TBI - how to get better fuel dispersal?

fordfanboi · Post by **fordfanboi** » Mon Jul 09, 2007 10:06 pm

I'm running the Holley Commander 900cfm TBI with 4 85pph injectors and my Injector Characteristics are set as follows:

Open Time 0.8ms
Battery Correction 0.20 ms/v
PWM Current Limit 30%
PWN Time Threshold 0.8ms
PWM Period 66us

REQ Fuel = 7.1 ( 408ci )
Control Alogorithm = Speed Density
Injections Per Engine Cycle = 4
Injector Staging = Alternating
Engine Stroke = Four Stroke
Number of cyls = 8
Injector Port Type = Throttle Body
Injectors = 4
Engine Type = Even Fire

I have the secondaries linked to the primaries to open 1:1. What can I do to get the finest mist from the injectors? My fuel pump maxes at *14psi, so maybe upgrade to something 20psi to apply more pressure to the injector which would create a finer mist?

Thanks!

BottleFed70 · Post by **BottleFed70** » Tue Jul 10, 2007 12:50 pm

Raising the fuel pressure is probably a good idea. What pump are you currently using?

Not much else that I can think of.. I'm using a very similar setup to you except on a 351W.

fordfanboi · Post by **fordfanboi** » Tue Jul 10, 2007 1:27 pm

BottleFed70 wrote:Raising the fuel pressure is probably a good idea. What pump are you currently using?

Not much else that I can think of.. I'm using a very similar setup to you except on a 351W.

It's a summit 14PSI ( I thought it was 16 all this time ) 140gph cheapie.

http://store.summitracing.com/partdetai ... toview=sku

Guess I should get this one:

http://store.summitracing.com/partdetai ... toview=sku

The injectors say 85pph at 21PSI... but I'm at 4800' elevation and am not getting the 500+ FWHP I do at lower elevations. Car dynoed at 402 SAE corrected RWHP down in Kansas City, KS two years ago on a 750 carbie that was running fat ( 11.5:1 AFR ). With a few changes since then, I'm guessing it's running around 450 SAE corrected RWHP ( 525+ FWHP ) on the dyno, and probably 400-425 FWHP at my altitude.

BottleFed70 · Post by **BottleFed70** » Tue Jul 10, 2007 2:24 pm

definite get a new pump. The pump you have is ment for carbs and probably doesnt give a nice constant pressure like an EFI pump.

Dont buy that other pump tho either...

I would reccomend a warlbro 255lph external pump. Do an ebay search for WALBRO GSL392

You will find something like this.
Edit: eBay links not allowed on the forums. ~Forum Admin Team
These pumps are high quality, work great (I use one) and wont break the bank either.

fordfanboi · Post by **fordfanboi** » Tue Jul 10, 2007 2:31 pm

Will rubber hose work with that pump or is it too much pressure? I have about 6" of rubber hose going into the TBI and 6" from the pump to the aluminum fuel line.

Thanks!

fordfanboi · Post by **fordfanboi** » Tue Jul 10, 2007 7:30 pm

Found some 100PSI rated hose at Autozone.
GOODYEAR INJECTION HOSE

I have two 6" sections of it and let it run with the motor off for 15 mins with no leaks. /cheer

Sound safe? Would a braid over the hose help? I do have some braided hose I could steal the braid from and use for the TBI connection.

Thanks!

fordfanboi · Post by **fordfanboi** » Wed Jul 11, 2007 9:19 am

Went ahead and ordered the following to do it right. Listed them in order of connection.

AER-FBM2112 Fitting, Carburetor Inlet, -6 AN Male to 5/8-20 in. Male
AER-FBM1112 Fitting, Hose End, 45 Degree, -6 AN Hose to Female -6 AN
SUM-230603 Hose, Braided Stainless Steel, -6 AN, 3 ft. Length
SUM-220690B Fitting, Hose End, Straight, -6 AN Hose to Female -6 AN
SUM-220632B Fitting, Coupler, Straight, Male -6 AN to Male -6 AN
SUM-220634-2B Tube Sleeves, -6 AN, Pair
SUM-220633-2B Fitting, Tube Nuts, -6 AN, Pair