Fuel Injectors

[mitsu29]

Ok my question is, if i want to run between 12-16 lbs of boost for my low and high settings with my turbo ( TDO5h/18G, Greddy) what would be the MINIUM size fuel injector for this setup/turbo to get the job done and get it done safely i just want a size that gets the job done safely, there will be no further upgrades than what i already have on my profile list, save for the rest of the supporting fuel modifications here and there so please no 'well bigger is better for the future" as im looking to find a set of injectors that gets the job done safely here and now

 

[93_tsi_fwd]

rc 550 should do the trick. but i suggest get fuel pump too.

 

[chavez408]

Why are you running 16psi on a 18g? I believe you will see more of a performance on a stock 14b at that psi than a 18g. It is too low.
I also don't see any tunning device for you to upgrade injs . Plus a fuel pump aswell.
But anyways to the original question.
So the mimn injs I would run are 650s since they are the same price as 550s. Even though sometimes you can find 950s for the same price aswell. But than again it will make a difference on what tuning device you will be using =)
NorCal! Ha

 

[mitsu29]

Why are you running 16psi on a 18g? I believe you will see more of a performance on a stock 14b at that psi than a 18g. It is too low.
I also don't see any tunning device for you to upgrade injs . Plus a fuel pump aswell.
But anyways to the original question.
So the mimn injs I would run are 650s since they are the same price as 550s. Even though sometimes you can find 950s for the same price aswell. But than again it will make a difference on what tuning device you will be using =)
NorCal! Ha

whoops, i guess i need to update my profile, as i have the 255 Walbro pump. Well, let me see, the last things i need to 'finish' my car are as follows:

DSMLink
FMIC
AFPR
Fuel Injectors
EGT Gauge
Downpipe

Thats the plan so far

Why are you running 16psi on a 18g? I believe you will see more of a performance on a stock 14b at that psi than a 18g. It is too low.

Oh really? im not very knowledgeable when it comes to the tuning parts of the car, i figured 12 PSI for daily driving would be fine and for aggressive driving 16psi would be a 'sweet spot' as my car is in fact a daily driver, to be specific a Freeway, commuting, daily driver, which is why i figured a 'low' setting would be best, but if i can push 18psi SAFELY then i would do it

 

[mitsu29]

Anywhoo, again i was looking to be able to 'get away' with grabbing some 550ccs because my friend has a set just chilling in his garage, umm Blitz ones i believe, and i can get them for free, which is why i was asking to begin with. Now to throw another question in there, how high a boost would i be able to safely reach with 550ccs? Can i hit Maximum 18psi with a 255 fuel pump?

 

[chavez408]

If you can get 550d for free than hell you get them for free! But blitz? Wtf is that ha. I suggest you do a quick search on your turbo and what kind of result did different people get with their set up.
And yes a 225 wally will be more than enough for a pump.

 

[mitsu29]

oops i meant to ask, With 550cc fuel injectors will i be able to hit 18 psi (max) safely

 

[turbolover10]

You'll be pushing the limits of the 550's @ 18psi, I would run the 550's @15psi and worry about your other mods like afpr and link. Then upgrade to a nice set of 780's or bigger, its not good to max out your injectors. From what I've read, you don't want your IDC to be any higher than 70%.

 

[timloomis]

Get a datalogger and that will tell you your injector duty cycle. You can run 18psi safely on 550's. An 18g is a nice sized turbo, so the 550's will run out over 20psi or so. You *should* have an adjustable fuel pressure regulator for that walbro 255 pump, so you can up the pressure if need be. You never want to go too high on duty cycle, they'll burn up. Personally I never go above 85-90%. Just make sure your buddies blitz injectors are top feed and low impedance.

Formula: The square root of (new fuel pressure/old fuel pressure) times old injector size=new injector size.

 

[mitsu29]

Get a datalogger and that will tell you your injector duty cycle. You can run 18psi safely on 550's. An 18g is a nice sized turbo, so the 550's will run out over 20psi or so. You *should* have an adjustable fuel pressure regulator for that walbro 255 pump, so you can up the pressure if need be. You never want to go too high on duty cycle, they'll burn up. Personally I never go above 85-90%. Just make sure your buddies blitz injectors are top feed and low impedance.

Formula: The square root of (new fuel pressure/old fuel pressure) times old injector size=new injector size.

Thank you so much! ill be getting Blitz (Denso) 550c injectors from my friend today for free

 

[2gGSX]

Get as big as you can! 550's on base fuel pressure with an 11:1 AFR can only support ~36 lbs/min of airflow at 90% IDC, and that's under ideal conditions. You wouldn't be able to run the 18g anywhere near its potential, and depending on your setup, you may or may not be able to hit 18 psi or whatever your goal is.

If you do decide to go with the 550s, monitor your airflow, AFR, and IDCs closely to make sure you're not outflowing your injectors. You should also be sure that you're not prone to boost creeping.

 

[chavez408]

Do it right the first time!!!
Don't use the 550s if you are going to replace them in the future. You cannot push more than 18psi on 550s or well atleast in my friends talon he couldn't. So get bigger injs so you can push more

 

[mitsu29]

Get as big as you can! 550's on base fuel pressure with an 11:1 AFR can only support ~36 lbs/min of airflow at 90% IDC, and that's under ideal conditions. You wouldn't be able to run the 18g anywhere near its potential, and depending on your setup, you may or may not be able to hit 18 psi or whatever your goal is.

If you do decide to go with the 550s, monitor your airflow, AFR, and IDCs closely to make sure you're not outflowing your injectors. You should also be sure that you're not prone to boost creeping.

Thats the thing though, im not trying to MAX everything out, i just want to be able to hit 16-18 psi MAX, with the 550cc's without pushing them too hard. It's not that i am being too cautious or too cheap, its the reason im building my car. My car is a daily driver/daily commuter. I drive this thing to work, 58 miles away from home. I have to take the infamous 405/5/14 freeways to get to work and home. That means i drive rain or shine, icy road or not, and the last thing i want to do is "max out the potential of my 18g."

Granted we are a performance community, and you guys are steering me in the direction for the best perfomance possible, but i made sure to point out that this car is a daily driver/ daily commuter, which in itself, restricts what i can/can't do this beast .

That being said once i get;

DSMLink
Greddy Intercooler
Fuel Injectors
Aeromotive APFR Kit
BR Downpipe
EGT Gauge

I believe i am officially 'done' with my car. So given those mods and the reasoning behind my car, i believe 550cc can get the job done safely, but i don't want to 'believe', i want to be as sure as possible. Its not that im against going bigger, its i have an opportunity to save some cash, and if i can take that opportunity then by all means im gonna take it, BUT not at the cost of dramatic performance. I would like to see 18 psi on 550cc on a 18g turbo SAFELY. But, if it can't be done at all, then i know the 650cc would have to do then, but again if i can make it happen with the 550cc which my friend has in his garage, with only 1k miles on them, i would like to go that route.

Just a DSMer trying to save a penny and get some knowledge and research before i do anything, just like ive always done, right now its like 50/50, some say it can be done safely some say it can't? so again my refined question remains:

With 550cc fuel injectors will i be able to hit 18 psi (max) safely running an 18g turbo, with a 255LPH rewired Fuel Pump and Aeromotive Fuel Pressure kit??

Anywhoo thank you all for the feedback, like all projects, the road to our goals is hard and perilous, but, and i know you all will agree, once we reach our goals (mmmm power....performance...,mmgooodd) it is all worth the blood, sweat and tears

 

[timloomis]

You'll be ok. It's not really a comparison, but I'm running 20psi on my 14b and it's in the low 70's idc last I checked. The 18g is a bigger turbo, but 550's can support some decent power. Some guys in my local club have pushed a 20g to its limits with 550's and additional fuel pressure. You cant beat free injectors though. Like these guys said, you can get 1600cc injectors if you wanted, since your going with the link. But those free 550's with another 10psi base fuel pressure is cheaper than buying 650's+.

 

[romeen]

It's impossible to predict how much boost you will be able to run on the 550's since there are variables unique to each particular setup. But more than likely the 550's will be sufficient for your goals assuming your car is tuned well.

If you scroll half way down this page you can see some general guidelines from RRE which may help:

Road Race Engineering's Eclipse Fuel Delivery Upgrades

 

[2gGSX]

Thats the thing though, im not trying to MAX everything out, i just want to be able to hit 16-18 psi MAX, with the 550cc's without pushing them too hard.

Like other people have alluded, there's no way of helping you define a max boost pressure, because there's no way for us to know how much airflow you'll make at 16-18 psi on said turbo. The 36 lbs/min airflow at 11:1 (3.31 lbs/min fuel) is as close to a max as anyone can give you really.

For comparison though, I hit 35 lbs/min at 20 psi with an Evo 3 on a stock head/intake manifold/cams 7 bolt.

But those free 550's with another 10psi base fuel pressure is cheaper than buying 650's+.

I don't know if anyone has tried to run 10 psi higher base fuel pressure constantly for a long period of time. This could hypothetically cause fuel to blow by the rings (especially on a worn engine), although it's hard to say if 10 psi more would be enough to do it.

 

[timloomis]

I did it for months at a time. I think the myth that it will fry things is bs. Since when you boost, say 20psi, your fuel pressure also rises 20 psi on top on the 37psi base pressure or whatever your running. They're made to handle the pressure since people boost anywhere from 10psi to over 40psi in some cases.

 

[2gGSX]

I did it for months at a time. I think the myth that it will fry things is bs. Since when you boost, say 20psi, your fuel pressure also rises 20 psi on top on the 37psi base pressure or whatever your running. They're made to handle the pressure since people boost anywhere from 10psi to over 40psi in some cases.

I doubt those people who run 40 psi are trying to make a reliable daily driver like the OP is trying to do. You running 10 psi over base fuel pressure is not the same as the OP given that he has a 2g. Comparing idle/cruise to WOT and 40 psi is not too valid either, as I'm sure you'll agree that the conditions between the two are much different.

 

[mitsu29]

Ok, cool. Thank you everyone for the awesome feedback, again this site proves to me how great it is when i need something answered. So, i decided to do this:

I'm gonna go ahead and grab the 550cc from my friend, as they are free. Ill get the rest of my mods within a couple months, income tax time should be the time i finish everything at the latest.

Now, if i go and tune the 550cc and i find the IDC to be too high ( 70% was the 'sweet spot ' right? i'll try not to run near that as, like i said i need the driveablity to be as reliable as possible) then ill go ahead and get some 650cc ( or something in the 600s) as that should be more than enough for what i need, and really it didnt cost much other than having to retune and pay for that again, which would still be cheaper or as much as having bought 550ccs and then having to buy 650ccs, or in that case a i would have come out even if i went ahead and just got 650ccs to begin with, so not really a loss if the tune goes correctly...hmmm i kinda rambled on there but i hope it makes sense.

Anywhoo again, thanks all for your feedback and i will keep you guys posted on my progress

 

[timloomis]

If I can remember, rc says not to go over 85%, they start to lean out over that. I agree on the difference between a dd and a 40psi drag car, but 10psi more base pressure more than likely isnt going to fry injectors.

 

[SBR Joe]

If I can remember, rc says not to go over 85%, they start to lean out over that. I agree on the difference between a dd and a 40psi drag car, but 10psi more base pressure more than likely isnt going to fry injectors.

It wont because most injector companies flow test the injectors at like 45-50 psi anyways.


Joe
SBR