Newbie Tuning Question for GTP?

[RNUOVR]

I've almost got all the parts needed to create version 1.2 of my car (Full-size IC, 42.5 injectors, PRJ fuel rails, ported & polished LIM & GEN3). I'm currently on a 3.4" pulley (with ZZP stage 1 TB, SLP headers & 1.8 rr's, fuel pump hotwire, FWI & an exhaust system) & a box tune (which is a pretty shitty tune, my LTFT's are usually around + 7 to + 13, now I know why tuners are so much more beneficial).
Well once I've swapped on my goodies I assume that I'll be able to run at least a 3.0" pulley (it's the smallest that I've got right now). Now my question is (as a newbie tuner) that am I better to start my tuning running the 3.4 or 3.2 or can I jump straight down to the 3.0? I will be starting from a 100% stock tune.
I've already got a good idea on my tranny settings and I'm starting to get a good grasp on how to do MAF & VE tuning after much reading.

[johnh]

My suggestion, err on the safe side. If you're running the full size IC, start with the 3.2 and get the VE, MAF, IFR, LTFT etc dialed in with the new 42.5# injectors. Then go from there....there's many tuning guides to help you from there....once you get the 3.2 running well then pull a bit of timing and try the 3.0...

[RNUOVR]

Also I wanted to ask kinda of a follow up question.
Would it be better to keep the stock injectors in there for now, get it dialed in with te stockers & the 3.2 see if I can drop to the 3.0 & then add the 42.5's then? or does it not really make a difference?

[johnh]

It doesn't really matter either way. You're not going to run out injector usually on a 3.2. The 3.0 might be questionable..so you'd want to do the 42.5# with the 3.0 or before. If it was me, I put the 42.5# in, tune it now, before the other mods...get it dialed in and then it should be easier as you add mods (rather than making a whole bunch of changes and then trying to tune)

[JerryH]

I ran out of injectors at the 3.2 range. Different cars do different things. Just monitor your IPWs and if they go above 90% (some say 85%, others say 95%), time to upgrade.

Go by IPWs, not mods. Only sure way. Year of car makes a diff too. 2004 and up have a constant pressure returnless system and their numbers are WAY higher than the 97-03 setups.

If you have the injectors now, install them, set up the bin for the new injectors (120 seconds of work), flash it and start your tuning from there. Start with a smaller pulley and work up.

[RNUOVR]

cool, thanks guys I can't wait till I can start tuning.
I put my mods in my signature but they are not showing yet (strange, now they are there). My car is a 2000GTP, I've got a fuel pump hotwire, PRJ fuel rails with an aftermarket fuel pressure regulator with the 42.5's for fuel system upgrades..Well that actually brings up another question, just to confirm I should set my fuel pressure @ 40 psi?
For changing the tables for the new injectors, it's only the one table I multiply by I believe 1.11805 right? (I've got the exact number written down @ home with the formula).

[JerryH]

Stock. If Zooomer can pull 400 HP on a stock fuel pump and stock pressures, you are way more than good to go at stock levels, IMHO. Stock fuel pressures are measured at the schrader valve and are between 48-55 PSI. Don't ever exceed 65 PSI as you can damage the pintles on your injectors.

[JerryH]

For changing the tables for the new injectors, it's only the one table I multiply by I believe 1.11805 right? (I've got the exact number written down @ home with the formula).

DHP or HPT? Different for both. HPT you highlight all the cells, enter 1.18055 and hit the multiply sign. Save the bin to something new so you know there is a difference and upload it to your PCM.

[RNUOVR]

cool, thanks again for the help. I'll set my fuel pressure @48 lbs @ at idle & go from there. I ended up with the aftermarket fpr as it was easier than trying to get the stock fpr to work with my new setup. Stupid me didn't document stock fuel pressure before taking things appart.
I only have HPT, never even looked at a DHP unit