1300 secondaries and 550 or 850 primaries?
 

i have a to4s and im wondering if i should put my 850s in my primaries or keep my 550s where they are. how much boost could i safely run either way. id really appreaciate the help! by the way, this is my daily driver.

always go with more than you think you will need. Saves you from buying injectors twice.

oh yeah, i have 1300 secondaires.

im running 850 and 1300 with 15psi and no problems and maxcooper is running 17 psi on the same setup

i f you plan on upgrading your turbo later on or running lot of boost, get a fuel system you won't have to upgrade. I'm running 1000cc pri, 1600cc sec and twin walbro pumps.

on high boost. i was looking for aroung 16-17 psi, and on low about 14 psi. this would all be done on 93 octaine gas. these numbers are safe right?

i mean, some people have told me not to go to 17 psi becasue its not too safe. ive searched this forum, and ive seen that alot of people do go higher than those numbers. i just dont want anything thats gonna make my engine pop after a few runs. as it stands, i dont ride that car really that hard in the first place. at this point though, i still have untill next sunday untill my car is tuned and finished. so what do all of you think about the saftey in boost numbers? i want 360-70 hp on low boost and 390-410 hp on high.

1300cc + 850cc = 2150cc
1600cc + 550cc = 2150cc

these are the two common configs that FD owners run. as you can see, they are the same. now, you can always go running 1600's and 850's, but i dont think youll need it with your desired psi/hp mark.

and going with the largest you can fit in there is NOT the way to go. you will run your injectors at low duty cycles and they wont be in their efficiency range if your hp goals are too low.

Well for what it's worth I'm running 850 and 1600's. The reason for the big primaries is that I originally tried just running 4 850's, but was running out of fuel, so then I changed secondary fuel rails. In retrospect I think I would have been happiest with the 550/1600 setup. Keeping the stock primaries helps you avoid a lot of idle richness, cold temp, and tip-in issues as well as keeping you from having to do much tuning to your cruising maps, while still giving you fuel and reliability for WOT. Obviously you can tune out all the problems from the 850's, but it's just an added headache. I personally stayed away from the 1300's since their modified instead of stock injectors.

ok so, if i use 1300 and 550's, how much boost can i safely run? sorry im a newbie when it comes to the single set up

It's not so much boost, as horsepower. You can make different horsepower for the same boost, depending on turbo selection and lots of other factors. Plus it depends on how rich you want to run for safety. Here's a calculator for ideal conditions, which gives pretty good ballpark numbers:
http://rx7.com/cgi-local/3rdgencalc.cgi

very cool. thanks

hey i am running the same setup as you except i have twin supra pumps. My question is did you use the stock fuel lines and are you running your FPs to seperate rails or Y them together?

Im running 550/1600's and have no issues. easy tuning and no fouled plugs!

PDviper77: I am still in the process of setting up my system, new engine just went in. I plan on using the stock lines as feed lines, one pump for each line and then y'ing them together into a -8an line which will run to the primary rail first then the secondary. I will then run a new return line.

I don't really like the idea of running a pump for each rail, just my opinion.

rotorbrain has a good point about NOT going with the largest system you can fit if your not going to use it. However, in my case I plan on running 30psi on a T78.

For your desires hp level I would say go with a 1600/850 combination.

Good luck and be careful with your tuning.

well this just blows.....ONE OF MY 1300CC INJECTORS CRACKED!!! we flooded the engine. thinking that it was the 850s, we switched them out to the 550s. tried staring the engine again with the plugs out, and more and more fuel came out. when we checked the 1300s, the rear injector had a huge crack on it ! so now, i have my stock injectors back in. no boost for me now. if anyone has just one 1300 injector lying around, or 2 more, ill buy them from you all asap! i dont want to drive around like this for long.

oh yeah, for now, the cars is running better than its ever been.

I will be running the same setup as you very soon and asked the same question here:

http://www.nopistons.com/forums/inde...howtopic=55673

The reason i wanted to keep the 550/1300 is to keep the stock secondary rail, the horsepower #'s you desire are reasonable with this setup according to the calculator and at a reasonable fuel pressure, 50psi. So if you wanted more power you can always up the fuel pressure a tad.

awsome! so now all i need is that damn 1300

well im getting my 1300s in tomorrow! i got em from a forum member so ill let everyone know how things are running. if anyone cares that is lol :D