[68Velle]

Anyone know anything about them?

People say to paint the exhaust, see where the paint comes off first, then put the x right there. Shouldn't this vary by rpm, sort of like how those velocity stacks on the intake side?

But then again, I read an article in mustang50magazine.com and a guy said to put the x pipe as far forward as you can, so it gets more heat and scavenges more. Any help would be splendid.

 

[4 Jaw Chuck]

It matters so little that people put the crossover where it fits on the car...usually after the crossmember and trans. The paint trick is "voodoo" science and is an old wives tale, you would need a dyno to find the optimum location/pipe diameter for your combination, you might be lucky to find two or three HP...assuming your dyno could read that accurately.

Put it where it fits.

 

[Siggy_Freud]

The idea of paint was the find where the exhaust was getting "backed up" thus creating more heat in that part. From my experience I have to agree with 4jaw and say put it where it fits. Unless your working on an old full size pickup its unlikely you'll have a variety of choices in location.

 

[snkbyt]

Man, I agree with Sig and 4 jaw completely. What you are talkn about is so insugnificant:drunk: Put the X over where it fits the best before the mufflers. The main thing on the Xover is the sound. Sounds like 2 four bangers without it. And real rappy.:thumbup:

 

[ratlover]

just finished putting a 3" exh with an X right behind the crossmember. (on a 67 chevelle)
Pros: seems to have improved performance, but that could be attibuted to the increase in pipe size
kinda acts like a driveshaft safety loop
Looks pretty cool
Cons: Does not have that nostalgic hot rod sound any more. has more of a new age muscle sound. Depends on what you are used to I guess.
Fabricated my own out of a 3" 180 degree bend. added another 40 bucks to the system, but I think the prefabbed units are upwards of $100-150.

 

[Old School Nut]

not to mention diffrent paints are affected by temp at diffrent temps (engine paint vs cheapo k mart paint)

 

[brainsboy]

not to mention diffrent paints are affected by temp at diffrent temps (engine paint vs cheapo k mart paint)

Yeah good point lol... just think if you use 1500 deg paint your cross member will be in your engine compartment

Ben

 

[Canzus]

The idea of paint was the find where the exhaust was getting "backed up" thus creating more heat in that part.

Actually, it finds the reversion point, or the point where the
hot gasses stall in the tube. It really does work...

 

[Siggy_Freud]

Canzus, hows is that different than what I said lol? Yes it does work however the added benefit from putting the crossover at THAT point is minimal enough that it hardly matters.

 

[Old School Nut]

what kind of paint would you guys use? also, wouldnt this point change with RPM and the ambiant temp? or maybe even density altitude? in theory of course... probobly not meashurable....

 

[GoneNova/406]

all the magazine articles i've read in recent yrs. (chevy hi perf.,super chevy,carcraft,hotrod magazine) all said 12-18'' behind the collectors.of the articles i'm refering to have since passed on to that archive in the sky so i don't have one to point you to right now,but i was looking earlier today and all the pictures i saw of exaust systems were close to that unless there just was room to do it that way.

 

[lluciano77]

Actually, it finds the reversion point, or the point where the
hot gasses stall in the tube. It really does work...

I just got the new Hot Rod magazine today. They have an article testing various collector lengths. They specifically said that the paint method never works for determining exhaust system requirements.

 

[Siggy_Freud]

So I guess the bottom line is that the paint DOES work in finding the hot spot on the tube, but the coorilation that has to finding the best spot for the x-pipe is nil.