Anyone pull their twins in favor of a single?

[Matt400]

The best turbo to run soon will be the VGT turbo from ATS.

If its the MST you are talking about, I been looking at that. Pretty trick with the diversion valve. They said 3-4 more months out.

 

[Luke Warmwater]

Don't know how much fuel your running or planning to run as I have a 12 valve, but if you want a real nice big single talk to J. R. Adkins. He is making his Lil 55' with a 14 housing as well as 16. It doesn't spool like stock but it ain't no lag pig either. And this thing moves extreme air. Good turbo fo a big single that's not a lag pig.



Travis

How do these compare with a full B1?

 

[AK RAM]

I think singles are great depending on what you want to do with your truck. Heck, I liked them so much I went through 5 of them. :-laf



I think sometimes people forget that twin configurations were originally invented so you can have the massive flow of a large single without loosing good spool-up capability. The way twins were made back in the day did just that. A lot of the problem today is that people have changed things too much over the years and have lost that characteristic. A lot of the talk of lag with twins is the result of kit manufacturers going to increasingly larger and larger secondaries in order to squeeze out a little more flow with a little less drive pressure. That is the result of competition…"My twins are better than your twins. " You have to have something to measure to quantify "better", and with twins, all you have is max flow and drive pressure. The easiest way to increase flow and reduce drive pressure at the same time is to go to a bigger secondary. When you add bigger secondaries, obviously lag is going to go up considerably.



A smaller secondary like a 35 or a S300 is going to provide absolutely awesome spool-up on a set of twins as long as the wastegate is not set to open too early and will still flow plenty of air. Are you planning on running 80 lbs of boost or more? If not, you don’t need a B1-2-04 or a 40 on top. Your not after bragging rights here on who has the biggest set……. . of turbos. If lag is your concern, go back to basics. Just because so-and-so says the "latest and greatest modified turbo from…. . has great spool-up", that doesn’t mean it will work great in a set of twins, yet we increasingly see these turbos turning up in twin kits. You want small on top…. . that is how they were designed to run. If you get away from that, well, you simply loose the characteristics that made twins great to start with. The Piers towing twins and the BD Power twins will light your hair on fire they spool-up so fast and you can still run 55 to 60 lbs of boost efficiently. Internal wastegate modifications and external wastegates take care of all drive pressure issues with smaller top turbos. Also, the smaller the top turbo, the more reliable/tougher it will be in the end…. . less rotating mass. Don't just take my word for it…. . talk to Piers or John at BD and then apply a little common sense to the decision process. You will be surprised what you come up with.



Another point I think people sometimes forget about is the air density coming from a set of twins. You hear a lot of talk about singles "will flow efficiently to 55lbs of boost. " Well sure it may, but the density you get from dual stage compression can not be matched by any single no matter how big it is or how much it will flow. When talking EGT cooling power, singles and twins are not in the same league and really can't be compared. Singles are great and technology advances over the last 5 years alone have made some of them awesome, but it is still a single and will still cool like a single whether it costs $1100 or $3200. 50 lbs of boost from a single still within its map will generally not cool as well as 40 lbs of boost from twins.



Just my $. 02.

 

[Diesel Freak]

Nice Post AK RAM!!!!

 

[Reb.B]

twins put in dense air, but there is a lot of horsepower lost driving two turbos and also trying to push all that air through the small turbo. Also the small turbo is working so hard trying to get the big turbo to spool up. I really think the twins are going to be left aside for medium to large VGT single turbos and huge turbos with superchargers off to the side. More and more guys are using little blowers and when they get them made with clucthes its going to be awesome. The VGT is also a great way to go, big turbo, very dense air, easy install, great spool up, and still able to flow the exhaust.

 

[Matt400]

I liked them so much I went through 5 of them.

Just what I am not interested in. Did you go through all 5 on your 03 already?

You made some excellent points and Piers did suggest for my needs a 35 on top would probably be better. BD questioned the use of twins for the way I drive and felt the one they use for the top charger might be more drivable as a single.

 

[AK RAM]

Did you go through all 5 on your 03 already?

Yep…. . I was a slow learner. One didn't blow and is still in use on another rig. It just wasn't big enough. Out of the other four, one may not have been the fault of pure HP, so I can only chalk up three for sure kills.



Here is a pic of the mighty B1-04 after 2,400 miles on my rig:

 

[Matt400]

Ouch!

 

[CRoth - BD-Power]

I think singles are great depending on what you want to do with your truck. Heck, I liked them so much I went through 5 of them. :-laf



I think sometimes people forget that twin configurations were originally invented so you can have the massive flow of a large single without loosing good spool-up capability. The way twins were made back in the day did just that. A lot of the problem today is that people have changed things too much over the years and have lost that characteristic. A lot of the talk of lag with twins is the result of kit manufacturers going to increasingly larger and larger secondaries in order to squeeze out a little more flow with a little less drive pressure. That is the result of competition…"My twins are better than your twins. " You have to have something to measure to quantify "better", and with twins, all you have is max flow and drive pressure. The easiest way to increase flow and reduce drive pressure at the same time is to go to a bigger secondary. When you add bigger secondaries, obviously lag is going to go up considerably.



A smaller secondary like a 35 or a S300 is going to provide absolutely awesome spool-up on a set of twins as long as the wastegate is not set to open too early and will still flow plenty of air. Are you planning on running 80 lbs of boost or more? If not, you don’t need a B1-2-04 or a 40 on top. Your not after bragging rights here on who has the biggest set……. . of turbos. If lag is your concern, go back to basics. Just because so-and-so says the "latest and greatest modified turbo from…. . has great spool-up", that doesn’t mean it will work great in a set of twins, yet we increasingly see these turbos turning up in twin kits. You want small on top…. . that is how they were designed to run. If you get away from that, well, you simply loose the characteristics that made twins great to start with. The Piers towing twins and the BD Power twins will light your hair on fire they spool-up so fast and you can still run 55 to 60 lbs of boost efficiently. Internal wastegate modifications and external wastegates take care of all drive pressure issues with smaller top turbos. Also, the smaller the top turbo, the more reliable/tougher it will be in the end…. . less rotating mass. Don't just take my word for it…. . talk to Piers or John at BD and then apply a little common sense to the decision process. You will be surprised what you come up with.



Another point I think people sometimes forget about is the air density coming from a set of twins. You hear a lot of talk about singles "will flow efficiently to 55lbs of boost. " Well sure it may, but the density you get from dual stage compression can not be matched by any single no matter how big it is or how much it will flow. When talking EGT cooling power, singles and twins are not in the same league and really can't be compared. Singles are great and technology advances over the last 5 years alone have made some of them awesome, but it is still a single and will still cool like a single whether it costs $1100 or $3200. 50 lbs of boost from a single still within its map will generally not cool as well as 40 lbs of boost from twins.



Just my $. 02.

You guys should really listen to this guy.



The fact of the matter is no matter what single you have, if you run 50 psi it will not be efficient (i. e. > 75%). There are three things that matter in a turbocharger, one is the compressor outlet air density, drive pressure compared to manifold pressure and its rotating mass. I challenge anyone to develop a single charger developing 50 psi of boost at 350°F before the intercooler.



Sure anyone can find a turbocharger that can hit 60psi, but can someone design a system that can not only hit that pressure but do it efficiently and flow enough air to support the engine. Soon I predict that we'll see a number of products come to market not to increase your boost but to decrease your boost but produce more power. Boost pressures mean absolutely nothing.



I ask everyone to do their own research and don't believe the hype on anything otherwise you will be disappointed.



For example who would of believed our Super B turbo flows equally the same amount of air the Turbonetics Jammer2 setup, yet our compressor map is almost 25% larger in the surge direction. Plus the map goes clear into efficient pressure ratios over 4. 2. All this with a wastegate as well, plus it we think it spools better. With all this we only feel our turbo is suitable for 400HP, sure it can make more but not the way we want it to.



With turbo's you just can't keeping on increasing the compressor wheel size without changing the turbine wheel size as well. It takes a lot of power to turn a large compressor wheel and its the turbine wheel's job to generate this power. Usually on a well designed system you want to keep the ratio between 1. 1 and 1. 3. Anything larger you'll have a hard time driving the compressor wheel.



Another big question is why can't I run a large turbo with a very small turbine housing. The problem with this is that not matter what technology you have on your turbine housing (i. e. VGT, slider) you are always at the mercy of the compressor wheel. If you try to spin the compressor wheel too quickly you push the turbo into surge. This can happen during driving conditions are when you let off on the throttle (i. e. HX40). As boost is directly related to wheel speed your are now sacrificing reliability when you are spinning a 4" passed 100,000 RPM.



You'd be surprised at some of these smaller turbos and how much they can flow from a small wheel. For example our Duramax turbo that should be released in the next couple of months can keep up with a BHT3b. Of course it should as it is a newly designed wheel and the BHT3b was designed in the 1980s. But the big plus is how wide this map is.



Like I said do some reading and research before you buy and remember designing a system is different than assemblying one.

 

[Matt400]

I ask everyone to do their own research and don't believe the hype on anything otherwise you will be disappointed.

Thats just the thing. . for the average drivers that are not so much in the know its hard to decipher what is really being said and what it means.

Example. .

For example who would of believed our Super B turbo flows equally the same amount of air the Turbonetics Jammer2 setup, yet our compressor map is almost 25% larger in the surge direction.

What is surge direction?

Plus the map goes clear into efficient pressure ratios over 4. 2.

Is that another way of writing 42 psi?

If you try to spin the compressor wheel too quickly you push the turbo into surge. This can happen during driving conditions are when you let off on the throttle (i. e. HX40).

The first part of what you say sounds like you are referring to spool up yet the second part relates to backing off, is surge a concern under accel or decel?

Like I said do some reading and research before you buy and remember designing a system is different than assemblying one.

Good advise but in the end the average consumer buys what they have been sold on unless they understand enough to know better, I am trying to learn more as you can see from my questions.

 

[Diesel Freak]

Howdy Christian!!!



I'm gonna try an make it to the next Dyno Day (I need to pick your brain)!

 

[CRoth - BD-Power]

Thats just the thing. . for the average drivers that are not so much in the know its hard to decipher what is really being said and what it means.

Example. .

What is surge direction?

Is that another way of writing 42 psi?The first part of what you say sounds like you are referring to spool up yet the second part relates to backing off, is surge a concern under accel or decel?





Good advise but in the end the average consumer buys what they have been sold on unless they understand enough to know better, I am trying to learn more as you can see from my questions.

The surge area of a map is on the left hand side of the graph. If you operate in this region you have the risk of causing a surge. Basically the engine is not consuming enough air from the compressor wheel, the air pressure then stalls the compressor wheel. A surge can happen during accleration or during decleration (i. e. quickly backing off the throttle, "barking the turbo").



Pressure ratio is a ratio of of the gain in pressure over atmospheric pressure. So for say if your atmospheric pressure was 14. 7psi. A 4. 2 pressure ratio woudl calculate out to (14. 7 x 4. 2)- 14. 7psi, which equals 47. 04 psi of boost. But for people in higher elavations your atmospheric pressures maybe 12. 0 psi, so then (12. 0 x 4. 2) - 12. 0 equals 38. 4psi. So you can see the less atmospheric pressure there is the faster turbo must spin to maintain a set boost pressure.

 

[Luke Warmwater]

Chris, good explanation on what causes surge. My question would be if you are experiencing a surge condition, what is that pointing to in regards to your setup? Too much of this or too little of that... that sort of thing. My B1-2 with 150hp sticks at 5500' elevation, will surge a little in the mid range with heavy fueling. It's sort of just a mild stutter as RMPs climb to about 2200 at which point it goes away. Nothing violent like barking but still noticable. Thx

 

[CRoth - BD-Power]

A lot of it has to do with the compressor wheel. You maybe able to solve it increasing the size of the exhaust housing but that would severly hurt your spool up. So its probably not something you would want to do.



The only other option you have other than changing the wheel is to try a smaller A/R ratio compressor housing.

 

[Luke Warmwater]

So by increasing the size of the exhaust housing you are not going to convert quite as much of the exhaust gas energy into shaft rotation energy and then into pressure energy on the compressor side?



Alternatively by using a smaller compressor wheel, you are doing the same thing but doing it by reducing the amount of pressure energy that can be produced by the compressor for the same given exhaust gas energy?

 

[CRoth - BD-Power]

Basically you are correct on the exhaust housing description. I my previous post I mentioned using a smaller compressore housing not wheel. A smaller housing restricts flow a little and helps reduce the air conversion from velocity to pressure.

 

[Luke Warmwater]

Got it. Thx

 

[rivercat]

Good thread!

 

[DJWrightson]

That's actually a very good question. I was just having that discussion with Ross at Dynomite Diesel just yesterday. I have a set of Super B's and was looking at a nitrous set-up. Ross 'suggested I trade'm in for a not yet released Turbonetics single if I went that route. He says the BD Twins can't handle the drive pressure like a big single can and I'd end up compromising the head gasket even though the head is studded. He said with what I currently have, if I replace the twins for the single and add nitrous, he could almost guarantee 750hpI have not decided yet. The twins are only a year old with very few miles.

 

[Forrest Nearing]

holy dead thread revival!!!!



gimme an II sps over a BB jammer any day