Quick Spool Valve

[chaloux]

Yup, this thing works. You use a non-divded manifold and a divided turbine housing.

We have a bit of fine tuning to do because we're sort of treading in unknown water. The main bit of experimentation is around the hotside size. Right now we have a 1.0A/R hotside, so it is divided in half down to .5. This makes it spool like a "normal" turbo. It MAY be that the hotside is too big, and instead of making a good spooling turbo better, it's making a too-big turbo spool like a decent sized turbo. After another trip to the dyno to tune for water/meth (mo' timing and boost) we're hoping to hit 500whp and find out if a smaller turbine housing is a good idea. There's a 35R .82 A/R T3 divded housing on ATPturbo.com that Comp Turbo would be able to machine to fit the turbo now, which would help spool a lot.

The blue line in the graph posted above is with the QSV opening too early - not even all the way open! As you can see, if it opens before full boost it slows spool and shifts the curve a massive amount. IF the QSV was stuck open, the curves basically follow RPM, which makes me think that the hotside just may be too large in the first place.

The turbo is a Comp Turbo CT3-6465 billet/triple ball bearing unit. 64mm inducer, 82mm exducer, bigger than a 35R. PLUS it has the massive hotside.

[Jamo]

Well let us know how you get on, personally that hotside and quick spool selection is screwed up as your spool is way to slow. I've seen 67mm plots on a 2.2 spool quicker than yours on a stroker which just isn't right.

Maybe it's all to do with the hotside, if it was me keep it simple geta .63r hotside which on that range of turbo should see you at 580 bhp

[JP]

Yep the power delivery looks of. My mates 2ltr 1.8t spools b4 5000rpm on a gt4094 with a 1.06 hotside and a true divided tubular mani with no fancy valve.

[chaloux]

We are working with Comp to get the turbine housing sorted. Finding a T3 .82 divided housing is not exactly easy. We're hoping to get one from ATPturbo, send it to Comp, and have them make it fit our turbo WITHOUT having to send our turbo to them.

We also may gain some spool through fine tuning. We have three things to setup: W/M injection, timing, and WG spring adjustment. Timing and W/G spring adjustment may bring the spool a bit lower by themselves without having to go to a smaller hotside.

RWD19T, What exactly do you mean "spools" - "full" boost, starts spooling, etc?

Let's not jump to conclusions just yet. The build's not quite done and these are all basically preliminary numbers/information. The QSV definitely works, there are just some factors that need to be sorted out to get it performing as good as possible.

[JP]

Running 1.6bar full boost at 4800.
Running 2.3bar full boost by 5200.
With solid lifter drag race cams peak power at 8450.

I've personally been looking at the quick spool valve as an option. The principle behind it is great as you're only using half the snail at low boost you are effectively running a 0.53 hotside instead of a 1.06. In theory that should be good for just over 1bar after which to retain decent egt's the valve has to gradually start opening. Open it too quickly and the sudden pressure drop would cause a drop in the rate of spool which you wish to avoid.

The best way to set it up is do a dyno pull with it closed permanently and map the car accordingly timing and fuel wise upto the rpm where it starts to choke.

Next run the car up with the valve completely open. Then overlay the two powerplots. Find the rpm where the two plots cross and the boost curves cross.

With this information setup the actuator to a desired boost setting relative to where the valve needs to be fully open.

With the valve now opening in the right place to get a constant progressive boost curve all you have to do is tweak the fueling and timing on the crossover to get curve of the dip in the power curve.

Much a similar concept when setting up the crossover point on variable valve timing.

Hth JP

p.s. eagerly awaiting the end results on the valve as it would enlighten me on my final turbo choice.

[chaloux]

That's actually a great way to tune for the optimal opening point, thanks! I'd never thought of it that way. DUH

We'll definitely share the finished results. In my gut I have a feeling that we'll be moving to a .82 housing (as there's no need/advantage to having a 1.0A/R housing power wise), but I'm not 100% confident in that yet. We'll see how setting the WG spring affects things first and go from there.

[Audi_CQ]

I'm also considering using such a valve, but I'm going to use the same size hotside that I would use witout the valve. My HP goal is the same with or without the valve so why increase the hotside?
Measuring backpressure would be useful for finding the correct hotside and maybe one could use the exhaust backpressure to open the valve instead of boost pressure?

[chaloux]

I'm also considering using such a valve, but I'm going to use the same size hotside that I would use witout the valve. My HP goal is the same with or without the valve so why increase the hotside?
Measuring backpressure would be useful for finding the correct hotside and maybe one could use the exhaust backpressure to open the valve instead of boost pressure?

Off boost pressure works nice because you basically always want it to open at the same boost, not rpm. The boost threshold changes in each gear, so you can't just set it at X rpm and go. What would the benefit be of working off of exhaust back pressure?

We're headed to the same place as far as hotside size. We initially thought - great, benefit of small and big turbo, but it's turning out that that's not quite true. It's proving to be a little different than all the Supra cars with QSVs, which is fine. That's what happens when you tread into unknown waters!

[Billman]

Off boost pressure works nice because you basically always want it to open at the same boost, not rpm. The boost threshold changes in each gear, so you can't just set it at X rpm and go. What would the benefit be of working off of exhaust back pressure?

We're headed to the same place as far as hotside size. We initially thought - great, benefit of small and big turbo, but it's turning out that that's not quite true. It's proving to be a little different than all the Supra cars with QSVs, which is fine. That's what happens when you tread into unknown waters!

you can set VEMS up so that you controll the QSV solenoid with a secondary boost controll channel (with a N75). That way maybe you can set RPM VS boost with changing dc. For example let it crank a bit open at 1 bar, further more at 1.5 and full open at 2.

[Audi_CQ]

What would the benefit be of working off of exhaust back pressure?

Don't know if there are any benefits of working off exhaust back pressure, but it's the back pressure you want regulate with this valve so just a tought

[jsol]

Sorry to revive such an old thread but who are the best manufacturers/retailers of QSV. I'm going to run one on my engine.

[chaloux]

Sound Serformance here in North America. Not sure if anyone produces them on your side of the pond. They're becoming semi-common over here on old Audi stuff with a handful of higher HP cars using them.

[jsol]

Ok, thanks for that.