S13 Twin Turbos Non-Sequential

[Bluewind]

Forget Sequential TT set-ups. For the drift or autox scene, you need good response time, not turbo lag. I really dislike to post this type of question, but has anyone done this? I realize it consumes much time and money (custom mani. and dp.) and space, so I'm curious if anyone has done it with 2 stock SR turbos. Thanks

[Bbandit]

I think Andrave is building a twin turbo KA

[tastyratz]

are you talking about mounting them in a series? if you are its been done before. your alot better off with a single turbo at that point. Think of the heat a turbo generates, then think of the unneeded passing through of a second turbo would do to that. that air would be scorching hot and harder to cool down before it gets in. that means no real serious gains and the second turbo very much will probabbly act as a restrictive heater and thats about it. twin turbo is the way to go if you want but even single turbo with equal length mani and ball bearing turbo works fine too.

[andrave]

you can click the german to see what I'm doing. its all nearing completion, so I'll know how well it works in a couple weeks.

[TheSnail]

Originally Posted by andrave

you can click the german to see what I'm doing. its all nearing completion, so I'll know how well it works in a couple weeks.

Looking good! Those are my turbos. Spool up time should not be bad at all, If you run over 14psi change the wheel to steel instead of ceramic. I will be swaping mine for diff ones in about 6 months, so if youy ever blow one, you can just shoot me an email and I'l hook you up on my gtr snails.
-Snail

[NZO]

Forget sequential? Seqential = fast spool and response...

[90RS13]

are you talking about mounting them in a series? if you are its been done before. your alot better off with a single turbo at that point. Think of the heat a turbo generates, then think of the unneeded passing through of a second turbo would do to that. that air would be scorching hot and harder to cool down before it gets in. that means no real serious gains and the second turbo very much will probabbly act as a restrictive heater and thats about it. twin turbo is the way to go if you want but even single turbo with equal length mani and ball bearing turbo works fine too.

You are talking about compound turbocharging. Many tractors and heavy machinery use it, as well as some semi's. The second turbo doesn't "act as a restrictive heater", the set up does generate more heat in the charge air, than a single or sequential system, but with a large intercooler it's usually not a problem. As far as spooling goes it's great. You use very small turbo's, so they spool very quickly. Just think, a 1.4 pressure ratio can be easily achieved with a very small turbo. Ok now look, in a single turbo system, when your turbo is at a pressure ratio of 1.4, you would get get 5.8 psi of boost pressure. [atmosphere at sea level)*(pressure ratio)-(atmosphere)=(boost pressure.]Not enough for most enthusiast. But when in series, with 2 turbo's at a 1.4 pressure ratio, you will have 14.1 psi, of boost pressure. So with the spool time you would get from a turbo optimized for 6 psi, you can have 14.1. For perspective, a turbo at a pressure ratio of 2, you would get 14.7 psi. If you know turbo's, the difference between 1.4 and 2 is more than it sounds. Now there has to be a catch right? There are many. It's alot harder to have the room for a compound turbo system. It also does generate more heat, so you need a bigger intercooler and seperate oil, and/or water feed lines for each turbo. It can also be hard to find small enough turbo's to use for daily drivers. Also, when you start flowing alot of air, the small tubines create a lot more back pressure. It has beed done, even on performance cars though, and with success. Hope that makes sense. Tell me if I forgot anything.

[TheSnail]

Originally Posted by 90RS13

You are talking about compound turbocharging. Many tractors and heavy machinery use it, as well as some semi's. The second turbo doesn't "act as a restrictive heater", the set up does generate more heat in the charge air, than a single or sequential system, but with a large intercooler it's usually not a problem. As far as spooling goes it's great. You use very small turbo's, so they spool very quickly. Just think, a 1.4 pressure ratio can be easily achieved with a very small turbo. Ok now look, in a single turbo system, when your turbo is at a pressure ratio of 1.4, you would get get 5.8 psi of boost pressure. [atmosphere at sea level)*(pressure ratio)-(atmosphere)=(boost pressure.]Not enough for most enthusiast. But when in series, with 2 turbo's at a 1.4 pressure ratio, you will have 14.1 psi, of boost pressure. So with the spool time you would get from a turbo optimized for 6 psi, you can have 14.1. For perspective, a turbo at a pressure ratio of 2, you would get 14.7 psi. If you know turbo's, the difference between 1.4 and 2 is more than it sounds. Now there has to be a catch right? There are many. It's alot harder to have the room for a compound turbo system. It also does generate more heat, so you need a bigger intercooler and seperate oil, and/or water feed lines for each turbo. It can also be hard to find small enough turbo's to use for daily drivers. Also, when you start flowing alot of air, the small tubines create a lot more back pressure. It has beed done, even on performance cars though, and with success. Hope that makes sense. Tell me if I forgot anything.

Good stuff, I wish we had more Germans on Zilvia.

[240KAT]

Originally Posted by 90RS13

You are talking about compound turbocharging. Many tractors and heavy machinery use it, as well as some semi's. The second turbo doesn't "act as a restrictive heater", the set up does generate more heat in the charge air, than a single or sequential system, but with a large intercooler it's usually not a problem. As far as spooling goes it's great. You use very small turbo's, so they spool very quickly. Just think, a 1.4 pressure ratio can be easily achieved with a very small turbo. Ok now look, in a single turbo system, when your turbo is at a pressure ratio of 1.4, you would get get 5.8 psi of boost pressure. [atmosphere at sea level)*(pressure ratio)-(atmosphere)=(boost pressure.]Not enough for most enthusiast. But when in series, with 2 turbo's at a 1.4 pressure ratio, you will have 14.1 psi, of boost pressure. So with the spool time you would get from a turbo optimized for 6 psi, you can have 14.1. For perspective, a turbo at a pressure ratio of 2, you would get 14.7 psi. If you know turbo's, the difference between 1.4 and 2 is more than it sounds. Now there has to be a catch right? There are many. It's alot harder to have the room for a compound turbo system. It also does generate more heat, so you need a bigger intercooler and seperate oil, and/or water feed lines for each turbo. It can also be hard to find small enough turbo's to use for daily drivers. Also, when you start flowing alot of air, the small tubines create a lot more back pressure. It has beed done, even on performance cars though, and with success. Hope that makes sense. Tell me if I forgot anything.

Did you copy that out of a magazine? Ive read that nearly exact same thing (including little formula) somewhere, i jsut cant remember.

[Bluewind]

Ok, well I'm glad many people are looking at this thread, and giving their opinions, but I want to know if it's been done! Tastyratz, you should read up more on non-sequential TT set-ups. But as 90RS13 said, you are right, heat will be an issue. But it won't be something that is a major concern. SPACE is the largest concern. Also, NZO, I beg to differ. Therefore, my main and original question still remains, "has anyone done this before in an S13?" I've seen a S15 with sequentials, but it's an S15 chasis... Anyhow, this would be great if anyone were to do it!

[andrave]

well you need to clarify what kind of turbo'in you are planning on. Cause there are quite a few ways to put two turbos on one engine. I'm running mine in parallel, which means 2 cyls to go 1 turbo and 2 to another and then after the turbos they Y back together.

[240Stilo]

Why not try it with all 4 pipes to one turbo and having the exhaust from the first turbo spool up the second?

[NZO]

Originally Posted by Bluewind

Also, NZO, I beg to differ.

Maybe we are thinking of something different but what I'm trying to say is if you use one very small turbo and a larger one in a sequential setup you will have very fast spool with the first turbo and then big boost all the way to redline with the 2nd larger turbo. The trick is setting something up to control the switchover point from one to the other.

[andrave]

I posted on this in the forced induction thread a long time ago at nico.
but I think a large racing wastegate could easily act as the switcher. its got all the diapraghms and such. you could run the exhaust first into a Y pipe, one of the legs gets the small turbo the other gets the large wastegate. The wastegate is closed at low boost, at, say 7 psi the wastegate sense the boost, opens, but instead of venting the smaller turbo it just opens the Y, so all that pent up exhaust is still going through the small turbo, but also flying around it, slamming into the larger turbo, making like the crazy NAWS on fast and furious 2.
I see no reason why it wouldn't work. Want me to make a photoshop drawing of it tomorrow? I like making photoshop drawings.

[KA240SX808]

Originally Posted by Bbandit

I think Andrave is building a twin turbo KA

Wow that would be the frist KA-TT I know of

[90RS13]

Why not try it with all 4 pipes to one turbo and having the exhaust from the first turbo spool up the second?

That is a compound setup.

Did you copy that out of a magazine? Ive read that nearly exact same thing (including little formula) somewhere, i just cant remember.

I'm pretty sure that one of the import magazines had an article about pressure ratios, and compound turbocharging. I can't remember which though.

I posted on this in the forced induction thread a long time ago at nico.
but I think a large racing wastegate could easily act as the switcher. its got all the diapraghms and such. you could run the exhaust first into a Y pipe, one of the legs gets the small turbo the other gets the large wastegate. The wastegate is closed at low boost, at, say 7 psi the wastegate sense the boost, opens, but instead of venting the smaller turbo it just opens the Y, so all that pent up exhaust is still going through the small turbo, but also flying around it, slamming into the larger turbo, making like the crazy NAWS on fast and furious 2.
I see no reason why it wouldn't work. Want me to make a photoshop drawing of it tomorrow? I like making photoshop drawings.

sounds good. The new BMW deisel engines use a nice sequential setup. It uses almost the excact setup you are describing. Makes for very quick spooling, and instant throttle response. The wastegate i think would have a tough job though. I'm thinking. The wastegate is set to relieve pressure at 7psi. Then it starts letting the extra gases go to the bigger turbo. Then both turbo's will be making boost, so the engine will have alot more aire flowing through it. Eventually the wastegate won't be able to flow enough, and too much gas will go to the first turbo. It will end up spinning faster than you expected.

[/QUOTE]Want me to make a photoshop drawing of it tomorrow?[/QUOTE]
yes, some people might not be able to visualize it.

I like how this thread is going. It's not getting covered in pointless posts, from people who post just to see their name on the thread.

[Bluewind]

Originally Posted by 90RS13

I like how this thread is going. It's not getting covered in pointless posts, from people who post just to see their name on the thread.

I'm with you on that. I think everyone is mutually interested in this set-up. It's not the average thread, and basically the people with knowledge and understanding are the people visiting this thread.

[90RS13]

I thought of something for the wastegate problem that I mentioned earlier. Using more than one wastegate would be good. For fun let's say you use 4 wastegates. They're set for 7psi. At 7psi, they will all start to open, like normal. Then when you're flowing alot more you would have alot more flow, (becuase of all the wastegates), while still keeping the first turbo at a lower rpm. With only one wastgate when set at 7psi, when the engine's flowing alot of air the wastegate won't be able to pass all of it, so the first turbo wil take in more than you want. Am I explaining this well? See,

one wastgate 4 wastegates
| | | || || || |
See, more wastegates can flow more gas when needed, but can also keep the first turbo from spinning out of it's effeciency range. Does this make sense?

[crioten]

instead of having a waste gate open, why not make a cutout (like an exhaust cutout)...just have it hooked up somehow that when it detects 7psi of boost on the smaller turbo it opens up and allows more air to go into the larget turbo...

while you are at it, why not make a proportioning valve that has the ability to limit the amount of air that goes to each turbo?

[andrave]

well just keep in mind that a waste gate diaphragm could control a larger valve if you wanted it to. Or you could always use a boost activated switch to control an electric cut out. The problem with that, is that they are very slow acting. vaccuum activated are, psh boom and they are open, just like a wastegate. electric, I can't think of anything that doesn't use stepping motors, which equals... "whhhiiiiirrrrrrrrrrR" and by then your engine hit redline and the system is theoretical.

[NZO]

If youre really serious about using a sequential setup just reverse engineer an FD or MKIV and see what they use.

[Pacman]

Originally Posted by andrave

you can click the german to see what I'm doing. its all nearing completion, so I'll know how well it works in a couple weeks.

No shit, thats yours?! I check on that car every few weeks to see if it has any updates. Yours is in my Favorites. Can't wait to see it done.

[andrave]

photo shop drawings are too big to post on zilvia, oh well. But anyway I know how the setups work on supras and rx-7s...
its not the same thing we are talking about. You would want to look at one of those porsches they made a while ago (called the ultimate porsche, I can't remember the number), they actually used a smaller turbo and a larger one. the Japanese cars stuck with two of the same size turbos, and basically a wastegate like device that just opens up both turbos.

[AAA240SX]

Twin Turbo GTO's use this setup, and still get heated up pretty bad . Managing engine temps. is critical with this setup.

Differently sized turbo's are better for overall powerband performance. Low end (Smaller) Top end (Large). The two larger turbo's can provide crazy top end horsepower (like Skylines, MK4's, etc.).
It justs depends really on what the car will be used for.

If a street car, 2 larger turbo's is better. The lag at low RPM's allows for better mpg.

[young gun]

awsome thread, would it be possible to build a sequentila set up with identical turbos using a wastegat as earlier mentioned?

[andrave]

Yes, read above. model the toyota supra twin turbo. You can buy the whole manifold and shit off ebay cheap, no one wants stock crap sequential.

[ftrs13]

haha .... big turbo and bigger turbo, t3/t4 and a T66
you would only have 1000-1500 powerband on the T66, but when it kicked in, plus you would have the t3/T4 from 2700-5500

[90RS13]

You would want to look at one of those porsches they made a while ago (called the ultimate porsche, I can't remember the number), they actually used a smaller turbo and a larger one. the Japanese cars stuck with two of the same size turbos, and basically a wastegate like device that just opens up both turbos.

The new BMW Turbo Deseils I mentioned use the "Porche" set-up.

Twin Turbo GTO's use this setup, and still get heated up pretty bad . Managing engine temps. is critical with this setup.

A sequential twin tubo system, won't cause higher intake temps than a parallel twin system, or even a single turbine, at the same boost. On a compound system, the charge air goes through one compressor, get's pressurized and heated, then through another compressor section, and get's pressurized and heated again. That's why the intake temp get's high. On a sequential, or parallel system, the charge air only goes through one compressor section. Then meet's together at a "y" pipe, or at the intercooler. If GTO's have heating problems, then it's from lack of engineering, not the sequential system. Also, most car's will have cooling problems when pushed to twice their origanal horsepower.

[young gun]

Originally Posted by andrave

Yes, read above. model the toyota supra twin turbo. You can buy the whole manifold and shit off ebay cheap, no one wants stock crap sequential.

so just buy a supra set up and reverse engenere a new amanifold

[tastyratz]

Ive always read about people doing compound turbo setups and getting told its a bad idea and not to do it. it never seemed like a good idea to me. this thread however has sparked curiosity with me... i like the idea of the larger turbo switching. what about chopping up a throttle body and welding it in front of the smaller turbo inlet. this way you could set it up in a way that when you reach x amount of boost you rig the tb to close which in turn would divert all the gas to another pipe going to the larger turbo. this whole idea is creative but its really complicated, and will involve some serious welding and margin of error... id like to hear more though...