Thinking about sequential options

[nissanconvert]

I was reading on a GTR forum about variable geometry turbos. One user (who seemed to know what he was talking about) alleged to have done some experimenting with them when they were common (Dodge shelby cars) While he appreciated the lag-free boost, the top end always left something to be desired. If i have some time later today i'll see if i can't find that topic.

[PortedRotorTuner]

I've been toying around with making a new manifold for our sequential setup.
The idea is great. Just needs some refinement.

[nissanconvert]

I found the thread i was talking about. Warpspeed is the guy that experimented with the vnt. In any case, with a larger better flowing manifold the larger small frame turbos gt28s, etc. will be available to us. I don't think that there would be any advantage to bodging in a vnt.

[Brent]

I'd like to bump this back up to the top. Does anyone know of anyone with an FD that is running sequential twins with a smaller primary? I'd be interested to see what Bryan@BNR thoughts were on the subject.

[SHPmainMAN]

Originally Posted by Prometheus

I have thought about running 2 GT28 turbos sequentially some how on my FD, but it seems like you have actually put more into investigating this idea.

For now, I'll stick with the BNR SIII's but that's only because that is currently the best sequential upgrade for our cars on the market.

I'd love to see a upgrade for our damn turbo manifolds

i thought that the BNR's were pretty much GT28's modified for the stock housings?

maybe im wrong but i remember reading that somewhere.

[Miata_mx5]

Boost logic is doing a "compound" twin turbo system for the 2jz-gte supra engines worth noting.

Granted there is a lot bigger displacement..

http://www.supraforums.com/forum/sho...d.php?t=527336

Worth a read.

[RotaryProphet]

I suppose it's my time to chime in:

I've always been interested in the possibility of combining the best of both worlds, and a non-twin sequential seems like the best bet to combine low end torque and a high top end. Hopefully as soon as I get the other stuff at my shop cleared up, I'm going to build a couple of different designs for manifolds, and start bolting up turbos and the various actuators necessary for sequential control. I've already built the control box for it; just a microchip and necessary circuits to run the actuators that connects to my Megasquirt system via the CAN bus to retrieve engine data.

Once the hardware is assembled, it's a relatively simple procedure to put the engine on the engine dyno and run some tests to find the best places to kick the various actuators over.

I'm sure I'll be doing a build thread, so stay tuned... and help me with all my current projects if you want to put a rush on it.

[ptrhahn]

I think that, the problem with twin turbo upgrades, at least SEQUENTIAL ones, is that everyone has focused on bigger, higher flowing turbos, when the bottleneck is the manifold.

That's why "upgrade" twin turbos never really make much (if any) more peak HP that a really good set of OE 93-95's. In fact, the efini '99's are slightly smaller. It's obvious Mazda chose them for "same" peak power, better spool up, because they likely know that no more peak power was to be made through the log.

I think that's why the M2's were ultimately GT25's, instead of the essentially GT28's that BNR uses. Have BNRs ever consistently made much more power than anything else sequentially? I've not seen that... yet consistently you'll see people say "don't get '99's they aren't an upgrade, get BNRs, they're bigger".

Not looking to start an arguement, just food for though. I don't think it would matter if you bolted twin GT42's onto the stock log, you'd probably make 365-385 peak HP depending on the rest of the system.

What we really need is a proper high-flowing stainless manifold with actuators to run a TT system. Then your GT28's would do something for you.

In terms of the rest of it, the only real other fault were the plastic solonoids and crummy factory computer—both solved with the PFC and saxyman's upgrade solonoids.

[Brent]

Good Points Peter... and glad to see you over here. Does anyone know if there have ever been any aftermarket manifold's for the twins made in Japan or Australia. I'm fairly certain there haven't been any fabricated/made in the states.

For my red FD/street FD, I picked up a set of 99spec twins to put on. I have since picked up a set of 99spec turbo's with a blown oil seal that I'm pretty sure I'm going to have turned into BNR Stage III's and use. I talked to Bryan@BNR about doing a smaller primary/larger secondary set up with the 99's and he recommended against it. I also have spoken with Dan Chadwick about the 99spec vs. BNR stage III's. He runs the 99spec on his SM2/SSM race car. He recently drove one of his customers car with the stage III's after Dan had went through the car, rebuilt the engine, etc... and said he was really impressed with them. Not sure where I'm going with this. More just sharing information that I have acquired in my turbo search I guess.

[ptrhahn]

A high-flow stainless/inconell TT manifold system, plus twin GT25s or GT28's, controlled by upgrade solonoids and bolted to a basic street port would RIP.

I really like my TT system for the track... it compares very favorably to single turbo cars making more peak HP. If you could reduced the heat, and up the peak while retaining that unmatched TT response and torque, you'd really have something.

[nissanconvert]

I was reading a build on the supra forums- they were using two t61's with basically an e-cutout in the downpipe and a one way valve in the intake of the "secondary turbo."

800hp IIRC. SP performance

[ptrhahn]

Surely someone could design something elegant?

[Brent]

Chris... you are an ME... and your engine is out of the car... and you have stage III's... you could put something together

[My5ABaby]

Originally Posted by nissanconvert

SP performance

Good lord, how is that stock tranny handling that hp?

[MOBEONER]

it would be awesome to control a true twin turbo set up electronically no damn vacuum lines and vacuum powered actuators.electronic actuators that can be controlled to activate when needed is just awesome.