Originally posted by robb99se:
SHO Sho did a dyno test with their Y Pipe on the MSDS and supposedly there was a significant difference.
The general consensus around here is (If I recall correctly)
1 MSDS WITH optomized Y best gains
2 MSDS With MSDS Y pipe SECOND BEST
3 MSDS with BAT/Sho Shop Y 3rd best


Shouldn't that be reversed? I'm not saying it should, just wondering, and I'd like to know.

I have both the MSDS Y-Pipe and the SHO Shop Y (Mystique & SVT). From looking at the stock Y-Pipe and the other two, it would seem to me that even after optimizing the Y you wouldn't be flowing as well as either of the aftermarket units, but that could just be appearances. I'm running the SHO-Y on the SVT because it's had a higher flow Cat, it's lighter and appears to flow better - I don't like the "V" bend in the MSDS and haven't done the fix.

Christopher Wong (CTA Motorsports) had some experiences with the SHO Y-pipes appearing to cause a lean condition in road racing situations, that he feels might be due to the very unequal runner lengths . I've kept an eye on mine and to-date my plug readings are fine (hope they stay that way ).

Also your statement,
Originally posted by robb99se:
But True Duals would give you the best gains overall

gives me some cause for thought . Optimal flow rate is typically achieved with fewer not more bends, less surface, etc., for any given tube sizing.

Running a single or "true dual" exhaust should have less effect on HP/TQ than the actual size and configuration of the exhaust itself. Running duals "true" or otherwise (my SVT has a Bassani) I've felt, and I could be wrong, is more for cosmetics than performance.

I see people here talking of going to 3" exhaust tube diameters for more power. All I can say is please do before and after dyno runs with no other changes, because I'd like to see some actual #'s. My thinking is that 3" is too big for a N/A SVT 2.5L. I don't know, but would think that 2.5"-2.75" properly done would be more than enough flow and larger would actually loose power.

When I was running my XR4Ti's (2.3L turbo) the best tuners in the US (whom I knew personally) were using 3" single exhaust and dynoing lower if they went to 3.25". Their 3" single exhaust was supporting 398 RWHP six years ago using a T3/T4 IIRC.

Power is made by properly managing the exhaust flow and that means dealing with many, many factors. The one that is often overlooked is the dynamics of the flow itself. With the XR4Ti's a 3" downpipe was the optimal size. Smaller and there wasn't enough flow. Larger and the flow was there but not in the best pattern. It would loose some of it's swirl effect and actually dyno lower.

Borla illustrated this very well years ago with their XR-1 Race Mufflers. IIFC, they dyno'd a Vette with a straight pipe on it and then with their muffler and the Borla muffler actually made more power than the straight pipe. From their website:
Quote:

from Borla.com
Q. Is a bigger pipe and muffler system better?
A. No, there has to be a balanced design to enhance the maximum engine output, exhaust gas velocity, and sound. If the diameter of the tubing is too large, the exhaust gas velocity will be reduced and rob the exhaust of thermal efficiency.


Regards, Alan



03 Volvo S60 2.5T AWD 98 Mystique 2.5 MTX 99 SVT - Inheriting Lil Monster's parts 98 SVT - Lil Monster (RIP) 183.7 whp Quaife/Fidanza/UR UD Clutch AFE/MSDS/SHO-Y/Bassani/MagnaCore GC/Koni/22mmR/EndLinks/ES/ KVR Slotted/1144's/SS Lines/MASItaly