Just like the title says is back pressure good or bad for an LS1?

 

If "back pressure" was good people would be making their exhaust as small as possible...

What do you think?

lol cmon

 

Back pressure is never that good for any engine. Think about it, if you have more pressure in your exhaust system, there is going to be less of a pressure differential between your cylinder pressure and your exhaust, and less cylinder gas is going to want to leave when that exhaust valve opens. So, do you think that would be good or bad?

 

What they said above.

What makes more torque over more HP as far as exhaust is concernd is velocity. Smaller pipes = more velocity= more bottom end (torque). Larger pipes = less velocity but more flow = more top end (HP). Some closet genius came up with the concept that it was back pressure since smaller pipe creates BP also and other dumb a$$es, I mean closet geniuses agreed so the myth grew.

Either way its always a balance between the 2. Don't want too small or too large.

 

I've got longtubes and 3-inch true duals on a stock cube/stock cammed LS1 like many others and have pleanty of torque (12.5@109mph 1.7 60'). That's about as little back pressure as you can get (aside from cutouts).

 

some of my cousins are like that in the old school way of thinking. when i told him about exhaust when i had a cutout, he like " what!?! dont you want any torque? no backpressure is no torque!"

 

David Vizzard suggests running less than 5 psi of back pressure. My last combo ran right at 5, and I'm sure my current [LS1] is a lot less than that.

Point is, less is more. Keep exhaust system pressure minimal and certainly below 5 psi @ top engine speed in gear.

If your exhaust makes more than 5 psi (listen up Flowmaster people) then install&open a cutout when racing.

cutouts = = no exhaust pressure

Ben T.