standard exhaust crossover modification

[charley]

I recently purchased a used crossover and thought about cutting it open and reworking it . Has anyone done this and is it going to improve performance.

[Skeeve]

I recently purchased a used crossover and thought about cutting it open and reworking it . Has anyone done this and is it going to improve performance.

 

It has been attempted in the past. The stock, under-tranny x-over is more a "pre-muffler" than a true cross-over: the volume is just too dang large, so all the exhaust gases come chonkin' down the headers at high speed, hit that big open space & come to a halt, then meander down the extremely restrictive stock mufflers based upon the higher pressure in the pre-muffler bit & pressure pulses from the exhaust hammering those stagnant gases further down stream. [Yes, this is a bit of hyperbole, but play along for a bit, it gets better. ]

 

If you open the stock x-over & pull out the central metal sponge space filler, you make the description above even more accurate, spoiling performance. Dyno tests have shown that the Stucchi x-over [which is designed to be a true x-over] has a slight improvement in the low-rpm hole in the power band, and also a slight improvement in top end power, with a raspier exhaust note.

 

The Mycroft Holmes [sorry, forget the name, but it's the other big alt. to the Stucchi, and starts w/ an "M"] x-over has almost no actual gas x-fer, & is more of a balance pipe [meaning sonic & pressure sharing, but no real joining of flow], does a better job of filling in the low-rpm hole but loses power on top in comparison to the stocker.

 

Ultimately, it has been clearly demonstrated that:

 

1) Dr. John did a very good job of coming up with a much more cosmetically appealing, but still quite adequate performing, alternative to the old "colostomy bag" x-over on the mid-90s Spot, Sporti & Daytona x-over.

 

2) If you want all out power or a more threatening exhaust note, you buy the Stucchi.

 

3) If you want to fit a centerstand or a more compliant throttle in traffic or just noodling around, you get the Myocardial infarction x-over [still haven't remembered the correct name... ]

 

4) It is ultimately pointless to mess around with the stock exhaust parts when pursuing performance enhancement: they were just designed too dang well upon European "don't mess with city hall" principles.

 

 

Ride on!

[pasotibbs]

I recently purchased a used crossover and thought about cutting it open and reworking it . Has anyone done this and is it going to improve performance.

 

It has been attempted in the past. The stock, under-tranny x-over is more a "pre-muffler" than a true cross-over: the volume is just too dang large, so all the exhaust gases come chonkin' down the headers at high speed, hit that big open space & come to a halt, then meander down the extremely restrictive stock mufflers based upon the higher pressure in the pre-muffler bit & pressure pulses from the exhaust hammering those stagnant gases further down stream. [Yes, this is a bit of hyperbole, but play along for a bit, it gets better. ]

 

If you open the stock x-over & pull out the central metal sponge space filler, you make the description above even more accurate, spoiling performance. Dyno tests have shown that the Stucchi x-over [which is designed to be a true x-over] has a slight improvement in the low-rpm hole in the power band, and also a slight improvement in top end power, with a raspier exhaust note.

 

The Mycroft Holmes [sorry, forget the name, but it's the other big alt. to the Stucchi, and starts w/ an "M"] x-over has almost no actual gas x-fer, & is more of a balance pipe [meaning sonic & pressure sharing, but no real joining of flow], does a better job of filling in the low-rpm hole but loses power on top in comparison to the stocker.

 

Ultimately, it has been clearly demonstrated that:

 

1) Dr. John did a very good job of coming up with a much more cosmetically appealing, but still quite adequate performing, alternative to the old "colostomy bag" x-over on the mid-90s Spot, Sporti & Daytona x-over.

 

2) If you want all out power or a more threatening exhaust note, you buy the Stucchi.

 

3) If you want to fit a centerstand or a more compliant throttle in traffic or just noodling around, you get the Myocardial infarction x-over [still haven't remembered the correct name... ]

 

4) It is ultimately pointless to mess around with the stock exhaust parts when pursuing performance enhancement: they were just designed too dang well upon European "don't mess with city hall" principles.

 

 

Ride on!

Mistral

see Greg Field's review here