turbo times 2 theory

[civichatch982]

so I'm not too sure if thise would work at all and even in the slightest case that it did it would be very complex to tune properly.

I was thinking about turbo systems on inline 4's and I kinda thought about a little ball bearing turbo comming off the the exhaust manifold and from the compressor housing on that have it connected to a much larger turbo 's exhaust houseing. therefor causeing the larger turbo to become fully spooled much faster. the larger turbo would have an internal wastegate. from there it would go to intercooler and then to intake, a BOV would be on the pipes to prevent harmful back pressure. each of the compressors would have a down pipe and you'd have dual exhaust haha. the wastegate on the exhaust manifold controling the ball bearing turbos boost pressure would then have its dump tube dump into the pipe comming from the compressor houseing of the ballbearing turbo into the larger so its kinda like a Y haveing 2 pipes (the dump tube from the wastegate and the pipe from the compressor of the ballbearing turbo) go into one pipe ... so it acts as almost as a bypass valve. circulating more pressure into the larger turbo without causeing too much problems /w the ball bearing turbo such as over boosting it and not being able to have it produce enough pressure to get the larger turbo working. Space is a large issue in this .. but for this idea dont take space in consideration.


So, the way I look at it is that you will have a big bad ass fully spooled turbo much faster that it would normally take. Though you would only get the max potential of the larger turbo's boost you would reach reach its potential much faster.

keep in mind that this was off the top of my head so I may have missed a couple parts that would be needed, but it sounded like it may work. I'd like to get some feed back on this to see what ppl think of my idea. and if people can think of any possible problems with it

[civichatch982]

I think you guys will have to kinda scetch it out as you read cause its a bit confusing

[tran_nsx]

sorry man, this has aready been done along time ago. its call a sequential turbo system or twin turbo set up. the main difference is that both of these turbos are usually moderate in size, not too big, not too small. at low boost only one turbo is operational, and when at @ wot, both turbines are running simutaneously at full boost. some examples of this is the twin turbo supra, 300zx, and most the other japanese muscle cars.

[Reed]

i think you might be saying that you want to make the charge air from the first turbo (instead of going to the throttle) going to the turbine of the second turbo and then having the charge air from that turbo going to the throttle?

not a good idea cause turbos use the pressure diff caused by the heat diff between the exhaust manifold and the atmosphere on the other side of the turbo. but you are pumping relatively cold air into a turbine made for very hot air. so there wont be that much of a differential.

i hope im wrong in reading your idea

[Jet-Lee]

Reed, I was thinking exactly what you were. Running the charge air from the small compressor to the exhaust turbine of the large turbo. It is a creative idea, except for what Reed pointed out. The trubines rely mostly on exhaust heat/pressure vs. atmospheric heat/pressure. You'd be better off running your small turbo for lower end (it would spool quicker) and the larger turbo for the higher end (spools slower with higher output).

[CBFryman]

been done many a time... a T3/T4 hybrid is the best compination ive seen so far...problem is the larger turbine isnt made for such low exaust flow so it puts quite a bit of back bressure on the engine...

[civichatch982]

cool, well thanks guys for the info. At least I learned something. haha for a little while there i thought I had a stroke of genius

[Sluttypatton]

The thing you have to keep in mind is that it takes energy to compress air, and if you extract energy from the exhaust to compress air, which is then further used to drive another compressor to essentially compress air again you are looking at a horribly inefficient setup that will lag worse than before. There are other substantial problems with it, but seeing as how the underlying premise is flawed there is no reason to list why the mechanics of it are also flawed.

[Broke_as_****]

Originally Posted by tran_nsx

sorry man, this has aready been done along time ago. its call a sequential turbo system or twin turbo set up. the main difference is that both of these turbos are usually moderate in size, not too big, not too small. at low boost only one turbo is operational, and when at @ wot, both turbines are running simutaneously at full boost. some examples of this is the twin turbo supra, 300zx, and most the other japanese muscle cars.

Actually the only one I can think of to run a true sequential (a smaller turbo for off the line then cuts out as a larger one spools or somethign of that nature) is the TT Supra. 300ZX turbos are identical to each other and so are the Skylines twin setups. Most people with Supras ditch the twins in favor of single large unit and find they make more horse power with alot fewer pieces

Not like you're ever going to need a twin turbo system on a I4 anyway. Hell, even I6s don't use them to any great extent. V6s and V8s are almost all twins just because the mounting wise it makes alot more sense. For the four banger just do some research and match your engine up with a nice mid range ball bearing turbo. Not like you're going to be running much past 20psi for street applications anyway so an uber huge turbo for insane power isn't needed.

[CBFryman]

Omg what about the FC...the 13B is probably the #1 most amazing HP per litre out there...

[tran_nsx]

[quote=Broke_as_****]Actually the only one I can think of to run a true sequential (a smaller turbo for off the line then cuts out as a larger one spools or somethign of that nature) is the TT Supra. 300ZX turbos are identical to each other and so are the Skylines twin setups. Most people with Supras ditch the twins in favor of single large unit and find they make more horse power with alot fewer pieces
QUOTE]


hhhmmm, i might be wrong about the 300zx, but off the top of head, i know the supra and rx-7 has a sequential set up. the turbos are the same sizes too and ur incorrect about it shutting off one turbo to a larger turbo. under low boost, only one turbo is activated, then it switches to both turbos when high boost is needed.

[Sluttypatton]

The sequential setup on the 13B is very heavy and generally problematic, anyone looking for serious power generally ditches the sequential setup and moves to a single large turbocharger. The fact that the 13B has a high hp to displacement ratio is due in part to the fact that it is a rotary motor, and in part because it is turbocharged, the fact that that setup happens to be sequential makes no difference.

[CBFryman]

I wasnt saying it was amazing because it was sequincial...i was saying it was amazing that you get over 150HP per litre OEM from ANY internal Combustion engine...the reason people ditch the sequincial set up for a single large turbo isnt because its problematic (even thought it is...turbo rotaries are like Go-Kart high maintenence) but because the smaller 1st turbo will never be able to hold the RPMs to make such high boost required to make any HP improvement...and it takes a hell of a wastegate to surpass enough exaust form the 1st to keep it from over reving when your running 1+ atmospheres at 8000+ RPM....and the fact that even NA rotories tend to not make any actual good power untill they get above 7000RPM. so why would you need to spool your turbos at 3,000RPM anyway...i mean if you are going for 350+ HP out of your wankle it isnt going to be stretable and your engine will be in the upper to redline RPMs all the time anyway...the amazing thing to me is that the 13B has ben known to sustain 700+ hp...try getting 700 semistable HP out of even an H22a... KABLOOMEY

[psychorallyfreak]

Holy Christ. The only time you'll see a "sequential" or series turbo system is in Semi Trucks that require MASSIVE boost, and can take it.
All of the "lowly" automobile twin-turbo systems out there are parallel systems. Like in the TT Supra, the 300ZXTT, the Skyline, even the FC.

[Sluttypatton]

Diagram illustrating the sequential turbosystem for relevant years of Rx-7.