Thread: Lt4 blower swap
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Old 01-19-2020, 08:40 PM   #36

Drives: SS 6 speed of course
Join Date: Jan 2016
Location: austin
Posts: 3,436
My engine still has cam and ported heads as well as a slightly lazy centri (d1x), I'm comfortable at 10 PSI on 93 with forged pistons.

I have not looked into pullied 1.7 on a stockLT1 engine, I think the LT4's stock boost is in the high 9 range, so we know what GM believes. I would look at a shop or somebody that has the car and see what they think. There have to be many guys now with this setup. IMO I like only builds capable of 100,000 miles. My first build was temp till I retired and even then within 5k or so miles I had a lifter failure. No bigs as I was going to change the cam and lifters on the rebuild, but scary it could have taken out the engine. My pistons look fine... mint in fact, don't know if I was lucky. Nut shell even at stock LT4 boost, you are starting with an engine with higher CR and cast pistons, at some point getting rid of pumping losses makes more sense vs boost.

I do think the front cats are very restrictive and will be putting in CA front cat deletes with Borla 60608 twin resonator mid-pipe (hope this keeps the sound near stock. If this does not work, I will put two high flow cats into the system, bringing the total to 4 cats, two resonators, two crush pipes, stock exhaust pipe. At some point, it has to be quite? I have tried 20 different combinations to find something I'll be happy with over the life of the car (1 to 20 years).

IMO this would be my first mod after blower; my only issue with any upgrade to the exhaust is my M6 car with my mods sounds terrible with no cats and just plain heck of loud with LT and cats. I'm looking for something fast but near-stock at 45 MPH or completely stock.
2016 to 2017 Stage 1, FBO, ported MSD, 103 TB, E85

2018 Stage 2, P1C, 4.0 pulley, Pray ported heads, Pray stage 1 blower cam, TxSpeed valvetrain, Katech ported 87mm TB, ported MSD, 1 and 7/8 headers

2019 stage 3: Forged short block 11.5 CR, huge duration sub .600 lift Cam Motion cam, Pray Ported Heads, 3.85 pulley D1X, stage II intercooler, 2 BOVs, DSX secondary low side, DSX E85 sensor, Lingenfelter big bore 2.0, CA-offroad pipe, 60609 Borla, Lingenfelter injectors, ZL1 driveshaft and half shafts, Katech ported TB,MSD intake, BTR valvetrain.
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