Well long story short, I have a Grand National with a stock 6.0-lq4.

Now for the long part of the story.

I swapped out my factory GN exhaust with a single 3" exhaust system which I made.

I have the exhaust manifolds from a firebird (for fitment).

My concern is with my Y-Pipe.

Essentially, my exhaust pipe(2-1/4") on the drivers side comes down and back just enough to cross under the torque converter.

Then it goes strait across and merges side by side with the Passenger side exhaust pipe(2-1/4") directly into a 3" pipe(which is made oval to match up). It then goes back about 15" before meeting up with the rest of the 3" system, which continues back and over the axle and out the rear with a magnaflow 5X8 oval-14" long with 3" in/out at the end.

Biggest problem is the massive amount of torque that was lost from the previous system.

The previous system: drivers side same. except it T'd strait into the passenger side. (all 2-1/4") Then continued back for about 18-20" all collected in a single 2-1/4" before splitting into the factory GN exhaust of duel 2-1/4" over the axle into single muffler out to duels tips.

After the fact, I have now read up a lot on exhaust velocity and how important it is for tuning your torque curve regarding scavenging. However, I kinda need to know what lengths the y pipes should be when they meet or if changing the Y-pipe size is best or even returning to the single 2-1/4, for a certain length, before dumping into the 3"

Everything I have built has been turbo so all my knowledge for N/A is book stuff. I eventually will turbo this car but, in the meanwhile I want my bottom end back! This is a Daily Driver.

I hope this isn't too confusing I just typed while I was thinking.

Joe

 

to the top

 

Wow! No GURU's
OK

 

Pics would make it less confusing. I got lost reading it, but I have a short attention span.

 

Yea, in Hawaii right now, be back in a week or so. I just wanna get this figured out so I can jump on it when I get back.

I just need some data on what size pipe and how long they need to be before they merge into the 3".(for my stock 6.0)

Thanks

 

More torque is the idea.