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  • 1 Post By matto20v

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  #1  
Old 18-12-2024, 02:44 PM
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Default Fuel injectors

Hey fellas, I’m looking at increasing the size of my fuel injectors, I’ve got a 1998 wrx gc8 with a tdo5 turbo and an upgraded fuel pump according to the previous owner, my question is, can my ej20 with stock internals that are 26 years old handle 1000cc injectors? If not how big can I go SAFELY?


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Old 29-12-2024, 01:54 PM
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just changing the injectors what add preformance but will defienitly hurt it if all you do is install and not tune.


Do you have a tuner? Or accsess to the ECU and able to reprogram?



If yes to all the above, its your tune at the end of the day that will cause damage to your engine.
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Old 29-12-2024, 08:09 PM
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If injectors are too big-
safety in unlikely to be an issue, the problem is they are more difficult to tune. (the fuel onff ratio gets very small, risk is bad fuel economy).

What size do you need? -
My guess 1000 is too large, what size are your current injectors? Is it 450? That could be small, Size 550 probably enough.

As redghsn above says- bigger injectors by themselves will not give more performance, what matters is the tuning and the tuner.
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Old 30-12-2024, 04:27 PM
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Hey guys thanks for the input, one issue I’m facing is that the nearest awd tuning place is a 2 hour drive and I’m not too sure how I’m going to get there and then do the injector change, I’m not too sure what size the stock injectors are I saw some where that they were 500/550 but I’m not entirely sure?

So, don’t just chuck in 1000cc injectors?

If I do figure out how to get my car to the tuner what size do we reckon, 700? 800? Even 600?

Not too sure what I’m really looking for but that’s why I’m here i suppose.


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Old 06-01-2025, 09:58 AM
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What are your end goals? Stay with the TD05? Use E85 or just 98?

Bigger injectors wont make more power unless the injectors are currently the limiting factor. If that makes sense? Running it up on a dyno will let you know what duty cycle (%) they're at at full load. General rule of thumb is 80% of rated capacity is safe. So if you run it up, get 250hp and DC is 70%, you need more air for more power, not more fuel.

740cc is common size replacement that fits the GC fuel rails. Will supply more than enough fuel for a TD05 and easy enough to tune for low load use.

Can you see what colour the current injectors are? Its been a lot of years and alot more beers, but i THINK pre 99 got the grey 380cc and 99+ got the yellow 440cc from factory.
Any other colour you see may mean it already has a set.

I wouldn't be going past 280-300whp.
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Old 06-01-2025, 06:28 PM
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Quote:
Originally Posted by Hurtenstein View Post
What are your end goals? Stay with the TD05? Use E85 or just 98?

Bigger injectors wont make more power unless the injectors are currently the limiting factor. If that makes sense? Running it up on a dyno will let you know what duty cycle (%) they're at at full load. General rule of thumb is 80% of rated capacity is safe. So if you run it up, get 250hp and DC is 70%, you need more air for more power, not more fuel.

740cc is common size replacement that fits the GC fuel rails. Will supply more than enough fuel for a TD05 and easy enough to tune for low load use.

Can you see what colour the current injectors are? Its been a lot of years and alot more beers, but i THINK pre 99 got the grey 380cc and 99+ got the yellow 440cc from factory.
Any other colour you see may mean it already has a set.

I wouldn't be going past 280-300whp.

I do plan on staying on 98 for the minute as I’m only 17 lol, that actually helped a lot I do understand what u mean and I doubt that the injectors are limiting anything at the moment, I’ll just have to get it on the dyno and check some stuff out, thanks


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Old 24-01-2025, 09:07 PM
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You're doing it wrong. You're doing it backwards almost.

Speak to a tuner or mechanic that will be doing the work and the tune (you gotta get a tune, I think you've worked that out by now), and ask what they recommend as they will be the ones doing the tuning.

At this point, you may have realised you need an aftermarket ECU. Means more money.

To be honest, and I say this with age and experience under my belt... at 17, just enjoy the car for what it is, respect it, look after it, and if you've still got it in a few years, then spend some money on it to make it go fast. But for now, just learn to drive, learn the car, have fun, and be safe.
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Old 27-01-2025, 07:28 PM
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Quote:
Originally Posted by matto20v View Post
You're doing it wrong. You're doing it backwards almost.

Speak to a tuner or mechanic that will be doing the work and the tune (you gotta get a tune, I think you've worked that out by now), and ask what they recommend as they will be the ones doing the tuning.

At this point, you may have realised you need an aftermarket ECU. Means more money.

To be honest, and I say this with age and experience under my belt... at 17, just enjoy the car for what it is, respect it, look after it, and if you've still got it in a few years, then spend some money on it to make it go fast. But for now, just learn to drive, learn the car, have fun, and be safe.

Yeah I’ve realised I’ve had a wrong idea of what upgrading fuel injectors really meant lol, I really appreciate the advice I’ve had a few people tell me to just enjoy the car lately so I reckon I’ll do that for a while until I’ve go some sort of direction in my life haha, thanks a lot


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