spdracerut

Keep in mind Church's dyno reads high. My bone stock AP2 dyno'd at 238hp. Figure AP2s put down about 205whp stock on a typical dynojet, and that puts you at about 380whp on a typical dynojet.

riceball777

The numbers don't matter but the issue is the power band here. That's what is in question.
The problem with his kit is the fact that he had a great turbo (gtx3576r) but the car completely stops making power past 7,000rpm. SOS is blaming the turbo saying it's too small and that's why it's not making power past 7,000 rpm. I have the same turbo and mine makes power all the way to 9,000 rpm. My car makes over 60whp from 7,000 to 9000 rpm. At the same boat level and on pump gas.

spdracerut

Just a note, if it bothers you, you can adjust your boost curve to give you your desired power curve and look exactly like your blower power curve. However, you will be leaving mid-range power and torque on the table. In the dyno comparison of your old blower setup to this turbo setup, it is evident the turbo setup will annihilate the blower setup on a road course. Making a rough eyeball estimation, the turbo kit makes an average of about 50whp more than the blower setup from 4.5k-7.5k rpms which is where you'll spend the most of your time on a road course. The blower only shows an advantage over the last 300-400rpm.

Let's be clear, there are compromises in every setup. This setup is designed to bolt straight in with minimal modifications. It is designed to have the best spoolup and response for the power. A short runner manifold is going to have great response (shorter runners, less volume, not to mention it fits with no relocation of anything which aids in overall reliability with the stock heat shield and I think makes the manifold more reliable) with the compromise being power.

Just for comparisons sake, let's look at some of the differences with the PTuning kit. I will venture to say the PTuning kit will have slower spoolup and transient response, but make more power. So, that is one of the compromises. The others being the custom engine mount and the required oil scavenge pump due to the low location of the turbo. So there's some extra wiring in of the relays and oil pump which is another compromise. However, the PTuning kit was designed with a different design brief. They decided they were willing to do the extra complexity of the custom engine mount and oil scavenge pump system. They apparently decided on greater power at the expense of response (which is the purpose of the twin-scroll and why it's used on nearly every performance 4-cylinder and 8 cylinder engine now sold).

So, everyone really needs to determine what their primary performance goals are and to then choose a turbo kit appropriately. The SOS and PTuning kits are just two examples but it's clear they were designed with different targets. An analogy would be the Shelby GT500 vs. the Boss 302 Laguna Seca. The GT500 is faster in a straight line, but the Boss 302 is faster around GM's proving ground road course even though it has much less power; hence why GM used the Boss 302 as the performance benchmark for the road course ready Z/28.

Moddiction

Car is still making plenty of power past 7k it just doesn't increase. Looks pretty steady at about peak power from 7k to redline. Torque dips however which would give the power drop feeling of course.

s2000Junky

Yeah... it seems hard to shake the mind set of more is always better, peak numbers that is. Part of the issue is there is a distinct mindset difference between road course power/function with a turbo, which is a relativity new concept for a s2k, at least as far as functional/reliable execution (SC being the dominate choice of past) VS just a non functional super laggy high dyno number, to drag racing competition. So some guys just need to separate themselves from their current wave of thought what ever facet of turbo school that is, and look at the different systems/configs for what they achieve best, and realize there is no one best fits all, but there may be a best fits x facet of racing/goal.

518135

Well lets see dyno charts of these cars making this kind of power all the way to redline. Its pretty obvious that the manifold is choking this setup. Also its not a question of fuel quality and psi level its the fact that it stop making power past 7k rpm.

spdracerut

To be fair, higher octane fuel along will allow for more timing at the same boost level creating more power. Higher octane fuel will also allow for more boost for more power if more boost were chosen. For example, going from 91oct to 93oct in my Evo, exact same boost levels with the only difference being the ignition timing map translated into ~25whp.

Also, I think if a GT3582 or GTX3582 were selected, it would carry the power to redline better without flatlining as that compressor wheel is more efficient at those power levels. Of course, the compromise is spoolup and response.

Though I think I know what you're getting at, maybe you'll want to reword it to more clearly state what you intended.

s2000Junky

Dude, generally speaking, tuning and engine function 101, if your running a restriction in the exhaust system which is what this kit is, it will run a hotter combustion and EGT vs a freer design, this means the detonation threshold is lower higher in the rpm, which means less timing/power at peak and or less boost possible. The way around that limitation is a higher detonation resistant fuel for more boost and timing to overcome the design. The turbo itself will support it fine, but it all has to work together. Fuel becomes the deciding factor for this set up beyond what RAIN8HR achieved.

With that, Chris@SOS is wrong in stating the limitation approach in all FI designs as a lump simplified grouping at x hp for x fuel. For example I mentioned maxing out the Novi1200 on pump 450whp/300 trq as a safe/doable option vs this Turbo kit, simply because the inherent design of our motor in how it flows naturally as well as how and where in the rpm the SC makes boost. There IS NOT THE SAME level of detonation occurring in a system that has less restriction/heat, it can offer a higher level of hp before detonation. You also hear of guys running huge turbos at minimal boost on our engine, saying GT40 at 10 psi making 480whp on pump, similar principal as the SC, there is so much lag, the boost doesn't start building until/upper rpms where the natural flow character of our high breathing/revving motor takes it willfully, Exhuast flow is freer, lower combustion temp etc all equates to a higher detonation threshold and more hp. I think we get the point here. Basically the SOS turbo kit is asking something very different from our motor then it was originally designed in its flow character and there is a price to pay for that, along with the benefits.

But to drive home again, not all hp/fuel limitations are the same Chris. From a vender perspective, I understand its a lot easier to make a general lump statement to your clientele, as potential risk vs reward isn't there for you to make any recommendations beyond this. But to the more experienced/savvy do it yourself guys out there, we see through the holes, and when it meets resistance from guys such as yourself it can be irritating, or simply we lose faith in your ability to make accurate recommendations to others based on the reality and that will equate to you losing business which I know you do not want. You yourself told me when I ordered my NV1200, that even with my built 9.6:1 low comp motor, I would not be safe running 92 pump with anything smaller then a 3.4" pulley, that seemed surprising to hear from you knowing what I know the proven tuning thresholds are with the set up. I would suggest you get a little more current/savvy yourself with the tuning aspect of these motors and find where the true limitations are so you can have a more accurate dialog with your future clientele.

ScienceofSpeed

This is definitely a great discussion to have.

Our design parameters of the system were very specific. The parameters were a system capable of 150-300 bhp gain with the following features:
Twin scroll, the best boost response using this turbocharger frame size, no removing of the oil filter off the cylinder block, relocation of air conditioning hard lines, electrical harness, fuse box, retaining the factory heat shield, retaining the factory mount, cutting of metal body or frame work, and no scavenge pump.

These objectives were achieved within the constraints of the packaging allowed by the car. Other designs will allow for longer runs, larger turbos, etc. but all will involve compromises that were not in the parameters of our design.

ScienceofSpeed

This is a simple mater of physics. Specifically for the 76mm turbo being discussed on the dyno chart posted above: at the pressure ratio used on the dyno chart, this engine's power becomes flat at 7000 RPM because its flow rate threshold has been reached. It is moving 42 lb of air at 7000 RPM which is the limit of this compressor. Increase pressure ratio, and more power can be achieved until the flow rate is reached at that pressure ratio.

This turbocharger has a higher flow rate, and this is at a higher pressure ratio. This is awesome boost response for a GT3582R: