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2004 CTS luxury package
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300 Posts
Discussion Starter #1
Has anyone attempted to increase their engine power by upgrading the fuel system and remapping the ECU?
Increasing airflow may also be necessary.

Results?

I have a weak injector that needs replacing anyway, so I am considering the possibility of replacing all of them with higher flow rate units and doing the other work needed to make good use of them, including upgrading the fuel pump if needed.
 

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2002 Eldorado Biarritz
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451 Posts
If you go to higher flow injectors you WILL need to remap. The car will probably figure it out in closed loop. But, it will always run rich in open loop on the factory calibration. If the injectors flow enough more than stock you could worsen the engines tendency to flood under certain conditions as well as affecting its ability to start and idle under hot restart conditions. And the extra fuel will cool the O2 sensors making the heaters have to work harder to get the sensors into closed loop. I've never done it to a 3.6 so this is all speculation based on what you would be changing. My approach to performance is to tackle the airflow issue first and add fuel capability as necessary as the limiting factor on most stock engines is airflow and not fuel delivery. If you have plans on doing some of that down the road anyway. It might be worthwhile to do the injectors now.
 

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'05 CTS-V
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8,245 Posts
Has anyone attempted to increase their engine power by upgrading the fuel system and remapping the ECU?
Increasing airflow may also be necessary.

Results?

I have a weak injector that needs replacing anyway, so I am considering the possibility of replacing all of them with higher flow rate units and doing the other work needed to make good use of them, including upgrading the fuel pump if needed.
Adding more fuel doesn't make more power. (Well, not on a gas engine, at least. If you had a Cummins diesel swap in your CTS it would be a different story. :p) In fact, adding more fuel would be counter-productive. The stock fuel system has more than enough capacity to support even basic bolt-ons, so there's no need to upgrade the pump or injectors unless you're making quite a bit more power.

If you want to make more power it definitely will be necessary to increase airflow.

My approach to performance is to tackle the airflow issue first and add fuel capability as necessary as the limiting factor on most stock engines is airflow and not fuel delivery.
^^^ This is the right methodology. Unless you've significantly increased the ability of the engine to "breathe" (freer-flowing exhaust manifolds, head porting, upgraded cams, etc) there's no need for more fuel.
 

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2004 CTS luxury package
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300 Posts
Discussion Starter #4
That's what I figured. Airflow first, intake side then exhaust side. Then work on fuel delivery.

Problem is, there's not a lot of aftermarket peformance options for the LY7 engine in the US. Even finding a set of headers isn't exactly easy.
 

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2007 CTS Sport 3.6
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256 Posts
You'll need to have a lot more mods than intake and exhaust in order to need injectors, the stock injectors have a lot of leg room before they get maxed out and necessitate the need for bigger ones.
 

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629 Posts
SuperDaveSTS said:
You'll need to have a lot more mods than intake and exhaust in order to need injectors, the stock injectors have a lot of leg room before they get maxed out and necessitate the need for bigger ones.
do you know this for a fact? (Not trying to be sarcastic) because if that's so it's really good news for me. What lbs injectors do we have? I think I read somewhere we have 36lb ers. Correct me if I'm wrong. Also if anyone knows what duty cycle they run? That would be helpful as well.
 

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1,882 Posts
We still use the stock injectors with our turbo and supercharger builds on the DI engines...plenty of fuel available to 400-450 whp. The LFX has a higher capacity HPDI pump, but it is difficult to tune for if swapped to the LLT. LY7 is a port injection, so not sure on how much power the stock injectors will support for them.
 
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