Question for those that have changed primaries on LP640

I am gearing up to replace the primary cats on my 6.2 with either cat bypass or sport cats intended for a LP640 that has the extra branch with the valves. I have heard it's a lot easier to change out the primaries on the 6.2 than the LP640 because you have to remove the engine accessories on the LP640 to get out the primaries.

 

My questions is why do you have to remove all that stuff on the LP640? Is it because of the extra branch on the LP640 primary cats with the valve makes it too long and bulky to get out without removing the accessories, or is it because the engine accessories are laid out differently in the LP640 and they would have to be taken off even if the LP640 primaries weren't longer?

 

I'll be able to get my OEM primaries out a lot easier than it would be on the LP640, but I am worried I won't be able to get the new parts in without a huge project. If I go without cats on the primaries, it will be a lot easier to maneuver with a thin pipe than bulky cats, but even if I go with sport cats, the cats will be significantly smaller in diameter than OEM to give me more wiggle room (pic). If it's a super pain to put in the sport cats, I'll go the route of catless primaries, and put back in my secondary OEM cats.

 

Not to distract from this specific topic, but if you're wondering, I am doing this so I can create my own remote controlled muffler bypass on the 6.2L to have the best of both worlds; quiet and beast mode.

 

TIA

Gotta love the internet. I found pics of an LP640 with a valved exhaust with the same muffler as mine being converted to Fabspeed.

 

http://www.ferrarichat.com/forum/lamborghi...ed-exhaust.html

 

Comparing the pic of the LP640 with the muffler removed and my 6.2, it seems very clear that my overall idea will work.

 

But looking at the pics, I can't figure out why the LP640 needs to have the engine accessories removed to get out the primary cats while the 6.2 doesn't. Can you?

 

Is it the bracket in the way on the AC compressor on the driver's side? That looks like that is a little more obtrusive than on the 6.2.

It looks like the sway bar is different in the middle to clear the center diff, which has a different hose compared to the pre-LP picture.

 

I was able to get my pre-LP primaries out without removing the accessories, but it was TIGHT and my car was on a lift, which was needed to get the pipes out (100% vertical coming out the bottom of the car.)

Never really thought of this before (not studied a drawing as shown in this thread) but if you have an aftermarket muffler and 2nd cat delete on a 640 unless you keep the valves shut all the time the path of least resistance would seem to be straight from the valves to the exhaust tip?

In essence when valves are open you might as well not have an aftermarket muffler?

 

I'm sure the above is incorrect as my LOC exhaust made a difference from when I had stock muffler with valves open.

Never really thought of this before (not studied a drawing as shown in this thread) but if you have an aftermarket muffler and 2nd cat delete on a 640 unless you keep the valves shut all the time the path of least resistance would seem to be straight from the valves to the exhaust tip?

In essence when valves are open you might as well not have an aftermarket muffler?

 

I'm sure the above is incorrect as my LOC exhaust made a difference from when I had stock muffler with valves open.

It looks like the sway bar is different in the middle to clear the center diff, which has a different hose compared to the pre-LP picture.

 

I was able to get my pre-LP primaries out without removing the accessories, but it was TIGHT and my car was on a lift, which was needed to get the pipes out (100% vertical coming out the bottom of the car.)

 

 

Thanks!

 

It looks like if you remove the sway bar there's tons of room to come back, up and out with the primaries?

Never really thought of this before (not studied a drawing as shown in this thread) but if you have an aftermarket muffler and 2nd cat delete on a 640 unless you keep the valves shut all the time the path of least resistance would seem to be straight from the valves to the exhaust tip?

In essence when valves are open you might as well not have an aftermarket muffler?

 

I'm sure the above is incorrect as my LOC exhaust made a difference from when I had stock muffler with valves open.

 

I could be wrong about this because I don't own an LP640, but I believe the reason the LOC made a difference is because you don't have manual control over the valves, so you are often using the LOC exhaust because the valves are closed. Opening the valves bypasses the secondary cats, so I would imagine Lambo was not able to give you manual control to do that at RPMs when the secondary cats are needed to clean the exhaust.

 

Do you guys have a button to control the valves? Even if you do, I doubt it will stay open all the time, similar to the way the bat wings don't stay open all the time.

Thanks!

 

It looks like if you remove the sway bar there's tons of room to come back, up and out with the primaries?

 

I'll let you know when I dive into it next week.