Howard Coleman

iTrader: (6)

i need 4300 cc's per minute and it seems there are two ways to do it... use 850 primaries and 1300 secondaries or 550 primaries and 1600 secondaries. i use a power fc and would appreciate advice as to which option would work best. i plan to have RC modify my injectors unless there is a reason to buy 1600s outright and go thru the resistor process etc.

Wargasm

Howard,

Good to see ya over here from the big list once in a while

I do not think that RC will be able to give you stock-mounting-location 1600s... so the way I see it you have the following options:

Option 1:
550 primary and 1600 Bosch secondaries with a new secondary fuel rail, an aftermarket fuel pressure reg (1:1 boost compensating type), and some Radio Shack resistors wired in.

Option 2:
850s in the primary (either overbored stock 550 or make stock secondaries fit) with overbored 850 -> 1300 secondaries in the stock secondary rail.

I went with option 1 on my car because I didn't like how stock 850s fit in the primary slots (not enough O-ring support area for my taste, I was worried about leaking fuel). I know that there are a fair number of people who do this, so maybe it's OK. I just didn't want to do it. At the time, I didn't consider overboring my 550s to 850s because I felt a little safer with "stock" 550 and "stock" 1600s. In other words, my theory was that a part that is configured as the factory designed it will always have more reliability than one that has been modified. It is more expensive to do it my way because you need to buy the injectors, the rail, and a new FPR.. as well as a few stainless braided lines and fittings to hook it all together.

I guess I would say that the advantages of option 1 are:

A) you are now using an aftermarket FPR which is nice because you can adjust your fuel pressure easily.
B) you are using all factory fresh parts that aren't modified by anyone so there might be an extra edge of reliability there. (maybe not)

Disadvantages:

A) cost of injectors, rail, FPR, lines
B) when secondaries kick in, you need to do a lot of fine tuning and tweaking to really make them kick in nicely. Once you get them tuned right they work just fine.
C) aftermarket secondary rail requires removal of air control valve which may be a problem if you need to pass emissions. (I still got my single turbo through emissions without it though).

For option 2, advantages are:

A) uses many stock components so you have to buy less stuff.

Disadvantages:

A) Modded injectors will never be 100% as reliable in my opinion, maybe 99.5%, but not 100%
B) Some users report large primaries might make for a crappy idle; other users report that this is not a problem if you just tune the PFC right.

So that's some of the debate that usually surrounds this discussion.



If you decide to go with the 550/1600 I can give you some tips for tuning the secondary kick-in to be as smooth as possible. I have spent a few hours tuning my setup with a wideband + datalogit on the street so I can give you ideas on what to try.

I know that you road race/autocross or whatever and with the 550/1600 on my car the "rough spot" where the secondaries are trying to come online is around 5700-6000 rpm with about -10 to 0 inches Hg on the vac gauge. This isn't a problem on the street if you're racing someone because you just mash the gas and go right past the rough spot... but on a road course, you might be trying to balance through the middle of a turn and you would not want the car to be misfiring/hesitating/bucking during that would you? So you need to carefully tune them to phase in "just right".

Regards,
Brian

P.S. I have those Tein HAs here but I haven't had a chance to install them yet... they look great though!

maxcooper

You'll also need a Datalogit to setup the PowerFC for "1600" injectors (which aren't 1600 cc/min, but rather more like 1625-1685 cc/min based on the flow tests I have seen). The Commander on;y lets you increase the size to 1500 cc/min, but the PowerFC itself works fine with larger injectors.

One nice thing about having RC enlarge your injectors is that you will know how much they actually flow. Of course, you could send your injectors out for cleaning and flow testing without having them enlarged to get the same info.

-Max

Badog

I have the 850cc and 1300cc combo and just (30 minutes ago_ tuned a 550cc and 1600cc combo. I'd do the latter.

Before you do the install, do yourself a favor and send out the 550's for a cleaning. You'll get a new pintel cap and o-rings, not to mention cleaned and flowed injectors.

Fuel pressure regulator is $130, polish 2ndary rail is $190, Bosch 1600's can be found for less than $100, switch the serial setup of the stockers, to running both rails in parallel, add about $100 in fittings hose.

130
190
100 (x2)
100
~$620

Biggest bonus, from a tuning standpoint, is the solid fuel pressure. Hook up an after market pressure qauge to the 1/8 port, and if you get the right sender you can datalogit that output. Or at least keep an eye on it.

Tony

mono4lamar

iTrader: (32)

bringing this back so i dont make a new thread! do i need resistors for the 850's in the primary rail? these 850s are not bored but true 850's. i had the kg secondary rail with 1680's and now have bought the primary rail and 850's. i just want to make sure that everything is ok! they sent me the injector harness/clips so might as well do it once and do it right. on the kg site where the tutorial is on putting the whole system in he uses resistors on the primaries but he doesnt specify what injectors hes using... heres the link on the kg website someone please help me i have off this week and im putting the whole motor back together and in so the more info i have the less stress that will be involved!

mono4lamar

iTrader: (32)

whoops forgot the link... http://kgparts.com/forums/tutorials.php?do=view&tutid=2

dubulup

I assume you are using a PFC...no resistors needed for 550 or 850cc injectors.

I was wondering why howard only needed 4300cc/min, haha!! didn't notice the date.

GoodfellaFD3S

iTrader: (213)

Kind of depressing really. There is quiet a difference in the people posting now vs 3 years ago.....

Zero R

iTrader: (1)

Boy do you have that right.

-S-

mono4lamar

iTrader: (32)

so i dont need them for the 1680's either right? theres a setting in the pfc to take care of this. next question is how to get the 850's that kg sent to me to seal. they gave me the "cup" spacer thing but am i suppose to slip it over the injector o-ring or have the o-ring go to the little index that is cut into the "cup" spacer thing? i'll post pictures if need be but i'll be in my shop for a couple hours . thanks again guys!

GoodfellaFD3S

iTrader: (213)

With the PFC and 1680cc top feed secondaries, you do indeed need resistors inline with your sec fuel inj wiring.

FWIW, I have been running 850 and 1300 injectors side feed injectors (stock rails and lines) for many years now.

Zero R

iTrader: (1)

I say boooo to your 1300's 1600's or go home.

-S-

Jason

iTrader: (5)

Im guessing you are running an aftermarket rail? The spacers go down in the block and then slide the injector in.

Jason

BoostedRex

I'm going to have to agree with Sean on this one. It's a simple fact of reliability. With 1300cc injectors just being bored out 850's they can't possibly be as reliable as a set of stock Bosch 1600cc injectors. But I do know that several people use the 1300's and have had success with them. I would just rather put my faith in a stock injector instead of a modified one.

And Rich, you made an excellent point about the post quality from 3 years ago versus today. It's very depressing when you sit and think about it.

Zach

mono4lamar

iTrader: (32)

i dont have bored 550's to 850's.... i have brand new unmodified 850's.

Jason i understand they go in the block but do i slip them over the o ring or let the o ring mate with beveled surface on the one side of the spacer? should i just post pictures?

mono4lamar

iTrader: (32)

also where in the pfc do i put in the chage for these 850's? and again thanks for the help guys im sorry to be multiposting questions im just in the midst of building the motor so i forget some things or i come up on problems. thanks

mono4lamar

iTrader: (32)

bumping this is the only thing holding me back to having the motor done!

Jason

iTrader: (5)

You slide them over the o-ring to where the beveled surface mates to the injector.

Jason

BoostedRex

mono, I wasn't talking about boring out 550's to make 850's. I was talking about boring out 850's to make 1300's.

And about where to set up your fuel injector size in the PFC, you might want to look in the Engine management forum. You can probably find that info by searching there. I don't have any experience with PFC's so I can't be of any help.

mono4lamar

iTrader: (32)

ok there is something really wrong here and i have pictures for this cause im completely confused here...

here is the cup on the injector

[IMG]
http://i27.photobucket.com/albums/c164/mono4lamar/th_DSC00738.jpg[/IMG]

here is it off



the next set of pictures are showing the problem i have. there is a gap that i cannot make up! the only way i could get them down would be to hammer them in and thats not an option. why is there so much gap? you can see on the last picture the kg rail support bracket extended all the way down and theres still a gap. also am i suppose to use the pastic spacer thats used under the stock support? i have no idea whats going on here maybe i got the wrong injectors from keith or something. HELP!!!

mono4lamar

iTrader: (32)

ughhhh photo bucket has everything all messed up. yet if you just look you can organise the pictures to see what im talking about.

rxrotary2_7

Just saw this. Please contact me and I can switch out the injectors. I was scratching my head the other day wondering what happened to those injectors. Sal or Steve packed/shipped that out and you were were sent the wrong primary injectors. Please call the shop or shoot me an email and I will get you all straight. Keith@kgparts.com
Sorry for this man.
-Keith

mono4lamar

iTrader: (32)

I KNEW IT! its ok though... as long i can get these over nighted it would be great! your very very hard to get intouch with i always talk with your reps and i think once to you! also im wondering if i have all the proper lines and fittings. the tutorial you have on the site does not look like how my kit is. i have the ultimate kit and with what im provided they cannot be fed in parallel. im sure i need the "T" fitting. im sorry for posting this im not trying to give you a bad rap its just i called many times and was never able to get YOU.

***edited personal info out of message****RX