I was reading posts about exhaust systems and suddenly realized there was something I didn't know! (hah, yeah right).

My exhaust system is dual 2.5 inch pipes leading to twin Borlas, (never the twain did meet) What's the advantage to having a crossover pipe?

Does it creat a pulse which assists in scavenging, or....what?

 

H crossover equalizes pressure, increases effective exhaust pipe size, some reduction in sound level.

X crossover will do all these better. See Dr. Gas.com

 

You're behind the times-- an X pipe is the must-have option- looks great for those on the lift pictures!
If you believe all that you read (from the guy takin' your money) they provide everything from horsepower to smoother sound.

I honestly don't know.

 

Based on exhaust scavenging, pulses from one side create a low pressure in the other side ( vacuum or sucking ) as they go by the crossover making a lower resistance path for the next pulse from the other side theoretically freeing up more HP

 

I do I changed a non-balanced dual exhaust system to one with an "H" pipe. The engine felt smoother with better "pick-up" afterwards. It wasn't a huge "WOW!" effect, but it was there. The exhaust note is much more mellow, nowhere near the harsh sound it was before, & is slightly quieter (it'd probably be a lot quieter if the mufflers actually muffled!). Power supposedly increases (5hp for "H", 8hp for "X"?????), but I couldn't say whether I noticed any gain or loss. Another big advantage is that there used to be an irregular popping in the exhaust at idle, that isn't there with a balance pipe fitted. This might not be heard with decent mufflers, but was very noticeable with my "mufflers". Apparently this is due to the irregular scavenging/pressure between the 2 banks of cylinders.

I've done the opposite on my bike & swapped out a balanced system for an unbalanced one. The results are surprisingly different from the Vette, apart from one thing - without the balance pipe the exhaust volume went through the roof. The balance pipe that was on it is equivalent to an "H" pipe, but it was fitted about 2" in front of the exhaust ports ie just about at the point where the exhaust gas is at its highest velocity. Even at high velocity the gas is making a 90* turn into the balance pipe & then another 90* turn into the alternate exhaust pipe. The model of bike used to be sold with unbalanced pipes (seems to run better, in complete contrast to the Vette), but a balance pipe was fitted to adhere to noise restrictions (each cylinder is breathing out via 2 mufflers with a balance pipe fitted).

 

I have straight back dual exhaust and I opted not to install a crossover pipes when I changed the mufflers to Flowmaster Delta Series 50's last spring. I did this for three reasons:

1) I really don't care about the few extra HP's. This car has plenty of kick already.

2) I wanted a more agressive exhaust note.

3) I didn't want to carve up the beautiful SS pipes to insert the X-pipe. More cutting and welding creates more chances of stuff going bad in the future.

 

I went to an X-pipe on a big block years ago and not only did it sound quieter, it felt like I LOST some low end torque. I got rid of it. I just did a 2 1/2 inch system on my 68 BB. No X-pipe for me any more.

 

Is there a specific location that the cross pipe should be installed. I.e. close to the headers, mid length of system or close to the mufflers?

Does the location effect the performance?

Bill

 

Yes - but it's better just to have a crossover somewhere than none at all. Here's a great article which covers everything - the second page has the crossover stuff.

Of course, I don't have a crossover because of my sidepipes.

Exhaust Science

 

i recently went from side pipes to undercarriage exhaust sistem, 2 3/4'' diameter all the way, and a nice X pipe just ahead the crossmember and 2 delta force 40 mufflers, what i've noticed?

1) i lost some torque up to 3.000/3.500 rpms, but maybe it's due to the 2 3/4 large bore pipes...clearly noticeable power increase all the way from 3.500 rpm to over 6.000 rpm..

2) sound: beautifully deep mellow and aggressive at a time, it has a deep throuty and metallic thunder scream (570hp from a 406ci powerplant) over the top rpms...

if you want to be critic...you can say it sounds a bit 'japanese'... like a modded 600hp subaru...

ok ok you can flame me some but leave me alive and take me to the hospital afterwards

 

For what it's worth...I was told by 3 exhaust pro's that an 'X-pipe' is a little better then an 'H-pipe' in theory. They also said that on C3's an 'H-pipe' is better because for an 'X-pipe' to work properly it MUST be close to the collector, and on C3's you can NOT get close to the collector be be effective. So I'm running duals with an 'H-pipe'.

 

Well..... The majority seems to favour the X pipe, but then some are reporting a slight loss of torque, and most say a quiter exhaust.

Is the added cost and labour worth adding in a crossover? So far I'm leaning towards the NOT.

My 2.5" duals sound great to me. Definitely not overly loud. Secondly, the gain in HP and potential loss in torque doesn't seem to be worth the effort.

I think I'll stay with what I've got for now.