Building a new ca build LM4
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Joined: Aug 2023
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From: REDDING CA
Building a new ca build LM4 IM getting ready to build a new engine for my 2004 chevy trailblazer ext ls that was the 5.3.LTR lm4 and was wondering what would be a good cam to go with that will pass smog with a small but noticeable lope and if you had and information on what the stock cam specs are. i am gonna do a randr on the motor so new rings barings and pistions later down the road i wanna do a stroker but hard living in ca with all the dumb smog rules.. any tips and advice would be greatly appricated.
If your in Cali, you cannot touch the tune. They check that. Your pretty much stuck with stock out there, even though I’m 1000% sure an engine can be built and tuned to be more efficient than an OEM one. Do what a lot of folks are doing and get the heck out of Cali if you want to mod your stuff. Plenty of room in this country for moving around.
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Joined: Aug 2023
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From: REDDING CA
If your in Cali, you cannot touch the tune. They check that. Your pretty much stuck with stock out there, even though I’m 1000% sure an engine can be built and tuned to be more efficient than an OEM one. Do what a lot of folks are doing and get the heck out of Cali if you want to mod your stuff. Plenty of room in this country for moving around.
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Joined: Jun 2016
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From: Central Cal.
You can tune your ECM for in Cali. You just gotta put the stock tune in it when you go and smog it.
Do you happen to know the stock cam specs of a lm4. I thought about putting a bigger throttle body in it with intake and exhaust and tune till I build my motor.
Do you happen to know the stock cam specs of a lm4. I thought about putting a bigger throttle body in it with intake and exhaust and tune till I build my motor.
The LM4 cam is the same as the LM7- 191/190, .457/.466, 114 LSA
Having said all that, if you can find a LQ9/early LQ4 cam (196/201, /467/.479, 116 LSA), it CAN be used without retuning. NOT optimum, but it will still show improvement you can feel.
The stock 78mm throttle body is all the 5.3 needs. Going bigger does nothing.
The stock truck intake is actually pretty good. Only a TBSS intake would really improve it, and not by very much.
Do NOT get a short runner sheet metal intake. They lose power all the way to 5K RPM.
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Joined: Aug 2023
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From: REDDING CA
i wasnt gonna fully returne the ecm just throw a parogramer on it. and i was thinking of putting a bigger throrrle body on it so it would be ready when i build my 6.0 stroker.the cam you told me to go with sounds like a good idea. do you think it would have the sound of a bigger cam or just as smooth as stock.i know its hard to get a cam that gives you a nice lump at idle and still pass smog here
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Joined: Oct 2016
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From: PDX-OR-USA
A friend of mine's solution was two motors, he has a low mileage stock engine and ecu and dash that he swaps out with a built engine/ecu/dash for inspection.. sick amount of work to beat the system. Its in a truck I cant imagine how painful it would be in a car...
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