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Discussion Starter #1
So back in April my SS went down while on vacation at the beach. I decided to build a 408 rather than rebuild the LS2. I worked on it on off days I had free. I learned alot and enjoyed it. I had only built 4G63s in the past, so this was all new to me. Here are the deatils.


LY6 block. (No issues with knock sensors or bolt holes.)
Callies forged assembly with -2.2 diamond pistons.
Melling oil pump with PCM pick up tube kit.
I used my 243 heads and had a valve job done on them only.
PAC 650 lift kit, 7.4 push rods.
Attitude V3 cam from PCM.
FAST 33lb hr injectors.
I used LS9 head gaskets.
I used my stock TBSS intake with a PCM 4" FWI.
LS1 fans from PCM.
Stainless headers and Y-pipe from Huron.
PCM wires and boots. TR6 plugs.
Level 5 FLT trans with trans cooler.
Circle D 3000-3200 stall.

Here is a short vid of the new set up before tuning and some attached pics.

https://youtu.be/ixrNl8HiM_Q
 

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TrailblazerSS
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Discussion Starter #3
Thank you. I'll update the thread with Hp ratings tomorrow when I get it back.
 

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TT AWD TBSS Jeep
TT AWD SS Pwrd Jeep
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Just an FYI - you cant use the old style knock sensors, they read and output different than the LS2 ones do. I welded a nut to side of block and reused the LS2 sensors in same place. Others have bolted the LS2 sensors up top, just curious how you did yours. Hoping you didn't just cut an splice the wires as that will not work right.
 

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Just an FYI - you cant use the old style knock sensors, they read and output different than the LS2 ones do. I welded a nut to side of block and reused the LS2 sensors in same place. Others have bolted the LS2 sensors up top, just curious how you did yours. Hoping you didn't just cut an splice the wires as that will not work right.
The LY6 block is a gen IV block so they are also located in the sides of the block.
 

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Discussion Starter #8
So I have been driving it a couple days now. I do have an issue with stabiltrak flashing on if I do any spirited accelerating. It will just do a quick little blink then disappear.

Another issue I am having is false knock at start up. I assume its from the stall. I'm not real sure yet. I can start it up, get the CEL, check it, delete it, and drive as normal and it never come back on until I restart it.

The Huron speed headers fit pretty well, the passenger side collector is a bit close to the frame. It doesn't hit so Its okay.

I absolutely love it! It is a different vehicle all together. It rides and shifts great, the FLT trans is super smooth. The Circle D stall seems to be a bit higher than I anticipated, but is not bad at all. Maybe bonus time next year I will upgrade the heads and cam and squeeze some more power out of it.
 

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Could the headr be hitting the frame at startup causing false KR?
 

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The false knock from a stall is from companies cheaping out on the clutches that don't lock up smooth from what I understand. Shouldn't cause anything at idle.
 

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Discussion Starter #11
I got with my tuner today. We hooked up the lap top and drove around a bit. It was throwing a code knock sensor circuit low input. We figured it must be a bad wire connection or a ground. I get back and crowl under and take all the grounds off and use a Dremel to clean them up. The ground that's on the driver side knock sensor harness got its own grounding spot on the block. I've driven it 5-6 times and started it 10 or so and it has not come back up.

We looked for the stabiltrack light issue but it would never show up on the lap top. Only on the DIC. He is researching it for now.
 

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Discussion Starter #12
Knock sensor circuit low input keeps popping back up....... this is annoying.
 

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Discussion Starter #16
I dropped the headers and found where it was hitting the frame, corrected that. So the false knock is gone. Now I have an issue with the motor pinging when I accelerate. It's far worse on hot days vs cool mornings. I've searched high and low for intake leaks etc and can't locate any. Talked to the tuner today again and we are going to throw it back on the dyno and see what we can figure out. I spoke with some other people and he suggested that maybe the 33# injectors couldn't feed the 408. This thing has never ran 100% since the swap.
 

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I dropped the headers and found where it was hitting the frame, corrected that. So the false knock is gone. Now I have an issue with the motor pinging when I accelerate. It's far worse on hot days vs cool mornings. I've searched high and low for intake leaks etc and can't locate any. Talked to the tuner today again and we are going to throw it back on the dyno and see what we can figure out. I spoke with some other people and he suggested that maybe the 33# injectors couldn't feed the 408. This thing has never ran 100% since the swap.
I'm curious whatever came of this I'm doing a ly6 and just a cam stall 4 inch intake long tubes.
 
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