The Project Pad

Out goal with this build the whole time was boost by/before 4krpm, and we're finally there.

If you look at the dyno graph on page 7, 26 psi was achieved at around 5k! With a log we'll be able to tell exactly when boost hits, but I was watching boost while dad was watching rpm and I said, "28psi," and he said it was around 35-3800rpm.

Ring, still plenty up top. It doesn't stop

Ob, with the QSV not operating full boost is around 4500-5000rpm. It appears to be making a pretty big difference.

Hank, do you plan on doing QSV with the 3794? It is pretty clever with the sleeve in there... and the crazy machining to get the spacing right. The turbo was perfectly lined up to the downpipe forwards and backwards, but we had to shift the downpipe towards the engine a little bit because the turbo effectively moved in a bit because of the smaller exh. housing.

chaloux wrote:Got the new turbo in. We seem to be getting full boost around 3500-3800 rpm now. The car feels great from 3000rpm. Pics/vids/logs to come... sleep now.

Very niiiiiiiiiice is that with the QSV engaged?

Jamo, yep.

Yes, I have contemplated using the qsv on my setup. I am pretty addicted to vband quick disconnect for the inlet and outlet. The spool valve concept is the reason I went with a big 42r tial hotside adapter so I can make a t4 flange that adapts. I likely will roll my own valve in the .82 housing. I am pretty sure forced performance is using the 68mm housing bored to 72mm to house the 37r turbine. Currently there isn't a tial housing for the 37r hotside, so I would be required to a 4 bolt flange in either t3 or t4.

Still, I bet your spool drops even more with the spool valve dialed in. It sounds like we have identical spool with basically 3582 billet ball bearing turbos. Sure, your inducer is 3mm larger, but flow is more to do with exducer value, and we are both on 82mm exducers. While other companies ridicule Garrett for it, the 37r-25r all use the same ball bearing section and shaft. This makes for an extremely light assembly when you get into the 35r sized turbos compared to the center sections of the comps, pte and borgy turbos.

QSV is doing work! I'm definitely going to use one of these on my car I think. Hank... sorry, but the dp is going to have to come back do you at some point for modifications lol

ShavedQuattro wrote: It sounds like we have identical spool with basically 3582 billet ball bearing turbos.

So to clarify, identical spool without a QSV? Which would indicate marginal improvement even after "tweaks"... am I reading this right?

I'm not insinuating that one setup is better than the other just pointing out that I hope there's more to be gained after tweaks to justify the added hardware ... I'm sure the logs would clarify alot too

Regardless spool in the 3k range in a turbo of this frame is ridiculous!

Sent from my Mobile Handheld device

The biggest problem I see with the valve is the concept of surge at lower rpm. If the engine can not physically digest 28psi at 3500 rpm because of head flow constraints, it will surge. The ball bearing GT turbos get a bad rep for being surge monsters if too small of exhaust housings are used. For example, a gt3582r on a 2.2L with a .63AR exhaust housing will surge at lower RPM. The turbine physically spins up faster than the compressor can force air into the engine. I will be interested to see if these valves induce surge issues on any applications going forward. (Janis's car with his old Comp turbo would not have benifited at all from the spool valve as he was having to bypass gas from the turbine in order to control boost until he was pas the surge line.)

Using that example, if you are using a variable spool valve to make a .48 down low and then .82 up top, you will probably run into the same issues as the guys with .63 housings are having. Some of the other turbo manufactures that use beefy shafts and huge bearing section get away with the surge problem with identical wheel sizes because the larger shafts physically take longer to spin up. The GT spool up is violent. If the engine can not take that sort of volume at that rpm, the surge will occur..

Your results on the 1.0AR housing were probably a little more exagerated because the 1.0AR was completely too big for htat turbo and our displacement. The results to a .82 housing should be more realistic for that turbo sizing.

With my setup, I chose to keep it simple. The tube header and tial stainless housing weigh half(literally) that of of a SQ Wagner/RS2 Wagner manifold. Turbos use thermal efficiency to spool. Having half the mass required to spool up a turbo is huge for spool. I would guess this is another variable why my single scroll .82 housing is spooling identical to your twin scrolled setup. We also have different manifolds, I lack head work, and I am also using e85. E85 has more volume post ignition event than regular petrol. I imagine I would be spooling 150-200 rpm later if I was on pump gas. There is also the rod ratio issue, but that should favor a short rod ratio in terms of spool. Low end filling characteristics of a short rod ratio would help low end, torque and ultimately spool.

I have tuned closed loop boost control enough to know that realiably controlling boost at varying altitudes and temperatures is a task. It is hard enough to get a reliable boost control without another system. Now take into account that the valve is a MAP based valve, so it too will need a closed loop system to control the timing of the opening up of the valve. Altitude, temperature and pressure ratios will all affect the spool rate, which will affect the close loop boost control for intake air. It sounds like a monster to get right. That said, Marc Swanson is completely capable and willing to help. I know he can get it right on Vems. If you spend the time and resources, you will end up with a complete monster of an engine!

Keep going!! You are saving me a bunch of time and money!

chaloux wrote:Jamo, yep.

Very nice, getting a 770 bhp rated turbo to spool like that is a good result

Just went out and took a log - 270kpa (~25psi) by 3500rpm on the nose. Also did a run with the QSV disabled (big turbo mode) - 25 psi by 4400rpm. Which is still better than the old turbo. Amazing.

It holds 296kpa to redline without problems. It was a bit slick out, and we were getting bad wheelspin in 4th gear. Wheeeeee!

Also of note, it's much easier to hear the turbo spool up now. That initial hiss is much clearer. All in all a very pronounced difference.

Now it's time to hit the dyno for extensive tuning! 26th... here we come!

Nice! Hope we can set up another dyno sesh at sfest

Nice! Must be a beast!

wow, that sounds awesome!

25 at 3500 now?!?!?!?!?!?! holy-hanna that thing must 'go' like an even-more-scared-cat than before lol. can't wait to see/hear/feel

Out of interest how is the valve connected to vems and what configuration are you using to control the valve? any screenshots of the configuration please?

I'm convinced by your results there might be something in this valve so will investigate further although finding a divided hotside and having it modified will be tricky uk side!

Jamo wrote:Out of interest how is the valve connected to vems and what configuration are you using to control the valve? any screenshots of the configuration please?

I'm convinced by your results there might be something in this valve so will investigate further although finding a divided hotside and having it modified will be tricky uk side!

The valve at the moment is operating independently from VEMS. We have it running off of manifold pressure. We've added a needle valve to control its onset. While the ideal setup would likely be operated using an N75 (or equivalent), this is actually quite effective for how simple it is. The reason the needle valve works well is that it operates on spool/boost, which is different for every gear. So, for example, we can set the valve to start opening at 5 psi, 10psi, 15, 20, etc. The only thing is that it's an analog adjustment, so we have to set it, do a log, and see what happens. Not as precise as an N75 with VEMS, but it's electricity-free (which I think has some merit).

Ah ok I'd do the same in vems electronically with the misc output to turn on a solenoid, and can set it to map limit by tps and rpm control

465whp, 430wtq, 950rpm earlier spool due to .82 A/R turbine housing, conservative 28psi tune with 0 knock thanks to water/methanol injection.

The car is unbelievably different compared to before the tune. The amount of timing we added is ridiculous. From 0-7000rpm, this thing wanted A LOT of timing. Free revving is very snappy now, and there's even more response down low. The car is very drivable around town from 2000rpm, and on the highway accelerating from 100km/h in 6th is perfectly fine (not *fast* until 3500rpm). Shift to 4th or even 5th, plant your foot and all hell breaks loose. The turbo noise starts out as a whine/hiss, and quickly transforms into, as best as I can describe, some sort of metal shredding machine.

The car is fast enough that when you hit 5000rpm you think "okay, time to shift" - then you realize you're only at 5000rpm and keeping your foot in it until 7500 is just pure bliss. It keeps pulls harder and harder. The car has been completely transformed since //S-fest. Once I have the dyno graphs from Brady you'll be able to see how the new graph dwarfs and consumes the old. New power/tq lines are 1000rpm to the left and about the same difference higher. We're VERY happy, especially considering we have another 2+ psi in our pockets (20+whp in a perfect world). As we've said before, this isn't a car that we're trying to play the ever-so-appealing and unwinnable numbers game with. One can jump in this car, drive it 1000+km without qualms, and when you want it to, puts a giant smile on your face. Would it beat an M6 in a straight line? No idea. If I found one on the highway, would he even want to play? Would there be traffic? Rain? Cops? ...what's the point?

Every time I passed someone on the way home from MTL (two lane highway), I couldn't believe how hard the car pulls and for how long. While I was initially disappointed we didn't hit 500whp (an arbitrary number I had in my head), after driving the car for a few hundred KM, I don't think 500whp would have made me any more happy.


Link to video

Sounds like a beast, glad you're happy.

Love the vid too.

Congrats again...and let's see some CSV data that I can graph 8)

Dyno showing psi and power vs. previous setup. Green = power, blue = boost

nice stuff, luve the kid smiling at every shift

that's awesome!

Love the write up and result. Must a fantastic that all the work has come together and the car is good.

I read your update as the first thing this morning. Just the kind of thing I want to see.
Congratulations.

PS: Why does the boy say: uh oh? Poopypants?

awesome! Glad to hear it is alive and very well!

Nice job. I always wanted an urS with my urq power. Well done