How Twin Turbos Work – All The Boost!


Hello everyone and welcome, in this video I’m going to be explaining twin turbos now this isn’t the place to learn how turbochargers work So if you don’t already know how turbochargers work, I’d recommend checking out my video explaining that. So twin turbos; In this video I will be explaining two different setups, one parallel and one sequential, both of which are going to utilize the same size turbo, Just have two of them, but they’re going to use them in different ways. Now, there’s another type out there which uses different size turbos which I will explain in a future video, so The first and the most simple setup to basically understand is parallel and basically all you’re doing is you’re having two separate turbochargers for two separate cylinder banks, so it’s almost like you’ve got two separate turbocharged engines. So here we’ve got a V6 You can see the cylinder banks, and you’ve got your two intakes so here’s your two turbochargers Basically, during your exhaust stroke, you’re going to have exhaust come out through these exhaust manifolds Spin up the turbos, the turbos are going to pull in air, the air will go through the intercooler through the throttle to the intake manifold, to the cylinders and then repeat that process. So it’s just like with a regular turbocharger the only difference is you’ve got two cylinder banks, so you split up the work between two turbochargers. So things to note on parallel is that both turbos are always going to be active for the entire RPM range Well they may not, say you sized them so that they spool up at a higher RPM, that’s fine, but point is they’re both always going to have exhaust flow directed towards them and both turbos are the same size as I mentioned. Now another type of Turbo setup is sequential So here we’ve got a four cylinder engine and basically what happens here is you have one turbo active at low RPM and then both turbos active at a higher RPM when you have more exhaust flow. So at low RPM you’ve only got a single turbo active and here we have a bypass valve, and this is basically what shuts off this turbo, so if air isn’t allowed to pass through here It’s not going to be able to spool up, and it’s not going to be able to put any boost through this Piping so basically what happens is after your exhaust stroke all your exhaust is going to be directed to this turbo here, and so it’s going to spool up this turbo, and then it’s going to pull in air through this intake along this channel, and so it’ll send that air Up here into the intercooler through your throttle into your intake manifold and then into your engine And then It’ll just keep recirculating like that along and then of course out the exhaust here Now why would you only have one turbo spooling at low RPM? Well the reason is you don’t have that much exhaust so you couldn’t spool up both of these turbos with the limited amount of loss Exhaust that you’re making so you send all of it to one turbo And that’s enough to spool it up and create boost for the engine now at Higher RPM Scenarios this bypass valve is going to open up You’re going to have a lot more exhaust and so all of that exhaust is going to be directed to both of these turbos So they’ll both be pulling in air, bringing it to the intercooler through the engine and then they’ll continue spooling out both of these turbos, and then finally out the exhaust so Basically the reason you can do that is because you have more exhaust flow and once again both of these turbos are the same size So if you have any questions, or comments feel free to leave them below and in my next video I’ll be explaining a twin-turbo setup in which you have different sized turbochargers

100 Replies to “How Twin Turbos Work – All The Boost!

  1. Does exist a twin SEQUENTIAL turbo in a V shaped motor? I'm almost sure that there isn't but I'd like to know, maybe I'm mistaken.

  2. Hi Jason, I love your videos and have been a subscriber quite some time. I am currently working on a second gen Pontiac Firebird. It will receive a twin turbo setup. I have this wild idea about deleting the original fuel tank and putting the radiator in its place. The intercooler would be in the front of the car. I was thinking a rear diffusor would suck air through the radiator at speed and electric fans while cruising. Do you think a setup like that could work? Or should I stick to my pedal cars 😉 ?

  3. how do engines get air for combustion prior to the turbo(s) spooling? does it travel the same way, just uncompressed? I always thought having air enter the filter, go through the turbo and to the engine wouldn't be very effective without the turbo actually pulling the air in or pushing it towards the engine. Or does the engine running by itself create a type of vacuum pulling air through the filter/turbo/intake manifold?

  4. I have question? so if I use the different size turbo in sequential twin-turbo setup. Small turbo for low rpm which means the turbine can spin a little bit fast, then goes to the high rpm, both of turbo work for the higher rpm boost?

  5. Im not gonna say your wrong. Most of the time though with the Sequential System, the Bypass is AFTER the intercooler and, sent through a pipe to the compressor side located at or near the main intake. It keeps the cooler air charge in the system and produces better results due to the fact that the air is cooler going into the compressor with less wasted energy.

  6. Does a twin turbo need a intercool im just getting into turbos and I'm putting t3 t4 turbos on my ls1 5.3l. PLEASE HELP!!

  7. I have a question . How can I check if the my twin turbo is pararell or sequential? Do I have to open up the engine and check or if you know it would be great! My car is a bmw 640d Gran Coupe '14

  8. In this setup, the bypass valve only prevents boost leak(as he says the turbo 2 is not spooling). I think there should be a solenoid valve at the exhaust side that goes to the turbo 2, and that should be opened by the ECU when the desired RPM is reached( similar valve at the compressor side as well or even an Non Return Valve will work there).

  9. i have a question for u sir.what if a person going a smooth road with sequential turbocharger installed; finds a turn or some obstacle so applies brake hence lowering the rpm leading to immediate valve closure on one of the compressor side hence leading to surge like effect on the turbocharger (somewhat like exhaust braking but at very high rpms) can cause a great disaster to the blades of turbocharger so instead putting valve on intake side ain't it be possible to place the valve on exhaust side of one turbocharger so that this problem is mitigated and even the desired logic of switching both the compressors 'ON' only at high rpms is also sustained.

  10. Interesting. I thought that the bypass valve for the second sequential turbo was on the exhaust side, not the boost side.

  11. Hi there! I just wanted to make a question. I have a s13 with a ka24de and I had this crazy idea of making it twin turbo with some small A/R turbos, low comp forged pistons and rods, maybe porting the head for some better flow of the exhaust gases and increasing the spooling of the turbo but I've never seen a ka24dett, my question is, will it be reliable or at least possible? My turbo options are gt22 or k04. I hope to get an answer! I've learn a lot from your channel, keep rocking!

  12. I'm wondering about the placement of the bypass valve on the sequential setup, it seems like it doesn't block 2nd turbo spooling at any time, which would be lost energy on low rpms

  13. Also, what can I expect temperature wise when it comes to sequential? Is one turbo gonna be more hot because it's working through the entire rev range, or is one gonna work low range and the other work higher range?

  14. Can I twin turbo A 4 cylinder SOHC or in other words a straight 4 engine? And what is a sequential Twin turbo? A RX-7 has a sequential turbo and I don't know how it works.

  15. if we speak about efficiency in terms of exhuast flow. would it be more efficient (on a 4 cylinder ) to run 2 exhuast ports per turbo or the way you have just explained……. what are also the pros and cons of run it 2 ports per turbo

  16. Hello I have a question does the parallel or sequential setup make more horsepower than the other setup? By the way I like your channel man thanks for the videos.

  17. This helps…i like to do things ppl say i cant do..i bought a 1990 cmc duelly diesel 4×4…blown motor.i put a gass 366 from a 1979 dump truck in it….so motor cant be boared out….but…i can always try to turbo charge it…hahahahahahaha…it might crap out but i will try it anyway..

  18. hi im building bmw m43b19 4cyl and im doing twin turbo one small to3 turbo and gt3071r how does this setup work ? i need help with that i dont know how to make that setup

  19. I have a twin turbo supra setup. And its currently running in seq mode. However i can just reroute a few vacuum lines& vsvs and run in parallel. However. In seq. Mode its already more lag than i like. And thats for when the 1st comes online and even the second. Its far worse if i run in parallel but kicks harder obviosly my question to you is. Do u know if i could modify perhaps how early turbo 2 comes online and maybe even turbo 1. By perhaps modifying bypass valve? Btw. I have elec boost control and ecumaster det3. And i already have a borg single set aside . but for now im trying to have a lil more fun with the twins. Thanks for any input!

  20. Can i make two manifolds for sequential so two cylinder per turbine would it be okey for engine and turbos to work

  21. Would it be possible to make a second turbo run on steam from waste heat from the exhaust manifold before the first turbo?

  22. Someone please answer me this.. On a twin turbo set up, does the air intake to both turbos need to be the same length or is that not relevant? I am thinking down the line of 1 turbo (shorter intake) scavenging air from the second? Fairly uneducated guess sorry

  23. You need to educate your self before you talk on a sequential twin turbo setup is one small turbo and one large turbo

  24. If you run two turbos on a v6 each producing 3 psi of boost do you have 6 psi or do you have a higher volume of 3psi

  25. So the twin turbos are the better design and the sequential was the dealership think tank to get you to screw your car up and take it back to the shop

  26. my question is can I set specific specs to engage each turbo like as in Dont kick on until i hit X gear X RPM X Throttle X Exhaust…??

  27. The only thing that is important about this is which has less low end turbo lag. Or to describe it better, which has a smoother acceleration like a naturally aspirated engine?

  28. My native language is not english but this simple explanation is the best under 5 mins, and even I understood the whole thing how its working. 🙂

  29. HOPEFULLY I GET A REPLY

    Wassup guys how much do think I need to spend to Twin Turbo my 2011 Ford Explorer XLT?!

    Got a 8 second clip of my truck on my channel if you wanna check it out! Would highly appreciate it

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