how much boost can i run?

[eclipsegst3131]

alright so here's the deal....i have a ported evo 3 16g about to go on my car...problem. stock fuel system. how many pounds of boost can i run with the stock injectors but a walbro 255 fuel pump? and when i go with bigger injectors (660 or 650 whichever they are) what will i need, just an safc? please let me know asap thanks

 

[GILZTSIAWD]

I wouldn't run over about 15-16 but I like to play it safe. Others may suggest more or less. You may also want to look into putting an afpr with that fuel pump or you are going to start overrunning the stock one very quickly. Another thing though, without any fuel control or any more fuel you really might want to actually stay at factory boost levels to be safe since you don't have a way of controlling the fuel and nothing to log what is happening with you engine. I would wait to turn it up until I atleast had an afc and a logger then get the injectors. The safc will be able to tune those injectors pretty good but it would be pushing it. I have 680's and an afc and I wish I would have just went with dsmlink and been done with it, then you have a datalogger and something to control the fuel along with MANY more options...

 

[GVR4592]

Yep stock boost until you get the logger and safc or something similar.

 

[blcknspo0ln]

get an AFPR.

I ran 16.5 psi on my unrewired 190 for about a year. Cranked it to 20 psi after my 660's and SAFC2.

 

[eclipsegst3131]

so with just a 255 lph pump, how much boost safely should i run, like 12 or 13 or something?

 

[skills]

you can run upto 16 psi safely.

ryan

 

[EclipseGST-95]

sorry to jack the thread but how much psi can i run with stock turbo... i have an intake... cat back 3 inch greddy...upper j pipe with greddy type s... and lower ic pipe and im hittin like 17-20 psi on stock turbo stock fuel... and i think im hitting fuel cut... any idea what i should be running? or if im running too much... by the way trying to get a boost controller soon...

 

[NewB2dsm]

First off, im sure this has been covered before.

Second, no one can tell you what is safe to run. Get a logger and see what you can run. Some people have ran 15 some 18. but each one is different. If it were me, Id probably run 14-15 TOPS! no more than that till i get larger injectors and a afc and found a dyno fast or a logger to assist in tuning.

 

[blcknspo0ln]

First off, im sure this has been covered before.

Second, no one can tell you what is safe to run. Get a logger and see what you can run. Some people have ran 15 some 18. but each one is different. If it were me, Id probably run 14-15 TOPS! no more than that till i get larger injectors and a afc and found a dyno fast or a logger to assist in tuning.

He doesn't know what he's talking about, don't listen to him j/p. I'll have to agree with the above statement

p.s., NewB- don't you find yourself answering this question waaaay too many times? I know I do.

 

[1fast97gsx]

This question has been asked 1000000 billion times already and its ALWAYS 16g people asking this so it shouldn't be hard to find. Since I feel like being helpfull though I will tell you 16-17 psi will be ok. Anything over that you will be starving for fuel and your stock intercooler won't like anything over that either.

 

[curtisimo]

I have a pretty close setup with a 255 pump and im running hella rich at 18 psi. Im pretty sure my injectors are running at full cycle.


P.S. I could lean out my fuel a little if you would hurry up and send the gm maft setup i bought from you

 

[slugsgomoo]

i would run 12-15, personally. Of course, that may be the fact that with 550's @ 18-20psi, you're pretty much maxing the injector- and that's with a rewired 255hp.

Get yourself injectors, and an AFPR- and get the AFPR FIRST! don't spend the $300 on an AFC that will be worthless until you take care of your fuel issues.

You are going to be over-running your injectors so badly that it will literally be impossible to tune the car.

 

[1fast97gsx]

I have a pretty close setup with a 255 pump and im running hella rich at 18 psi. Im pretty sure my injectors are running at full cycle.


P.S. I could lean out my fuel a little if you would hurry up and send the gm maft setup i bought from you

True you may be rich but that doesn't mean shit. Do a few passes in 4th gear and datalog it. Look at your timing curve and let us now how that stock smic is doing and why the car feels a little weaker each time. 16-17 psi is the max.

 

[NewB2dsm]

True you may be rich but that doesn't mean shit. Do a few passes in 4th gear and datalog it. Look at your timing curve and let us now how that stock smic is doing and why the car feels a little weaker each time. 16-17 psi is the max.

I was going to ask this along with how do you know your running rich?

Get yourself injectors, and an AFPR- and get the AFPR FIRST! don't spend the $300 on an AFC that will be worthless until you take care of your fuel issues.

A FPR should not be used unless you need it and KNOW how to use it. Every person on ehre that installed a 255 everyone jumps and says AFPR, but half of them probably have no idea how to use it but to set it to stock fuel pressure which a Stock FPR could do. 255 rewired might be good to use. but it not necessary 100%. I have seen many AFR and timing charts with a 255 with the stock Fuel pump and the AFR stays perfect each pull.

And a rewire doesnt nessasarly mean anything. A rewire will help if the fuel pump is running short on flowing enough fuel. On a AFR chart it will start to go lean up top almost no matter what you do with your afc settings or any other settings. My 190 pump on the stock rewire was not out of fuel when i made my 338awhp pass (sorry the 288 before correction) still held the AFR rock solid.

 

[oldman]

A FPR should not be used unless you need it and KNOW how to use it. Every person on ehre that installed a 255 everyone jumps and says AFPR, but half of them probably have no idea how to use it but to set it to stock fuel pressure which a Stock FPR could do. 255 rewired might be good to use. but it not necessary 100%. I have seen many AFR and timing charts with a 255 with the stock Fuel pump and the AFR stays perfect each pull.

Sounds like you don't have a very good understanding of what a stock fpr overrun is and the main function of an afpr. The reason the stock fpr gets overrun by a larger pump like 255 is that the return orifice on the stock fpr is too small and the fpr is unable to bleed off the extra fuel genrated by the larger pump in order to maintain the 1:1 ration between the intake and fuel pressure. An afpr fixes this problem because it has a greater fuel return capacity. You are fine during WOT pulls because fpr overrun occurs only during idle or part throttle, or until the system is able to use up the extra fuel . When does the system use up the additional fuel is tricky because it's load based, 30% vs 40% throttle at the same gear and rpm will net different results, making fpr overrun impossible to be tuned out by an afc or the likes. Sure, the afpr can also be usefull during fine tunning but the major purpose of it is to prevent fpr overrun. Hope I made it clear.

 

[curtisimo]

I was going to ask this along with how do you know your running rich?

Black smoke when i get on the gas in any gear.

 

[NewB2dsm]

Sounds like you don't have a very good understanding of what a stock fpr overrun is and the main function of an afpr. The reason the stock fpr gets overrun by a larger pump like 255 is that the return orifice on the stock fpr is too small and the fpr is unable to bleed off the extra fuel genrated by the larger pump in order to maintain the 1:1 ration between the intake and fuel pressure. An afpr fixes this problem because it has a greater fuel return capacity. You are fine during WOT pulls because fpr overrun occurs only during idle or part throttle, or until the system is able to use up the extra fuel . When does the system use up the additional fuel is tricky because it's load based, 30% vs 40% throttle at the same gear and rpm will net different results, making fpr overrun impossible to be tuned out by an afc or the likes. Sure, the afpr can also be usefull during fine tunning but the major purpose of it is to prevent fpr overrun. Hope I made it clear.

Its clear, if this is the case, who cares? part throttle doesnt really help you go fast does it

And i have more of a understanding of what a FPR does during tuning than part throttle/idle situations. Only part iv read up on enough to say somthing about. But anyway, i understand what you are saying. But then what are the symtoms of over run then? If its not during WOT?

 

[slugsgomoo]

over run just causes a few nasty side affects:

shitty idle
crappy fuel economy (in lower rpm's)
major carbon buildup in combustion chamber
possible engine damage.

When you are running stupidly (and i mean stupidly) rich, you run the risk of actually washing the oily film off the cylinder walls- Before i had the afpr on my car, with the HP 255lph, and the stock injectors, I was having an issue with the oil viscosity dropping REALLY quickly. Oh, and i got worse mileage cruising than I did doing WOT pulls on the freeway.

My car doesn't idle as badly as it did then until i turn the base fuel pressure up to like 50+ psi. I'm running 40psi base now, which while a bit over stock for a 1g seems to be a good pressure for the car.

Mainly the reason for the afpr is eventual advanced tunability, though like adjustable blow off valves, 99% of people out there have no idea what they are doing, and have done it wrong. The real advantage is that it helps preserve the ability to run a nice, stock feeling idle while you're able to deliver a shit-ton of fuel.

on the other upside, it helps you get rid of shitty rubber hoses.

 

[1fast97gsx]

Black smoke when i get on the gas in any gear.

I'd hate to see your timing curve / knock count if that's how you tune. I suggest turning the boost down to 16 or so. I bet you have boost leaks as well otherwise you would NOT be running rich enough to do that.

 

[curtisimo]

i know for a fact i have a boost leak, i was gonna wait til i got my fmic on to worry about it but i cant do that until eclipsegst3131 sends me the gm maf and tanslator i bought from him. I was hoping he would see these posts and be inspired to send it to me.

 

[eclipsegst3131]

alright, well the evo 3 16g is coming in tomorrow and going in hopefully tomorrow. i talked to my buddy that had a big 16g on his 2g auto tsi awd. he had 255lph fuel pump, ic pipes and injectors and he said that at 4k rpm the car would just shut off on him. something about the bigger turbo adds supposedly to much air and the mass air flow can't read it??? does this sound right? im only going to run 9 pounds of boost with intercooler pipes and a 255 fuel pump. is that really going to happen to me?

 

[eclipsegst3131]

can anyone help me with my question? im in desperate need of help

 

[slugsgomoo]

I don't know why things are shutting down on him. Have you logged his car?

I'm running an Evo3 16g, RC550's, walbro255hp, and a 2g MAF and the car pulls like a mofo all the way up towards 7k (couldn't tell you where power actually drops though).

anyway. I'm guessing that your upcoming mod list looks something like this:

AFPR (buschurs version is very inexpensive, compared to a full -6/8 AN setup)
EPROM (dsmchips or dsmlink)
SAFC (if dsmchips- it's unnecessary with DSMlink)

Good luck!

p.s. i'm running my evo3 @ 16~17 psi on 92 octane w/ the supra smic. With proper supporting mods, I don't see why the car should have a problem with running past 4k. He could be knocking like crazy and getting pulled timing. Without a log of one of his runs, I couldn't really say.

 

[eclipsegst3131]

so are you running the turbo injectors pump etc without dsmlink or an safc? cuz he was running those mods without anything to tune it....i mean i only plan on running 9psi for right now with just a walbro 255. i still have about 1500-2000 to put on my new motor before i beat it badly. i might just have to make a pull or two to see if it happens to me. also, is dsmchips stage 3 chip good, or should i go with dsmlink, im definitely on a budget unfortuneately. i have a blow thru setup, just need an ic pipe, will that help at all? thanks

 

[Turbo96DSM]

i have a evo 3 big 16g on my

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with all stock fuel sustem i mostly got it because my 14b was done. i run at 20 psi all day and havent had a problem and the car sounds fine and i feel the power the car pulls sooo good. i love this turbo