550s or 650s

[danyz250f]

I have heard that 550 cc injectors can be good up to 20 lbs of boost but if 650s cost the same would it be better to use those and just not max them out as much. These will be tuned off of a safc 2. Also do i have to mod my stock mass air flow sensor at all.

 

[JDNSBR]

Are 550cc injectors capable of running semi-high boost on 16g's and 14b's? Yes. 650cc injectors give you more room to play with and a little bit more room to "grow". I would suggest running 650's. The worst thing for your injectors is to be running them anywhere over 80% duty cycle. This is pushing the injectors past their limit and killing them long before their time.

Are you staying with your 16g or going a little bigger?

 

[dalatinromeo]

It would be wiser to get the 650s, because you have more room just in case you decide to go bigger. Buy it right the first time and you don't have to repurchase injectors in the future.

 

[manwithaGSX]

Is there a chance for idle problems with the 650's?

 

[JDNSBR]

Idle problems come mostly from the TPS (Throttle positioning sensor). This is located on the throttle body. The 650's should not cause any issues with the idle as long as they are tuned properly.

If you are running a 255 fuel pump I would also recommend getting an FPR.

 

[calcifer]

not to hijack the thread, but how big of injectors can the 190 pump support?

 

[JDNSBR]

For the 190 pump 650cc injectors would be pushing the limits of this pump. Anything past this would be wise to jump to the 255.

 

[calcifer]

Cool, thanks.

 

[danyz250f]

ok so go with the 650s, but i also read that they might be harder to tune is this the case, or will the safc 2 be good and tune just like any other injector. I just put in a walbro 190 in last night so would i need anything else to get rid of my fuel cut.

 

[JDNSBR]

You will be able to tune the 650cc injectors with the SAFC2 fairly easily if you have tuned before. If you have put in the fuel pump, injectors, and SAFC 2 you should be able to run without any fuel cut. Just as long as you are not running an insane amount of boost and you are running a decent octane gas. This way you will not detonate.

 

[danyz250f]

sweet, but i have never "tuned" before so is there a place i can read up on it?

 

[2gGSX]

not to hijack the thread, but how big of injectors can the 190 pump support?

Based on calculations, a rewired 190 lph pump at 20 psi boost (63 psi fuel pressure) can support just over 90% IDC on 660's, or somewhere around 595 cc/min

Using the AFC to tune 650cc injectors will require you to pull over 30% airflow, which will cause your timing to get bumped up. This is both good and bad--more timing = more power, but it may also cause you knock.

 

[JDNSBR]

sweet, but i have never "tuned" before so is there a place i can read up on it?

Here you go. These should help you out.

http://dsmtuners.com/forums/showthread.php?t=105569

http://dsmtuners.com/forums/showthread.php?t=58403

 

[gthompson97]

....and another. this is more of an overall description of tuning and what things mean.
http://www.dsmtuners.com/forums/showthread.php?t=103469

 

[danyz250f]

ok thanks for all the info but i was just skimming over the articles and it says insert fuel pressure and desired a/f mixture. So do you just enter what the 190 fuel pump should be doing or do i need to get a fuel pressure guage, and in my in my "bible" the tech book i bought for my car it says the propper air to fuel ratio is somthing like 14.3 to 1 , i think i cant remember the right number of the top of my head. So do i insert that into the safc or what.

 

[bird man]

dsmlink can handly up to 880cc i think, and run perfect. HAHAHA enough said. i love my dsmlink, its the best thing i have ever bought for my dsm

 

[dsm-onster]

dsmlink can handly up to 880cc i think, and run perfect. HAHAHA enough said. i love my dsmlink, its the best thing i have ever bought for my dsm

There's a fellow running 1400cc injectors with DSMLink, my friend . I love my dsmlink too. But it's expensive compaired to your basic piggyback set up. I say this:

If your going to get the mods it takes to use the 650s then you'll need dsmlink or dsmchips with the eprom. If you're not going to spend the money on the other mods to get you into "the thick" of the 650s (80% duty cycle), then don't buy the 650s in the first place.​

Juggling the timing/compensation balls is not easy especially with the magnified deadtimes. But it can be done. I wouldn't get the headache of it unless i knew i was going bigger soon.

 

[JayZDMX21]

I would go with the 650's because later down the road if you get a bigger turbo or more mods then it makes it easier to tune with bigger injectors.

 

[blcknspo0ln]

:insert:

I remember the days when 550's and a 20g were enough to get you into 11's

:/insert:

.. here's some food for thought.. sorry if someone mentioned this already. When step from 450's to 660's.. you will have to compensate the SAFC dramatically to get the car tuned correctly. This means the -30 or more range. When you do that, IMO you are tricking the ECU entirely way too much and the ECU is compensating by putting everything on an entirely too aggressive timing map. The only way to change it back to the base maps are to have a chipped ECU/inj compensation or DSMlink or stand alone.

But also keep in mind there are plenty of people (like myself) that are using ONLY the SAFC2 to tune 650's. Of course the amount of compensation also depends on different variables including how much boost your running, etc.. but it should be close.

what this all means to me? IMO if I can pull 2-3 car lenghts on a 2003 M3 on an SAFC2 tune.. I can do double that with dsmlink

 

[JDNSBR]

ok thanks for all the info but i was just skimming over the articles and it says insert fuel pressure and desired a/f mixture. So do you just enter what the 190 fuel pump should be doing or do i need to get a fuel pressure guage, and in my in my "bible" the tech book i bought for my car it says the propper air to fuel ratio is somthing like 14.3 to 1 , i think i cant remember the right number of the top of my head. So do i insert that into the safc or what.

Your stock FPR is a 1:1 rising rate unit. Stock fuel pressure with the factory FPR is 36psi. Unless you have a wideband O2 sensor you will not be able to read your air fuel ratio accurately. With the SAFC you will only be able to read the O2 voltage if you do "the blue wire mod".

A good voltage for this is .8 or .9. If you dip down to .7 or lower you are runing lean and you need to richen up.

 

[blcknspo0ln]

Your stock FPR is a 1:1 rising rate unit. Stock fuel pressure with the factory FPR is 36psi. Unless you have a wideband O2 sensor you will not be able to read your air fuel ratio accurately. With the SAFC you will only be able to read the O2 voltage if you do "the blue wire mod".

A good voltage for this is .8 or .9. If you dip down to .7 or lower you are runing lean and you need to richen up.

why not just tune for no knock?

 

[JDNSBR]

why not just tune for no knock?

Correct, you should be tuning for no knock as well. Knocking pulls timing. However for the best tune it is good to look at all the aspects of the car. This will give the most accurate tune.

However this is my opinion and to everyone their own

 

[danyz250f]

ok im really confused now. So to run 650s i need more than just an safc II Like a chip or a dsm link. Well i looked into a dsm link and it looked like it only had serial ports, well my dell notebook only has usb ports and i guess i could get a ps2 converter, because a normal usb to serial converter doesnt work, at least it doesnt work with a datalogger. Plus ps2 converters are like 70 bucks from best buy and they are huge an have lots of wires. Plus a dsm link is really expensive, then add another 70 bucks on top and its even more expensive. So i dont know what to get i did buy an safc II and it is on its way via u.p.s. But i still dont know what injectors to get, i wont ever get a bigger turbo than my evo III 16g but i dont want that to max out my injectors, wich might happen with 550s.

All i want for X mas it to run like 15-20 psi and not have any fuel cut.

 

[2gGSX]

If this is your goal then 550's will be fine for what you want. At 90% IDC they'll flow 3.31 lbs/min fuel (again assuming pump) and 3.68 lbs/min at 100% (just as a comparison figure). Based on what AFR you tune for this is more than enough to support an Evo 3 (38 lbs/min at 11.5:1 with a 90% IDC) for most cases. If you do decide to run insane amounts of boost (24 psi) then this is also possible with a good tune on race gas.

It's been proven that 550's are fine for an Evo III car to be very quick.

Edit: Thus an AFC will definitely be good enough to control 550cc injectors, although as always DSMLink will do it better.

 

[danyz250f]

what if i ran 650s and only did like 80% duty cycle. Then would that be ok to because i really dont want to be maxing out or running lean. and if the 650s are the same price why not get those?