Anybody make a 2.5 inch Dual exhaust kit?

[Scorpion]

Im still gonna contact the local exhaust shop that did my dads 66 chevy. I think they charged like 350 bucks including labor and mufflers. they did a killer job on it. it looks a lot nicer when you don't have a bunch of pipes sliding into eachother. I cant believe its like twice the price to go from 2.25 to 2.5". what a joke

Huh...twice as much? I wonder if they don't do 2.5-inch setups that often so their cost on the bigger tube is higher...or they don't do many and they're trying to pay for the dies. Seems the difference should only be a hundred.

Seems don't look bad in moderation if you weld them (nice welds) and then spray them. When they start to look bad is when they begin to rust and stand out like a sore thumb. My opinion anyway.

 

[bloodrunner83]

Thanks for the pictures and Info scorpion! Your exhaust looks really nice actually. Im sure I can find the aluminized spray on summit. I think im just going to do the duals, no h pipe or x pipe. what do you think about that? The part I was worried about was making the curves that go around the transfer case. the rest seems like cake, cause all im running for fuel tanks is the stock driver side tank and im smoothing the p side filler hatch.

 

[Scorpion]

The J-Bends in the kit nicely fit around the 4L80E and NP241 off of a set of full length headers. I'm not gonna lie, I didn't think they were gonna work without modification but they did and there wasn't a whole lot of room on the passengers side so the fact that it was a universal kit was impressive. If it worked on mine, I'd be surprised if it wouldn't work on most others.

Duals without an H-Pipe will work. Most of my truck projects have been setup that way. I think the value of the H-Pipe is the smoothness you get from the balancing of the exhaust banks and, supposedly, a little low end torque. Do you need it? No. It'll sound good without but maybe a little better with but that's my opinion. Exhaust sound preferences vary. I never ran one because there's too much crap under a 4x4 to find an easy place for it.

 

[bloodrunner83]

The x pipe makes sense to me, youll get the sound of 8 cylinders in each tail pipe instead of 4 and 4, but at the same time, with a cam, I think it would sound chunkier with true duals. H pipe seems to me like it would just decrease the exhaust velocity. does that kit give you an option of tail pipe exit? I want mine wide, but straight out the back, not angled. do you think theres enough pipe there to widen the distance between the 2 tail pipes after the rear shackles and strait out the back?

 

[Scorpion]

The x pipe makes sense to me, youll get the sound of 8 cylinders in each tail pipe instead of 4 and 4, but at the same time, with a cam, I think it would sound chunkier with true duals. H pipe seems to me like it would just decrease the exhaust velocity. does that kit give you an option of tail pipe exit? I want mine wide, but straight out the back, not angled. do you think theres enough pipe there to widen the distance between the 2 tail pipes after the rear shackles and strait out the back?

Chunkier with true duals is a good way to describe it, I agree. I think the H just balances the pressure on all cylinders making the motor run more balanced which is where the benefits come in.

The kit comes with two exit choices: 90 degree for exit just behind the rear wheel well and 45 for the rear quarter exit. You'd need one of the S bends to make the exit wide rear like you want. There isn't enough pipe in the kit for a straight out the back exit which also bugged me a little. They could have done so much more with the kit by adding two 40-inch straights.

 

[bloodrunner83]

That sucks! you figure for the price, they would give you enough pipe to do what you want with it! I wanted to run electric cut outs behind the front tires too. this is gonna be like a 700- 800 dollar exhaust system! the electric cut outs are like 250 for a pair and that doesn't include the pieces of pipe you need to do it.

 

[Scorpion]

That sucks! you figure for the price, they would give you enough pipe to do what you want with it! I wanted to run electric cut outs behind the front tires too. this is gonna be like a 700- 800 dollar exhaust system! the electric cut outs are like 250 for a pair and that doesn't include the pieces of pipe you need to do it.

Electric cutouts on a truck? You must like it loud. I used to run done the track with open headers but that was years ago. It has been proven that running with an exhaust is faster than going open so it's unlikely I'll ever roll ear plugs loud again. All things considered, running that loud got me too much unwanted attention anyway.

With all of the parts I have in my exhaust, I'm probably at about $700 (including mufflers). The same system would probably be over a grand at a local shop and not fit nearly as well. My time is free (to me anyway).

 

[Green79Scottsdale]

I used to run done the track with open headers but that was years ago. It has been proven that running with an exhaust is faster than going open...

There is actually a tipping point between open headers and full exhaust as far as power goes. I have seen dyno results that show having a couple of feet of pipe after the collectors will boost power compared to open headers. But when you put a full exhaust on, it will reduce power from the collector/pipe set-up. Follow?

My dad did this test back when he was racing. He would go to the track with full exhaust. Draw a line on both pipes with a wax pencil. Make a run down the track. The point where the wax pencil mark got melted too is the point where you want to end the pipe for best power. He would put in a junction so he could uncork the exhaust, move it over to get the rest of the exhaust out of the way, but still be held under the car. Make his runs through out the night, then at the end of the night hook it all back up and drive home with a nice quiet system.

 

[Scorpion]

There is actually a tipping point between open headers and full exhaust as far as power goes. I have seen dyno results that show having a couple of feet of pipe after the collectors will boost power compared to open headers. But when you put a full exhaust on, it will reduce power from the collector/pipe set-up. Follow?

My dad did this test back when he was racing. He would go to the track with full exhaust. Draw a line on both pipes with a wax pencil. Make a run down the track. The point where the wax pencil mark got melted too is the point where you want to end the pipe for best power. He would put in a junction so he could uncork the exhaust, move it over to get the rest of the exhaust out of the way, but still be held under the car. Make his runs through out the night, then at the end of the night hook it all back up and drive home with a nice quiet system.

Cool trick. So there's some correlation between exhaust temp decrease and power. Did he try different size tubing to see if that made a difference? Would be fun to have the facilities and resources to do testing to better understand.

 

[Green79Scottsdale]

Cool trick. So there's some correlation between exhaust temp decrease and power. Did he try different size tubing to see if that made a difference? Would be fun to have the facilities and resources to do testing to better understand.

No, he never bothered to go that far. The theory was that at the point were the wax pencil stopped melting is where the scavenging effect stopped working. After that point the fumes are just tumbling down the rest of the exhaust and not pulling the next exhaust pulse down the header pipes. Him and his buddies did this a lot back in day, and the cars they did this with included '65 Corvette, '69 and '73 Z/28's, '72 Cuda, '70 Mach 1, and others that I can't remember. These were all cars that were driven daily and raced on the weekends in full street trim.

As far as diameter goes, he said 1 5/8" primary tube headers are great for street motors and quite a few "race" motors even. He found 1 3/4" to slightly lose power on the street, and around that 500 hp mark is about when race motors start to benefit from them. I remember him saying once they never ran bigger than 2 1/2" diameter for exhaust, they never had cars that seemed to benefit from a bigger diameter.

I should also note my dad hung with guys that would build there own tuned pipes for their snowmobiles, two of the brothers built and campaigned a highly competitive alcohol powered big block 4x4 pulling truck (Tibb's Toy), countless drag cars, some race sleds, and even a race boat. To this day they all have a "toy" car, and one of them is putting EFI on his boat that is equipped with twin 540's putting out 800 hp each. I am blessed to know this group of a dozen or so guys personally, and when any of them talks about anything, I know to shut the hell up and listen! These guys know what they speak of and I get to learn from any and all of them. And they have kick ass stories from "back in the day"!!

Thanks for letting me brag! Carry on!

 

[Scorpion]

Crap, now I'm questioning the choice to go 3-inch on my exhaust. A little too late to change now so I'll have to see how it goes. Great stories though. I've had similar life experiences with my hobbies and what I call old-timers who lived the life. There probably isn't a better way to learn.

 

[bloodrunner83]

Electric cutouts on a truck? You must like it loud. I used to run done the track with open headers but that was years ago. It has been proven that running with an exhaust is faster than going open so it's unlikely I'll ever roll ear plugs loud again. All things considered, running that loud got me too much unwanted attention anyway.

With all of the parts I have in my exhaust, I'm probably at about $700 (including mufflers). The same system would probably be over a grand at a local shop and not fit nearly as well. My time is free (to me anyway).

My trucks back in Wisconsin where im from. Ill be driving it there, and its pretty country up there, so you can get away with it no problem. Plus all the cops are family friends and will turn a head. Its more for novelty than anything.

 

[Kevin.Hanchett]

What size motor is in your truck Scorpion? I am thinking about using the 3" u fit flowmaster kit and I'm told that the 383 stroker should use 2.5. Wanted to see what you had and if you notice a difference in sizes.