Lt1 cam intake center line?
09-07-2003, 04:09 PM
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Car: 1991 Firebird
Engine: 383 stroker
Transmission: T-56
Lt1 cam intake center line?
Anyone know what the intake center line is for the Lt1 cam?
Tom
Tom
09-08-2003, 08:25 AM
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Car: 1991 Firebird
Engine: 383 stroker
Transmission: T-56
Originally posted by Vader
"The" LT1 cam? What part number? There were about 4-5 of them from the factory.
"The" LT1 cam? What part number? There were about 4-5 of them from the factory.
Tom
09-08-2003, 12:44 PM
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Car: 1991 Firebird
Engine: 383 stroker
Transmission: T-56
Thanks for the info Vader. I don't even see the numbers for the specs that I found...kinda weird. But anyway..what I'm trying to is track cylinder pressures using DD2000, but the only way to get it close enough is to know LCA so I can find the intake closing point ABDC. I'm trying to decide what chamber heads I should order. So I figured that I'd try and track the cylinder pressures of an LT1 since I know that they run on pump gas with aluminum heads and 10.5:1. So with my big cam, if I can still keep the cylinder pressures close to that of an LT1, I should be fine right?
Tom
Tom
09-08-2003, 04:44 PM
#6
Tom,
My '94 LT1 with iron heads (Impala) runs 10.8:1 on pump gas and a Comp Cam that is beyond the LT4 "Hot" cam in lift and duration. The major reason is not the heads (mine are modified/ported stock cast iron with bigger valves), but the PCM. The newer PCM will monitor every spark, sequence the injectors individually, monitor knock on a cylinder-by-cylinder basis, and alter ignition timing and fuel rate differently for each cylinder according to feedback. Our older ECMs only look for general conditions of detonation (knock) and alter the overall timing and fuel, not on a cylinder-by-cylinder basis. That alone allows the LT1s to run on 87 octane fuel at 10.5:1 stock CR - aluminum or iron.
My '94 LT1 with iron heads (Impala) runs 10.8:1 on pump gas and a Comp Cam that is beyond the LT4 "Hot" cam in lift and duration. The major reason is not the heads (mine are modified/ported stock cast iron with bigger valves), but the PCM. The newer PCM will monitor every spark, sequence the injectors individually, monitor knock on a cylinder-by-cylinder basis, and alter ignition timing and fuel rate differently for each cylinder according to feedback. Our older ECMs only look for general conditions of detonation (knock) and alter the overall timing and fuel, not on a cylinder-by-cylinder basis. That alone allows the LT1s to run on 87 octane fuel at 10.5:1 stock CR - aluminum or iron.
09-08-2003, 04:52 PM
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Car: 1991 Firebird
Engine: 383 stroker
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Well there's a difference between being able to compensate for detonation(engine managent), and actually setting up to prevent detonation. I'm not gonna be running a factory ECM anyway. I'm using the Holley commander 950 with the HSR but I haven't put it together yet so I'm not sure of it full tunability, but I'm sure it's better then a stock ECM, especially with the ability of tune on the fly.
Tom
Tom
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