pokosl

Anyone here done any port and polishing to the stcok GT heads here?(2VAlve)
Just a few questions on while doing the port and some working on the heads its a certain that you need to tune the computer a bit to eliminate crappy performenace. My question is can this be achieved using a hand held tuner or do you actually have to get a dyno tune. I have a friend in the buisness for machine work but really cant answer the tune question casue all he does is machine work. Any help would be appreciated..I would like to go 1mm larger valves and a stage 1 maybe 2 cam. The price for the work and the valves i can get dirt cheap. I figured why not go for the oppurtunity to save some money while I can.
I got a 2004 GT with the usual bolt ones just trying to go deeper with the whole street monster thing.

sctguy1

If you do what you say, you will need a custom tune. The handhelds are okay for minor stuff, but many do not allow you to make fuel adjustments in places other than WOT. Also, if you change the cam, there should be more than just fuel adjustments. I recently put a flowmaster catback and a K&N cold air kit on an 01 GT and when I hooked up the wide band 02S, the short term fuel trims were way off (it had to add a bunch of fuel) and the a/f was never any richer than 14.7 EVEN at WOT...at WOT the computer was trying to comand a 12.6:! a/f!!! So, my point, even with those small changes, the airflow characteristics changed a lot!! The car was faster, ran well, but was way too lean for me to sleep at night. So, I adjusted the MAF curve in the computer so the actual a/f was what it should be, and the car ran like a scalded cat... If you don't get a custom tune (via a dyno or 4th gear highway pulls) you may be able to get you car to run okay...but if you want the best, find someone who can give you a custom tune, preferably sct, but there are others out there too. Oh, and your porting question can be answered in the book "4.6 Liter Ford Engines" by Sean Hyland. Be careful if you have not done this before, and be especially careful if you are not using a flowbench. I've seen MANY people ruin heads and their airflow...bigger is not always better...

good luck!

pokosl

Hey thanks for the help on the head tuning question. Its not like the old days on a set of iron heads and just adjust the carb you know? there is a couple of shops here in Phoenix to tune the car on a dyno so I am not lost there. Do you think its would be wise to continue on the mods with
an injector/maf upgrade as well? I havnet touched that area yet but if I need to I will do that since I am in the task.

sctguy1

To upgrade inj/maf or not.... Well it depends on what you want your car to be when it grows up. I see many people upgrade their MAF when they don't need to, and same with their injectors. You mentioned that you may put a cam in...stage 1 or 2. If you can decide on exactly what you want your car to be, you can choose which mods you "need" to get it there based on what others are doing to get that power number to the ground. Once you have a somewhat "realistic" expected power number (estimated at the flywheel) it is very easy to estimate fuel requirements.

For a N/A 8 cyl, use these equations to estimate injector sizing:

(Horsepower) = (inj lbs per hr) / (0.075)

(inj lbs per hr) = (horsepower) x (0.075)

These equations assume a BSFC of 0.5 and a safety margin of 20%....FYI.

If the power number you want and (can realistically achieve???) calls for bigger injectors, then a bigger maf might be a good idea. The Lightning 70mm maf is a good one...if you are using SCT to tune with.

My advice, don't mess with the injectors and maf until you know exactly what you want, and then, only if you have to...no need to waste the money...