2G Recommended size of injector to run with 20G?

[T'd Up Steve]

Hello guys.

I am soon getting a Billet 20G turbo by installed into my 2G Eclipse GSX. I have all necessary mods. AFPR, straight pipe, 1G BOV, walbro 255lph, DSMlink v3, gauges, boost controller…. thing is I bought some used but cheap 650cc injectors (60 bucks). I know that the 20G can push some high PSI, but now looking at it, a lot of people recommended a bigger size injector especially with a 20G. To give you guys an idea, my goal is to have a fun street car, pushing around 300-400hp. Just want some thoughts and recommendations on what to run. Thank you all for reading.

 

[99dsmer4g63]

I used 850cc on a 20g for years on 93. I was in the low 300’s.

I have since upgraded to 1200cc since switching to e85.

What fuel do you plan on using?

-Daniel

 

[19Eclipse90]

South Bay Fuel Injectors Calculators

Deatschwerks Fuel Injector Calculator


Calculators like these will help give you an idea.

 

[90fiveGSX]

Injector Dynamics 1050cc with resister pack delete. Should get you to 400 wheel HP easily with the correct supporting mods and tune.

 

[llxkevinxll]

https://www.dsmtuners.com/threads/injectors-and-fuel-pumps.244522/

 

[T'd Up Steve]

I used 850cc on a 20g for years on 93. I was in the low 300’s.

I have since upgraded to 1200cc since switching to e85.

What fuel do you plan on using?

-Daniel

I plan on staying on pump gas.

 

[Justin DuBois]

I plan on staying on pump gas.

"I plan to stay on pump gas" said everyone who doesn't

To quote a old tuner mantra - Air is Rare - fuel is plentiful. The question is how much air can you pump through the engine, and that will reveal itself in the data. In simple terms, you need an injector that delivers fuel at WOT without maxing out the injector duty cycle. The down side to a very large injector is a fussy idle.

Note: The difference between 91oct and 93oct pump is a bigger difference than you know (yet). With pump gas, you will reach a tuning threshold where you will choose between timing and boost. Fast cars keep all the timing and lower the boost. If you want all the boost, you need a more stable fuel to keep you out of the knock and detonation zone. This is what pushes us to go with E85, or blends of it to achieve more oct, and extract more power at the expense of fuel efficiency.

 

[trogador2005]

To answer your question directly, on pump gas those injectors will hit around 90% duty cycle at the max potential boost that a typical 20g can make. so by the numbers, they should be fine. but listen to these guys, they know what they're talking about!

My advice, if they're already installed, turn up the boost until you hit 85% duty cycle on the injectors, and if you want more, get bigger injectors. but you'll be close to maxing out the 20g right there. assuming you don't have a pig rich AFR.

 

[T'd Up Steve]

Injector Dynamics 1050cc with resister pack delete. Should get you to 400 wheel HP easily with the correct supporting mods and tune.

"I plan to stay on pump gas" said everyone who doesn't

To quote a old tuner mantra - Air is Rare - fuel is plentiful. The question is how much air can you pump through the engine, and that will reveal itself in the data. In simple terms, you need an injector that delivers fuel at WOT without maxing out the injector duty cycle. The down side to a very large injector is a fussy idle.

Note: The difference between 91oct and 93oct pump is a bigger difference that you know (yet). With pump gas, you will reach a tuning threshold where you will choose between timing and boost. Fast cars keep all the timing and lower the boost. If you want all the boost, you need a more stable fuel to keep you out of the knock and detonation zone. This is what pushes us to go with E85, or blends of it to achieve more oct, and extract more power at the expense of fuel efficiency.

I really do plan on staying on pump gas. Getting everything needed for E85 capability sounds complicated so I'll happily settle with just pump gas. I thought DSMlink allows you to tune any size injector and have a nice idle?

To answer your question directly, on pump gas those injectors will hit around 90% duty cycle at the max potential boost that a typical 20g can make. so by the numbers, they should be fine. but listen to these guys, they know what they're talking about!

My advice, if they're already installed, turn up the boost until you hit 85% duty cycle on the injectors, and if you want more, get bigger injectors. but you'll be close to maxing out the 20g right there. assuming you don't have a pig rich AFR.

Im assuming then just to be safe maybe some 1000cc injectors?

 

[trogador2005]

Im assuming then just to be safe maybe some 1000cc injectors?

That's up to you! Know the limitations of what you have and make a decision based on your budget and goals.

 

[T'd Up Steve]

That's up to you! Know the limitations of what you have and make a decision based on your budget and goals.

Ok! If my power goal is 300-400hp, and i want to stay on pump gas, run 20-25psi of boost, will it suffice in your opinion? and I can tune the idle on dsmlink correct?

 

[curt-s]

1000s will do that HP goal on pump fine. 1000 isn't even large anymore. Just get good quality injectors that are tried, tested, and validated by the community to operate well on short pulse widths (idle). In the early days they used to be finicky.

 

[Justin DuBois]

I run 1000cc, with a Big16G, and I even mix 1:4 E85:91oct pump to boost the octane up to 94 (E25 final mix) 20lbs of boost with 8.5:1 CR pistons. The idle is good with stock cams, but not as perfect as 450cc stockers. There is still more room to grow, as the max IJDC is around 65%, and I’m targeting 11:1 AFR

Which is to say the same thing - 1000cc will reach your goal.

 

[steve]

I thought DSMlink allows you to tune any size injector and have a nice idle?

DSMLink gives you lots of tools but shitty injectors give shitty idles.

 

[1990TSIAWDTALON]

FIC Hi-Z injectors and be done. Choose the size you will NOT need (because you will). I run Hi-Z 1120s in a basically stock GSX. 2150s in the 2 others cars, just scaled to work. Idle is fine. No throttle peddling to keep it running. Those two big injector cars start right up and run like normal if tuned right. Just some opinions and experiences.

 

[T'd Up Steve]

1000s will do that HP goal on pump fine. 1000 isn't even large anymore. Just get good quality injectors that are tried, tested, and validated by the community to operate well on short pulse widths (idle). In the early days they used to be finicky.

FIC injectors I heard are the way to go...

DSMLink gives you lots of tools but shitty injectors give shitty idles.

I totally agree. Now looking at it, im going to go for 1000 and above. Want to have some room to grow.

FIC Hi-Z injectors and be done. Choose the size you will NOT need (because you will). I run Hi-Z 1120s in a basically stock GSX. 2150s in the 2 others cars, just scaled to work. Idle is fine. No throttle peddling to keep it running. Those two big injector cars start right up and run like normal if tuned right. Just some opinions and experiences.

Any real difference in running a highz or low z? I mean what truly is the difference? some people say get the low one since it is what came with our cars... others saying getting the high Z...

 

[1990TSIAWDTALON]

Yes. Transition from low to high pulse widths are definitely easier to tune on the hi z injectors. Some large low z injectors just don't like going from cruise to WOT without a hickup or stutter or stumble and you would be tuning around a issue that is hard to go around smoothly. That is the whole reason I went from low z 1800s to hi z 2150s and then went hi z on my other 2 DSMs.

 

[We're on Boost]

Any real difference in running a highz or low z? I mean what truly is the difference? some people say get the low one since it is what came with our cars... others saying getting the high Z...

As far as I know, the newer injector designs are mostly high-Z. And they are better, not necessarily because they are high-Z, but because they are newer designs using the most recent improvements in injector design.
As for how this happened I'm not 100% sure, but I think there was a bit of tail wagging the dog.
Low-Z injectors are suitable for Peak and Hold type injector drivers but not so great on simple basic drivers like we have in our DSM cars. Peak and Hold drivers can put out a lot of energy in the first part of the pulse, which gets the injector moving real quick.
But Peak and Hold drivers are expensive if they are good.
The car OEMs didn't want to have that extra expense in the ecu, or as an add-on either.
A resistor pack is a cheap add-on, and it makes Low-Z injectors usable with ordinary non-fancy injector drivers like what the OEMs wanted to make, like ours. But the injector performance is not very optimized that way.
At some point, the people working on new injector designs said OK screw it, we'll just make the injectors suitable as is for these simple cheap injector drivers that are not Peak and Hold.
And from then on it was so, and we all lived happily ever after.
With High-Z injectors.

If anybody has better facts or a better story, throw it in here!

 

[curt-s]

Let's just say that high z injectors get sprinkled with magical fairy dust.
That's what makes them better.



Srsly

 

[jdxnc]

FIC 1200cc high-z are direct plug in with no adaptors, these are my go to for a street car these days.

 

[Justin DuBois]

FIC 1200cc high-z are direct plug in with no adaptors, these are my go to for a street car these days.

High-z - as in high resistance? You would need to bypass the stock resistor pack.

 

[jdxnc]

High-z - as in high resistance? You would need to bypass the stock resistor pack.

Correct and correct but I was referring that they use the oem DSM plug, no adaptor required.

 

[T'd Up Steve]

Yes. Transition from low to high pulse widths are definitely easier to tune on the hi z injectors. Some large low z injectors just don't like going from cruise to WOT without a hickup or stutter or stumble and you would be tuning around a issue that is hard to go around smoothly. That is the whole reason I went from low z 1800s to hi z 2150s and then went hi z on my other 2 DSMs.

Looks like I’m getting some high z injectors… going with some 1200cc looks like the wave. The price tag is a little scary but why not

 

[jdxnc]

Looks like I’m getting some high z injectors… going with some 1200cc looks like the wave. The price tag is a little scary but why not

Buy once, cry once.

 

[curt-s]

Buy once, cry once.

I say that every time I pass the Oreos when shopping for groceries