gear, lubed the crap out of it and it is still wearing out the gear...if im lucky i get 200 miles out of it....and less on a brass gear....my only guess now is that there is something wrong with the block that it is not letting the two mesh right....any suggestions or have you heard of this prob before?
I am now having another problem.....I am going through distributor gears this is my third cam and 5th dist. gear this last time i went with an edelbrock cam instead of comp, new rebuilt dist. with new iron gear, lubed the crap out of it and it is still wearing out the gear...if im lucky i get 200 miles out of it....and less on a brass gear....my only guess now is that there is something wrong with the block that it is not letting the two mesh right....any suggestions or have you heard of this prob before?
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