Rotrex vs Turbo (AVO) for Track use (transient response, IATs, heat management, etc)

[raul]

Originally Posted by Sportsguy83

I was lucky and recieved mine very FAST, but have heard and read a few horror stories of 5+ months after paid full....

Wasn't I there when we were trying to fit the damn thing and the fitment was over an inch off? We had to pull the radiator hoses really hard to slip it on lol.

[sw20kosh]

Originally Posted by ultra

Interested to hear more from folks who've tracked these cars with FI.

What kit setups, what supporting mods (particularly cooling), what power levels?

So far the CSG Rotrex car seems to be good on track running the base tune. Any turbo kits proven to be reliable as well?

The AVO kit looks solid for a good price but i'd like to see some real world examples. The Ptuning kit looks interesting as well due to the low mount turbo set up. Imperious Rex's Greddy turbo car seems to run well too.

Any verdict between front/top mounted turbos versus low mounted ones?

I'd really like a 'set it and forget it' type solution...something that's reasonably easy to set up and won't blow up in my face assuming routine maintenance.

From what I have casually observed on these boards as far as turbo's go...

@ImperiousRex regularly tracks his greddy kit. I would ask him questions about his experience. I also think @CSG Mike has had lots of seat time in this car.

The avo kit is being tracked hard on the AVO car in Japan and also a shop car in the UK (the name evades me).

No one has been pushing the ptuning kit on track, to my knowledge (which may change since I am installing one on my car). The only track footage released by ptuning is AutoX.

Element tuning is tracking a FA20club kit hard on track (or was, until an unrelated engine fire stopped them).

Team VCMC is tracking the full blown turbo kit still as far as I know.

[ImperiousRex]

Originally Posted by sw20kosh

From what I have casually observed on these boards as far as turbo's go...

@ImperiousRex regularly tracks his greddy kit. I would ask him questions about his experience. I also think @CSG Mike has had lots of seat time in this car.

The avo kit is being tracked hard on the AVO car in Japan and also a shop car in the UK (the name evades me).

No one has been pushing the ptuning kit on track, to my knowledge (which may change since I am installing one on my car). The only track footage released by ptuning is AutoX.

Element tuning is tracking a FA20club kit hard on track (or was, until an unrelated engine fire stopped them).

Team VCMC is tracking the full blown turbo kit still as far as I know.

My Greddy kit has seen nearly 15 track events since installation at the end of last Sept (including several podiums at GTA/SLB and RTA). The kit is pretty reliable and so far I haven't had any engine issues (except for DI seal failure shortly after the install but there were several signs pointing to their imminent failure before the turbo even went on).

The main issue with the kit is managing heat soak since the turbo is front mounted and the engine intake piping is surrounded by the turbo and the exhaust manifold. @CSG Mike had been complaining that on track my car felt like it was like stock S2k power and there was no way it was making the numbers that were achieved on the Evasive dyno and I personally felt like the car was making quite a bit of power on the street. So we had the car tested at multiple dynos to verify and we had some interesting results. I'll post on my member journal regarding the numbers soon. But let's just say neither of us was wrong...

Regarding the Robispec cooler though, it's been up to the task for the most part. The coolant temps typically level out at about 190 (since it is water cooling the oil) and oil temps on the street range from about 180-205 depending on whether or not I'm running WOT. On track oil temps reach 220-230 and coolant temps get up to about 210-215 but they stay pretty stable at those levels. I did have a fan fuse blow out though and had to replace the stock radiator fans when they melted from not running and being in close proximity to the turbo manifold. So I used the opportunity to upgrade to Spal fans with a @Carolina Dyno shroud. After fixing the fuse and upgrading the fans, the car has been pretty stable.

My biggest lesson with tracking the car with FI though is that you need to be religious with the routine checks and maintenance. There are many things that can build up over time and a failure at any one point could chain reaction into other issues.

[Sportsguy83]

Originally Posted by raul

Wasn't I there when we were trying to fit the damn thing and the fitment was over an inch off? We had to pull the radiator hoses really hard to slip it on lol.

That was V. 1, which I ended up returning.

I kept V. 2.

Thanks for mentioning it as I had completely forgotten.

[sw20kosh]

Originally Posted by ImperiousRex

The main issue with the kit is managing heat soak since the turbo is front mounted and the engine intake piping is surrounded by the turbo and the exhaust manifold. @CSG Mike had been complaining that on track my car felt like it was like stock S2k power and there was no way it was making the numbers that were achieved on the Evasive dyno and I personally felt like the car was making quite a bit of power on the street.

I have a vivid memory of myself following a stock BRZ down the main straight at Laguna Seca and we were both accelerating at the same rate through the gears and I couldn't get any closer. At the time I had a non-intercooled innovate kit and it was lap 5 or so.

[glamcem]

Originally Posted by sw20kosh

I have a vivid memory of myself following a stock BRZ down the main straight at Laguna Seca and we were both accelerating at the same rate through the gears and I couldn't get any closer. At the time I had a non-intercooled innovate kit and it was lap 5 or so.

wow, that bad huh?

[TemeCal]

Originally Posted by sw20kosh

I have a vivid memory of myself following a stock BRZ down the main straight at Laguna Seca and we were both accelerating at the same rate through the gears and I couldn't get any closer. At the time I had a non-intercooled innovate kit and it was lap 5 or so.

On the flip side, my brother and I have always been within 1/10th of a second of each other. @ImperiousRex has been there with the two of us....we're nearly identical. Since installing the Innovate (intercooled), I am aprox 5-10mph faster at the end of straights now than he is (even towards the end of a 20min session).

There may be heat soak still, but I'm definitely faster on the straights now. It's not a huge difference, and it doesn't seem like I pull that much harder, but it's definitely more than it was before.

[sw20kosh]

Originally Posted by TemeCal

On the flip side, my brother and I have always been within 1/10th of a second of each other. @ImperiousRex has been there with the two of us....we're nearly identical. Since installing the Innovate (intercooled), I am aprox 5-10mph faster at the end of straights now than he is (even towards the end of a 20min session).

There may be heat soak still, but I'm definitely faster on the straights now. It's not a huge difference, and it doesn't seem like I pull that much harder, but it's definitely more than it was before.

Intercooler!

[CSG Mike]

Originally Posted by sw20kosh

Intercooler!

Even that will heat soak...

[gmsii]

Originally Posted by glamcem

As the title says I would like hear about your experiences exclusively for track use, and supporting data of any sort would be highly appreciated. And yes, I searched but couldn't find anything other than the subjective opinion(s).

Below are the information I gathered so far on both FI application:

Turbo advantages:

• Makes more power at the given boost level (more efficient)
• More low and midrange torque
• Less noise meaning less need for muffler/resonator on the exhaust
• Upgradeability, ability to unleash more power down the road
• Avo kit looks very appealing and simple and has the stock-like appearance ( but at the end it's a turbo)

Turbo disadvantages:

• A bit more complex project since it generates more heat which requires more heat insulation to prevent heat soak issues (wraps, turbo blankets, hi-temp coating ..etc)
• Possible lag and unpredictable power delivery (may not be the case for smaller turbo setups)
• Transient response is somewhat delayed even with smaller turbos
• More prone to back pressure so it possibly requires a larger exhaust setup

Rotrex advantages:

• More like a "turn-key solution" because of the simplicity and reliability
• Boost builds up as the engine speeds increases so less load on the low RPM levels to the engine (which ultimately affects the reliability), it makes the most power on top end so only when you need it.
• Less heat due to its design (some people claim that they can touch the intake after dyno pulls)
• Linear and predictable power delivery that feels like a higher displacement engine under the hood, better transient response
• KW claims the stock exhaust and header car made 270whp on dynojet which is more than adequate for me

Rotrex disadvantages:

• Lacking the advantages of the turbo ( see above) and
• Possible belt issues (I think it's addressed on the newer kits though)

i think it would be good to qualify some of the above statements to more accurately reflect the differences between Rotrex vs Turbo


Turbo advantages:
- Makes more power at the given boost level (more efficient)
** actually this is not true...because the rotrex's high rpm capabilities, it can run compressors with the same efficiencies as turbos. however, at the same boost levels and same piping and intercooler configurations the rotrex should make more power because the charge air temps should be lower. the Rotrex has a maximum operating oil temp of 180F, so compared to the exhaust side of the turbocharger there should be less heat bleeding over to the compressor side. with the rotrex there will be a few hp used to turn the blower, so the question is if the power lost in turning the blower greater or less than the power gained from having cooler charge temps.

-More low and midrange torque
** this depends on the size of the compressor housing. the power on a smaller turbocharger may come much more dramatically at lower rpms, but may also run out of air on the top. but generally speaking the power of a supercharger will come in much more linearly than a supercharger.


Turbo disadvantages:
- A bit more complex project since it generates more heat which requires more heat insulation to prevent heat soak issues (wraps, turbo blankets, hi-temp coating ..etc)
** yeah...turbos run hot hot hot...protecting and managing against the additional heat is paramount
- Possible lag and unpredictable power delivery (may not be the case for smaller turbo setups)
-Transient response is somewhat delayed even with smaller turbos
** yes..the sc responds instantly

Rotrex disadvantages:

- Lacking the advantages of the turbo ( see above)
- Possible belt issues (I think it's addressed on the newer kits though)
** this is more a possible kit developer related issue and not inherent to the Rotrex itself. on the KW kit, the sc belt drive is independent from the engine accesory belt, so even in the case of breakage, you can still drive the vehicle.

[Pitman]

Originally Posted by sw20kosh

The avo kit is being tracked hard on the AVO car in Japan and also a shop car in the UK (the name evades me).

The UK car is that belonging to Fensport Performance:

http://www.fensport.co.uk/FensportCars/GT86_Race.aspx

[glamcem]

Originally Posted by gmsii

i think it would be good to qualify some of the above statements to more accurately reflect the differences between Rotrex vs Turbo


Turbo advantages:
- Makes more power at the given boost level (more efficient)
** actually this is not true...because the rotrex's high rpm capabilities, it can run compressors with the same efficiencies as turbos. however, at the same boost levels and same piping and intercooler configurations the rotrex should make more power because the charge air temps should be lower. the Rotrex has a maximum operating oil temp of 180F, so compared to the exhaust side of the turbocharger there should be less heat bleeding over to the compressor side. with the rotrex there will be a few hp used to turn the blower, so the question is if the power lost in turning the blower greater or less than the power gained from having cooler charge temps.

-More low and midrange torque
** this depends on the size of the compressor housing. the power on a smaller turbocharger may come much more dramatically at lower rpms, but may also run out of air on the top. but generally speaking the power of a supercharger will come in much more linearly than a supercharger.


Turbo disadvantages:
- A bit more complex project since it generates more heat which requires more heat insulation to prevent heat soak issues (wraps, turbo blankets, hi-temp coating ..etc)
** yeah...turbos run hot hot hot...protecting and managing against the additional heat is paramount
- Possible lag and unpredictable power delivery (may not be the case for smaller turbo setups)
-Transient response is somewhat delayed even with smaller turbos
** yes..the sc responds instantly

Rotrex disadvantages:

- Lacking the advantages of the turbo ( see above)
- Possible belt issues (I think it's addressed on the newer kits though)
** this is more a possible kit developer related issue and not inherent to the Rotrex itself. on the KW kit, the sc belt drive is independent from the engine accesory belt, so even in the case of breakage, you can still drive the vehicle.

Thanks for the explanations. I guess I am leaning towards to KW kit but can you please tell me whether or not I can use the SUBARU oem oil cooler with a smaller nut (the one behind the idler pulley)? The bracket size is my only concern with your kit, other than that it looks very good. I know you guys will soon offer an oil cooler kit as well but I would like to use the OEM cooler for OEMish look, simplicity and cost.

[sw20kosh]

Originally Posted by gmsii

because the rotrex's high rpm capabilities, it can run compressors with the same efficiencies as turbos. however, at the same boost levels and same piping and intercooler configurations the rotrex should make more power because the charge air temps should be lower.

So a rotrex supercharger (of some size) on this engine theoretically can produce >340 whp at 11 psi on 93 octane? I had no idea they were so efficient?

11 psi GT3076R 93 octane

[Sonolin]

Originally Posted by sw20kosh

So a rotrex supercharger (of some size) on this engine theoretically can produce >340 whp at 11 psi on 93 octane? I had no idea they were so efficient?

11 psi GT3076R 93 octane

Also...

With that torque curve?

Saying superchargers are *more efficient* than turbochargers is stupid... Yes the IAT will be lower but that doesn't mean its more efficient in terms of a power adder. Its a trade off, either way.

Yet another reason *not* to buy KW.