Something New

[Slava]

I've never seen this before.

http://images.turbomagazine.com/features/0106tur_24zoom+Acura_Integra_Drag_Racer+Top_View_E ngine.jpg

[STIBungy]

Twin turbo even. Nice. I wonder if its rwd because of how the tranny is now flipped.

[sirtef9]

think ive seen this before from APEX

[dsm king]

so theres 2 cylinders for a turbo? i wonder how well that works.

[sirtef9]

looks like the left turbo blows into the other? like the diesels?

[Skaterkid]

If it is Apex's Integra, they only went twin because IHI doesn't make a large enough single. As I remember, it wasn't that successful.

[RiceNwateR]

looks like the left turbo blows into the other? like the diesels?

It's called sequential. Supras were set up like that so were the Legacy's. One smaller turbo helps spool the other, theoretically removing lag. For the most part, the smaller turbo would fail and people would just get one big turbo.

[Skaterkid]

It's called sequential. Supras were set up like that so were the Legacy's. One smaller turbo helps spool the other, theoretically removing lag. For the most part, the smaller turbo would fail and people would just get one big turbo.

Sequential turbos are when you have one small and one large turbo operating in parallel. So you have a system of valves to switch the exhaust energy from the small turbo to the larger one. What the other guy is talking about is series turbos which allows you to run big pressure in a flow limited situation.

[jackmode9316]

Sequential turbos are when you have one small and one large turbo operating in parallel. So you have a system of valves to switch the exhaust energy from the small turbo to the larger one. What the other guy is talking about is series turbos which allows you to run big pressure in a flow limited situation.
So the small turbo is used at first, then the bigger one takes over after it gets up and going?

[M@]

You can clearly see in the pic it has two runners to one turbo, and two to the other.

Actually, now that I look again... there's a runner at the collector running to the other turbo. Interesting.

[asianjkim]

Thats nice. Some dude did that with a integra but not twin turbo.

[hrcDSM719]

You can clearly see in the pic it has two runners to one turbo, and two to the other.

Actually, now that I look again... there's a runner at the collector running to the other turbo. Interesting.


I think that may be the plumbing to the wastegate, if Im looking correctly.

Also, fd rx-7's, 300zxtt, etc had sequential twin turbo's, each with slightly different compressor maps. You'd have one spool, followed later by another, hence "sequential" or spooling in "sequence".

Sorry if that sounded asshole-ish....im trying to quit smoking...

[Skaterkid]

A 300ZX did not have sequential turbos. It had two identical turbos running in parallel. Each bank was treated as its own individual 1.5L I-3. And the Supra had two identically sized turbos operating sequentially. So at 4500 rpms each turbo was running closer to its sweet spot than the single would.

[u13se]

what is that pic from.. is there more?

[hrcDSM719]

A 300ZX did not have sequential turbos. It had two identical turbos running in parallel. Each bank was treated as its own individual 1.5L I-3. And the Supra had two identically sized turbos operating sequentially. So at 4500 rpms each turbo was running closer to its sweet spot than the single would.

Why then, did the 467rwhp 300zxtt that I worked on have the feeling of "spoolage" (I know, I know, not a word) at roughly 4200rpm, and again at 5600rpm?? Just curious. (factory turbo's BTW, basically a rolling Stillen catalog. Intake, ported intake manifold, turboback exh, i/c upgrade,hardpipe upgrade, re-flash, underdrive pullies, "boostjets"<--little brass orifice type inserts that slow down the pressure to the w/g actuator, letting it open later, creating more boost)

I know Nissan had their VTC on the VG30dett's as well as the non turbo. But, that doesnt feel anything like spoolage...

[Skaterkid]

Why then, did the 467rwhp 300zxtt that I worked on have the feeling of "spoolage" (I know, I know, not a word) at roughly 4200rpm, and again at 5600rpm?? Just curious. (factory turbo's BTW, basically a rolling Stillen catalog. Intake, ported intake manifold, turboback exh, i/c upgrade,hardpipe upgrade, re-flash, underdrive pullies, "boostjets"<--little brass orifice type inserts that slow down the pressure to the w/g actuator, letting it open later, creating more boost)

I know Nissan had their VTC on the VG30dett's as well as the non turbo. But, that doesnt feel anything like spoolage...


I can't answer that, but the plumbing alone will tell the story. In order to have a sequential system you need to have both turbos on a common manifold which the Z did not have. Each turbo is mounted on its own manifold, plumbed to its own IC and into the corresponding bank's throttle body. If you're running a sequential setup, you need a way to block of exhaust and intake air from one turbo and force it all into the other. The Z does not have provisions for these either. So what you felt was something like the VTC, a tuning issue or a wastegate issue.

[hrcDSM719]

Wouldnt having two different turbine wheels (different spool rates) create a sequential effect? A slighlty smaller turbine wheel will spool faster, while a larger takes longer...

With only a few RPM separating each spool, I would think it to be very possible...

Dammit, Im losing comp access! Ill be back Monday!

[Skaterkid]

Wouldnt having two different turbine wheels (different spool rates) create a sequential effect? A slighlty smaller turbine wheel will spool faster, while a larger takes longer...

With only a few RPM separating each spool, I would think it to be very possible...

Dammit, Im losing comp access! Ill be back Monday!


If the turbos were stock, then they are identical. And running each bank of a V6 at different power levels would put a lot of strain on the crank.

[Martian]

The term being looked for is Compound.
Diesels use a compound system not a sequencial.

[hrcDSM719]

Yea, I see now what you are saying. The first feeling of spoolage was the VTC kicking in. I was simply under the impression of syncronized turbo's due to the sensation. But, alas, I stand corrected.

I guess you really do learn something every day....Haha :cheers:

[Skaterkid]

The term being looked for is Compound.
Diesels use a compound system not a sequencial.
That's also known as series turbos. Sequential turbos are still in parallel.

[Denkigroove]

So the small turbo is used at first, then the bigger one takes over after it gets up and going?

The fist image here, is the vacumm layout for the varous components used on the engine. The left handside area relates to the System components used in the Sequential operation. Jspec car do not have the EGR system
http://supras-ireland.net/Gallerynew/cpg146/albums/userpics/10001/vacroute.jpg
The next pic is the actual Sequential system layout and components
http://supras-ireland.net/Gallerynew/cpg146/albums/userpics/10001/seq.jpg
What it all means..
There are four VSV/actuator assemblies that control the sequential turbo operation:
Intake Air Control Valve (IACV)
Exhaust Gas Control Valve (EGCV)
Exhaust Gas Bypass Valve (EGBV)
Wastegate
VSVs switch manifold pressure (boost) to and away from actuators. The actuators open/shut valve butterfly flaps.
IACV
When this switches, boost generated by #2 turbo is allowed to join the intake stream
When it isn't switched, there is a small flap in the IACV assembly that allows any boost generated by #2 turbo as it prespools to join the intake stream, preventing turbo stall.
EGCV
This allows exhaust gas to flow through #2 turbo, causing it to spin up. When it's shut, there is no gas flow through the impeller of #2 turbo and therefore it doesn't spin.
EGBV
This allows some exhaust gas to bypass the EGCV and join the output of the first turbo. It serves two purposes - one, it prespools the second turbo by allowing some exhaust gas flow through it. Two, it controls the amount of exhaust gas going through the first turbo in much the same way as a wastegate - therefore controlling the maximum boost pressure generated by #1 turbo.
Wastegate
This bypasses exhaust gas from the first turbo, lowering the overall amount of exhaust gas going through *both* turbos and controlling the maximum boost pressure generated by both turbos in parallel.

So how it all comes togather :-
You get 0.7bar of boost on turbo 1, a slight dip in power between 3500 and 4000rpm, and then 0.8bar of boost with both turbos online. This should be a smooth and linear power delivery.
When modified with a boost controller/decat, you'll see an increase in boost after 4000rpm when the second turbo comes online. You may also get 0.8bar of boost on the first turbo with a decat. You'll feel the same power dip at 3500rpm but then a noticeable surge in power at 4000rpm when the second turbo comes online and hits over 1 bar of boost. Full boost is acheived before 4500rpm.

copied from http://www.supramania.com/forums/showthread.php?p=787423#post787423 "the 2jzgte sequential system explained"

[M@]

I think that may be the plumbing to the wastegate, if Im looking correctly.

You know what, I think you're absolutely right. I hadn't even considered that to be honest.

[hrcDSM719]

...at least Im right about something...finally!

So, after looking at the above diagram, would a 3KVR$ be considered sequential?? They have the y-pipe as pictured above....

[Skaterkid]

No. Again, you need a common exhaust manifold. The y-pipe was simply because they could not manifold two throttle bodies on the engine.

[hrcDSM719]

Ah, ok. I see, I see...

[cherrybombcivic]

That build is probably 6 or 7 years old. Yes, it was an APEX'i car, and was driven by Christian Rado at the time.