Can someone please explain how this works ?

 

I know a turbo's size is a trade-off between turbo-lag and boost. I assume a sequential turbo is to overcome this to some extent, but I need to know the mechanism for it.

The Z is a twin turbo but not a sequential system - it just uses a turbo for each bank of the V6.

 

A sequential system has 2 turbos one designed to spin up quickly and get the car moving and a bigger one that comes in for big power.

 

Single turbo cars just have one turbo...

 

Then again I'm no expert so could be talking bollocks

 

 

I believe they have two turbos of slightly different specs, so that they operate at different rev ranges. Kind of like having one auto and one manual turbo ! LOL

Pukka write up must be on A Supra site somewhere.

Sequential uses one smaller turbo and one larger turbo, the smaller one spins up quickly then the larger one spins up later in the rpm range. So you dont get as much lag as having one large turbo, but can still achieve the power of a larger turbo.

Or thats how i read the situation anyways.

Still need to know HOW exactly it works. I understand why they exist and when they come in (one after the other) but need to know HOW.

 

Are Skylines sequential TT's ?

 

I this why Supra's are preferred by many and the main car in the Fast & the Furious ?

Don,t know if this is what you are talking about.but i have seen systems where the pressure of one turbo feeds the other turbo for monster boost with small(er)turbo's reduced lag,etc so instead of 2 turbos with (say)350cfm producing 15psi=700cfm@15psi you would have one turbo 15psi@350 cfm feeding into another same turbo but producing(15x15psi and 350cfm x 350 cfm=225psi boost and 122'500cfm)it doesn't quite work out like this in real life but you get the idea.They use this system on tractor pulling with very good results and years back turbo technics did a system on sierra cossy's using two very small turbos(T2's)and had a car with no turbo lag and 350bhp but even better 430lb.ft of torque,so if it's not what you are talking about then it's something else to look into???lol

Imagine if the 300 could be modified to have 2 sets of sequential twin turbos [QUAD TURBO aka ENGNE DETONATION !!] !!

 

The reason for my question is that I was thinking of a possible way of making a turbo which expands laterally as it spins faster and thus slows and acts as a larger heavier turbo thus acting like a sequential twin turbo thru one turbo.

I'll have a pair of those when you've made 'em

 

ok, the larger the turbine wheel, the longer it takes to spin up to reach boost pressure as it requires a larger mass of exhaust gasses passing over it to move it.

 

a smaller turbine wheel spins up faster at lowers speeds as the smaller amount of gasses passing by is enough to create pressure from the compressor wheel, however, as it is a smaller compressor wheel, it will shift a lower amount of air into the cylinder, so runs out of puff if you like at higher speeds. by which time, the larger turbo, with its bigger turbine & compressor wheel is producing boost.

 

make sense????

 

The reason for my question is that I was thinking of a possible way of making a turbo which expands laterally as it spins faster and thus slows and acts as a larger heavier turbo thus acting like a sequential twin turbo thru one turbo.

 

they have kinda done this already - variable vane turbos, also eliminates the need for wastegates, the actuator shifts the pitch of the vane to control the boost.

 

 

 

 

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I feel the need, the need for speed!

 

Am I correct in saying VW currently use variable turbos in their new TDI engines??

 

Robert.

 

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I only use the brakes so I can accelerate all over again.

quite possibly, we use them in our merc CDi diesels.

 

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I feel the need, the need for speed!

 

Your talking about Variable Vein Turbos i believe - Yes a very good idea !

 

Only one problem - wont fit in the Z not enuff room for all the shit that you need for em. Actually fitting big turbos in a Z is a major problem - mine are queit small compared to what i will be running in my RX7 and i still had to shave a shit load off the motormounts and mount the wastegate actuator with the turbo on the car to get it to fit !

 

If you get 4 turbos to fit in a Z engine bay i will give you my car - and i dont just mean Fit on the Engine ! i mean acutally cram them in any old how and get the bonnet to shut and everything to work with comprimising the structural integrity or cooling of the car !

 

And tunning wise the good thing (HP wise) with a Seuqential turbo car is you can throw all the shit out and replace it with a nice Biggass turbo which will flow more Air than Gods Ass ! - all the big HP Supras, Sklines and 7's run them

 

 

 

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Z ya

 

Nico91TT

 

 

God is coming ...and he dont have stock turbos . . .

Sequential turbos on the Supras work by having 2 turbos the same size, but only one gets the airflow from all 6 cylinders until 3000rpm when a small bit of pipework opens up to pre-spool the 2nd turbo and then at 3,500 rpm the second turbo gets the air flow as well as the first. This means the 1st turbo can spool up quickly when theres less airflow and once the airflow is greater the 2nd turbo comes on line with it to give that extra kick of power.

 

The electronics controlling it are stupidly complex and also the manifold in to the turbo is very specific which means if you want to improve the airflow you can hone it out a bit but not much, which is why the big power supras have to go single or twin turbo so they can get more power from more airflow.

 

Import Supra is good for about 400bhp, UK spec 450bhp on stock sequentials, add another 50-80bhp for hybrids at which point the fuelling is insufficient, so up the fuelling and cooling is insufficient, so better IC and that should give a damn quick car. My import on stock sequentials ran a 12.9 at Pod.

 

Once you junk the sequential system you can go true twin, or big single.

 

Hope that helps explain it.

 

JB

www.mkivsupra.net

Thanx 4 that -just the xpalanation I needed.

 

So sequential is not superior to twin trubo in terms of overall power. Just sequential provides more even power across the rev range.

 

Cheers,

Dave.

 

PS. does anyone know where the exhaust goes when the turbo's on the 300 are working to their limit -those on the Auto are smaller I've heard than the manual -so at high revs aren't they in danger of spinning too fast or is there a safety wastegate ?

Originally posted by Nico:

If you get 4 turbos to fit in a Z engine bay i will give you my car - and i dont just mean Fit on the Engine ! i mean acutally cram them in any old how and get the bonnet to shut and everything to work with comprimising the structural integrity or cooling of the car !

 

Sounds like a challenge

 

 

Originally posted by Nelson MainFella:

PS. does anyone know where the exhaust goes when the turbo's on the 300 are working to their limit -those on the Auto are smaller I've heard than the manual -so at high revs aren't they in danger of spinning too fast or is there a safety wastegate ?

 

The turbos have internal wastegates. This is how the boost pressure is governed - once 9psi is reached, any extra exhaust gases bypass the impellor...

 

HTH

 

CheerZ,

 

Andy