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 Sr20det Upgrade With Injectors - 480cc injectors upgrade  

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woznoz
  • woznoz
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  • Member No.: 194,767
  • Joined: 8-June 10
  • Posts: 246
Post #1 post 8th June 2010 - 01:53 AM
hey i have a redtop sr20det engine out of a s13 silvia

mods are :

microtect lt10 comp
3inch dump pipe
t28 bb turbo
aftermarket coil packs
s14 fuel pump

now i have brought a set of brown top injectors out of a s15 sivlia

the question i have is

S15 injectors will discharge 440cc (at 2.5kg/cm2 fuel pressure) and 480cc (at 3.25kg/cm2).

there are so many disputes of fuel pumps and fuel pressure regulator changes when upgrading injectors.

My understanding is that the standard fpr will be sufficient to run the injectors, but what pressure will i be running off the standard fpr i cant find that info anyway. And how can i get the 3.25kg/cm stats for the injectors.

obviously im getting a retune that part is standard.
Im sure the pump will do its job nicely too.
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pipster11
Post #2

leave the stock fpr alone and get a nisstune to run it all

the tuner will be able to sort it all out

is the t28 steel wheeled? if not its only good for maybe 14psi (which wont need the injectors)

i'd also replace the s14 pump with something new, walbro or bosch s14's are still 10+ years old

woznoz
Post #3

the turbo is off a s15 silvia so thats all i know.

i'll only be running 10psi, so i only need a standard pump, is that correct?

if my pump is in good condition do u think it really needs a new one?

pipster11
Post #4

if its only 10psi then you dont need injectors unless it was an sr20de

run 12 through it and get a tune, you will pick up power, torque and fuel consumption

nistune is the way to go, about $800 installed and tuned

iamhappy46
Post #5

He has a Microtech already though so it rules out a Nistune ECU upgrade.

The S15 brown top injector flow figures you have are wrong though. Stock they flow 444cc@3bar(44.1psi) which is the factory fuel pressure. 2.5 bar is idle pressure and they flow 'less' than 444cc when in a flow tester at 2.5bar as there is not inlet manifold vacuum to 'suck' fuel out of the injector pintle. Put them in the engine and they will still flow 444cc at 2.5 or 3 bar rail pressure depending on manifold vacuum. The brown top injectors are seriously overkill for the mods you have on less than 15psi boost. Purple top 370's will support the power limits of your turbo wink.gif

Obviously, with say 10psi(0.7 bar) boost the fuel rail pressure will be at 3.7bar(54.1psi) and since your still only 3 bar difference between manifold and fuel rail pressure they will remain at 444cc/min. If you fitted an adjustable FPR and say cranked fuel pressure up to 4bar, then you could get around 510cc/min from them(there is physical laws of diminishing returns on cranking up rail pressure) but as above, your engine has no need of injectors this big and it would likely be a pig to get a decent idle from wink.gif

I would be at minimum fitting a Bosch 044 or Walbro intake pump despite the low boost pressure. It means you have plenty of fuel flow and will never 'starve' the engine.

woznoz
Post #6

i might aswell explain what i want from the motor, is reliabity i have read about ppl detenating there motors due to boost around 9-12 pis on stock injectors, the standard injectors seem to lean out around 9-10 and get worse around 12-13, this seems to be the most common reason for standard motors to blow. I figure with a bigger injector that , it will cure the problem of lack of fuel and leaning out issues .Yes the standard injectors will run 10pse but it will cause the injector to run at a higher % cycle and might cause problems, i thinkthat putting biger injectors in that will help with this, do u agree? or am i wrong?

iamhappy46
Post #7

SR20DET's in most cases run 10psi stock... and even on 13psi with a stock turbo I have never seen the stock injectors get over 70% duty cycle(80% is considered safe but I have run 90% without issue) I have tuned enough SR20's to know the limits of these engines wink.gif 15psi on a stock computer and stock S13/S14 turbo is where some issues can oocur but I have never known a 12psi or less engine to detonate unless it had something seriously wrong or the ECU was tuned by a retard with a laptop still running Win98(dont ask! lol).

The issue with detonating is actually ignition timing and that most japanese 'tuned rom' ECU's have too much ignition advance for our fuel and the hotter air we get here.

The factory ECU is easily modified and has knock mapping and full O2 sensor control, which unfortunately makes the Microtech a little less appealing but since you have it installed then it really comes down to finding a tuner who can provide a safe ignition timing map. SR20's are likely to knock from 1800rpm to 4000rpm as they start coming on boost, under high load and that will be where you know if you have a good or bad tuner wink.gif

woznoz
Post #8

QUOTE (iamhappy46 @ Jun 8 2010, 09:46 PM) *
SR20DET's in most cases run 10psi stock... and even on 13psi with a stock turbo I have never seen the stock injectors get over 70% duty cycle(80% is considered safe but I have run 90% without issue) I have tuned enough SR20's to know the limits of these engines wink.gif 15psi on a stock computer and stock S13/S14 turbo is where some issues can oocur but I have never known a 12psi or less engine to detonate unless it had something seriously wrong or the ECU was tuned by a retard with a laptop still running Win98(dont ask! lol).

The issue with detonating is actually ignition timing and that most japanese 'tuned rom' ECU's have too much ignition advance for our fuel and the hotter air we get here.

The factory ECU is easily modified and has knock mapping and full O2 sensor control, which unfortunately makes the Microtech a little less appealing but since you have it installed then it really comes down to finding a tuner who can provide a safe ignition timing map. SR20's are likely to knock from 1800rpm to 4000rpm as they start coming on boost, under high load and that will be where you know if you have a good or bad tuner wink.gif


well you seem to know what your talking about, i havent actually brought the injectors yet there sitting in my ebay account waiting for conformation. i have been trying to find a tuner that will do it, i have already the current tune had it looked at buy a professional and the opinion is that there is fuel and timing issues in it. now i had to bring the boost down from 10 psi to 6psi to stop the detenation. now as i said before u seem to know what ur talking about so ill take on what ur said and will listen to you. now the guy i had that looked at the tune said it will take about an hour to fix. but 999 automotive wants it for 6 hrs and 900 and another guy wants 3 hrs and 585. do you know of anyone?

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