fuel management/tuning in a remote turbo 4.7 Jeep...paging Duner/4.7/ turbo gurus

[RyanWJ]

Hi y'all, names Ryan, I do not own a Dakota but i am a 4.7 brother, i own a '02 Jeep Grand Cherokee with a custom intake w/ 11" UNI filter and i just ordered a magnaflow exhaust.

i am currently doing some research on doing a remote turbo on my jeep. After seeing the homebrew versions of it and the results, combined with how well the 4.7 reacts to turbocharging (as opposed to supercharging), this is what i want to do. Since i offroad, I was worried about turbocharging and water entry, but after seeing STS'd tacomas, etc splash right through mud and water and have no problems, i'm sold. I'll just need to re-route the intake .

anyways, i am somewhat familiar with turbos, but where i am unsure of what to do is fuel management and timing.

now i know that the 4.7 uses a basic speed-density system, which is just lovely for NA modifications given a PCM flash, but horrendous for boosted applications. as soon as you go into boost, vacuum is lost...and so is the PCM. the PCM thinks you're backing off the throttle, when you're doing the opposite, and stops sending so much fuel...creating lean condition= KABOOM.

now, i understand that some guys have used a mustang vortech FMU. what is a FMU, and what does it do? from what i understand it manages the amount of fuel needed. i think it works in conjuction with the fuel pressure regulator to regulate how much fuel is getting in, and at what pressure.

what is done to the timing on these things? IIRC retarded timing allows you to run more boost, but advanced timing ups the performance in a different way but you cant run as much boost. would a B&G flash take care of this?

lastly, what kind of turbo should i use? T4?


BTW, if someone has duner's contact info, i'd really like to get it. i'm sure he could help me out.

[Slow97dakota]

[QUOTE=RyanWJ]

now, i understand that some guys have used a mustang vortech FMU. what is a FMU, and what does it do? from what i understand it manages the amount of fuel needed. i think it works in conjuction with the fuel pressure regulator to regulate how much fuel is getting in, and at what pressure.
[QUOTE]
the fmu works with a inline fuel pump. the fmu hooks up to a vacume source from the manifold and for every lb of boost it sees it will up the fuel 12lbs if u have a 12:1 disk in there. very simple and easy 2 use. i duno what the 4.7 people use for pulling timing, but 3.9-5.9 can use msd btms and things like that

[steeda2h]

i saw on a website where a jeep owner had installed a supercharger and installed a resister inline on one of the wires to the map sensor and resolved his issue but i cant remember his issue lol...www.junkyardturbos.com is a good site to use

[HemiDak]

If you offroad, there's nothing better than a supercharger IMO. I wouldn't do a turbo if it were me.

[RyanWJ]

If you offroad, there's nothing better than a supercharger IMO. I wouldn't do a turbo if it were me.

I respect your opinion, but i'm going to stick to the turbocharger. you yourself said in the thread about the fella putting down 475+ tq @ 3800 rpm in a 4.7 turbo'd dak that you like how the power comes down low. turbo lag is mostly a myth, due to the fact that most turbo'd cars are 4 cylinders and/or poorly matched.this will be about midrange power- not top end scream, and not necessarily about low end grunt- i feel the 4.7 has plenty of that stock.

i'm curious to hear what you think of the STS turbocharged tacomas. tacoma owners are actually buying the STS kit OVER the factory-installed supercharger. hmmm...

dont get me wrong, KB blowers are awesome but also are a pain to find, and if i have to do ANY guesswork, i'd rather build the whole thing myself, with a brand spankin' new turbo. this is also the most cost effective route. I predict that i'll spend no more than 2000 and get better gains than a used KB blower.

i am looking into something like the SMT-7 for managing everything. not sure if i'll need another fuel pump for that or what.

[DanDB64]

How about you go introduce yourself first you flaming queer. God ihate stupid idiot new people, they suck.


Kidding, this is my good buddy Ryan :D

[jmm756]

i've always tried to talk people into a turbo under the hood instead of in the back. splashing throught some puddles is nothing like running across water. if i were you, i'd do what i did and put it up near the motor. also my filter rides about where the stock one dose. no water in my motor, ever. and no water on my turbo crusing down the road. and alot less dirt and dust off the wheels up in front.

i roccomend for a turbo a t04 e hot side p trim shaft .9-1.15 ar ratio, with a t 67 compressor.

I'm the one that put down the 476 ft-lbs. i bet now that i have a bigger hot side on mine its more like 550 rear wheel tourq, and 375 hp