Well I will try to answer all this the best I can. I have a custom tune from John Garner who runs the HP ranch out in the seattle area.

He set my rpm limit at 5000 because my fuel pump couldnt handle anymore then that.

The tune helped the problem I am having but it still exist.

I dont know my air/fuel ratio.

I'm only wanting to get 425-450 rwhp so I'm hoping that new 39lp injectors, a new pump, pulley, and efan setup will get me there. I was also told by John to get the Diablo Mafia. What are your thoughts on where these additions will get me? Also with the injectors and Pulley, do they have to get from Whipple or can I get them somewhere else?

For right now I just want to get what I have running properly, I should probably get a boost guage so I know what kind of boost I'm getting.

 

Fuel injectors are to small, causing the pump to work extra hard and increase PSI to compensate, which decreases fuel flow/volume. Increase your fuel injectors to AT LEAST 39# and you can run 8psi fine. Slightly above 400 rwhp you are reaching the limit of the 39# injectors. Yes you can run them, but honestly a decent hick up could end up in disaster. I'm sitting just above 420rwhp and mine are knocking on that door of being completely maxed out.

Interesting.... Did he data log any? Was he looking for this hesitation or just tune for full throttle?

Did he give you a dyno sheet? Normally they put the a/f on them.

The 39# injectors will be at their very limit. A 310lph pump may or may not be able to keep up. You might need to look into a boost a pump, or read into the fuel pump thread in this forum to see the discussion taken place.

I could have swore the Whipple setup came with a larger maf housing? If so you should not need a maf extender at all. I haven't heard of anyone using a device on any application where a larger maf is furnished.

You can buy the injectors anywhere. Pulley you might can get from superchargers online or the likes. You might want to look into getting a 4lb lower. This will give you good wrap belt rap on your upper pulley with the benefits with more boost. Although I'm not sure how restrictive your exhaust is, but you should see a solid 11lbs with your Gibson shorty's and cat back.

Injectors and 310lph fuel pump will help GREATLY. Your dyno tuner should have a boost gauge he can slap on temp while on the dyno to see what boost you are hitting. He should also have a boost a pump in stock on stand by in case it needs to be installed.

 

Thats interesting, John ran a couple test to see if it was the injectors or the pump that wasnt keeping up and he determined it was the pump based on how rich or lean the fuel was.

When the truck was on the dyno the problem wasnt occuring, he did only have the tranny set to stay in third gear. And if you punch it past 3100 rpm you never notice the problem anyways.

11.3 is the average I believe, now that I know where to look.

I have been reading that thread, I was looking into the boost a pump but is it only for the lightnings? what would be better, the gt 500 pump or boost a pump?

The 10psi upgrade kit they sell comes with a larger maf, I believe 95mm, as well as a pulley and 39lb injectors for around $900. Is that a good value or is going elseware cheaper?

I was looking at getting the injectors just from an online site originally but then someone told me they have to be from Whipple because they have to be machined matched to fit. If this isnt true then where is a good place to get them?

The dyno guy did have a boost thing that he hooks to his computer but it could not read the boost with my setup. Not sure why. But he did not have a boost a pump.

 

It's the injectors more then the pump. He should know there is no way 24# injectors can do more then 360rwhp....

So in other words he never tried to really fix the problem....

Good range.

I think you(and a lot of people) are getting confused on the gt-500 Pump... The gt-500 pump(s) are 310lph. The Gt-500 fuel pump assembly comes with two 310lph pumps, wiring harness, and an additional fuel pump driver. A boost a pump can be put on any vehicle. Your tuner should be more then capable of understand this if he is a speed shop and does installs also. I have a single 310lph pump AND a boost a pump. The 310lph pump alone was not enough for me, some people it is.

The 39# injectors on my setup, and a few others, are at or exceeding there "max" at or around 420rwhp. Anything past 85% duty cycle should be upgraded. I know mine and a few others are close to or at 90% with 39# injectors. So if you are looking for 450rwhp, I highly suggest bigger injectors then 39#

The only way get the 39# injectors to work in that situation is to run a dual 2-3 pump setup, where the pressure is VERY high, but the 2-3 pumps will keep the flow/volume up...

In case you didn't know, when fuel pump pressure goes UP, fuel volume goes DOWN. So a 310lph pump might only be 310lph at 30 psi, but when at 50psi it's 220lph. Which is why if you can increase the injector size to 60# an hour, you can flow more fuel through the injector at a lower pump psi where the fuel pump itself is more efficient. This is a very general explanation, and there is much much more to it.

You will want that larger maf setup for sure.

The pulley is a smaller upper pulley which could increase the chance of belt slip, which is why I suggest a 4lb lower pulley. You will see around 11-12psi with that setup which will up your torque output greatly. As far as finding the upper pulley's cheaper, maybe, but not much. The lowers are $250-400+

I keep reading we have "special injectors," but I don't see the difference? Perhaps someone can actually clue me in on what is so special on our injectors? I don't see ford making oddball injectors for our trucks only...

 

You can run the same 39# injector in these trucks as the stock 2003 and up Cobra injectors. Blue Oval Motor Sports in Virginia has the best price that I was able to find. Forget where they are in Va. You will have to google them.
Most reputable tuners will tell you what injector they prefer as they normally know the specs. related to that particlar brand.

 

id recomend the 10 psi upgrade from whipple for sure. the cobra injectors need to be modified to fit the whipple intake and whipple does this before they are shipped out. If going to 10 psi whipple recomends a .032" plug gap. If you are going to run a 3.125 pulley you will need to put a bigger pulley on your tensioner, the one to use on the tensioner is the idler you removed from the drivers side on the install.

 

What you are saying about the modified injectors make no sense. The whipple kit uses f-150 stock injectors in the base kit, but all of the sudden it requires "special" injectors to work when not using stock?

 

THERE ARE NO SPECIAL INJECTORS required. Ford Motor Sport Part Number M-9593-M39. They are 39lbs injectors. www.blueovalindustries.com has them for less than $250. They are the same ones that go in the 03-04 Cobra. I installed mine in the parking lot of the tuning shop in about 22 mins. They snap right in and plug in with no problem.

 

That's what I thought...

 

Factory injectors fit without modding. If you are running 39lbs i find it very strange you didnt haveto mod them. The injector holes in the whipple manifold will not allow an unmodded 39lb injector to fit. If you look at the pictures below you will see why. look at the lower 1/2 inch of 39 lb injector in the middle. You see how those steps stick out further then the o-ring? Those steps need to be machined off. Because the injector holes are only as big as the o-ring. It has been discussed in other threads as well. My injectors in the box from whipple clearly had written on them "already modified".

 

What fuel pump are you running with your kit and how is it holding up?

 

factory fuel pump, no problems yet but im also running the 10psi tune from whipple. I actually sent my PCM direct to them to get it tuned for the upgrade. The dyno will tell all i guess but as of right now I see no drop in fuel pressure on my edge and have an A/F of about 11.4 wide open.

 

this is a great learning thread.. i plan to boost after my deployment.. i will be asking tons of questions before hand,,,

to the OP, good luck, sounds like these guys are getting to the root of the prob.

 

Very strange. My injectors went in fine. Dennis nor the other guy whose name I can't recall never mentioned anything about modifying them in any of our conversations.

 

Heres some helpful info on when to upgrade your injectors. Copied from a Stang site. The math is here you just have to get your actual numbers. For example my fuel consumption is roughly 0.730 according to the online calculator. I will get hard numbers from Mr. Troyer. But by then I'll have my GT500 pumps on and the Zone 5 harness.

"There is alot to this. They have their rated flow 39 lbs in your case. Flow rate is rated at a certian psi drop across the injector. Yours as an example would be 39#/hr which is rated to deliver 39# of fuel at 42.5 PSI. The injector will flow 39#/hr as long as the pressure at the supply side, minus the pressure in the manifold is 42.5 psi. In ford systems the psi drop across the injectors is 39.5.

On a blown car your fuel psi must increase 1 psi per pound of boost. Lets say your going to run 14 psi boost, so for fords you should have under boost 39.5 psi + 14 psi boost = 53.5 psi that has be maintained to make the injector work like its rated.

To calculate injector hp ratings roughly you have to know BSFC (brake specific fuel consumption) and on a blown 4.6 liter it is 0.6 actual maybe slightly different but this is close. Take you 8 injectors times 39# = 312 #/hr of fuel divided by the BSFC of 0.6 = 520 hp flywheel. How ever all this changes when you change pumps install a boost a pump. The cobras i have seen with stock injectors 39 # have supported over 550 to the tire. You should be fine with the gt500 pumps and 39# injectors. I am running the ford gt pumps and 39# injectors. The duty cycle will have to be logged you dont want to be maxing the injector out all the time. If you wanted to be on the safe side a 42# or 60# injector will give you room to grow also the Mass air flow sensor maybe close to pegging depending on the sensor you have. My head hurts now"