VorTecxas
American Nightmare
Some of you may have seen my little rant on not having evidence to back up your claims on performance mods. So, I have created this thread for that purpose. Please no "I felts" or "I thinks", NUMBERS PROVEN ONLY. Put any numbers proven gains or losses here. Preferably with a screenshot of your before/after numbers. I am going to start this thread with what some of you saw in my "Free or cheap mods" thread (http://www.gmt400.com/forum/showthread.php?15258-Free-or-cheap-quot-mods-quot-with-dyno-results), and I will scan the dyno sheet as soon as I can and put it in here. Since we know what an L31 puts out from the factory, it's safe to assume what the starting numbers were here. These are the numbers that my '96 350 Sierra put down on TrueStreet's dyno. I copied this from the "Free or cheap mods" thread simply because I really didn't want to type it all out again. Granted, most posts will be about one or two mods, I just threw in everything I had done that produced those numbers. This is from December of last year. I will do the same for the 454 soon.
1996 GMC Sierra SLE ECSS (pictured in my signature)
227,787 miles as of 12-16-2012 (about 227,500 on dyno day)
Everything drivetrain wise is original (L31 350/4L60E/3.42 rear)
Out of 4 pulls, my maximum output to the wheels (I still have a 98MPH limiter)
is 219.47 HP@4400 RPM and 286.71 ft-lbs@3300 RPM
With a 24% drivetrain loss (which is what I was told by the tech running the dyno), that comes out to 272.14 HP and 355.52 ft-lbs at the flywheel. About 17HP and 25 ft-lbs over stock specs (255@4600 and 330@2800, not to mention any power lost due to high mileage wear)
Here is the list of alterations (I wouldn't really call them "mods") I have done, mainly because I had the time or the parts already laying around. I'm not saying any one of these individually will really do anything significant, but as a whole they made a small difference, especially in throttle response (I've put 25,000 miles on this truck in the past 13 months, please don't try and tell me it's "mental" or I'm using a "butt-dyno", I know my truck and how it drives extremely well).
-Straight air intake (or Cold Air Intake, if you want to call it that). Just a generic 4" tube style, nothing fancy. It was on the truck when I bought it, but you can pick one up at AutoZone or Oreilly for about 35-40 bucks.
-Cone Gauze-type oiled air filter (K&N, Spectre, etc.). I have the Spectre (again, on the truck when purchased) mid-length size with the open end. It's mounted straight to the MAF. If you just pick one up from AutoZone or Oreilly they're about 25 bucks and work just as well as a K&N, I've had both on the truck and noticed no difference between the two. Kind of like having a blonde and then a brunette. They're different, but they all do the same thing for you.
-Descreened MAF. I've seen arguments both ways on descreening the MAF, I have had no issues. The screen simply pops out. I used emory cloth and sensor cleaner on the inner surface to clean the housing up a bit (take it apart and remove the sensor itself first), it was pretty nasty. And then I painted it red. Because I can.
-Cap the noise box hole. The big box that says "Vortec" on your throttle body hat is just a noise suppressor, I removed it and used a 2" plumbing pipe cap to block it off. About 3 bucks at Lowes or Home Depot, I already had one in my toolbox. Makes the truck sound a little meaner at WOT too.
-454 Throttle Body. Off of a '96 or later L29 or L21 454. The 8.1L one might work too, i'm not sure. I got it for 10 bucks at a local boneyard. It's the same size all the way through instead of tapering like the L31s, and it doesn't have that foot on the bottom of the throttle blade. You will need to modify it slightly to work with the throttle cable.
-Exhaust. I have the stock tubing (cats deleted and straight pipe run) to dual Flowmaster 40s. Had a local hole-in-the wall shop do the work, cost about 120 bucks. Dual pipes run out under the fender directly behind the tires to 2nd Gen Trans Am splitter tips. That part has nothing to do with the performance, I just think it looks good and sounds awesome.
-Cooling system. Electric fan. I pulled mine off of a Texas State Trooper Crown Vic. It can suck the air out of a blimp. I also have a 4 core radiator from a '99 3500 and removed my shroud and clutch fan. If you run e-fans its best to use a thermostatic switch instead of a flip switch or key power. It's much more consistent and doesn't rely on you maybe forgetting to turn them on after having a few at the local Hot Gals With Big Boobs Serving You Beer joint.
-170F Thermostat. May not be necessary for some of you. I live in Texas. It gets really damn hot. It helps.
-Tune-up. Plugs, wires, cap, rotor, PCV valve (yes, it is important), and fuel filter. I had done all of this about 8,000 miles before the dyno.
1996 GMC Sierra SLE ECSS (pictured in my signature)
227,787 miles as of 12-16-2012 (about 227,500 on dyno day)
Everything drivetrain wise is original (L31 350/4L60E/3.42 rear)
Out of 4 pulls, my maximum output to the wheels (I still have a 98MPH limiter)
is 219.47 HP@4400 RPM and 286.71 ft-lbs@3300 RPM
With a 24% drivetrain loss (which is what I was told by the tech running the dyno), that comes out to 272.14 HP and 355.52 ft-lbs at the flywheel. About 17HP and 25 ft-lbs over stock specs (255@4600 and 330@2800, not to mention any power lost due to high mileage wear)
Here is the list of alterations (I wouldn't really call them "mods") I have done, mainly because I had the time or the parts already laying around. I'm not saying any one of these individually will really do anything significant, but as a whole they made a small difference, especially in throttle response (I've put 25,000 miles on this truck in the past 13 months, please don't try and tell me it's "mental" or I'm using a "butt-dyno", I know my truck and how it drives extremely well).
-Straight air intake (or Cold Air Intake, if you want to call it that). Just a generic 4" tube style, nothing fancy. It was on the truck when I bought it, but you can pick one up at AutoZone or Oreilly for about 35-40 bucks.
-Cone Gauze-type oiled air filter (K&N, Spectre, etc.). I have the Spectre (again, on the truck when purchased) mid-length size with the open end. It's mounted straight to the MAF. If you just pick one up from AutoZone or Oreilly they're about 25 bucks and work just as well as a K&N, I've had both on the truck and noticed no difference between the two. Kind of like having a blonde and then a brunette. They're different, but they all do the same thing for you.
-Descreened MAF. I've seen arguments both ways on descreening the MAF, I have had no issues. The screen simply pops out. I used emory cloth and sensor cleaner on the inner surface to clean the housing up a bit (take it apart and remove the sensor itself first), it was pretty nasty. And then I painted it red. Because I can.
-Cap the noise box hole. The big box that says "Vortec" on your throttle body hat is just a noise suppressor, I removed it and used a 2" plumbing pipe cap to block it off. About 3 bucks at Lowes or Home Depot, I already had one in my toolbox. Makes the truck sound a little meaner at WOT too.
-454 Throttle Body. Off of a '96 or later L29 or L21 454. The 8.1L one might work too, i'm not sure. I got it for 10 bucks at a local boneyard. It's the same size all the way through instead of tapering like the L31s, and it doesn't have that foot on the bottom of the throttle blade. You will need to modify it slightly to work with the throttle cable.
-Exhaust. I have the stock tubing (cats deleted and straight pipe run) to dual Flowmaster 40s. Had a local hole-in-the wall shop do the work, cost about 120 bucks. Dual pipes run out under the fender directly behind the tires to 2nd Gen Trans Am splitter tips. That part has nothing to do with the performance, I just think it looks good and sounds awesome.
-Cooling system. Electric fan. I pulled mine off of a Texas State Trooper Crown Vic. It can suck the air out of a blimp. I also have a 4 core radiator from a '99 3500 and removed my shroud and clutch fan. If you run e-fans its best to use a thermostatic switch instead of a flip switch or key power. It's much more consistent and doesn't rely on you maybe forgetting to turn them on after having a few at the local Hot Gals With Big Boobs Serving You Beer joint.
-170F Thermostat. May not be necessary for some of you. I live in Texas. It gets really damn hot. It helps.
-Tune-up. Plugs, wires, cap, rotor, PCV valve (yes, it is important), and fuel filter. I had done all of this about 8,000 miles before the dyno.
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