fuel issues

Alright, I just ordered an Evo 16g turbo, flapper mod, ported and clipped. And I am porting out my stock o2 housing. I was wondering if I need to get bigger injectors and a 255 pump to even put the turbo on... Or can my stock fuel system support a 16g? I am planning on running 16 psi if possible for just day driving. I have a turbo back exhaust, intake, mbc, and a boost guage.

You would definitely need a fuel pump, either the 190 or 255 will do. If you go with the 255 you will need an adj. fuel pressure regulator.. On the 190 you won't. I would think you would need injectors too, probably 550's depending on your goal.

you wont need injectors since its only 16psi...(stock is 14) a fuel pump might be neccessary, might not! if you dont plan to run any more boost than that you should be alright on the stock fuel pump. but the question is, since you are only gunna be running 16psi why did you buy such a big turbo? a 14b will do that easily and reach full boost at about 22-2500rpm! if i were you i would just upgrade the fuel pump anyways to a 190, a 255 will be to big and a waste of extra money to you right now, cause then you will need a AFC or DSMlink to control it! if you wanna get rid of the 16g for a 14b, i will trade you mine + some cash!!! :iceslolan

I disagree with you (Eclipse RST).. Even if he doesn't run more boost than 16 psi, IMO I think he'll need a larger fuel pump than stock. I am thinking he might hit the fuel cut b/c he is moving a lot more air than stock. Just my thoughts, safer than sorry. I am still learning though, so I could be totally off..

yes you are somewhat right, if he was racing! but 2psi more over stock on regular day driving isnt gunna cause you to hit fuel cut! now if he was planning on racing the car where there is a constant boost of 16psi through all gears then yes he would most likely hit fuel cut...

Pump shoudl be done. At least a 190. Its only a hundred bucks, and a lazy afternoons work. If this is the largest you think you will be going for turbo, dont bother with the 255 and hassle of doing a regulator. Injectors would be nice. I would recomend at least datalogging the car to see when you really do max out those injectors. The stock turbo isnt too bad at 15 psi, but the evo16g will still flow more air at the same boost. Not a lot more though :) I have seen well setup cars hit fuel cut at 15 psi for what its worth.

I think he chose the right turbo, since he has plenty of turbo to run low 12s (or even high 11s) in the future as he mods the car. Though the flapper mod is something I suggest people dont get, and it will be a limiting factor over 20 psi.

I would run the turbo on the stock injecots until you can ford to upgrade, but at least datalog in the meantime. There is no magical boost number that will be safe. Every setup is different, so chances are you will either be on the limit of blowing things up, or making less power than you could if you knew what was going inside the motor. Get a datalogger.

Remember that the fuel injected is not based on PSI. The MAS reads air flow in cfm, and a 16g will flow more air at the same psi as the stock T25.

The DSM ECU never uses CFM for anything. In my humble opinion CFM is a bunk ass way to measure things, but you coud argue it several ways. The ECU actually cares about mass flow (lbs/min, kg/sec, etc), not volume flow (CFM). Which makes sense since the air and fuel are mixed by mass, not volume ;) So at 10:1 AFR, 10 lbs/min of fuel would require 1 lbs/min of fuel.

A larger turbo will only move more air than a smaller turbo at the same psi if the smaller turbo is out of its efficiency at that boost level. At 15 psi, both turbos will be very similar. I'm guess a 1-2 lbs difference. At 17 psi the difference will be bigger, and at 20 psi its obviously huge. Take my current turbo (huge) at 25 psi compared to the significantly smaller TDO6H 20g at the same 25 psi on the same setup. Same flow, 45 lbs/min. ;) Turn the boost up to 32 psi, and the difference will be substantial. Etc.

So you are right, if one turbo is out of its eficiency range.

thanks for all your input. i am planning on running more than 16psi on the track.. but just not on the street. and pretty much i just want to put the turbo on my car :biggrin: . anyway.. datalogging software such as dsmlink? sorry but i know absolutely nothing about datalogging :rolleyes:
OH yes. i was not aware that the flapper mod restricted you to only running under 20 psi. i am planning on definitely running more in the future but just now now. any sugestions?

the way the flapper works is like this: more volume = more pressure, as you know that the more boost pressure, the higher volume of air you flow. so if you have a larger flapper area it will be pushed open easier as you increase the flow of air. call your order taker and tell them you don't want a 34 flapper. also you need to start thinking of a real front mount intercooler [FMIC] and ditch the puny sidemount that's stock, unless you already have. definitly get the 190 pump. stock injectors will be enough as long as you keep the boost down... and like 95 gsxracer said, there is no magic boost level to go by. you may find that 16psi is too much and you are hitting fuel cut, or you could possibly boost it more and still be comfortable on the street. it's nice to tell all your friends that you are running 16psi on the street, but it would be better to be able to say that you are getting the most you can from the turbo for your current setup... data logging is just that. recording of sensors so that you can go back and see exactly what's going on within your engine and do some fine tuning. try checking this link:

pocketlogger.com (http://pocketlogger.com/)

there is some good info that should help to enlighten the topic. as far as DSMlink goes, it is basicly a piggyback ECU that has a variety of functions, datalogging included. here is a link:

dsmlink.com (http://dsmlink.com/)

also check out some of the tuning guides on dsmtuners.com and roadraceengineering.com

i understand that maybe i will not be able to run 16 psi, but that is what im at least aiming for. i also don't have the supporting mods to run 20 psi yet thats why i thought i needed the flapper mod... and a fmic is comming when i get the cash :rolleyes:

1st, getting a bigger fuel pump is essential. make sure it is wired with 10ga. or bigger [check the vfaq on the pump wire]. you will probly want an electronic boost controller [i recomend the GReddy Profec B-spec II] that you can adjust from within the car. the amount of boost you can push is directly related to fuel cut. ie, you will have to be able to adjust your boost as to slip right under it. fuel cut will kick in when the ECU reads more air than it is has a fuel ratio [i.e. out of injector space] charted for, killing spark to the engine. your boost level may or may not be 16psi, and the most you can boost will difer with outside air temp. i can hit fuel cut at 16psi on my stock t-25 if i jump on the freeway and my car is cold and it is a cold night outside.

Believe it or not, the point at which the ECU decides to cut fuel/spark has nothing to do with the capacity of the stock fuel system. This is a common myth. Since i was running my 14b at 24 psi on the stock pump and injectors without running out of fuel, and obviously this would have triggered fuel cut if not for my TMO chip, you can see there is no correlation there.

And well said boosted, 3 posts up. ;) The simple way to explain the flapper thing though is just hte forula for hte force on the flapper, force = pressure x area. Increase area (larger flapper) and increase the force blwoing it open... I have completely given up on internals. :D

ok thanks for info. one more question :smile: if i get an the safc fuel controller do i need to get a datalogger? or can the safc do it on its own?

You still need a datalogger. The safc is a fuel controller but it doesn't log important data like timing and such, which is used to tune your car.

Correct. The AFC will let you tune the car. The datalogger will tell you what to do with the AFC ;)
If you car is a 95, I would strongly recomend the DSMlink over the logger/AFC, and roughly the same cost. I forget what year your car is though.

i should have left the i.e. out, i only meant it as a visual cue to what the ECU was thinking, not as to what was really capable of the system... not trying to create more myth...