Power Gain From Y-pipe To Duals?
Power Gain From Y-pipe To Duals? I plan on getting a nitrous kit in the future with maybee a cam. Would it be a waste of money going to duals from my current y-pipe settup or would I gain alot of power with the duals? how much power do you think I would gain?
I was told a canadian guy named Eugenio gained 15 rwhp going from a y setup to a dual setup, but his is also a 500rwhp 402? ls2 motor. Your gains would be somewhere inbetween. I picked up 20rwhp going from a hooker muffler to a dynomax ultraflow as a H/C car. I am looking into doing a dual setup because I always leave my cutout open anyways.
There is a discussion going on here
https://ls1tech.com/forums/showthrea...=635076&page=2
on whether or not you can claim gains with true duals. I'm of the opinion it will add midrange tq, because of scavenging. A ypipe setup doesn't scavenge, just like long tube headers, scavenging will gain you more tq.
As far as backpressure, good duals have ZERO backpressure, just like a cutout. This is good. However duals with xpipe crossover will scavenge, thus making more hp and tq than a cutout.
Here is my dyno graph, from switching from stock ypipe configuration to Bassani True Duals, I gained almost 20 lb/ft of tq in the midrange:
https://ls1tech.com/forums/showthrea...=635076&page=2
on whether or not you can claim gains with true duals. I'm of the opinion it will add midrange tq, because of scavenging. A ypipe setup doesn't scavenge, just like long tube headers, scavenging will gain you more tq.
As far as backpressure, good duals have ZERO backpressure, just like a cutout. This is good. However duals with xpipe crossover will scavenge, thus making more hp and tq than a cutout.
Here is my dyno graph, from switching from stock ypipe configuration to Bassani True Duals, I gained almost 20 lb/ft of tq in the midrange:
its hard to read that. so as far as mods go the only changes on the car were y pipe to true duals? the headers were the same? what was the weather like on both days?
it looks like you lost hp is this correct? i cant really read it.
it looks like you lost hp is this correct? i cant really read it.
Yes the headers were the same. The weather doesn't matter because the graph was SAE corrected for atmospheric conditions.
The way to read the graph is to 1). Compare the hp gained/lost. It was less than 1 hp, which is nothing. So hp stayed the same. 2). Compare the tq gained or lost. It was almost 20 lb/ft of tq gained, all in the midrange. Although the graph is tight you can see the red line is much fatter in the middle than the blue (old run) line. That means more midrange tq.
It's the area under the curve that makes the most difference you can feel, not peak numbers.
The way to read the graph is to 1). Compare the hp gained/lost. It was less than 1 hp, which is nothing. So hp stayed the same. 2). Compare the tq gained or lost. It was almost 20 lb/ft of tq gained, all in the midrange. Although the graph is tight you can see the red line is much fatter in the middle than the blue (old run) line. That means more midrange tq.
It's the area under the curve that makes the most difference you can feel, not peak numbers.
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to tell you the truth i cant tell what color those lines are. but i know what your saying. and yes i agree with you the power gain is at the right spot under the curve. thats what i want.
i just saw the other thread and ragtop said you had STOCK cats and y-pipe on the first dyno but not on the last. is that correct?
i just saw the other thread and ragtop said you had STOCK cats and y-pipe on the first dyno but not on the last. is that correct?
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Yes, I went from stock ypipe and cats to high flow converters and duals. Obviously the cats were not holding me back as I didn't make any more hp, but because of the crossover in the duals made more tq.
True duals wouldn't be worth much with your current setup. You would really need to step up to a big cam, stroker, etc. to make it worth while. Your current exhaust is a great combination and I wouldn't touch a thing unless you're going 10 sec. or less....
Originally Posted by 99Andrew
True duals wouldn't be worth much with your current setup. You would really need to step up to a big cam, stroker, etc. to make it worth while. Your current exhaust is a great combination and I wouldn't touch a thing unless you're going 10 sec. or less....
Yup I agree. But my 3"catback is gonna start holding me back soon so i'm gonna have to do something. I'm going with a cam and nitrous in the future so when I get to 370 hp or above which i plan on being more like 500 hp then i'm gonna have to either,
a - get a 4" catback to suport the hp without any restriction
b - leave what I have in now but add cutouts and open them when its time to race
c - spend more money and get 2.5" duals from my current headers back.
I dont know what to do yet. Seems like the cutouts would be the cheapest route but i also dont like the idea of having to mess with anything when i wanna race or make more power.
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Joined: Jun 2005
Posts: 2,660
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From: England
Originally Posted by lsx24
There is a discussion going on here
https://ls1tech.com/forums/showthrea...=635076&page=2
on whether or not you can claim gains with true duals. I'm of the opinion it will add midrange tq, because of scavenging. A ypipe setup doesn't scavenge, just like long tube headers, scavenging will gain you more tq.
As far as backpressure, good duals have ZERO backpressure, just like a cutout. This is good. However duals with xpipe crossover will scavenge, thus making more hp and tq than a cutout.
https://ls1tech.com/forums/showthrea...=635076&page=2
on whether or not you can claim gains with true duals. I'm of the opinion it will add midrange tq, because of scavenging. A ypipe setup doesn't scavenge, just like long tube headers, scavenging will gain you more tq.
As far as backpressure, good duals have ZERO backpressure, just like a cutout. This is good. However duals with xpipe crossover will scavenge, thus making more hp and tq than a cutout.
And back to scavenging a Y will scavenge in the same manor as an X pipe. Think about how a header scavenges, it doesn't have a X or cross over pipe, it is a collection of multiple pipes merging into one, same as a Y.
Infact a proven header design is a tri-Y setup, each pair of cylinders from one bank goes into a Y this leaves two remaining pipes which again goes into a Y at the collector, it's designed for efficent scavneging and high velocity gas flow.
The only limitation a Y pipe setup has is pipe diameter. However for a real noticable degration or restriction you need to be talking h/c as a minimum. Remeber there have been many people running well over 600rwhp thru Y pipes.
Time and again True Duals with xpipe crossover has been proven to have more tq than a ypipe. It's not a myth. There's a reason Vette's come with True Duals standard, and it's not because they fit better. A ypipe configuration is a compromise because of packaging constraints, not an exhaust that flows and performs better.
I don't buy that a ypipe scavenges as good as duals, or even headers. On duals, if the xpipe is nice and volumetric, the crossover volume is a good 2 times the size of each individual pipe. On headers, the collector volume is multiple times the size of each individual runner. On a ypipe setup, the collector is at most 1.5 times the size of each individual pipe, hardly enough to claim good flow or scavenging to nearly the same degree.
As far as people running high power setups with ypipes, well they are just leaving hp on the table. Just because you are high powered and run a ypipe, doesn't mean it's the most efficient configuration. Anyone can make 500 rwhp on pretty much any kind of exhaust, just like anyone can make over 400 rwhp with stock manifolds, but it's just not the most efficient way of accomplishing exhaust gas evacuation.
I don't buy that a ypipe scavenges as good as duals, or even headers. On duals, if the xpipe is nice and volumetric, the crossover volume is a good 2 times the size of each individual pipe. On headers, the collector volume is multiple times the size of each individual runner. On a ypipe setup, the collector is at most 1.5 times the size of each individual pipe, hardly enough to claim good flow or scavenging to nearly the same degree.
As far as people running high power setups with ypipes, well they are just leaving hp on the table. Just because you are high powered and run a ypipe, doesn't mean it's the most efficient configuration. Anyone can make 500 rwhp on pretty much any kind of exhaust, just like anyone can make over 400 rwhp with stock manifolds, but it's just not the most efficient way of accomplishing exhaust gas evacuation.
Originally Posted by 99Andrew
True duals wouldn't be worth much with your current setup. You would really need to step up to a big cam, stroker, etc. to make it worth while. Your current exhaust is a great combination and I wouldn't touch a thing unless you're going 10 sec. or less....
As an example, take v6 Taurus SHOs. They come standard with a H.O. Yamaha v6 engine. Going from the standard ypipe configuration, to a true duals configuration, you can gain over 20+ hp. It doesn't matter if you are a v8 SBC or a v6 mustang, duals are superior.
The size of the engine or power of the engine don't make any difference, True Duals scavenge and outflow ypipes in all situations.
Originally Posted by ls1plus
I was told a canadian guy named Eugenio gained 15 rwhp going from a y setup to a dual setup, but his is also a 500rwhp 402? ls2 motor. Your gains would be somewhere inbetween. I picked up 20rwhp going from a hooker muffler to a dynomax ultraflow as a H/C car. I am looking into doing a dual setup because I always leave my cutout open anyways.
on my 402 ls2, i'm back to a catback approach and e-cutout.
ok, so i think i'm back to square one. lsx posted a dyno chart which showed he gained about 20 rwtq but on the first dyno he had stock cats and stock y-pipe on there so i dont give total credit to the duals for the 20rwtq. I believe that there will be a gain but it may not be worth spending the money for 10hp or whatever.
So back on track with this thread before it was hijacked about scavenging.
So back on track with this thread before it was hijacked about scavenging.
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Joined: Jun 2005
Posts: 2,660
Likes: 14
From: England
Originally Posted by lsx24
Time and again True Duals with xpipe crossover has been proven to have more tq than a ypipe.
what you normally see is biased results where someone has gone from a crappy Y pipe setup (crappy because of components used not because its a Y. Meaning tubing diameter, merge collector and most importantly muffler)
To what is a good X pipe dual system, so of course they gain power. But the reason is not purly because they went duals.
In fact as long as the tubing and muffler aren't being a restriction a Y pipe will most likely make the most torque becuase it will have a higher gas velocity than a dual setup, espcially at part throttle.
Originally Posted by lsx24
It's not a myth. There's a reason Vette's come with True Duals standard, and it's not because they fit better. A ypipe configuration is a compromise because of packaging constraints, not an exhaust that flows and performs better.
Originally Posted by LG Motorsports
When we used a hand built Merge collector they cost us $450 each. that made the original headers cost $2500 per set without cats.
When we made the deal with Borla we specified a production, machine made collector to get the price of the complete set of headers down but we did not want to compromise the quality or power of our headers.
When we got our first set of prototype headers, we switched back and forth from the Production Merge collector to the Hand built collector and there was less than 2 hp difference. That is why we chose to supply the collector the way we do.
The alternative was to cheap out and use a plain stamped collector that had no relationship to a Merge collector. Or do what we did. We know from dyno testing that the Merge collector built the way we have them built causes a "venturi" effect where the collector necks down to 2 1/2" before the tapered transition up to the 3" out let. It is this "Merge down and Transition up at a specific angle that provides the effect that has come to be known as a "Merge" Collector.
The cone in the center is only 1 or 2 hp and since the full Merge collector that we use provided most of the gains without it, we chose to leave it and the other $900 out of the equation.
Again, the results speak for themself. We use our LG Pro Long Tube headers in our World Challenge race car exactly the way you get them for your street car. The only difference is that we turn the X pipe into a Y pipe and exit the exhaust out the side of the car, over the passenger floor and through the right side frame rail and rocker pannel.
Our headers run down the straight equal to the fastest Cadillac CTSv and every fast Corvette runs our LG headers.
We could get a couple more hp if we did some extensive exhaust testing on Merge angles in and cone angles out but the cost is prohibitive.
Thanks
Lou Gigliotti LGM
When we made the deal with Borla we specified a production, machine made collector to get the price of the complete set of headers down but we did not want to compromise the quality or power of our headers.
When we got our first set of prototype headers, we switched back and forth from the Production Merge collector to the Hand built collector and there was less than 2 hp difference. That is why we chose to supply the collector the way we do.
The alternative was to cheap out and use a plain stamped collector that had no relationship to a Merge collector. Or do what we did. We know from dyno testing that the Merge collector built the way we have them built causes a "venturi" effect where the collector necks down to 2 1/2" before the tapered transition up to the 3" out let. It is this "Merge down and Transition up at a specific angle that provides the effect that has come to be known as a "Merge" Collector.
The cone in the center is only 1 or 2 hp and since the full Merge collector that we use provided most of the gains without it, we chose to leave it and the other $900 out of the equation.
Again, the results speak for themself. We use our LG Pro Long Tube headers in our World Challenge race car exactly the way you get them for your street car. The only difference is that we turn the X pipe into a Y pipe and exit the exhaust out the side of the car, over the passenger floor and through the right side frame rail and rocker pannel.
Our headers run down the straight equal to the fastest Cadillac CTSv and every fast Corvette runs our LG headers.
We could get a couple more hp if we did some extensive exhaust testing on Merge angles in and cone angles out but the cost is prohibitive.
Thanks
Lou Gigliotti LGM
Originally Posted by lsx24
I don't buy that a ypipe scavenges as good as duals, or even headers. On duals, if the xpipe is nice and volumetric, the crossover volume is a good 2 times the size of each individual pipe. On headers, the collector volume is multiple times the size of each individual runner. On a ypipe setup, the collector is at most 1.5 times the size of each individual pipe, hardly enough to claim good flow or scavenging to nearly the same degree.
As far as people running high power setups with ypipes, well they are just leaving hp on the table. Just because you are high powered and run a ypipe, doesn't mean it's the most efficient configuration. Anyone can make 500 rwhp on pretty much any kind of exhaust, just like anyone can make over 400 rwhp with stock manifolds, but it's just not the most efficient way of accomplishing exhaust gas evacuation.
As far as people running high power setups with ypipes, well they are just leaving hp on the table. Just because you are high powered and run a ypipe, doesn't mean it's the most efficient configuration. Anyone can make 500 rwhp on pretty much any kind of exhaust, just like anyone can make over 400 rwhp with stock manifolds, but it's just not the most efficient way of accomplishing exhaust gas evacuation.
Here's a tri-y header design. Also note the text from David Vizard, who claims this type of merge helped to fatten up the torque curve:
Originally Posted by David Vizard
Another header/collector worthy of note (our example is again from Kook's) is the type shown in photo number 2. This is much favored by Busch and Nextel Cup engine builders. Essentially it is a long 4-into-a-short-2-into-1 system. The parts that go to make up the system between points A and B are shown in the top right hand corner of number 2. About 10 years ago, Flowmaster introduced a collector that converted a regular 4-into-1 system into the system seen here. This was my introduction to testing this configuration of collector. The dyno indicated only marginal gains in peak power. Like the merge collector, this collector style fattened up the torque curve, but usually to a greater extent.
and too many people have been led to believe any dual exhaust will give them 15-30rwhp increase when the reality is they may see no increase or even a reduction in performance depending on what Y pipe setup they had previous and how the new exhaust is designed and built.
I see what you're saying, but I still think duals are superior. I don't want to get in an arguing match, let's just say I agree to disagree. 
I agree with you here, Duals are not going to net much more if any hp over a good flowing ypipe system, as long as the ypipe diameter is big enough (which most of the time it is not), because the outright flow is good, but duals do offer more tq, every before-after graph I have seen shows it to be so.
As a side note most high power systems that are running a ypipe doesnt have it optimized for hp. You need at least a 3.5" intermediate pipe to support 500 fwhp, maximum for zero net loss, and most ypipe systems only have a 3" pipe, at least that are noted around here. This means you need at least a 4" intermediate pipe to support 500+ rwhp, and how many people do you know are running that.
And from the LG quote all I got out of it was they ran a ypipe, with exit out the side, it didn't say why, nor did it presume it would make more or less hp. I'm sure they are not short on hp, so it very well could have been for packaging constraints.
The tri-Y header design is all good in theory, but in practical applications it has yet to be explored. If it was truly a superior design, Manufacturers would be making Tri-y headers moreso than they do now. As far as I know there are ZERO tri-y headers designed for the ls1...that means either they haven't gotton around to developing it (highly unlikely) or it doesn't yield the performance gain as expected. Honestly I don't know why there aren't any Tri-y headers out for ls1s, if it truly fattens up the tq curve like presumed.
Regular header collectors are closer to an xpipe design than a ypipe design. Not only because of the size of the collector in comparison to the runner size, but also because it opens up to an 'open' area (the collector), doesn't neck down into a smaller diameter piping.
It just doens't make sense that a ypipe will scavenge as good as an xpipe. I mean look at the physics of it, more specifically the pipe size constraints necking down to a single pipe. I still think Vettes and Mustangs come from the factory with duals for a reason, and it's not purely just for sound.
Originally Posted by 300bhp/ton
and too many people have been led to believe any dual exhaust will give them 15-30rwhp increase when the reality is they may see no increase or even a reduction in performance depending on what Y pipe setup they had previous and how the new exhaust is designed and built.
As a side note most high power systems that are running a ypipe doesnt have it optimized for hp. You need at least a 3.5" intermediate pipe to support 500 fwhp, maximum for zero net loss, and most ypipe systems only have a 3" pipe, at least that are noted around here. This means you need at least a 4" intermediate pipe to support 500+ rwhp, and how many people do you know are running that.
And from the LG quote all I got out of it was they ran a ypipe, with exit out the side, it didn't say why, nor did it presume it would make more or less hp. I'm sure they are not short on hp, so it very well could have been for packaging constraints.
The tri-Y header design is all good in theory, but in practical applications it has yet to be explored. If it was truly a superior design, Manufacturers would be making Tri-y headers moreso than they do now. As far as I know there are ZERO tri-y headers designed for the ls1...that means either they haven't gotton around to developing it (highly unlikely) or it doesn't yield the performance gain as expected. Honestly I don't know why there aren't any Tri-y headers out for ls1s, if it truly fattens up the tq curve like presumed.
Regular header collectors are closer to an xpipe design than a ypipe design. Not only because of the size of the collector in comparison to the runner size, but also because it opens up to an 'open' area (the collector), doesn't neck down into a smaller diameter piping.
It just doens't make sense that a ypipe will scavenge as good as an xpipe. I mean look at the physics of it, more specifically the pipe size constraints necking down to a single pipe. I still think Vettes and Mustangs come from the factory with duals for a reason, and it's not purely just for sound.
Intresting discussion....
As always I know nothing ..but still I have an opinion...pleas feel free to correct me where Im wrong
Ive always thought of it like this...HP is nice but torque is what moves teh car....you can feel a dsmall iff in torque Vs a small HP gain Hp is effeciency torque is what turns the wheels and somthing you can feel in the seat of your pants..
HP will limit the avaliable torque will it not?
As always I know nothing ..but still I have an opinion...pleas feel free to correct me where Im wrong
Ive always thought of it like this...HP is nice but torque is what moves teh car....you can feel a dsmall iff in torque Vs a small HP gain Hp is effeciency torque is what turns the wheels and somthing you can feel in the seat of your pants..
HP will limit the avaliable torque will it not?