Low Speed Pulsing
Thread Starter
Racer
Joined: Jan 2001
Posts: 425
Likes: 0
From: Frederick MD
Low Speed Pulsing
When driving around a parking lot at low speeds, in first or second gear (manual) and the rpms are around 1500-2000 the car seems to have a slight pulsing, hard to describe, almost like you are quickly alternating pushing the gas pedal and then pushing the brake. Noticed it slightly before, but after the HotCam install seems to be more noticeable. Not sure if it's a problem and if so where to start. Thanks.
Drifting
Joined: Jan 2002
Posts: 1,606
Likes: 1
From: Las Cruces NM
Re: Low Speed Pulsing (tdock)
A pulsing feeling is typical on LT1's and LT4's. This is due to the extremely short runners. It is usually noticed in the range you are feeling it, around 1500-2000 rpm. My LT1 Trans Am does it noticably right at around 1700 or 1800 rpm. The hotcam, because it's a more aggressive cam, the valves are going to be open longer, so you would notice this pulsing feeling more. I wouldn't worry about it. It is considered normal of the LT style motors.
If it gets worse over time without you doing anything to the motor, like heads or something like that, then it would be worth worrying about.
Chris
If it gets worse over time without you doing anything to the motor, like heads or something like that, then it would be worth worrying about.
Chris
Race Director
Joined: Sep 2001
Posts: 14,676
Likes: 751
From: NEwhere Ohio
Re: Low Speed Pulsing (tdock)
I have the hot cam too, and get this same feeling at low speeds. basically the car (With the more aggressive cam) does'nt want to be driven slow.....
Driving in reverse up a hill slowly is hard with the hot cam.............I might add
Driving in reverse up a hill slowly is hard with the hot cam.............I might add
Burning Brakes
Joined: Feb 2002
Posts: 1,232
Likes: 28
From: South Riding VA
Re: Low Speed Pulsing (tdock)
I'd have to agree with okinawa86vette, engine pulsing at low RPM is one of the drawbacks of short fat runners. Its due to the effect of pulses from one cylinder slightly disrupting airflow into another causing slight variations in the power produced in each cylinder from one firing to the next. Longer runners tend to isolate each cylinder from the others and minimize flow disruptions. It is definately felt in the LT1 motors and I believe the LT4 runners are similar.
Mike
96 CE - LT1 Stock
Mike
96 CE - LT1 Stock
