Time to go Stage II!
- Thread starter Alky V6
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In my application with the large turbine housing, I believe it has more to do with simply getting the exhaust gases out of the cylinder as quickly as possible with as little resistance offered by the exhaust piping as possible. Stepping the piping (primaries and collectors) helps to keep velocity up while offering minimal resistance to flow.
My new calculated peak hp figure is 1535 at 8500 rpm. This recent change brought about by playing with the intake and exhaust manifolding dimensions. A 224 cid V6 at 1535 hp is 256 hp per 37 cid cylinder. 6.85 hp/cid. That is a lot of spent gases that need to be evacuated as quickly as possible to keep pumping losses to a minimum.
A 274 cid V6 at 6.85 hp/cid = 1877 hp.
turbofabricator
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Then go look at a 200+ MPH LSX with cast iron manifolds and scratch your head. Helicopters and bumble bees can't possibly fly on paper. KISS. Keep It Simple, Stupid. Seriously. I work with some really over the top engineers. Some can't tie their own shoes, though. Over thinking things can cause brain hemmoraging.
When the Ohio Boys went to purpose built tubular headers (due to cylinder head change) they figured it gained them nothing. I love unique more than most. But sometimes it never pays off. Years ago I was building Rolls V-12's (2,240 cid) and really wanted to go turbocharged. The crew chief said: "we can spend all winter fabricating new exhaust manifolds and intake systems and "try" and tune it, or we can throw more gear at the supercharger and go win races with what we have. I couldn't argue with that logic. I really do like to discuss this level of thought process, though. Good thing we don't live in the same town, Donnie..............There would be ALOT of beer consumed and we could solve the worlds engineering problems.
Believe your compter simulations as much as a politician on TV. I am currently involved with repairing computer simulations that were WAY....WAY...WRONG. And this is some of the highest power systems out there. BILLIONS of dollars spent in development and it just isn't up to the task. Nothing wrong with trying to look at things from a differnt angle. We all can learn someting from it. It would be alot of fun to run your system (which I look forward to seeing) and then slap a set of ATR headers on it and see what if any change it makes. That kind of stuff intrigues me. If I had Bill Gates $$ I would be blowin' stuff UP on the dyno every week!!!!! Or sitting on a beach in Tahiti...........Come to think of it.............Tahiti WOULD be more fun. (for about a week then I'd HAVE to blow something up on a dyno.) Lets keep this going. I like to see what you're thinking.
When the Ohio Boys went to purpose built tubular headers (due to cylinder head change) they figured it gained them nothing. I love unique more than most. But sometimes it never pays off. Years ago I was building Rolls V-12's (2,240 cid) and really wanted to go turbocharged. The crew chief said: "we can spend all winter fabricating new exhaust manifolds and intake systems and "try" and tune it, or we can throw more gear at the supercharger and go win races with what we have. I couldn't argue with that logic. I really do like to discuss this level of thought process, though. Good thing we don't live in the same town, Donnie..............There would be ALOT of beer consumed and we could solve the worlds engineering problems. Believe your compter simulations as much as a politician on TV. I am currently involved with repairing computer simulations that were WAY....WAY...WRONG. And this is some of the highest power systems out there. BILLIONS of dollars spent in development and it just isn't up to the task. Nothing wrong with trying to look at things from a differnt angle. We all can learn someting from it. It would be alot of fun to run your system (which I look forward to seeing) and then slap a set of ATR headers on it and see what if any change it makes. That kind of stuff intrigues me. If I had Bill Gates $$ I would be blowin' stuff UP on the dyno every week!!!!! Or sitting on a beach in Tahiti...........Come to think of it.............Tahiti WOULD be more fun. (for about a week then I'd HAVE to blow something up on a dyno.) Lets keep this going. I like to see what you're thinking.I enjoy batting ideas back and forth also, Ken. You're right that sometimes simpler can turn out to be just as good or better than a more complicated solution, but then how do you find out if the more complicated solution might end up working better than the simpler solution if one never bothers to try the more complicated solution? Isn't that what most people settle on doing in this world way too often? Go with the simpler solution, and by doing so, thwart the discovery of a possible better solution?
Personally, I'm hoping the engine analyzer is way off. Way off in the direction that will surprise me in a very good way. And, if the sim ends up closely matching the real world result, I certainly won't be disappointed.
Personally, I'm hoping the engine analyzer is way off. Way off in the direction that will surprise me in a very good way. And, if the sim ends up closely matching the real world result, I certainly won't be disappointed.
I'm a firm believer in the use of tapered piping on the exhaust side. The benefits can be similar to those when tapered manifold runners are used on the intake side. The advantage of tapering the intake runners is well known.
The sim is showing me that a large ID exhaust side would work best. The size is not very practical to mount directly to the head, so I have four options.
1) Manage to mount the large primary ID tubing from the head to the collector.
2) Settle with a smaller, more practical ID tubing to mount between the head and the collector.
3) Mount a tapered ID tubing between the head and the collector.
4) Use a more practical ID tubing mounted at the head for a certain distance, then step the piping size to the larger ID tubing size before the collector. The lengths of the different ID sizes of tubing (steps) would be specific tuned lengths, important to tuning the pipe to the engine.
The fourth solution would be the best one, second to a fully tapered primary pipe.
The sim is showing me that a large ID exhaust side would work best. The size is not very practical to mount directly to the head, so I have four options.
1) Manage to mount the large primary ID tubing from the head to the collector.
2) Settle with a smaller, more practical ID tubing to mount between the head and the collector.
3) Mount a tapered ID tubing between the head and the collector.
4) Use a more practical ID tubing mounted at the head for a certain distance, then step the piping size to the larger ID tubing size before the collector. The lengths of the different ID sizes of tubing (steps) would be specific tuned lengths, important to tuning the pipe to the engine.
The fourth solution would be the best one, second to a fully tapered primary pipe.
So now we have short stepped primary tubing meeting at a collector, and now starts the collector tubing lengths and ID size considerations.
When using a single large, efficient turbocharger, the turbo ends up being mounted in a position where collector lengths, either for one bank of cylinders in a V engine, or for both banks, will end up being exceptionally long. Especially if the primaries are designed to be as short as possible.
Collector IDs and lengths are just as important to tuning the exhaust manifolding to the engine as the primary piping is.
In my rare situation, I have to accomplish two important things. Evacuate the exhaust gases as quickly as possible while maintaining a good velocity to properly work the turbine side of the turbocharger. With the turbocharger that I'm using having such a free breathing turbine side, I can't afford to have the exhaust piping itself offer up more resistance to flow than the turbine side of the turbocharger.
If the piping ID is too large, then much needed exhaust gas velocity to work the turbo is lost and obtaining max planned boost levels may not be obtained. If the piping ID is too small, then the exhaust system will become the major exhaust flow restriction instead of the turbine housing, and the turbine will not get the best flow through the turbine to maximize work there, and the restriction will affect the basic engine breathing of an engine set up to take full advantage of combustion chamber crossover flow.
When using a single large, efficient turbocharger, the turbo ends up being mounted in a position where collector lengths, either for one bank of cylinders in a V engine, or for both banks, will end up being exceptionally long. Especially if the primaries are designed to be as short as possible.
Collector IDs and lengths are just as important to tuning the exhaust manifolding to the engine as the primary piping is.
In my rare situation, I have to accomplish two important things. Evacuate the exhaust gases as quickly as possible while maintaining a good velocity to properly work the turbine side of the turbocharger. With the turbocharger that I'm using having such a free breathing turbine side, I can't afford to have the exhaust piping itself offer up more resistance to flow than the turbine side of the turbocharger.
If the piping ID is too large, then much needed exhaust gas velocity to work the turbo is lost and obtaining max planned boost levels may not be obtained. If the piping ID is too small, then the exhaust system will become the major exhaust flow restriction instead of the turbine housing, and the turbine will not get the best flow through the turbine to maximize work there, and the restriction will affect the basic engine breathing of an engine set up to take full advantage of combustion chamber crossover flow.
What do we do with the collectors? The sim is again showing that it prefers a relatively large collector ID and a specific tuned length.
There are a few options.
1) Go with the tubing ID recommended by the sim from the collector all the way to the turbine housing.
2) Use a tubing ID smaller than recommended for packaging reasons.
3) Use a tapered tubing ID from the collector to the turbine housing.
4) Create a stepped tubing from the beginning of the collector to the turbine housing. The lengths and diameters being very specific to create a preferred tuned effect.
There are a few options.
1) Go with the tubing ID recommended by the sim from the collector all the way to the turbine housing.
2) Use a tubing ID smaller than recommended for packaging reasons.
3) Use a tapered tubing ID from the collector to the turbine housing.
4) Create a stepped tubing from the beginning of the collector to the turbine housing. The lengths and diameters being very specific to create a preferred tuned effect.
If we decide to step the collector tubing, could we step the collector tubing in a manner where the collector tubing becomes an extension of the primary tubing? Creating one long primary pipe where the collector tubing simply becomes a common extension of the primary piping?
Instead of the primary tubing ending at a collector continuing on with a significantly larger diameter than the primary tubing, have the primary tubing end at a collector that first continues on with a more traditional step up in size you would normally find within a stepped primary tubing. A 1/8" step up in ID. Then, the collector tubing would continue to step up as the length continued on to the turbine housing. The position of the steps being important for maximum tuning affect.
What sort of tuning affect would this create? If a tuning advantage could be had by doing this, where would the advantage show up? Top end? Mid range? Spooling quality? An overall increase across the board?
The sim likes this approach.
Instead of the primary tubing ending at a collector continuing on with a significantly larger diameter than the primary tubing, have the primary tubing end at a collector that first continues on with a more traditional step up in size you would normally find within a stepped primary tubing. A 1/8" step up in ID. Then, the collector tubing would continue to step up as the length continued on to the turbine housing. The position of the steps being important for maximum tuning affect.
What sort of tuning affect would this create? If a tuning advantage could be had by doing this, where would the advantage show up? Top end? Mid range? Spooling quality? An overall increase across the board?
The sim likes this approach.
A large diameter tubing will quickly move a large volume of gases with little pressure drop.
A smaller diameter tubing will move the volume of gases with a little more resistance to flow, and at a higher velocity.
The properties of a tapered or stepped tube is a good compromise between the differing properties of the large and small diameter tubes.
A smaller diameter tubing will move the volume of gases with a little more resistance to flow, and at a higher velocity.
The properties of a tapered or stepped tube is a good compromise between the differing properties of the large and small diameter tubes.
If there is an advantage to bothering with stepped tubing, how big is the advantage, and is it worth the effort?
When you're talking about a projected bhp level of 1500 hp for a 3300 lb car on a small tire, it's pretty obvious that the advantage, if there is one, would be very small, if noticeable at all.
So why bother? That's a good question. First off, I'm not one that normally is comfortable with settling for the simple solution. I would always be wondering if I was missing out on something. Second, I'm more than capable of producing this more complicated system, and I'm bored.
It's time to create some industrial ART.
When you're talking about a projected bhp level of 1500 hp for a 3300 lb car on a small tire, it's pretty obvious that the advantage, if there is one, would be very small, if noticeable at all.
So why bother? That's a good question. First off, I'm not one that normally is comfortable with settling for the simple solution. I would always be wondering if I was missing out on something. Second, I'm more than capable of producing this more complicated system, and I'm bored.
It's time to create some industrial ART.
turbofabricator
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Industrial art. Go for it. You can always hang it on the shop wall. I prefere someting different, too. Start cutting material and fire up the TIG. I'm waiting.
Normally aspirated, a stepped header is less sensitive to primary lengths. (in my experience). Have you seen the headers on Poteets' Dutweiler built Bonneville car? Pretty dang interesting how they tackled the room constraint for the collectors.
Here's a link: http://blogs.hotrod.com/video-462mph-in-the-poteetmain-speed-demon-20501.html
I prefere someting different, too. Start cutting material and fire up the TIG. I'm waiting.Normally aspirated, a stepped header is less sensitive to primary lengths. (in my experience). Have you seen the headers on Poteets' Dutweiler built Bonneville car? Pretty dang interesting how they tackled the room constraint for the collectors.
Here's a link: http://blogs.hotrod.com/video-462mph-in-the-poteetmain-speed-demon-20501.html
Here is an interesting comparison between my Stage I project and the Stage II project. The same turbocharger (FI91X) is being used in both comparisons using the same parameters, including the turbine nozzle size. Notice how the two configurations spool the same turbo differently, and the difference in the amount of boost created even though the same cid is being used in both engines.
Notice the difference in the HP level at the same 7,750 rpm level.
Notice the difference in the HP level at the same 7,750 rpm level.
turbofabricator
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Is that graph derived from header design, or the fact that you are gaining significant head flow going StageII? The difference in gain in both flow and combustion chamber design makes a big difference. Head flow also doesn't always make more power, but flow quality, i.e. flow INTO the cylinder and where into the cylinder it goes has alot to do with power output. Years ago a guy I know went from Dart Buick heads (Similar to the StageII V6 for his Comp Eliminator) to the latest and greatest Brodix heads which flow a fair amount more. The car slowed down. He felt the Dart heads put the air into the cylinder more efficiently. He would have changed back, but had already sold his old combo. There is so much to this that just doesn't make it easy to input info into a Sim. Maybe what I'm trying to say is that don't get all hung up on simulations. You still gotta build it to fit the chassis which always creates compromises.
What did you think of the headers on the Poteet car? No equal lengths and a very odd collector. But that little engine flat out makes a TON of power!!!!!! (for a long run to boot.) Running simulations is a good way to challenge the thought process, though.
I'd love to fab up a simple Schedule 40 log manifolds and swap it in place of your wizzy headers and see just what really happens. Time consuming and costly, but man that would be fun. (and I'd love to be proven wrong, even though I'm disagreeing with you) I'll buy a Lotto ticket and if it pans out I'll ship a set to you. If anyone wants to help with material, I'll do all the fab work to see if it makes a difference. My gears are spinning.
Just wondering Donnie........What you takin'? I mean, you don't come up with SH!T like this after just a cup of coffee!
Ha-ha..... (that's an old line from the comedian Gallagher) Now start the build. We NEED pictures.
What did you think of the headers on the Poteet car? No equal lengths and a very odd collector. But that little engine flat out makes a TON of power!!!!!! (for a long run to boot.) Running simulations is a good way to challenge the thought process, though.
I'd love to fab up a simple Schedule 40 log manifolds and swap it in place of your wizzy headers and see just what really happens. Time consuming and costly, but man that would be fun. (and I'd love to be proven wrong, even though I'm disagreeing with you) I'll buy a Lotto ticket and if it pans out I'll ship a set to you.
If anyone wants to help with material, I'll do all the fab work to see if it makes a difference. My gears are spinning. Just wondering Donnie........What you takin'? I mean, you don't come up with SH!T like this after just a cup of coffee!
Ha-ha..... (that's an old line from the comedian Gallagher) Now start the build. We NEED pictures.Here's an interesting example of exhaust manifolding used with a turbocharged Buick Stage II engine in a CART Champ open wheel car.
3.4 L, 805hp at 8200 rpm. 566cc cyl capacity. 6 primary pipes 28" x 2" dia, 2 secondary pipes 19" x 2.25" dia.
Bare in mind, this was only an 805hp application.
3.4 L, 805hp at 8200 rpm. 566cc cyl capacity. 6 primary pipes 28" x 2" dia, 2 secondary pipes 19" x 2.25" dia.
Bare in mind, this was only an 805hp application.
That's interesting about the Buick/Dart heads. If I were building a SBC, those would be the heads I would use.
The above comparison involved the latest Stage I sim configuration, including the modified (inflated) Stage I head flow numbers to get the sim to match real world results, and the latest Stage II sim configuration using unmodified Stage II head flow numbers I recieved from my head man.
The Stage II configuration also included the latest exhaust system configuration. Short stepped primaries and stepped collectors. The latest exhaust configuration pumped just shy of 100 more hp into the output. Most of that gain was brought about by the new exhaust configuration being able to push the turbine a little harder, allowing the compressor to create a little more boost, and bringing the boost level to the target max boost level sooner in the rpm band.
The turbine and the exhaust system should be treated as one system.
The above comparison involved the latest Stage I sim configuration, including the modified (inflated) Stage I head flow numbers to get the sim to match real world results, and the latest Stage II sim configuration using unmodified Stage II head flow numbers I recieved from my head man.
The Stage II configuration also included the latest exhaust system configuration. Short stepped primaries and stepped collectors. The latest exhaust configuration pumped just shy of 100 more hp into the output. Most of that gain was brought about by the new exhaust configuration being able to push the turbine a little harder, allowing the compressor to create a little more boost, and bringing the boost level to the target max boost level sooner in the rpm band.
The turbine and the exhaust system should be treated as one system.
750H.P.V6
Brutal 6 Racing
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That's kinda what I'm hoping.
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