stack question

hpprose

hpprose

In the Dark
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What is the hp lose of dual stacks vs a single?

Has anyone tried running smaller dual stacks to see if the hp loss is still there?
 
I have no idea, but I remember reading a post about a year ago, where a 1000hp truck gained another 60hp by removing the y pipe for dual stacks and switching to a single stack setup. But I highly doubt it makes that much of a difference on a 500hp thruck.
 
I believe that Lubeowner said he is around 30 or 40 hp less but I don't remember for sure. With what we are trying to achieve with Project Underdog, I need as much help as I can get!

Do you know of anyone trying smaller twins and have any success?
 
no, most everybody around here runs a single setup. But, we also dont look that deep into trying to get more power by doing stuff like that. I am sure there is a difference though.
 
hpprose said:
I believe that Lubeowner said he is around 30 or 40 hp less but I don't remember for sure. With what we are trying to achieve with Project Underdog, I need as much help as I can get!

Do you know of anyone trying smaller twins and have any success?
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hood stack, unless it needs to be street drivable, then single stack, if you're not sure then go with whatever SEEMS to be the least restriction aka less bends
 
Grandrock or somebody similar needs to do a true to form dyno test. No BS. Just the truth.
 
Yeah. If you think of it from a business stand point, dual stacks are probably the most popular and I would assume most profitable. So, would you be willing to publish something that shows your most popular to be less powerful than the cheaper less popular one?

I'm hoping that one of the stack companies are going to get on here and hopefully chime in. I would really like to hear some good numbers.

My wife wants dual stacks and I want power. Only time will tell which way project underdog goes.
 
why not make your own setup. you don't need to buy a cookie cutter kit. just larger dia pipe for the y pipe since that is the restriction in the kit, and just have it be the same size as the stacks you want to use. I.E., a 4"dp to the 6" y-pipe to 6" stacks...... just me $.02
 
BigB82789 said:
Grandrock or somebody similar needs to do a true to form dyno test. No BS. Just the truth.
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The dual stacks are primarly for appearance only. The only gain you would get would probably be a lower EGT over stock exhaust. Now performance I heard each bend you lose a % of power. If this is true, then the less bends you have the more power you should have.

This would be a great test to try. It would be cool to see Diesel World do a little story on it even.

TI Dyno has their Rocktober Fest Dyno Day coming up :)doh: I gotta post up that info still :doh:) and it would be cool to see two similar trucks run a little test to see if there is a power difference....hmm...maybe I should call Wally, and see what we can do....
 
i just went form dual 5 in stacks to a 7 inch single, the dual set up had a total of 7 bends from the turbo back and the single has a total of 3 bends. noticeable difference in driveing.
 
HPAddict said:
why not make your own setup. you don't need to buy a cookie cutter kit. just larger dia pipe for the y pipe since that is the restriction in the kit, and just have it be the same size as the stacks you want to use. I.E., a 4"dp to the 6" y-pipe to 6" stacks...... just me $.02
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To build a 6" y-pipe, or 7" y-pipe correctly would cost the end user alot more money than the way they are built now. Our universal kits come 1 of 2 ways. Either it has a 4" inlet, or for guys running bigger turbo's and running 5" exhaust under the truck we have a 5" inlet y-pipe. MOST of our stock short stacks are reduced to 5" O.D. (because most of the heavy duty truck mufflers have 5" I.D. Outlets) so we are using parts we are currently already manufacturing.

Going from 4" to a 6" stack through a 5" y-pipe does not cause a restriction.
 
So, the loss isn't based on size or splitting the flow, it comes from redirecting it, via bends and what not.
 
hpprose said:
So, the loss isn't based on size or splitting the flow, it comes from redirecting it, via bends and what not.
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Yes and No. When someone has stock turbo, and wants to run a 5" down pipe, and has no other mods, you will see a change in power. (usually a power loss they say) Mostly because you're flowing the same amount of air through a 5" pipe it has more area to cover than a 4" pipe would. That's why they say unless you are pushing over 500 hp, a 5" turbo pipe is not needed. Now when you run the exhaust back to the y-pipe, the less bends you have the better, but a mandrel bent set up will flow better than a box tube set up. It's all about flow of air.

Didn't one of the diesel magazines do a test on horse power and what size turbo pipes should be used? I thought I seen an article about that somewhere.
 
Yeah, I think it was Diesel Power. But they tested normal exhaust not stacks. They, also, didn't get into single tail pipe vs dual vs side exiting etc.

Since I'm a 6.0, I'm pretty limited to size of the exhaust pipe. Our set-ups make it extremely difficult to get anything larger than a 3.5 down pipe in there. The only people using larger, are custom welding the down pipe together and move it. Since this is going to go on Project Underdog, I need something mass produced not a one off setup. There are very few readers that are going to want to or have the ability to do a one off setup with the cab off.

Good information and I'm going to keep working on it.
 
hpprose said:
Yeah, I think it was Diesel Power. But they tested normal exhaust not stacks. They, also, didn't get into single tail pipe vs dual vs side exiting etc.

Since I'm a 6.0, I'm pretty limited to size of the exhaust pipe. Our set-ups make it extremely difficult to get anything larger than a 3.5 down pipe in there. The only people using larger, are custom welding the down pipe together and move it. Since this is going to go on Project Underdog, I need something mass produced not a one off setup. There are very few readers that are going to want to or have the ability to do a one off setup with the cab off.

Good information and I'm going to keep working on it.
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Our down pipes are a 2pc down pipe. The top part connecting to the turbo is a 3.5" diameter pipe, it's only maybe 20" long if that, then the 2nd pipe that connect's to that is 4". We use the 3.5" top piece because it is such a tight fit, and expand it out as soon as we can for the most air movement.

DSC08684.JPG

Here is a picture of what it looks like.
 
I know this spring nobody offered a single stack kit that went where most single stacks sit. They offered some but they were offset against the bed rail.

I chose to make my own for a whopping $180.

Personally Im a single stack person. When your at a pull and people see the single, they think that your truck means business. That And I just dont like dual stacks on a Duramax SRW.

From an exhaust standpoint, you dont need huge pipe near the end of the exhaust.

I would just run a 5 or 6" single stack.

THey are cheap, easy and legal. Besides for most organizations you need your exhuast to go straight up or straight down. I like it when people shoot it up because it makes less dust and makes for a cleaner run.

A hood stack should be out of the question as you will get kicked out of a lot of pulls even if your truck is stock. Besides its illegal
 
Chad-

I think a single stack(a little offset from center) 5" or 6" would be great, just like Durallymax said.

I dont think there is much of a HP difference in a single vs dual stack, but thats my opinion.

Joefarmer had a good write-up of a dual stack kit on his website, with part #'s and all.

are you going to run a 5" pipe from the downpipe(3 1/2 I'm guessing) to your stack?
 
I don't know what size we will end up with. Part of me says single 4”, but that's a little small for a single stack (from a looks stand point). As I had mentioned, the wife wants dual 5" stacks. I need all of the hp I can get trying to compete with the Duramax and Cummins powered pullers. My little 6.0 isn’t a big hp making machine.

All I know is this winter, I have my work cut out for me getting everything done that we want to get done in order to be really competitive.
 
hpprose said:
I don't know what size we will end up with. Part of me says single 4”, but that's a little small for a single stack (from a looks stand point). As I had mentioned, the wife wants dual 5" stacks. I need all of the hp I can get trying to compete with the Duramax and Cummins powered pullers. My little 6.0 isn’t a big hp making machine.

All I know is this winter, I have my work cut out for me getting everything done that we want to get done in order to be really competitive.
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I tell ya what, talk to Wally (aka Jackthebear3) from FTE Diesel. He's a site sponsor here. He has a single stack set up that will use our dual stack set up pieces. He could sell you the dual stack kit to drive around with, but when it's time for competition, you can pull the dual y-pipe out, and drop this single stack set up he has in, and just run one of your dual 5" stacks. If you PM him, I'm sure he could explain his set up much better than I.
 
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