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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
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The optimized Y does not have the restriction of the crush piping any longer, and the bend from the rear bank is beautiful and smooth compared to the aftermarket pipes.
Smooth flow = less turbulance = higher exhaust velocity = better scavenging = better performance.
Not necisarily in that order, but you get the picture.
Must be that jumbly-wumbly thing happening again.
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3" is definitely too big!
99 SVTC, T-Red, #652/2760-12.8.1998
Mother#@%@!* did I sound abstract?
I hope it sounded more confusin than that!
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If my memery serves right buckshot is running 2.5 in. on a supecharged 3.0l I would say that that is plnty big for anything short of a big block.
95 mystique daily driver
96 mystique parts car
95 contour 3.0L oval port swap in the works
check my classified ad
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i think i read somewhere recently that demon is running 2" diameter piping on his true duals. and thats with all the mods he has done.
00 black/tan svt, #2052 of 2150, born 2/1/00
formerly known as my csvt
"Nothing in the world is more dangerous than a sincere ignorance and conscientious stupidity." -Martin Luther King, Jr.
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Russell
Oval Port 3L Nearly Done
MTX75 w/ Homebrew Zetec FD and Torsen Complete
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Quote:
most torque = 3L swap!!
I assume you meant to put + a turbo.....
99 SVTC, T-Red, #652/2760-12.8.1998
Mother#@%@!* did I sound abstract?
I hope it sounded more confusin than that!
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Joined: Aug 2002
Posts: 283
CEG\'er
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CEG\'er
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TourDeForce, do you recall if they're all the same diameter on their exits. I thought there was a difference but my memory is fading with age.  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
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Hard-core CEG'er
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I've had both an SE and SVT Y & main cat on my car. The pipes are the same as far as I could tell. I got a good close look at both, but I never actually measured because there appeared to be no noticable difference in the pipe sizes. I'll put a calliper across the pipe at my flange if somebody would be willing to do the same for an SVT - then we'll know for sure, once & for all. We gotta measure the pipe going into the flange because of the different flanges - the piping is what counts anyway. My stock SE Y pipe has a 3 bolt flange, the SVT unit had the spring loaded 2 bolt flange thingie that mated up to the converter pipe. I sold the SVT pipe & cat system & kept my modded Y pipe. I like it. 
Must be that jumbly-wumbly thing happening again.
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Originally posted by acrdklr:
i think i read somewhere recently that demon is running 2" diameter piping on his true duals. and thats with all the mods he has done.
2" I.D. piping and I have absolutely no trouble making a strong power curve.
Anything larger for true duals on any NA car is significant overkill.
2.25" dual for a built S/C 3L (S/C hating aside)
3" single for a turbo car.
2.5" single for a NA quasi-dual setup.
Everything mandrel bent of course. No sense in WASTING your money on POS crush bends. Do it right or don't bother!
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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