Looks like I have some retuning to do
Thread Starter
Joined: Sep 2004
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From: Stockbridge GA
Forgot how much of a pain in the *** it is to find a "friendly" emissions guy around here, so I just committed turbo heresy and put cats back on. I was afraid of how much it will hurt power, but I can always gut them later and still pass visual. The test drive showed a bit rich everywhere, so they definitely hurt flow, but it still smokes the tires at 50% throttle in 2nd gear, so I guess I can live with that for a bit. No chance to wind it out yet, so no idea how much they choke the top end.
Do you have blender pumps by chance? We have E20, E30, E50 at the pump. So its pretty handy. But with a flex sensor you should be able to eyeball 50-60% pretty easy. “E50” is a great option that offers about the same performance as E85 with much less demand on your fuel system. You could always run higher base pressure and over pump it? Or spend $100 on some OEM flex injectors and decap them. They flow 75lbs with OEM reliability. That will go pretty dang far on E50. Then add the water/meth for some wiggle room. I made 560/600 (without an intercooler) on 11lbs with a 5.3 on decaps OEM flex injectors with 43 base. (ran out of pump). Added another AEM400 in parallel and bumped base to 60 and boost up to 19lbs (still no IC) before I capped the injector DC.
For one thing, there are tons of fakes floating around. Even with a legit set of injectors, you then have to go with a source you trust has flow matched them properly. And on top of that, everyone I have seen or read talking about good idle and zero issues with any injector that oversized for the application generally has a large cam in front of a high stalled auto, so I take that with a grain of salt.
Thread Starter
Joined: Sep 2004
Posts: 4,905
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From: Stockbridge GA
So as I suspected, working in the engine bay is now a nightmare. I figured it was time to retorque all the header stud nuts, since it has several heat cycles on the new exhaust gaskets now. Had to take the wastegate dump tubes off to even get to 3 of them on each side. The second one back on both sides was still a nightmare to get to even then. Don't even want to think about doing a plug change in the future. Looks like that will require pulling the dump tubes and downpipes.
Thread Starter
Joined: Sep 2004
Posts: 4,905
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From: Stockbridge GA
The FIC 1000s showed up tonight, so I should be able to see how they work tomorrow night. If their flow sheet is to be trusted, the set is matched to within 1.7%. Even with that small difference, I still put the highest flowing injector in #7, lol.
Thread Starter
Joined: Sep 2004
Posts: 4,905
Likes: 906
From: Stockbridge GA
I started wondering how much the stock 2.25" catback with crush bends was hurting flow, so I looked around at aftermarket setups. Wal Mart lists the OBX 2.5" mandrel bend stainless catback for the 2004 GTO at $109.80. For that price I had to order. If I don't like the sound, I can always repurpose the pipes and mufflers for something else.
IMO "flow matching" is just a marketing thing to charge more. A few years back I bought a set of Holley 120# injectors. Before I sold them I sent them in to be cleaned and flowed. There was a before and after cleaning flow sheet, once cleaned and flowed they were all within 1.5% and actually flowed 135 lb/hr. I paid $450 on sale for a new set
