sequential turbos endless possibilities

jbeaton9292 · Nov 2, 2014

so ive been thinking about what im going to want out of a future setup. the next car is gonna be a full blown track car not daily driven like all my others have been, so im wanting to go all out and have something nobody else has. so im thinking a sequential turbo setup would be really cool to do. this way i can have low end power that we all seek while being able to make a pull through 10k rpm without dropping off. maybe this is wishful thinking but this is the first im reading into this. if this is how it can work then why arent more of us doing this and making some crazy power and screaming all the way down the track. i feel with the proper setup this would be an awesome setup for road racing on them big tracks.

so here is what im thinking something like a t28 as a primary and a huge like a super 99 or bigger. this way we can make boost very early on in the rpm range because of the t28 (which have made pretty good power numbers) and it in turn will spool the super 99 with a now higher flowing exhaust gas then what comes from the exhaust runners. so now when the t28 has had enough and starts dropping boost the super 99 will be already making power and going pulling like crazy and will have all the air we would need to finish the run without falling off.

now i know that with what im thinking the t28 probably wont live very long but being a track car not a daily that is something that can be taken care of more frequently. also i know with all this added torque it will cause havoc on all the driveline parts. i would want this for an auto car in all honesty so that it dont drop boost when you shift and snap hard on the drive and will not die down.

now what im not sure about how does something like this work as for setting boost. im assuming this would have to be some crazy sort of twin scroll setup. and find at what boost the t28 will begain to spool the super 99 and set the wastegate for said amount of boost and then it would dump just like a single turbo setup. except the boost produced going into the super 99 now and building boost on that. because correct me if im wrong but adding boost to in engine is kind of like adding displacement, i know its still a 2.0 but with x amount of boost on a 2.0 is like running a 5.0 liter which i know wouldnt have a problem with a super 99 strapped to it.

if im right with all of this why arent we doing this more often with our engines. then if we even went 2.3l would could spool something like a hx35/40 for a primary like we would spool a stock frame trubo. i think our power and trap speeds would just be that of a different world that people wouldnt ever see coming till it was way to late.

sorry this seems like a big mess im trying to think about all this new info and how its gonna work LOL

1990dsmkid · Nov 2, 2014

Look into compound setups. Theres a couple threads on here about. Will be good for you to read through them.

Eddie Tsi · Nov 2, 2014

1990dsmkid said:
Look into compound setups. Theres a couple threads on here about. Will be good for you to read through them.

Compound setup, best of both world! I was thinking of doing this but the cost, complexity and limited space in the 1g engine bay, deterred me from it.
I image it would be a great track /road racing setup.
very hot engine bay temp. maybe an issue?

jbeaton9292 · Nov 2, 2014

see what i dont know is how the science behind it works. like can you just pair any two turbos together. or like say just for example because i dont know exactly so these numbers are not right but just to get an idea.

if a 4.0l would spool the super 99 by 3000rpm because im assuming our 2.0l is spooling it by around 6k and we are just revving crazy high to make big numbers with that turbo. so a t28 running (again just say) 20psi makes our 2.0l essentialy a 4.0l. and by the time that would hit 20psi that should be moving enough air to have the super 99 building boost and then we wont have lag issues with that and will make more power at a lower rpm as we are making with single at high rpm.

maybe im just thinking all of this wrong i dont know[DOUBLEPOST=1414953995][/DOUBLEPOST]

Eddie Tsi said:
Compound setup, best of both world! I was thinking of doing this but the cost, complexity and limited space in the 1g engine bay, deterred me from it.
I image it would be a great track /road racing setup.
very hot engine bay temp. maybe an issue?

yes you are thinking like me a track car would be awesome with this kind of setup think lemans race it has a huge straight away. so with this kind of setup you would be able to get some crazy trap speed in the straight and in the turns you could pull hard through them and would have the big boy spooled exiting the turn and rip out of the turn like none other. and make crazy power on the small straight before your next turn. also with this setup there shouldnt be much traction loss problems like with just a single turbo that comes on hard because it wont pack a punch like before because there was already boost built up. the butt dyno would feel very shitty im assuming but the real numbers would say otherwise!

91-GS · Nov 2, 2014

Eddie Tsi said:
Complexity and limited space in the 1g engine bay, deterred me from it...very hot engine bay temp. maybe an issue?

would it be possible to move one or both turbos further down the exhaust, maybe even to the very back? That would bring efficiency down some due to all the piping that exhaust and air would have to go through, but maybe advantages will outweigh the disadvantages? Never worked with turbo anything, so that is just an idea.

jbeaton9292 · Nov 2, 2014

i think that would just be more negative effects then it would be good i cant think of anything good that could come from that i know in order to fit the stuff under the hood and not be a big mess would be to make a partial tube front end which most full blown track cars do anyway

LandSpeed-DSM · Nov 3, 2014

As noted, the term you're looking for is "compound" or series/staged turbochargers.

The sizing split between a Super99 and a T28 is way too big. For a variety of reasons.

You need to be far more specific on what kind of track you're actually talking about.

Then consider if you have the budget for such a project, and the fact that you want less complexity where possible in a race program.

You can make a T28 "work" with the Super99, at the cost of a ton of compromises that would effectively negate the reasons for going compound in the guest place.

That's not just my opinion either, it's a function of how these systems work.

jbeaton9292 · Nov 3, 2014

So im not sure how the science is behind these setups and budget isnt a issue as it will be over time with a spare engine but sequential is the word i was looking for im not sure why here they are called compound as if you do some investigating sequential is the common word its the same thing though and im wanting a car that is kinda all around track car not that it would be the best in all of them but perform well in everything

LandSpeed-DSM · Nov 3, 2014

Sequential and compound are two different concepts, where sequential is more complex yet with even more drawbacks.

I and others here do know the science, perhaps you should investigate further. I have hands on experience with this not some Internet Expert.

You started a thread seeking advice right? Or were you only looking for pats on the back and what you want to hear?

warren · Nov 3, 2014

My fp t-28 is at full boost at 3700 with cams but start spoiling at 2800

mercaholik · Nov 3, 2014

If you wanna know about sequential turbo systems check out turbo supras, rx-7, older audi s-4 and I think hks developed a system for the 2jz. For compound (where one feeds into the inlet of another turbo) check out what they are doing in the diesel world. Like 80-100+ psi in useable rpm ranges. While the sequential is a great idea, in the real world they can malfunction. They were tried and abandoned (but then again so were turbos). Just like land speed said, you want to keep things simple in a race car, but if you have the resources and finances to push forward that would be awesome.

johneclipse · Nov 3, 2014

Sequential is generally referred to as two turbos working together. Whereas compound is generally referred to as one turbo feeding another.

Easier way to do what you want would be a twin charged. Supercharger feeding a big turbo. Absolutely no lag on low boost, then big turbo takes over once supercharger runs out of steam

Christoph · Nov 3, 2014

99gst_racer has/had a compound turbo setup, I read through every page of his thread on the subject and there is way too much information for me to explain in a post. Here is the link. http://www.dsmtuners.com/threads/my-compound-turbo-set-up.336541/

Fullthrottle7 · Nov 3, 2014

johneclipse said:
Sequential is generally referred to as two turbos working together. Whereas compound is generally referred to as one turbo feeding another.

Easier way to do what you want would be a twin charged. Supercharger feeding a big turbo. Absolutely no lag on low boost, then big turbo takes over once supercharger runs out of steam

Wrong. Sequential is exactly what the word sequential means, one after the other. As in a small turbo feeds into the engine and a larger turbo to improve the low end, then is bypassed once it is spooled to allow for the larger turbo to do all of the work. Twins would be two of the same turbo working together to both do half the work all of the time. Twin charged still has the penalty of parasitic losses of the supercharger system and the lag associated with a belt drive system that doesn't make boost till the RPM raise high in the engine's range and this would still be a sequential setup since you can't feed exhaust energy from a turbo to spool it. You could potentially make something similar to a compound setup by feeding a turbo's compressed air into the supercharger or vice versa but this would be a silly way to setup and engine when you could just use two turbos in a compound setup and package it in a way that fits easier without wasting all that extra exhaust energy. Turbos can provide a wider powerband and more overall power and torque...

Compound is the exact opposite of the sequential setup and for all of the guys posting with no clue of how the system works or why it is a better idea for a small four cylinder engine, you should do more research before posting. The idea is to make the widest powerband possible and this is accomplished by taking advantage of the fact that turbos are pressure multipliers, not just big hair dryers that accelerate air. They take a charge of a specific pressure (normally atmospheric) and multiply it to a more dense charge. In a compound turbo, a large turbo is the first to ingest intake air and a small turbo the first to ingest exhaust. The larger turbo is fed energy from the outlet of the small turbo and in turn feeds its pressurized air into the small turbo's intake. This allows the small turbo to reach pressure ratios much higher than it normally could on its own and act as a much larger turbo without the penalty of lag and also spools the larger turbo faster by pulling air through it. There are actually several members in the community with compound setups working very well such as John Whalen and Paul Volk, they both make over 600hp through an auto and the setup spools around 2800-3k which is insane!

If the OP still wants to stick with a sequential setup he can do as he likes, but the compound setup WHICH IS DIFFERENT is a much better option so people should stop telling him its the same and understand the different options before making suggestions.

LandSpeed-DSM · Nov 4, 2014

Fullthrottle7 said:
Wrong. Sequential is exactly what the word sequential means, one after the other. As in a small turbo feeds into the engine and a larger turbo to improve the low end, then is bypassed once it is spooled to allow for the larger turbo to do all of the work. Twins would be two of the same turbo working together to both do half the work all of the time. Twin charged still has the penalty of parasitic losses of the supercharger system and the lag associated with a belt drive system that doesn't make boost till the RPM raise high in the engine's range and this would still be a sequential setup since you can't feed exhaust energy from a turbo to spool it. You could potentially make something similar to a compound setup by feeding a turbo's compressed air into the supercharger or vice versa but this would be a silly way to setup and engine when you could just use two turbos in a compound setup and package it in a way that fits easier without wasting all that extra exhaust energy. Turbos can provide a wider powerband and more overall power and torque...

Compound is the exact opposite of the sequential setup and for all of the guys posting with no clue of how the system works or why it is a better idea for a small four cylinder engine, you should do more research before posting. The idea is to make the widest powerband possible and this is accomplished by taking advantage of the fact that turbos are pressure multipliers, not just big hair dryers that accelerate air. They take a charge of a specific pressure (normally atmospheric) and multiply it to a more dense charge. In a compound turbo, a large turbo is the first to ingest intake air and a small turbo the first to ingest exhaust. The larger turbo is fed energy from the outlet of the small turbo and in turn feeds its pressurized air into the small turbo's intake. This allows the small turbo to reach pressure ratios much higher than it normally could on its own and act as a much larger turbo without the penalty of lag and also spools the larger turbo faster by pulling air through it. There are actually several members in the community with compound setups working very well such as John Whalen and Paul Volk, they both make over 600hp through an auto and the setup spools around 2800-3k which is insane!

If the OP still wants to stick with a sequential setup he can do as he likes, but the compound setup WHICH IS DIFFERENT is a much better option so people should stop telling him its the same and understand the different options before making suggestions.

This^ guy gets it.

There's no way in hell a "twincharged" setup would be easier at any point in development or use. Sequential systems "switch" between turbos. While there's something of a hand-off employed in a well conceived compound system.. you don't need the insane valving/piping a sequential requires, the inefficiencies and compromises inherent in them or the massive increase in the number of failure points that come with both sequential/twincharged setups.

These threads always become such a sh!t show.

There's two main reasons to go with any of these routes: wider powerband or spool a turbo your Displacement/VE/RPM can't on it's own.

In almost every application, compound is the way to go.

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sequential turbos endless possibilities

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mercaholik

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