How much boost should I run?

[odormat000]

I am about to have my car tuned and I would like to know how much boost I should run. My car is a daily driver but I'm not worried about boosting so much my turbo blows up. I'm looking to have over 300hp with this set-up and want to max my stock turbo.

A little about my car.
91 Plymouth Laser RS
upgrades:
3 inch intake
FMIC
GM MAF-T
crushed 1g bov
evo exhaust manifold
ported 14b
ported 2g o2 housing
3 inch turbo-back w/ test-pipe
walbro 255
boost controller
272 cams
3g lifters
arp studs


I have the stock injectors and I was wondering how many pounds of boost I can max my 14b to with them.

I am also looking for a 7cm manifold-turbo gasket. I went to baxters and they had one for $40 and I figured I could find something much cheaper.

Any other advice on things to do would be appreciated thank you

 

[Bluefire16]

Well for starters, you will need to bump your fuel pressure, and you are using a wally 255. So you are going to be running pig rich. You need to first get a AFPR.

Once that is done, you need a program to actually tune with.

Lastly, i have run 19psi before on my 14b i used to have. It all varies with the mods and the car however. With the right supporting mods you can run well over that, but it comes down to the efficiency range of the turbo, and im not sure where the 14b dies off at.

 

[LiquidX]

Please search next time

You can have all the mods in the world but without fuel mods and tuning device you cannot run more than 15psi on a stock turbo. You also need a logger so you know what your engine is doing. One person could run 17psi and be fine where as you could run14 psi and knock.

As for the turbo-manifold gasket, ge an OEM MLS 7cm gasket. ExtremePSI carries it for sure; reusable and won't have sealing or cracking issues like the SS gasket.

You also need a wideband to get you going. Once you have your proper fuel mods then you can boost to about 23psi IIRC. I would leave your fuel pressure alone until you can tune as that will completely mess put the internal tune on the ECU as it's expecting a lower fuel pressure. Also you cannot raise boost to get to the goal ARF either since doing that you max out the IDC% and will cause problems with them. That is all done by tuning since the ECU is set to run at a specific AFR in both open and closed loop settings.

 

[odormat000]

Well both the wideband a/f and the afpr have crossed my mind but when I spoke to the people at English Racing they told me i could still have my car tuned on their dyno it would just be safer for when i'm driving around to have wideband so i could watch it and that it's not mandatory to have an afpr.

and I do have a program to "actually tune with" it's my maf-t. Yes I understand it's the most basic tune you can possibly have but it will still do something. It should still be able to be tuned to where it can run fine at 20 lbs.

so i understand that you can't tell from car to car how many lbs i can run but does anyone know of the science between the 14b and 450cc injectors? I know their will be a certain point when I will hit fuel cut but what is it?

 

[Bluefire16]

...i have a 2g and am running a evo 9 fuel pump. I ran a 14b at 18psi.... at 19 i would hit fuel cut.

What your doing is not safe for the car.

If you do not wish to listen to US who care to give you advice and help, feel free to blow up your car. Me and liquid have both put our 2 cents in, and sounds like you wish to ignore them.

 

[black_gst]

id say tune for 30 psi

 

[LiquidX]

Again, DO NOT run more than 15 psi on the sock fuel system without a logger. Each car is different and you cannot go ask what someone else runs and expect your car to be the same as theirs. Please heed our advice or don't bother asking if you are just going to do your own thing.

 

[odormat000]

I understand what you're saying and I do appreciate your advice. I said I was getting my car tuned and I have people telling me I need something to tune it with. If you look at my mod list i do have something to tune it with. And i don't need wideband installed in my car to have it tuned it's just something i should get soon down the road. I'm having it tuned by some of the smartest people in the DSM community on a very nice dyno. We'll just see how it goes. Thanks for the help.

Again, DO NOT run more than 15 psi on the sock fuel system without a logger. Each car is different and you cannot go ask what someone else runs and expect your car to be the same as theirs. Please heed our advice or don't bother asking if you are just going to do your own thing.

I will let someone with a stock fuel system and no logger know this. Thank you.

 

[97-gst]

Stock injectors and the maf-translator is not gonna be near enough to reach 300 horsepower. If i were you id save the cash your gonna waste to have your car tuned and get dsmlink and larger injectors, AFPR as well. So seriously on your set-up do not run more than 15 psi

 

[LiquidX]

Yes, you still have stock parts (injectors) keep boost at 15 psi max, not due to fuel cut but because your injector IDC% will be high and you may be knocking. Tuning with a MAFT is hardly a tune as each day your setting will be thrown off by temperature and humidity.

 

[odormat000]

Yes, you still have stock parts (injectors) keep boost at 15 psi max, not due to fuel cut but because your injector IDC% will be high and you may be knocking. Tuning with a MAFT is hardly a tune as each day your setting will be thrown off by temperature and humidity.

Yes that is true about the GM MAF I forgot about temperature and humidity affecting it. But can't the 450's pump enough fuel to go into the 20's?

 

[97-gst]

Just crank it to 20 and find out

 

[snowborder714]

Ok - do you have a logger? It doesn't sound like you do, so how are you going to know how to tune your car? As Scott has been saying, you need to be able to view the car's vitals to know how much boost you can run. But as you said, you don't care about blowing up your turbo, so just crank it up and go. What's the point of tuning that anyway?

It is true you don't need a wideband. You just need one to tune, which they will have to install. Not a big deal whether you get one or not, but it'd be nice to have if you ever want to adjust stuff on your own.

You will want to get an AFPR with the 255lph pump. Yes, you don't really need one, but it can cause issues (fuel washing down the cylinder walls), so why risk it for a $150 part?

If the car is set up correctly you won't necessarily hit fuel cut, but more you'll run out of fuel and just go very lean during a WOT pull. I ran about 12-14psi on a small 16g on stock 450's and was hitting 126% IDC's. Not a good thing, especially if you want to romp on it daily. Going lean during WOT is not good.

Again, as Scott mentioned, tuning with a MAFT is like having a blind man tune your car. It will not give you a good tune (if you even want to call it a tune).

All we're saying is if you want a 300+hp car running 20+psi, you need to think about your setup and what is necessary. We can only do so much to tell you and if you don't want to listen, then that's up to you. And if this is the case, just crank the boost with the current mods, don't waste money on a tune, and see how long it lasts. Just don't come back crying when things break.

 

[odormat000]

I completely understand what you are trying to say. Ideally I want to run at 18 or 19 lbs of boost. To answer your question yes I do have a logger but I am not personally tuning it and never said I was. It will be done on a dyno. Would it help if i did the fuel pump rewire? I'm not going to romp on my car until I have the afpr or the wideband, i'm just getting it tuned now so it can drive. Would an SAFC help with having a better tune?

 

[snowborder714]

You should do the fuel pump rewire regardless. You don't want your fuel pump voltage dropping during a pull.

Yes, an S-AFC would provide you with a much better tune than a MAFT. But you'll still need the MAFT so you can run the GM MAF. Keep in mind that an S-AFC is only able to support up to 660cc injectors.

 

[97-gst]

safc is better than a maftranlsator
you might as well save up for a fuel pump
sure the rewire will help some but just get a bigger pump to be done with it
I personally recommend for you to save up cash for dsmlink, wideband, injectors, afpr, and a wideband

 

[LiquidX]

Here is your injector and fuel pump information that you have asked above.

http://www.dsmtuners.com/forums/articles-tuning-ecu/366003-injector-fuel-pump-supported-airflow.html

14b flow rate is 405cfm (stock un ported)
405 cfm*0.0807=32.6835 lbs/min

A cubic foot of air is approximately 0.0807 lbs

So in all honesty, when you get a flow rate of 405cfm from the 14b (upping psi) you will already be at 100% IDC and target IDC is 80% (a reason why stock PSI is low). Being ported, you have a larger CFM flow rate. So lets say you are at 100% IDC at 15 psi (stock un ported), once you bolt on that ported 14b and hit 15psi again, your IDC will no longer be at 100% they will be much higher due to added airflow causing the ECU trying to get all numbers back in check and ultimately unable to richen the mixture because the injectors were already flowing max fuel pre porting at 15psi.

Get what we are saying? You need to log to verify where everything is at to be sure that the changes you make are "compatible" with your other parts and how they are running.

 

[Bluefire16]

^^ Liquid, idk why this guy even bothers asking us? He is just arguing and disregaurding everything we say. So let him turn up his boost and blow his motor. If he says he is having the guys at English Racing, then at least they should no better.

Im done wasting my time with someone who will not listen.

And yes you do have a stock fuel system. You have a wally, but no way to control how much of that.

You would be able to get more out of your 450s if you bumped the fuel pressure, but you still need to log before you crank the boost

 

[odormat000]

Thank you liquid that was actually the exact answer I was looking for. It makes sense that a ported 14b will flow more cfm and cause my injectors to max out sooner. If I wanted to run 20 lbs what size injectors should I run on pump?

 

[FluidKaos]

After installing the other mods discussed above (AFPR, S-AFC, or better yet Link, etc.) to control the fuel flow, if you bump pressures up to 20psi, 650/660's should meet your fuel flow needs at a normal fuel pressure and 80% IDC target.

This link has a lot of good info and calculators for air/fuel flow, turbo efficiency, etc. It's a 3kGT site, but the math is all still the same.

 

[odormat000]

Here is your injector and fuel pump information that you have asked above.

http://www.dsmtuners.com/forums/articles-tuning-ecu/366003-injector-fuel-pump-supported-airflow.html

14b flow rate is 405cfm (stock un ported)
405 cfm*0.0807=32.6835 lbs/min

A cubic foot of air is approximately 0.0807 lbs

So in all honesty, when you get a flow rate of 405cfm from the 14b (upping psi) you will already be at 100% IDC and target IDC is 80% (a reason why stock PSI is low). Being ported, you have a larger CFM flow rate. So lets say you are at 100% IDC at 15 psi (stock un ported), once you bolt on that ported 14b and hit 15psi again, your IDC will no longer be at 100% they will be much higher due to added airflow causing the ECU trying to get all numbers back in check and ultimately unable to richen the mixture because the injectors were already flowing max fuel pre porting at 15psi.

Get what we are saying? You need to log to verify where everything is at to be sure that the changes you make are "compatible" with your other parts and how they are running.

I guess I don't understand because when I look at the chart it says that my walbro 255 can run 59.9lbs/min at 15 psi so wouldn't that mean it can support more than enough for my injectors and turbo? I think I may be confused or something. Any help?

 

[LiquidX]

The 255 will be able o supply the fuel to the rail but the injectors can only inject so much before they they are to the point of staying open to "meet" fuel needs; injector duty cycle.

It's just like a metal chain, it's only as strong as the weakest
link. You could have a chain made of titanium and a link made of lead. Sure the rest of the chain is strong but it will break at the lead. Same principle as your fuel system. Strong pump, way to tune, and AFPR will still limit you to stock boost settings because the injectors are too small and cannot keep up regardless of what you do.

 

[odormat000]

at what cfm do the 450cc's max out?

 

[snowborder714]

Did you even open the link Scott posted?

450cc @ 100% IDC will support 32.30lbs/min
450cc @ 80% IDC will support 25.84lbs/min

 

[odormat000]

Did you even open the link Scott posted?

450cc @ 100% IDC will support 32.30lbs/min
450cc @ 80% IDC will support 25.84lbs/min

Ok but how do I relate that to what I have?

Walboro 255lph

10psi = 63.53lbs/min
11psi = 62.88lbs/min
12psi = 62.20lbs/min
13psi = 61.48lbs/min
14psi = 60.72lbs/min
15psi = 59.93lbs/min
16psi = 59.10lbs/min
17psi = 58.23lbs/min
18psi = 57.33lbs/min
19psi = 56.39lbs/min
20psi = 55.41lbs/min
21psi = 54.39lbs/min
22psi = 53.34lbs/min
23psi = 52.26lbs/min
24psi = 51.13lbs/min
25psi = 49.97lbs/min