Restrictor Plate calculations
Thread Starter
Pro
Joined: Dec 1999
Posts: 673
Likes: 0
From: Venetia,Pa,USA
Restrictor Plate calculations
If I wanted to reduce HP by a given amount is there a calculation that relates to the area of the throttle opening. As a example :
engine HP 400
twin 58 mm throttle body
Lets say I want to drop 10 HP [ 2.5% ] would dropping the throttle area [ A = pi r sguared ] by 2.5% work??
Why? In one of the racing series I run in I need a 9 lb / HP. Other series no limit. I know I could adjust tlming however it is just as easy to slip in a restrictor plate.
Thanks for info
engine HP 400
twin 58 mm throttle body
Lets say I want to drop 10 HP [ 2.5% ] would dropping the throttle area [ A = pi r sguared ] by 2.5% work??
Why? In one of the racing series I run in I need a 9 lb / HP. Other series no limit. I know I could adjust tlming however it is just as easy to slip in a restrictor plate.
Thanks for info
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
I don't think you could use a formula to calculate hp loss because there are a number of other variables involved. Also it your motor is speed density, restricting the intake could result in a rich condition. The motor is in open loop at wot and the fuel parameters are determined by the map sensor and the throttle position sensor. If you have a maf sensor, that is a different story. You'll just have to experiment on a dyno.
Melting Slicks
Joined: Sep 2008
Posts: 2,376
Likes: 111
From: Cherokee National Forest TN
Be easier to add weight to meet the spec. You then have the option to put the weight where it will do the most good. IE: on wheel scales if your light @ the right rear put it there. Keep the added weight between the front/rear wheels. You don't want more weight behind the rear axle or in front of the front axle. Think pendulum.
