Ok, the LS1 starts out as a 346. And even the LS2 is only a 364. So SBC sizes like 1.75 and 1.875 seem about right.

However, there are a lot of 408, 427, 434, 441, and 447 LS1s also. Chevy big block sizes are more like 2 and 2.125".

Does anyone make/use headers like that on their LS1? How would you ever get them in an F-body or Y-body?

Thanks,

David

 

For stock cubes 1-3/4" is the best size primary, for bigger cubes 1-7/8" will really help the engine breathe. I don't believe there are any bigger, nor would you need bigger for the LSX platform.

 

Someone and can't remeber who posted that 1-7/8 picked up 12 HP across the board compaired to 1-3/4 on a stock motor. After I bought 1-3/4 I picked 17 HP peak

 

Depends on the cubes and the revs. Either is small for a 447.

 

kooks makes a 1 7/8 stepped to 2"

 

Does anyone use it?

 

somebody just posted pics like a week ago, you can PM and ask for results when there done installing them if he hasnt already.