help on 18g fuel setup

[96Tsiguy]

This is what i have on my 97 gsx right now and i really am not sure what companies and what not to deal with for my fuel setup and what type of fuel pump or injectors or fuel rail i should buy... please no flaming here's my setup
ported 18G turbo
ported EVO III exhaust manifold and O2 housing
2.5" downpipe, 2.5" inlet/3.0" outlet high flow cat
3.0" Thermal R&D Cat-back
Upper and Lower intercooler hard pipes
S-AFC air fuel controller
AVC-R electronic boost controller

 

[jott5555]

hit up martin at www.thespeedfactor.com

personally it depends on what your goals are for your engine

i would go with some 660cc injecots

walbro 255

and the stock fuel rail is good for a LOT of ponies

 

[96Tsiguy]

alright how does denso 660cc injectors with Aeromotive fuel pressure regulator with the accessories from slow boy racing plus the Walbro 255 LPH (do i need the high pressure one?) also should i buy the aeromotive fuel rail?

 

[98spydert]

alright how does denso 660cc injectors with Aeromotive fuel pressure regulator with the accessories from slow boy racing plus the Walbro 255 LPH (do i need the high pressure one?) also should i buy the aeromotive fuel rail?

I don't think anyone will recommend upgrading your fuel rail unless you plan and maxing out the 18G and eventually moving on to some hardcore turbos.

The high pressure pump won't be needed either. Sounds like that's the perfect set up for your turbo though. ~660s, 255, AFPR.

 

[jsigone]

660s should be fine unless u live in Cali or AZ.

 

[TurboJimbo]

Slowboy Racing is the place to get what you need for fuel. The stock fuel rail is fine for a 18G turbo. An Aeromotive FPR, Walbor 255 HP, and FIC 650cc injectors are just what you need to feed that 18G. Slowboy also sells stainless fuel lines to go with the Aeromotive FPR, making the install extremely easy.

 

[98spydert]

Extreme PSI has lower prices on the pumps and injectors AND free shipping but both vendors are A++++ in my book, I've had awsome experiences with both. Anyways, you've got all the info you need, good luck with the project.

 

[VRMAN]

660cc injectors
190lph fuel pump hotwired
AFPR

 

[doug]

What VRMAN said, plus maybe a high-flow fuel filter setup like the AutoAlchemy one. Then you won't need a 255 pump, especially the HP one.

 

[meh]

well, others may not agree, but you could throw in a 255lph pump and run 18 psi on pump gas with stock injectors. I have had my 20g for 2 months now, and no problems running on 18 psi daily w/stock injectors

 

[droptopgst]

I have the 18g also and run 19-20 psi daily and have for the past year with no problems. check my profile for mods. they are about the same as yours

 

[Kevin Jewer]

You cant talk about injector or fuel pump size based on boost pressure (or HP, or track times, etc). Boost isnt power, airflow is (potential), and thats what determines how much fuel you need. Base fuel requirements on airflow, fuel presure, and richest potential AFR. At 12:1, and 30 psi boost, a 255HP is good to 70 lbs/min airflow. Most poeple are familiar with the 60-1/Red, thats rated to 60 lbs/min, for reference. The 18g will be low 40s maxed out. Now how effectively you use that air/fuel flow is up to you. For more info on this concept see my site. If you are going to get a 255, by all means get the HP version. Up to ~15 psi of boost, it flows the same as the LP, so it wnt affect fuel presure creep, and you're (wisely) doing an AFPR anyway.

Then choose injectors based on what type of ECU/fuel controller setup you are running. If you are using DSMlink, standalone, or a chip with injector compensation go big right from the start since timing wont be adversely affected. 950s is common (andthey match the 255HP pretty well). If you are using a piggyback style setup (AFC, MAFT, or other device that alters airflow signal), only go as big as you need to. The bigger the injector, the more timing advance the required compensation adjustments will provide. For anything over 550s, I would like to see injector compensation, unless you will be flowing enough air to be mostly in the highest load timing tables.

If I had know all this 4 years ago, I wouldnt have gone through a couple pumps and half a dozen different size injectors.

 

[Blue92]

Yeah, from my personnal experience 660's are a waste. I run 550's on my car with a 20G @ 20psi on 93 octane, no knock. Most people overfuel these cars, but that is what they want to do, no skin off my back. Either way, if you upgrade you injectors you will spend some money, so it doesn't really matter which ones you get. I am pretty sure some guy in a Supra made like ~650whp on stock injectors, 550cc. Granted he has 6 of them, but that is still over 100 whp per injector.

 

[Kevin Jewer]

Cant judge injectors based on what one setup or another has done for HP on them. There are too many variables. What was his AFR? What fuel? How efficiently does his setup make use of that given fuel supply compared to ours?

Over fueling is better than underfueling Why poeple like to stick to this tiny injector thing, and post about it every possible chance they get, is beyond me...

 

[98spydert]

Over fueling is better than underfueling Why poeple like to stick to this tiny injector thing, and post about it every possible chance they get, is beyond me...

I hear ya! The whole "I got away with it! So can you!!!" :thumbdown

 

[Blue92]

I'm not trying to knock anyone here, just putting in my .02 I use 550's with no problem with a good sized turbo and a good amount of boost, I am just trying to pass info along to the next guy.

The whole "I got away with it! So can you!!!"

I am pretty sure that having enough fuel is a proven thing, either you do or you don't. I am not just having enough fuel by some chance.

 

[98spydert]

What do you say about ktp4321 maxing out 550s on his 14b? Is he overfueling and wasting fuel?
The PSI you run your 20G on doesn't matter when you're trying to determine how hard your pushing your fuel injectors. If you could tell us your lbs/min, that would be more helpful. If you could give us some IDC numbers that didn't show the injectors staying wide open near red line, or a WB graph that doesn't fade to lean at high rpm(even though you're not knocking), then you could honestly say you don't need larger injectors.

edit: I'm not telling you, you need bigger injectors for the record. But you may down the road.

 

[Blue92]

Ok, my turbo is advertised to flow 45 lb/min @ 15 psi. That is converted from 650 cfm. 10 lb/min=144.7178 cfm That is plenty more flow than a 14b could dream about. Regarding some other guy "maxing out" his 550's with that, I seem to doubt.

Wide O2 RPM *100 Knock Narrow O2 Throttle timing
12.29 46.56 0 0.86 100 19
12.29 48.43 0 0.86 100 19
12.15 49.06 0 0.86 100 19
12.29 50.62 0 0.86 100 20
12.22 51.87 0 0.86 100 21
11.78 53.43 0 0.86 100 21
11.93 54.68 0 0.86 100 22
11.71 54.68 0 0.86 100 23
11.71 56.25 0 0.84 100 23
11.78 57.18 0 0.84 100 25
11.93 57.81 0 0.84 100 25
11.71 59.06 0 0.84 100 27
11.71 59.68 0 0.84 100 26
11.63 60.62 0 0.84 100 26
11.63 62.18 0 0.84 100 26
11.63 62.50 0 0.84 100 25
11.63 63.75 0 0.84 100 24
11.49 63.43 0 0.84 100 25
11.71 64.68 0 0.84 100 25​

Here is a log from my car a couple of nights ago. Sorry it is all messed up, I can't get it to line up. My O2's are actually going rich at the end of the powerband. I am just saying that 550's are enough for me and will be enough for 96Tsiguy's 18G. That is what he asked isn't it?

 

[98spydert]

doesn't seem to follow the "trend" does it? What fuel pressure are you running?

 

[Kevin Jewer]

When my car went from ~12.8:1 to 13.5:1 and cooked the motor, the stock O2 sensor voltage did not change. So you have no idea if you are leaning out up top or not. Let me see if I can get a pic up to illustrate. Note that the mumbers reflect the point where the vertical line is. Further to the left AFR is as rich as 12.4:1, but the front O2 says the same thing. I wouldnt trust my motor to the front O2 sensor voltage.

 

[FireyIce01]

The PSI you run your 20G on doesn't matter when you're trying to determine how hard your pushing your fuel injectors.

Actually, the PSI on the turbo sorta does matter, because the more PSI you're running, the more air you're trying to push into the cylinders, and the more air you push, the more fuel you need... however, I would tend to err on the side of slightly large injectors just because you don't need to worry about leaning out your system...

 

[Kevin Jewer]

Compare a 16g at 25 psi to my setup at 25 psi. Thats ~35-38 lbs/min for most people, compared to 60 lbs/min on my car. We're talking a 50% difference in fuel requirement here, at the same boost pressure. No, I dont think boost pressure is the right way to measure fuel requirements.


Cams, ehxuast, intake, manifold, displacement, etc all change airflow for a given boost presure. Setups vary widely, so airflow does as well, at the same boost. Not to mention AFR, rail pressure, etc.

What one setup can get away with another may not. Its that simple.

 

[Blue92]

95GSXRacer, I see your point, to an extent. The point I am trying to make is that a certain turbo can only flow a certain amount of air. So by choosing a turbo, one should be able to choose an injector size quite easily. So if a 16G flows 38 lbs/min then you need an injector that will fuel that. I think the problem is that people just say, "Oh you need 660's or 720's" for just about any turbo when that is a lie!! You don't NEED that large of an injector. Will it hurt? No, you just have a bigger injector and spent a little extra money.

95GSXRacer, what are you talking about my narrow band O2's for? I have a wideband readout in the far left column, I even bolded them for you. I just put narrows there because they were in the chart. Now when you look you will see I am running rich, 11.7:1 and making a lot of timing too.

98spydert, what trend are you talking about? I am running 40psi base pressure w/out vacuum.

 

[98spydert]

The trend, is making about 350 hp requires just below a 650 injector. It's a simple formula.
HP x BSFC / # of injectors x duty cycle

So from a mathematical stand point, you're not making much power at 20 psi. MAYBE 300?

 

[Blue92]

Looks like I'm going to the dyno within the next week to make a point.