Bracket Talk
Carburetor restrictor plate with a roots blower?

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April 26, 2024, 01:11 PM
Jason Haley
Carburetor restrictor plate with a roots blower?
Will running a restrictor plate with a blower hurt anything? I have a few index races this year that I want to run. The car is several tenths too fast with the blower, but will be several tenths too slow without the blower.


Slow S-10
Slower Cutlass
April 26, 2024, 01:39 PM
Jonesz
Change pulley? Lower timing? I think either would be a better option
April 27, 2024, 08:47 PM
NEMO963
Never intentionally restricted the inlet side but have changed adapters from more restrictive to less and picked up a decent amount of boost. Some overdrive numbers prefer a smaller opening so depends on the combo. Agree that lowering your overdrive, reducing timing, shifting earlier is probably a better option.


2015 M&M T/D
Nemo
Duty-Pride-Tradition
FTM/PTB
April 28, 2024, 09:51 PM
seabass
a good air filter?


J.R. Baxter

""Fathom the hypocrisy of a Government that requires every citizen to prove they are insured ..but not everyone must prove they are a citizen."

2024 Miller
Rolla Competition Engines
ProCharger
Hoosier Tires
Abruzzi
April 28, 2024, 09:51 PM
seabass
slowing the blower would be the best option imo


J.R. Baxter

""Fathom the hypocrisy of a Government that requires every citizen to prove they are insured ..but not everyone must prove they are a citizen."

2024 Miller
Rolla Competition Engines
ProCharger
Hoosier Tires
Abruzzi
April 29, 2024, 12:17 PM
BJs Wild Ride
Could definitely speed it up with a restrictor plate if you aren’t careful. I’ve had two different blower combos that picked up .1 - .2 to the 1/8 by restricting the blower inlet. The first time I was trying to slow that car down. The second time I was actually trying to speed it up and it worked
April 29, 2024, 05:57 PM
wideopen231
Agree with those saying just slow the blower. Less boost,less lower air temp and less we33ar on blower.Souynds like win, win and win if wanting less air.




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April 29, 2024, 10:47 PM
Goob
quote:
Originally posted by BJs Wild Ride:
Could definitely speed it up with a restrictor plate if you aren’t careful. I’ve had two different blower combos that picked up .1 - .2 to the 1/8 by restricting the blower inlet. The first time I was trying to slow that car down. The second time I was actually trying to speed it up and it worked


That's very interesting.....
Would that indicate that fuel delivery was lacking?


"Despite the high cost of living, it remains popular."
Dave Cook
N375
April 30, 2024, 03:26 PM
BJs Wild Ride
If you have a fuel deliver issue on blown alky, it doesn’t usually show up as a small change in the time slip. Usually a little more dramatic.

No, roots blowers like airspeed. Just like an intake port. Seems like 500-600 fps is probably ideal. Anything faster and the power will just flatline. Anything below 300-400 and you aren’t filling the rotors completely. The promod guys figured this out a long time ago, but they always talk about opening size vs. OD. Well, that’s because the motors and blowers are all similar size. the real metric is opening size vs. mass airflow through the motor
April 30, 2024, 05:45 PM
Goob
I can get that logic, but the OP indicated it's a carbureted application. I assumed he was talking about an under the carb restrictor.
Don't know. Confused


"Despite the high cost of living, it remains popular."
Dave Cook
N375
April 30, 2024, 08:18 PM
BJs Wild Ride
Basically the same thing I’m talking about. I used a plate inside a hat once and a tiny single throttle body the other time. Will look the same to the blower as a restrictor under a carb
May 05, 2024, 09:12 AM
Jason Haley
Thank you everyone for the input. I ended up holding almost 4-5 tenths (it was a 1/4 mile race) and unfortunately that didn't work out very well for me.


Slow S-10
Slower Cutlass