Just thought i would give an update to the thread after doing some work on a new Twin Scroll Turbo with Owen Developments and Chevron Motorsport.
We tried a couple of specs before finalising on my current one, i was looking to retain the OEM spool of the VF37 yet gain the top end of a turbo in the 450BHP range, i'm very happy with what we have ended up with.
My engine has been built with a high compression 9.1:1 to sharpen up off boost throttle response, so on pure v-power we are having to take a bit too much timing out to generate really good power and take full advantage of the turbo, it's probably worth a revisit to this with some octane booster to get the timing back (car was mapped the night before TOTB so didnt have time to try it, but we took 6 degrees out from my previous v-power+NF map), so on V-power we are circa 420BHP, 430lbft. A standard compresion engine on v-power should work better on pure V-power IMHO.
On a 20% mix of methanol with v-power it comes alive, it's producing at the wheels using Delta Dash 387BHP @ 6371rpm, 395lbft @ 3906rpm, this equates to aprox 468BHP and 478lbft at the flywheel.
At the moment the samco inlet hose i have is collapsing at the top end, so there is more to come from the turbo up top when that is sorted, we are also only using 50% waste gate duty mid range and are limiting the boost to the max it's safe to run on the OEM ECU with stock MAP sensor, the turbo will give more mid range than this.
In 4th gear it is producing 1 BAR of boost at 2900rpm, 1.85 BAR of boost at 3500rpm, it's holding 1.6 BAR at 6000rpm, 1.55 BAR at 7000rpm, even with the dodgy inlet hose. It hits those same figures in 3rd gear too with the use of MegaRom.
The really nice thing about this turbo setup is the way it drives, which you never really get a fair impresion of from full throttle dyno runs. Response is fanatastic, and what's really nice is the way you can be cruising in 6th and just boot it, there is no waiting for spool at normal motorway crusing speeds, it just picks it's heals up and goes.
I suspect based on previous experience, putting the car on a rolling road will bring the turbo spool 500rpm earlier than it shows on EcuTek Delta Dash Road Dyno, i'll try and get a run on a well known rolling road soon to put some plots up, but for now here is my road dyno results.
Dyno Test: 4th
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Maximum Wheel Power: 387.3 BHP @ 6371 RPM
Maximum Wheel Torque: 395.7 LbFt @ 3906 RPM
Power to weight ratio: 243.6 BHP per ton
Terminal velocity due to power: 199.5 mph
In Gear Acceleration:
40 - 60mph = 2.0 seconds
50 - 70mph = 1.8 seconds
60 - 80mph = 1.9 seconds
70 - 90mph = 2.1 seconds
Dyno Test: 3rd
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Maximum Wheel Power: 399.4 BHP @ 6995 RPM
Maximum Wheel Torque: 387.5 LbFt @ 4969 RPM
Power to weight ratio: 251.2 BHP per ton
Terminal velocity due to power: 201.6 mph
In Gear Acceleration:
30 - 50mph = 1.7 seconds
40 - 60mph = 1.4 seconds
50 - 70mph = 1.5 seconds
60 - 80mph = 1.7 seconds
Speed per 1000 RPM:
1st: 5.3 mph
2nd: 8.1 mph
3rd: 11.0 mph
4th: 14.4 mph
5th: 18.2 mph
6th: 22.9 mph
Maximum Speed per Gear:
1st: 43.6 mph
2nd: 66.7 mph
3rd: 90.0 mph
4th: 117.7 mph
5th: 149.2 mph
6th: 188.1 mph
Total Vehicle Mass: 1590kg
Drag Co-efficient: 0.37
Frontal Area: 2.20 square metres
Wheel/Tyre Setup: 235/45/17
Tyre Diameter: 643mm
Tyre Circumference: 2021mm
Engine Rev Limit: 8200
Test gear: 3 and 4
Max Speed of gear: 90MPH and 118 mph
Air Intake Temp: 17°C (62°F)
Atmospheric Pressure: 1.01 bar
Basic engine spec info:
MY05 JDM STi with stock heads and cams etc, rebuilt as a 2.1Litre at 9.1:1 compression.
Owen developments Twin Scroll Turbo
Chevron Motorsport TMIC
800cc EcuTek Injectors
BRD large MAF tube with K&N filter
Walbro 255 fuel pump
Stock FPR
Samco inlet hose
Stock ECU remapped by Bob Rawle using EcuTek Magarom
Engine rebuilt by myself and Chevron Motorsport
So there is now another Twin Scroll turbo option on the market.