Sapphonica

I just found out from GReddy that there's a few people using RC Engineering injectors to get more fuel to their boosted 8s:

http://www.rceng.com/

They make higher-capacity injectors that plug right in to the stock fuel rail.

Fanman

I'm about ready to do this. Do you know what size they were using ? Was it the 440cc's or the 550cc's ?

PUR NRG

So the question is why? The stock injectors can already deliver enough fuel to reach 320 rwhp using a modified greddy turbo.
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Coach purses

Fanman

Safety. I know Manuel swaped to a completely new fuel system, which included new injectors. Debate on if the stock fuel system can really handle 12+ lbs. for long term.

MadDog

sounds like people are starting to get more agressive with the boost. Glad to see it.

Spyder_doo

I've been looking at these for a little while now and I'm wondering what boost levels these would allow us to go to. Any idea?

Jamie

Fanman

Well Manuel had 550's on his car that he was pushing about 12+ psi.

Sapphonica

Mwaa-ha-ha... mo' RWHP is bettuh!

PUR NRG

I do not believe you can safely exceed 320 rwhp without using a different turbo, fuel/timing map and lots of motor/drivetrain work. Sticking larger injectors on the Greddy kit is a solution looking for a problem.
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Erica_Lopez

Sapphonica

Perhaps. Everyone seems to be saying 'the stock injectors are good for 300 whp and the stock GReddy's mass flow rate won't support > 300 HP', but I want a safety margin so I don't go lean when I turn up the boost.

Nemesis8

iTrader: (3)

Won't it also lower the duty cycle at low boost using larger injectors, thus giving them back their life?

PUR NRG

Even with Scott's turbine improvements you can not physically push more boost through the Greddy turbo than what the stock injectors can already handle. So once again, what are the benefits of using larger injectors with a Greddy turbo? Please don't tell me this is a stupid bling-bling "larger must be better" thread.

Sapphonica, if you want a safety margin then there are other components at greater risk than the injectors at those hp levels.

Nemesis8, larger injectors would require changing the entire fuel map. The ecu assumes the injectors are a given size and drives them accordingly. On the other hand I'd rather run smaller injectors at a higher duty cycle--I believe it will atomize fuel that much better.
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SexyLexa

Fanman

I'm not sure what/how you are saying it. CFM from a turbo has nothing to do with the fuel injectors. If you have a larger turbo it will push more air through the engine. If you do not have enough fuel then you run into a lean condition. With larger injectors you open up the fuel flow & put more into the engine (if that is the impediment area). Can the fuel system flow more than the stock injectors. If you are saying that the stock injectors & fuel system are maxed out together than I understand, but fuel & turbo have nothing to do with each other (turbo does not provide fuel to the engine). The secondaries are supposed to be 380 cc's. if you go to 440 cc's you will not need to reprogram the ECU. If you go to 550's then you will probably have to.

Sapphonica

It's not a size thing :D

I've been told (haven't seen dynos but have it from a reliable source) that the STOCK GReddy turbo has a mass flow rate capacity to support > 300 WHP.

Anyway, at some point I am going to find out & I'll post results/dynos.

PUR NRG

CFM is related to the fuel injectors in that the more air is forced into the engine the more fuel needs to be delivered as well. The stock injectors can deliver more than enough fuel to handle an upgraded Greddy turbo.

And what I'm telling you is that the stock injectors can deliver enough fuel for a modified Greddy turbo that has dyno'd at 320+ rwhp on a Mustang dyno. I'm pretty sure you can't get more hp without replacing the turbo altogether. So what I'm saying is if you are using a Greddy turbo, why use larger injectors if the stock ones can already handle anything the Greddy can put out? I'd really like to know.
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BODY SCIENCE

Fanman

I think where it comes up what we have to do & the effect of larger injectors was that the first person that pushed this car past 10 psi (manuel) wound up swapping out his fuel system. Several other knowledgeable poster on the board posted that the stock injectors were the restriction point of the fuel system, and that the stock system petered out at around 10 psi. Also that the duty cycle was 100% at 10 psi. Mazsport has pushed their Greddy past where people thought you could push a stock fuel system RX8. Interesting results. I hope somebody else can repeat these results.

In reducing the duty cycle of the injectors, you are increasing their life. I'm not sure that an injector would atomize fuel that much better if it at a higher duty cycle. Pushing fuel to the engine is pushing fuel. So an injector working at 100% vs a larger injector pushing say 80% you are still getting the same amount of fuel in the same way, no atomization or fuel breakup, or anything. I'm looking at swapping the 380's for 440's.

TORacing

Mazport has the potential to go higher than they have already achieved by adding larger injectors, right now they are lowering the duty cycle i high rpms for safety reasons. If they were to use larger injectors they could tune higher. My plans are to get the Interceptor-X, replace the secondaries and primary 2s with 550cc injectors and get a bigger turbo which can support more CFM. I plan on having all this by mid-October.

RX8PR

Just for a corection,

I'm using 850 cc injectors not 550cc..............
I used them with the greddy turbo but the turbo
can't provide the cfm that we needed.

Manuel

brillo

question for those changing injector sizes -

the stock primary injectors use a nozle that has 12? holes vs. the primary 2 and secondaries which have nozles with 4 or 6 holes. The whole point is that the primaries can atomize fuel better which aids in fuel economy at idle and low speeds.

So, what are you guys doing about this? Can you get injectors with different size nozle holes?

on a similar subject, the idle vibration i've found is caused by the injectors switching on and off at idle trying to maintain a really lean mixture. could you change the primary injector size to sort of force a richer idle mixture, therefore, smooth out the idle?

TORacing

I personally wouldn't switch the primary 1s out because there only used until about 3500 rpm.

RX8PR

I keeped the primaries and only change the secondaries

Manuel

Fanman

Never heard of anybody changing out the primary1 injectors. Always the secondaries.

TORacing

what brand?

RX8PR

Look the pictures, the're accel.
you can use accel or any other brand.

Manuel

TORacing

Did you just go with there universal fit 83lb/hr ones?
Where did you get them from?