Does a drag race only car need exhaust boxes?
My 340 drag only dart has exhaust cut outs with plates that unbolt.
The car was ran on a rolling road for a base line figure and the afr showed a steady 12.
The car then had 2 runs with the cut outs opened. Afr dropped to 11 and then 10. Hp was down 5% and torque down 10% on both runs. Carb is a 750dp. If the carb was rejetted to get the afr back to 12 would the hp and torque be better with the open exhaust or does a car make more power with exhaust boxes over an open exhaust? Or do I need a bigger carb? I suppose what I want to know is what is going to make the most power, an open exhaust or one with boxes or is it not that simple?
From the header, where the 4 tubes connect is called the collector. From here, the length of the collector will dictate the amount of low rpm torque the engine will make. Top end power may increase slightly.
The length of the collector should be tested on dyno for best length to maximize torque. Once this is a know length, you can run it open or add a torque cancellation box and then continue with exhaust pipe to where ever you want to end the system.
If you want to add a muffler, the muffler itself must flow at least 1.2 the amount of cfm flow as the HP the engine makes in HP.
I suggest a center in and out muffler for the path of least resistance. This should very well create a zero loss exhaust system.
A car that runs 12’s is kind of broad. High 12’a or low 12’s?
In general, getting into the 12’s requires approximately 400hp.
Search for a muffler that flows a minimum of 400+ cfm. Then pick up a pair for the car.
AFAIK, or remember, there isn’t a turbo muffler on the market that flows 400 cfm. Perhaps dynomax?
Hookers Aero Chamber flows 441.
AFAIK, the straight through glass pack style muffler like ghe Hooker or Dynomax “Max Flo” mufflers are able to move 1,000 cfm.
If an exhaust box is a muffler then no, you don’t need that.
You need a 36 inch collector extension.
If an exhaust box isn’t a muffler then I haven’t a clue what the hell we are talking about.
The exhaust box, IMO, of which he is talking about is a pressure wave cancellation box.
I don’t know how you come up with a blanket statement or needing a 36” collector extension. The extension length should be dyno tested. It will vary in length per each engine tested due to changing perameters of each engine. Ending with the header used.
