Which injector would be better to use with a star stage II kit, vortec s-fmu with 8:1. need your opinion so that I can place the order. how good do they Idle???

Accordng to Murix, you can run 440's on the stock ECU and will idle OK. The initial start up is a little rough but just let it run its course and after that things are all good.

well, from personall expeirence tuning 96venger's car, 440's will idle perfectly fine off the rip with low fuel pressure.


A.D.P.
"...If you do too much, people become dependant. If you do to little, people loose hope. If you do it right, people won't be sure you've done anything at all."
bring it on...........

From personal experience, 440's will also allow you to drive around almost completely normally. No SAFC needed, but you do need to lower your idle pressure with an FPR/FMU. You'll get a CEL "too rich" after a few days. Power will be noticeably less under vacuum. The engine will run like this on 2-5psi idle pressure, all the way up to about 20-25psi idle. Sounds weird, but I have witnesses ;)

Armond -- What did you set the idle pressure to on 96venger's setup? I'll be doing my fuel setup this week with 450s.

I am wondering if he is referring to a super fmu or a standard fmu both made by vortech.

The 8:1 disc/ring set is only used in the standard fmu.

The super fmu calibarates them by actual size, not a ratio.

All this said, I will be trying 335cc injectors off the stock ecu with a standard vortech fmu at stock idle fuel pressures. I will keep the 8:1 disc/ring combo installed. My goal is to drop the egt down to 1575 max. I will have a new front mount that cools the intake charge even more than my starion and the denser air requires a bit more fuel. I would also like my AF voltage to be .970 at 12psi.

I have the 97 ecu and this seems to work well with idling bigger injectors. There have been other cars that have had problems with idling even 310cc injectors(no problems for me). These have been mostly mustang injectors. I have the accel or hahn, which is the same thing.

If you plan on running 9psi in the summer and 10 psi in the winter, you will be just fine with 310cc. It will also give you less cold start issues.

Deano, you will run VERY rich using stock fuel pressures for the 335's.. I have to idle around 20- 23 psi to get the fuel trims close to stock. I got a too rich CEL(fuel trims maxed out) at anything over 25-27 psi idle fuel...Just as info.. Using those injectors with stock 50 psi idle is just too much fuel. To put it this way, i need 50 psi of fuel to run about 5 psi of boost on the 315cc injectors..

If you INSIST on keeping the 8:1 - then go with the 310s. They should work good from about 25psi idle fuel pressure. That'll put you at 120 psi fuel pressure at 12 pounds of boost - so keep it under that.

The 335s might work with the 8:1(not sure), but the 390s will not.


95 Eclipse RS : 5 speed
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

I have datalogged and will not go into the results again. My trims will be pretty much at 25%STFT/LTFT at idle with the 335cc injectors.

My trims are 25% LTFT and 18%STFT right now on 315cc(30LB) injectors.

I do not want to be running zero fuel trims with my fmu. When I go into boost(1 psi)my trims are both at zero. My STFT is at zero around 10 vacuum if I remember correctly. This tells me that I could be running lean and detonate during the onset of boost with zero fuel trims at idle. This is my theory anyway.

I have been tuning off of an egt and now the digital AF meter(backup to my egt). I was at .962-.965 voltage from 5000-7000rpm in a 3rd gear pull at 11psi in 50 degree weather. I just touched 1600 egt at 7K when I let off. This is tuned pretty damn good if you ask me for no S-AFC. This is also on a completely stock motor.

YOU may need 50 psi of fuel pressure at 5 psi, but you cannot be using a T3/T4 then.

I could care less about the CEL. I use a datalogger anyway to check which codes are coming up.

I am just trying to give the guy another option and what it is doing for me. I wish everyone would only quote what they are running or what they have actually worked on. Quoting others is not a good practice. I am not saying that you are doing that, but I usually give many facts to back up my numbers and reasons behind what I say and do.

I am not going off on anyone, so do not get excited. I just wish people would throw out hard data when they post and back up their opinion with some data that SHOWS why their idea is a better one.

Just some thoughts from an old fart with nothing better to do than type tonight.....thanks for the space guys.


BTW: should have been more specific. When I say YOU guys, I do not necessarily mean the guys posting in this thread. I mean it in general, when it comes to posting real data and not repeated data found on other threads. I have read numerous errors in others post when I know they actually read it on another topic and they just repeat what they read. I guess they like to see their words in type. I think misinformation is worse than no info.

>I have datalogged and will not go into the results again. My
>trims will be pretty much at 25%STFT/LTFT at idle with the
>335cc injectors.
>
>My trims are 25% LTFT and 18%STFT right now on 315cc(30LB)
>injectors.


Well is it -25% or +25%??? If its -25%LTFT, then that means the ECU is correcting fuel long term by 25%. Its leaning out the injector pulse witdth by 25% to cut back fuel. If your short term fuel trim is - 18%, then that means the ECU only has up to -25% STFT LEFT to adjust fuel. If both STFT and LTFT get maxed out at -25%, the CEL trips, which is no big deal. BUT the big deal is this: If both your fuel trims are maxed out, then once going into closed loop, light throttle boost, you run the risk of going too lean, becuase the ECU is already cutting back a lot of fuel. Make sense? Ideally, you want your at least your STFT to be as close to 0 as possible. This gives the ECU enough head room to adjust fuel for changing engine conditions.
>
>I do not want to be running zero fuel trims with my fmu. When
>I go into boost(1 psi)my trims are both at zero.

If both your trims are at 0 when you go into boost, then most likely you are in open loop mode, when the ECU is not reading and adjusting the A/F ratio. I always know when i go into open loop when i see my fuel trims go to 0. This does NOT mean you are tuned properly, as you are not seeing the data from the 02 related to your fuel trims.
My STFT is at
>zero around 10 vacuum if I remember correctly. This tells me
>that I could be running lean and detonate during the onset of
>boost with zero fuel trims at idle. This is my theory anyway.

No, not at all. Actually, you want to be close to 0, because this gives the ECU PLENTY of fuel adjustment headroom when in closed loop driving conditons.
>
>I have been tuning off of an egt and now the digital AF
>meter(backup to my egt). I was at .962-.965 voltage from
>5000-7000rpm in a 3rd gear pull at 11psi in 50 degree weather.
>I just touched 1600 egt at 7K when I let off. This is tuned
>pretty damn good if you ask me for no S-AFC. This is also on a
>completely stock motor.

I actually just blew my motor with 10.5 psi in third gear, with .96 o2's. EGT's never went over 1500 degrees. Be careful at that boost on the stock motor.
>
>YOU may need 50 psi of fuel pressure at 5 psi, but you cannot
>be using a T3/T4 then.

Nope, the S16G, which needs very close fuel requirements as the hybrid. I will guess around a few more psi of fuel at each pound of boost.
>
>I could care less about the CEL. I use a datalogger anyway to
>check which codes are coming up.
>
>I am just trying to give the guy another option and what it is
>doing for me. I wish everyone would only quote what they are
>running or what they have actually worked on. Quoting others
>is not a good practice. I am not saying that you are doing
>that, but I usually give many facts to back up my numbers and
>reasons behind what I say and do.
>
We are just trying to give advise, cause I have personally spent a lot of time datalogging and tuning fuel trims. Its more important than you might think. I guess my main point is if you are maxing out your fuel trims, then you run the greatest chance of runninng lean, esp in closed loop, part throttle boost. Running rich is good, and safe, but when you max out the ECU's ability to control fuel, well thats not good :)

Great reply, hope you caught my edited BTW paragraph. It should explain further my thoughts.

You did cut out some of my words in your cut and paste quote. The 10 vacuum with 0% STFT is what I mean. I reads differently, but if someone reads all the threads they will understand.

It does interest me that you blew her up with those numbers. I never run over 10 in the warm weather unless I have a mix of race gas.

During this cold weather, I have been getting on it a bit hard at higher boost levels. Nothing like 28F weather and doing some runs with LS1 cars at 12psi. I have run 13 psi with slightly colder weather and a few gallons of C16 added.....damn she pulled good and never got over 1600F. I was also doing pulls from 40-120mph and some 70-125mph. I guess I will do some rethinking on this and turn down the boost to no higher than 10psi in the cold unless I have some race gas.

I do run 93 pump gas. The stuff here on our Air Force Base resists detonation and gives me lower egt numbers than any of the national pumps downtown. It is really good gas and very consistant.

***to comment on the last paragraph. When I get zero STFT and zero LTFT at 1 psi of boost, this is in open loop with me at WOT. I have not datalogged a partial throttle, low boost pressure and read fuel trims. I usually avoid ever doing this as the spark advance is higher than I want it.

Now with my new dual stage boost controller setup, I do not have to worry about partial throttle all the way through first gear and the beginning of second. I can be at open loop throughout my run at the track or the street.

Later

cool man. Yeah, i did blow at temps in the 20's also :( But no race gas or octane booster. I always run 93 octane too. On the last datalog run, i noticed something very interesting. As SOON as i got into boost, i mean at 1 psi, the timing was immeadiatly pulled back to around 12-15 degrees advace. This was even like this in closed loop. I tested it several times and it was always like that. I always thought the timing stayed advanced in closed loop when under boost, but it didn't. I also datalogged Matt_95tg's car, and his did the same on his 95 eclipse stage 4. It must have somehthing to do with the MAP sensor when it reaches 0 vacuum..

>I am not going off on anyone, so do not get excited. I just
>wish people would throw out hard data when they post and back
>up their opinion with some data that SHOWS why their idea is a
>better one.

Thats a good point. I suppose it appears that I fell into this bracket with my answer. Actually, my opinion is strictly theoretical. I created a spreadsheed to help calculate injector sizing with these high-rising-rate fuel systems(like HRC or Star). All I did was run 315, 335, and 390 through the simulations using a 8:1 rising rate - comparing the boost corrected HP numbers to that of the stock injectors. Theoretically(for this particular question -which injectors with the 8:1 riser), the trick is finding a "best fit" idle fuel pressure.

Here's a link to the spreadsheet - http://www.users.fast.net/~metaljim/garage/TurboCalc.xls

The results are rated at 6psi boost with 85% injector Duty Cycle
Stockers - 155hp @ 50psi / 211hp @ 98psi
310s - 145hp @ 25psi / 237hp @ 73psi (not drastically different from stock)
335s - 150hp @ 23psi / 253hp @ 71psi (fuel pressure is a bit low at idle, and fuel output is a bit high at boost, but it might work)
390s - 163hp @ 20psi / 287hp @ 68psi (fuel pressure is pretty damn low at idle, and the fuel output is pretty damn high at boost, so much so that it looks like it would be too rich)

Alot of people ask about injector/disk sizing on this site. Its easy to find all of the information about injector sizing and how they flow and how much HP and how they're effected by boost pressure/fuel pressure. So why all the questions? Well, it's because high-rising-rate fuel systems(like HRC or Star) are not "stock"(1:1 rising system), and there's not much help on tying all of this information together for this type of fuel system. Are these numbers better than real results? No, but I do think using a tool like this MAY be a better starting place for high-rising-rate fuel system questions.

I've had alot of problems with getting this spreadsheet right, but I'm pretty confident about the numbers at this point. I'd like to get it in a web-based(java-applet/app perhaps) format, cause the spreadsheet format is just cumbersome and amerature. If I can get it in an app, then it would be easier to use and I could normalize the fp/boost curves, add comparisons(for high-rising-rate systems), accumulations(for 8 injector systems), as well as other more usefull features.

Please don't take this as me being excited...I just think you're right about backing up what you say. :7


95 Eclipse RS : 5 speed
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

well said