4 into 2 V8 exhaust?

[Alex]

I was discussing exhaust building with the guy who'll be doing my superlite's exhaust, and one suggestion he had was, instead of merging the headers 4 into 1 was to do a 4 into 2.

I've never heard of that before (i know there's 4 into 2 into 1, but this would be just 4 into 2 with 2 pipes total exiting each side (instead of 1 total on each side). Would there be any benefits to doing that? Would it be raspy? More exotic toned? Torque loss? I didn't know how to answer it because i've never heard of that idea before.......

 

[Terry Oxandale]

deleted

 

[Terry Oxandale]

deleted (need coffee)

 

[Doug S.]

When Shelby built up the 289 Mustang into the Shelby GT350, he used "Tri-Y" headers...essentially a 4-into-1 system on each side.

The Daytona Cobras used a 4-into-2 system...two sidepipes on each side.

Both systems worked well....preserved the low-end torque and allowed the engine to breathe well enough that it could rev well with the intake upgrades Shelby also used.

The two external mods (intake and Tri-Y headers) raised the reported output of the K-code 289 from 271HP to 306HP....but, we all know Shelby did other things, not quite sure what they were, but the GT350 sure ran better than any 306HP engine I'd ever seen. Perhaps it was the chassis mods that helped it?

Cheers!

Doug

 

[Ron Earp]

Two recommendations: call Burns Stainless and get them to model the system for you and tell you how to build it for what you need, and get PipeMax and do the same.

 

[Thomas Rouw]

altough Burns absolutly know how stuff works this offcourse is cheating for the self builder.

This Entirely depends on the firing order of the engine used, figure out which pulse comes at which time and try the place the most opposite pulses of the system line up against eachother in the Y piece.
the end result in doing this will for a crossplane v8 be 180degrees headers / cross headers / bundle of snakes.

the pusles in a crossplane v8 don't line up very well for use of a 4-1 per bank. although through the lower rpm range of these engines the result is not that big.

the thing you want to chase is called "scavange effect".

grtz Thomas