Hey,
Well last time we all talked about turboing a tbi setup, alot of ideas were thrown around. The main barrier that I was told was to run a turbo a 2 bar map sensor must be used, which means reprogramming computer. And I was told 2 bar's are only needed with turbos not superchargers, because of something to do with the boost.

Anyway I was taking to a friend who drives a turbo'ed probe. He has a map sensor setup basically like what ours would be. And he is running a 1 bar map sensor not a 2! This is working because of a 3 dollar one way check valve on the vacum line between the throttle body and map sensor. This way the boost is vented into the atmosphere and vacum is still read at closed throttle to wot.

Let me know what you guys think. It seems like this could be the answer, unless the boost people on here already know of this and our setup still requires more crap, but I don't really see the need if this valve works.

:lala: :lala: :lala: :lala:

 

sounds good

 

how are you going to add the appropriate fuel? hte issue isn't the map seeing vacume, under boost it is still just going to read 0 vacume. the problem is, the more the boost increases, the more the fuel requirments increase.

NOW. some helpful info.

a 2 or 3bar MAP is not required for boosted applications. you can use a FMU unit from vortec or ATI, these units sense boost, and up the fuel pressure as the boost level changes.

Depending on how much money your are talking about, there are other options, a 900cfm TB unit from holley with the commander950 ECU, can be had with either 2bar or 3bar MAP sensors, they will accuratly sense boost, you also get highspeed datalogging with them MegaSquirt may also be an option, i am still looking into this myself, one of my co-workers and fellow Quattor Club members runs MegaSquirt on his S4 race-car, he is very happy with it, and it works well with the turbo setup on his Audi.

 

Well I already have the FMU from a vortech kit along with a BTM from the same kit. I was planning on using those already, but the FMU has a 30# injector disk in it so I'm thinking that may be kinda hit and miss. I'm not talking about spending alot of money on this. My plan would be to get it running for under a grand. So the 900 cfm dfi kits would be out of the question, atleast until I'm out of college.

 

If you want to properly do a Turbo, or S/C and run no more then 15 PSI of boost, then you need to run a 2 bar calibration. If you want to run ~20 then you're going to need a 3 bar.
There are all sorts of makeshift ways of patching something together, but boost eats engine parts real quick when things are wrong. FMUs are just away around using the right parts, and as often as they fail, it's not the way I would go.

You have alot of homework to do, but I'll give you some clues.
The Syclone P-Us used the 1227749 ecm and it's designed for being used with a 2 bar application, and can be configured to operate the TBI injectors.
The 91 SS 454 guys have been using vac referenced fuel pressure regulators with alot of success, I've been told.
The 1227749 uses the later, and faster ALDL data stream and that's really handy when doing boosted calibrations.
You'll have to get familiar with doing you own chips if you want this to be any where near right. No one is going to be able to do a chip over the phone for you project.
Might read thur and/or search the DIY Prom Board for some ideas of where to start, and what's involved. This ain't no minor project, and doing alot of homework will save you lots of aggravation.

 

This is off topic, (and probably way off the wall) but...

I noticed mention in here about a check valve in the MAP line. This made me curious.

I have a 90 RS TBI Auto, 416 heads ported/polished, 1.5 ex, 1.94 in valves, 1.6:1 rockers, LT1 cam, headers, hiflo cat, 3.08 posi, AFPR. Having chips made now to get her running, but...

Ever since these mods, I get a MAP code. Replaced twice with 2 different brand new MAP sensors, still get the code. Would this check valve do anything for me? Would it at least "settle" anything down long enough to get better chips tuned? The chip tuner guy is stumped with the MAP sensor, and also stumped in that the car just isn't running as well as it should, no matter what he does in the chip.

 

Where do you have the the problem? In the idle area or further up in the rpm's. Have you hooked the sensor to straight manifold vacuum or ported vacuum? Does your vacuum line have any cracks or holes in it? The lt1 cam should not give you any problems as far as causing you to have a map sensor malfuction. I would double check all my vacuum connections and go from there.

Steve

 

hey guys

All a fmu does is blow up the fuel pressure. In which is a bad way to tune it. because you go from a lean conditon to a rich condition way to fast in which can cause knock If you use the 2-bar map 14.75 vac - 14.75 boost then the ecm can control the fuel tables under wot not by playing with the fuel pressure.

you can use the 749 ecm from a syclone-typhoon that will accept the 2-3 bar map with no problem. the other obstacle is how are you going to boost reference the stock fuel pressure regulator. and have you thought about what injectors the only ones i know that might have enuff fuel flow would be the 454 injectors the 90 pph ones. I have sit and thought about the idea of turboing a tbi for yrs since i lost my grandnational.

other than that there is really no other reason for it not to work

 

chuck the stock fuel pressure reg and use a mallory (pt# 4309) 3 port fpr that's adjustable from 3-50psi. This reg has a port to boost refferance to increes fuel psi.