Fuel system advice from experienced SR20 tuners please!

[Pergatory]

Hi all, first and foremost thanks for your time, I'm afraid this is rather long but I can't help it. I'm wordy. Sorry.

So I've got this project Sileighty I'm working on... I'm rather inexperienced, but fairly knowledgeable, if that makes any sense. I do a lot of reading and pick up on things very fast. So I'm choosing each part rather carefully, and trying to make my idea of the 'perfect' SR20 a reality. Problem is when it comes to fuel systems, I know nothing. I've never upgraded any component of a fuel system before, as I've never pushed a car very far past its stock limits before now. That's where you come in!

The engine is an early blacktop SR20DET from a '95 180SX. My goal is to build an engine that has strong power without sacrificing response or midrange power. Anywhere from 350-400 whp would be great. Cost is only a mild concern. I don't wanna go spending $10k on a complete stand-alone system but a few thousand is acceptable. In other words, I'm not looking for the "cost efficient" devices that are made cheaply or made by companies that aren't passionate about their products (as you can see from the list of parts below).

I've picked up a good deal of the parts needed for the buildup already, though much of it isn't installed yet for reasons I won't get into. To give you an idea of the characteristics of the engine here are the mods so far:
GT2871R turbo
Greddy FMIC
Greddy intake manifold
HKS SSQV blowoff (recirculating)
HKS step 1 cams (256in/264ex)
Soon-to-be ported & polished head
Megan Racing equal-length bottom-mount header
Greddy/Trust turbo outlet elbow
3" exhaust (HKS downpipe, APEX'i cat-back)
APEX'i AVC-R boost controller
Koyo radiator & flex-a-lite dual fan
Greddy underdrive pulleys
Greddy rocker arm stoppers
Nismo polyurethane engine/tranny mounts
Walbro 255lph pump
Lots of new braided hoses, metal gaskets, and such (mostly from FRSport's T28 install kit which is a really great little package btw)

There's also a mystery Mine's ECM which came with the front clip. It's sealed with a Mine's sticker I've not yet broken, so I don't know what modifications have been made inside.


Now for the questions:

1. From what I've been able to learn just by poking around, the Nismo 555cc injectors seem like a good match to my buildup. Does that sound about right? Is there anything I need to know before choosing my injectors? I've seen it mentioned a few times that there are specs of the injector which must match what the fuel management system expects, can someone explain the things I need to be careful of?

2. Is the stock fuel rail any good for this level of modification? Would I benefit much or any from upgrading to a higher flow fuel rail, or is that more for the drag racers and really high-output engines?

3. Do I need to upgrade the fuel pressure regulator? I believe the engine has gotten some good use out of it, should I at least replace it with another OEM one or maybe a Nismo one?

4. The tough one: What do I need to do in order to manage the increased fuel flow? Looking for a brief overview of the options for fuel management on an SR20DET, just get me pointed in the right directions, some pros & cons and such. Don't bother going into options that are over a couple thousand dollars. Also please advise if you think the Mine's mystery ECU I mentioned might interfere with any possible solutions.


Thank you so much in advance for any assistance you can provide! I'm trying to make sure I cover all my basis and lately I keep coming back to the fuel system with questions I don't know the answers to!

[Koopa Troopa]

[quote=Pergatory;1699198]
Now for the questions:

1. From what I've been able to learn just by poking around, the Nismo 555cc injectors seem like a good match to my buildup. Does that sound about right? Is there anything I need to know before choosing my injectors? I've seen it mentioned a few times that there are specs of the injector which must match what the fuel management system expects, can someone explain the things I need to be careful of?

I'd go with bigger injectors. 740's maybe? That way it's one less thing to change if you ever want to go bigger which you always will.

2. Is the stock fuel rail any good for this level of modification? Would I benefit much or any from upgrading to a higher flow fuel rail, or is that more for the drag racers and really high-output engines?

Stock fuel rail is capable of quite alot of power.. You won't need to replace it unless you change to topfeed injectors.

3. Do I need to upgrade the fuel pressure regulator? I believe the engine has gotten some good use out of it, should I at least replace it with another OEM one or maybe a Nismo one?

You'll want an adjustable FPR, goes hand in hand with an upgraded fuel pump.

4. The tough one: What do I need to do in order to manage the increased fuel flow? Looking for a brief overview of the options for fuel management on an SR20DET, just get me pointed in the right directions, some pros & cons and such. Don't bother going into options that are over a couple thousand dollars. Also please advise if you think the Mine's mystery ECU I mentioned might interfere with any possible solutions.

Apex*i Power FC's are a great, cost effective ECU. They have a limit though but I doubt you'll ever reach it. An L Jetro is highly recommended for your setup. There are also plenty of cheaper, DIY EMS kits out there that I am not familiar with.

I don't however recommend using that Mines ECU. It was tuned for a specific engine and unless you know exactly what the ECU was tuned for then the tune will be off when used on your motor.

[rps13drift]

1- for injectors i like to shoot a little higher than what an injector is rated for for safety of my motor and not to always run the injector at 100% duty cycle - 740's seem perfect for your application

2-stock fuel rail is fine!

3- an adjustible fuel rail with a fuel pressure gauge is a must for me!

4- as for management you will get more opinions in this catagory of car modification than choosing a paint color! lol! Go with something that is widely used and succesful! Something that you know you can find basemaps and shops that are experienced with the system! I personaly run a power fc/datalogit combo and i love it! Easy to tune and easy to get useful advice/information on it for alot of people have been using it for along time.

[Pergatory]

Thanks for the advice! Going with the higher injectors does sound like a good plan. Can't hurt. Power FC also looks like a very nice unit. Will it replace both the fuel controller and the ignition controller, or just fuel? If it's just fuel, that still leaves me with the Mine's ECU in the ignition controller which has lord knows what timing map.

But honestly, it doesn't scare me too much having that Mine's ECU in there. I've done my research on that company and I like them, furthermore they seem like a rather conservative tuning shop so I doubt the setting is aggressive enough to start causing knock at the boost levels I plan to run. From driving it, just as a butt feel, I suspect they advanced the timing in the lower RPM but not much if at all in the upper RPM. The way the power rolls on reminds me of my last turbo'd car, a Saab 9000T which also had DI and a similarly advanced timing at low rpm/boost.

Also... how do I tune an adjustable FPR? I'll mount a permanent inline gauge, always liked that idea. Should I just see what the current pressure is at idle and match that with the new FPR, and let a tuning shop take it from there?

[SHIFT_*grind*]

I didn't see a wideband O2 in your list. With all that you're going to be doing to your air/fuel, you definitely shouldn't be without one, especially if you insist on using that Mine's ECU. It might feel nice the way the power comes on, but since you don't know exactly what map it's running, if you're leaning out, you won't know it until it's too late and something blows up.

They can be had pretty cheap, around $200 used in the forsale section here. I think there's one for sale right now at ~$350 that includes wireless datalogging as well.

[Koopa Troopa]

Originally Posted by Pergatory

Thanks for the advice! Going with the higher injectors does sound like a good plan. Can't hurt. Power FC also looks like a very nice unit. Will it replace both the fuel controller and the ignition controller, or just fuel? If it's just fuel, that still leaves me with the Mine's ECU in the ignition controller which has lord knows what timing map.

The Power FC will do both ignition and fuel. It replaces the whole ECU with it's own unit. You'll definatly want two things if you're tuning yourself. A good EGT and a good wideband.

But honestly, it doesn't scare me too much having that Mine's ECU in there. I've done my research on that company and I like them, furthermore they seem like a rather conservative tuning shop so I doubt the setting is aggressive enough to start causing knock at the boost levels I plan to run. From driving it, just as a butt feel, I suspect they advanced the timing in the lower RPM but not much if at all in the upper RPM. The way the power rolls on reminds me of my last turbo'd car, a Saab 9000T which also had DI and a similarly advanced timing at low rpm/boost.

You gotta remember, the ECU is set for a car with:
x cams
x turbo running at x boost
x timing
x engine work

The Mines ECU is probably extreamly awesome but for the motor it was originally for.

Also... how do I tune an adjustable FPR? I'll mount a permanent inline gauge, always liked that idea. Should I just see what the current pressure is at idle and match that with the new FPR, and let a tuning shop take it from there?

Eh, I'm not too sure myself... I just adjust it if I am running too rich or lean at idle or if the pump is starting to go...

[RPS1392]

You might, just out of curiosity, contact Mines. I had a tuned JUN Auto Mechanic ECU come with my 95 180sx halfcut. I was able to contact JUN, and by the numbers on the EPROMs, was able to tell me exactly how the ECU was tuned.