Will It Run Lean?

[SloRide]

if i up the boost to 14 on my daytona via a grainger or other similar boost controller will i have to worry about running lean?

im wondering because the computer is still "seeing" the 14psi
will it compensate for the added boost?





1990 daytona es
t1
3" from cat with a saber
now intercooled with a audi 5000 with new welded end tanks
turbo xs blow off (i can see how that psssshhhh sound can get annoying after awhile)
k & n air filter
stock boost... for now

[ZEROLAG]

You shouldn't have a problem. The computer can handle boost up to 14.7psi at which point the computer will hit "overboost cutout." I believe at cutout the computer shuts off the coil and a few other electronics.

Go for it!

[89daytonaTII]

with that little mitsu be prepared to hit cutout if your trying to set it at 14psi. Especially if you have the exhaust opened up. Not saying it's guarenteed but your boost will spike to cutout, when trying to set it up that close.

[HYDCSX400]

IIRC the cutout on the stock T1 comp. is less than that of the T2 you guys are thinking about.....

IIRC it is around 12psi, and I would be carefull trying to run 14psi on T1 injecters and sutch. If you want to try still, get a A/F ratio meter, and even better, an EGT gage to go with it. Those are pretty much manditory gages when your not sure if your boost goal is too high for your fuel sys.

unless of course you have a few spare bottom ends kicking around.........

[ZEROLAG]

Good point. I didn't look to see that you were running a T-1.

[Lebaronguy2001]

Quote:

Originally posted by HYDCSX400 IIRC the cutout on the stock T1 comp. is less than that of the T2 you guys are thinking about..... IIRC it is around 12psi, and I would be carefull trying to run 14psi on T1 injecters and sutch. If you want to try still, get a A/F ratio meter, and even better, an EGT gage to go with it. Those are pretty much manditory gages when your not sure if your boost goal is too high for your fuel sys. unless of course you have a few spare bottom ends kicking around.........

i thought cutout was 14.7 for all our cars?

[89DodgeSpirit]

I have a boost gauge and a/f gauge in my 89 Spirit ES 2.5 Mitsu T1

I had unplugged my wastegate line because my stock boost control system is bad (wastegate solenoid bad i believe)

Well I floored it and I got almost 15psi without hitting cutout for about a solid 4 seconds before I backed off... And A/F gauge was in good shape.

I do believe that the cutout is 14.7. I am aiming for 14 with my Spirit ES T1 Mitsu - I have about maybe 4 inches of vacuum line between the turbo nipple and the wastegate can... Just enough for my g-valve and my restrictor and that's about it.

I have the vac line to the g-valve then the g-valve to a vacuum-T

On the nipple that sticks off at a 90 degree angle I have about 1/2" of vac line with a .025 restrictor (small bleed for when I let off throttle) and the other nipple on the T goes straight to the can.

I have VERY little if any boost spike. When I floor it boost goes up and sits pretty at what I have my g-valve set to - no spiking - at least not that I can notice. So I am pretty sure I can dial it in to 14psi. Once I get it up to 12/13 I am going to go VERY slowly with the process because I do not want to hit cutout.

Also before I up the boost beyond 7psi I am going to mount/plumb my talon intercooler. If you have the Mitsu T1 I wouldn't recommend going past 10psi without an intercooler... Most people don't recommend going over stock level without an intercooler but it shouldn't hurt anything.

[89DodgeSpirit]

Also: the shorter the line the less spiking. The g-valve is amazingly responsive and opens/closes rapidly enough to hold boost at a certain level. The more vacuum line there is the longer/further the boost has to travel and the more line it has to pressurize. You may think it's only very small line and no big deal but trust me it makes a difference.

[HYDCSX400]

Quote:

Originally posted by lebaronguy2001 i thought cutout was 14.7 for all our cars?

I'm not positive but I don't think so. If you think about it for the Chry. engineers to set it at 14.7 than the stock T1 would have to live up to 14.7 with no IC and on stock T1 injecters. Once again, I'm not positive but i don't think it would stay together up to 14psi with no IC, T1 injecters and some bone head filling up the tank with 87. You got to remember, the engineers have to plan for the worst case on a stock car. Even then they will round things down a bit, just to keep the warrenty dept. happy.

But the more i think about it, I remember seeing a list of diode part no.'s not long ago. and the diodes for T2 cars was the 4.7v and IIRC the diode for T1 cars was 4.3v. I do remember 2 diodes tho.

[Lebaronguy2001]

Quote:

Originally posted by HYDCSX400 I'm not positive but I don't think so. If you think about it for the Chry. engineers to set it at 14.7 than the stock T1 would have to live up to 14.7 with no IC and on stock T1 injecters. Once again, I'm not positive but i don't think it would stay together up to 14psi with no IC, T1 injecters and some bone head filling up the tank with 87. You got to remember, the engineers have to plan for the worst case on a stock car. Even then they will round things down a bit, just to keep the warrenty dept. happy. But the more i think about it, I remember seeing a list of diode part no.'s not long ago. and the diodes for T2 cars was the 4.7v and IIRC the diode for T1 cars was 4.3v. I do remember 2 diodes tho.

good point....but IMO they set it at 14.7 P.S.I. as a "fail safe" the "stock boost" was only 9 or 11 depending on the year....14.7 was just when they told the engine to "just say no" and shut off....

[DarkWolf]

Injectors are the same size

2.2 Turbo 1 injectors flow 27 pph
2.5 Turbo 1 injectors flow 33 pph
2.2 Turbo 2 injectors flow 33 pph
2.2 Turbo 3 injectors flow 33 pph
2.2 Turbo 4 injectors flow 33 pph

cut out is still 14.7

"If you have a stock computer, you must use the 4.3v diode. If you use the 4.7v the boost reading the computer still sees is higher than the programmed boost "target" and you will still get overboost shutdown. You must have a MP computer to use the 4.7v diode, they have a higher "target" boost voltage and won't shut down at the 4.7v map sensor reading."
http://www.thedodgegarage.com/turbo_map.html

[HYDCSX400]

Quote:

Originally posted by DarkWolf Injectors are the same size 2.2 Turbo 1 injectors flow 27 pph 2.5 Turbo 1 injectors flow 33 pph 2.2 Turbo 2 injectors flow 33 pph 2.2 Turbo 3 injectors flow 33 pph 2.2 Turbo 4 injectors flow 33 pph

I know the 2.5 T1 injectors are the same as 2.2 T2 but a 2.5 at 14psi will use more fuel than 2.2 at 14 psi. I was taking a wild guess that the "step up" in inj. size would closely match the "step up" in fuel needs for the added displacment, sort of "canceling out" the fact that the 2.5 T1 inj. "are" T2 injecters because there "T2" rateing was for a lower displacement.

Quote:

cut out is still 14.7 "If you have a stock computer, you must use the 4.3v diode. If you use the 4.7v the boost reading the computer still sees is higher than the programmed boost "target" and you will still get overboost shutdown. You must have a MP computer to use the 4.7v diode, they have a higher "target" boost voltage and won't shut down at the 4.7v map sensor reading." http://www.thedodgegarage.com/turbo_map.html

??? your first line says cutout is the same but the rest means that it isn't!

The computer cuts out at a given voltage from the MAP sensor. The diode is there to stop a voltage greater than "X" from going to the computer. "X" is the brakedown voltage of the zener diode that is used. So for a MP comp. if the comp. cuts out at 14.7 psi (can't remember what voltage that equals to, IIRC 4.9v) than you want to keep the voltage from the MAP to the comp less than what ever voltage equals to 14.7 (4.9v?). In this case we use 4.7v. Now if you found data that says the stock comp. cuts at a voltage just over 4.3v than that means the psi that equals it is less than 14.7.

Untill now I've been trying to pull all this stuff of the top of my head but to try and clear this up a bit, I'll go find the info I found in the past that goes with all this.

[HYDCSX400]

OK, I went back and re-found the info I'd found before, It looks like a mix of all of the above is the truth. It turns out the info i was pulling off the top of my head was pretty close for earlier years, but he said later year T1 are said to all cut at 4.74v So for the sake of the orig. question at hand.....
You should beable to get up to about 13 psi with out cut on a stock computer.

I found this here.

just remember that this chart is for "stock" computers, not the MP computers.