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It also shows a 15% drop in torque to the wheels and an 18% drop in horsepower do to the driveline. That is pretty good.....I amazed at how much power could be gained just with a couple upgrades. :D
 

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Also this is the first I have heard of this. The Dyno is showing a 5 to 7 horsepower increase with the water spray. So it actually works! :lol:
 

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I'm willing to bet that the STi has more crank hp than 300 based on those numbers.....they sure didn't find a way to bypass physics. AWD drivelines usually have at LEAST 20% drivetrain loss.

And just as a technicality, horsepower is derived from torque....so there really isn't any difference in the losses from the two. If the hp number changes, that means the torque is being applied differently than before.
 

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CloNeGTS said:
And just as a technicality, horsepower is derived from torque....so there really isn't any difference in the losses from the two. If the hp number changes, that means the torque is being applied differently than before.
Ah, I see. Thanks for the clarification
 

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Discussion Starter #13
My STi

Hit 301 whp today and 312 ft lbs of torque at only 16.8 PSI. I'm very surprised. Can't wait to get the new turbo on it. Right now I have my guy workin on the ECU plugs so I can make a plug and play harness. Hoping to either adapt a UTEC or maybe an E-Manage.
 

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NOOBIE ALERT!!!!

I am new to turbocharged engines, so this will seem stupid. I was taking a look at those plots and noticed that after a peak in the boost levels at fairly low RPM, the boost starts to taper off in the higher RPMs. According to what I know about turbo's (not much) is that as the RPM increases the extra gas being pushed through the turbo should be able to increase the boost up to the desired level and keep it there as long as the turbo has enough waste gasses running through it? I know this obviously is not true because of those plots. Why does this happen? Also, besides the extra boost a larger turbo gives, is this also one of the benefits to having a larger turbo?
While I am asking NOOBIE questions I might as well go farther. Although I know what a vaccum is, I do not understand how that applies to a turbocharged system. How is it created? Is it a problem?
I have looked at a few resources to learn to basics about turbo's...but they are just that, pretty basic. If anybody knows a site that explains turbos in a little bit more detail I would really appreciate it.

And one more thing. "Engine management" has been repeated to me as being a major factor in the ability of an engine to reach maximum potential in a major upgrade such as this. Exactly what is the goal of this engine management process, and how can this type of upgrade throw off the balance of the system?

I know that I am asking a lot of questions here. I am sorry about that. Just point me to a site for N00bs on this stuff and I will be very grateful.

Guru, I am excited to see what you are going to be able to do with that STi. Are you going to take pics of things like the Greddy GT-35 install? 500whp is amazing. As of now, what do you think the possibilites are that you reach that?
 

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Guru said:
Hit 301 whp today and 312 ft lbs of torque at only 16.8 PSI. I'm very surprised. Can't wait to get the new turbo on it. Right now I have my guy workin on the ECU plugs so I can make a plug and play harness. Hoping to either adapt a UTEC or maybe an E-Manage.
Amazing man....simply amazing. Just as a ballpark, what would the modifications you have in place now cost retail? I'm sure the EVO guys are watching this close and we all know that it's running them ~$1600 to get to 300 hp.
 

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Discussion Starter #16
Well the total price for our downpipe, Blitz SUS and the Turbo XS HPBC is $750. Now I would probably recommend and SBC-id instead of the manual boost controller. THis way you have a boost gauge in there. I'm doing that tomorrow.
As for the Noob's question, the reason the turbo is dying at higher RPM's is that the turbo can not deliver any more boost. It is completely maxed out at and starts delivery less and less boost. By redline I'm only getting around 13 PSI. The engine management is crucial to tune your AF mixtures and also your timing. It is crucial when changign turbos and of course fuel setups. We are doing some more tests tomorrow and will be sending our injectors and fuel rail to Japan for Power Enterprise to hopefully some up with a nice 800-880cc injector for us.
 

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For those of us that want to stay in SCCA Street Prepared class instead of going to Street Modified right away, it would be interesting to see what gains can be had without touching the turbo, boost, and BOV/wastegate. Just intake, exhaust, and non-boost ECU changes / S-AFC II type stuff. While having an SBC-ID and setting it to factory settings would probably work in my region, I'm sure having one anywhere near the car would get you protested at nationals.
 

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Ahhhhhh, I see. In the lower RPM's the turbo meets its max RPM and flow potential. Then as the revs are going higher, more flow is needed to keep the boost at the same levels, and the turbo just doesnt have the capability to keep up with the engine. I see now. Thanks for the help. :D :D :D
 

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shoeeater said:
Ahhhhhh, I see. In the lower RPM's the turbo meets its max RPM and flow potential. Then as the revs are going higher, more flow is needed to keep the boost at the same levels, and the turbo just doesnt have the capability to keep up with the engine. I see now. Thanks for the help. :D :D :D
As engine airflow (RPMs) increase, the turbo must push more air at a given boost level. So it needs more exhaust energy to drive the compressor. This results in a rise of exhaust backpressure. If the engine flows enough air to push the turbo outside of its effeciency range, it starts to need even MORE exhaust energy. Garrett defines effeciency as the percentage of turbine power that actually goes into compressing the air. The rest is wasted, and the lower the effeciency, the more waste heat that heats up the intake charge (bad). If the airflow increases past the turbo's flow range, it reachs what is known as choke, where it basically can't flow anymore. This is really ineffecient, and can cause the turbo to overspin. My car (with an effecient turbo at 16 psi of boost) gets 14 psi of backpressure at 5000 RPM, and 17 psi of backpressure at 7000 RPM.

On a stock car, two things usually happen. One the exhaust back pressure gets really high. This is caused by an ineffecienty compressor (for higher boost levels) a restrictive turbine and exhaust housing, and various other pieces of the exhaust plumbing. Two, the stock wastegate spring is really weak. In an internally gated turbo, the wastegate spring defines the maximum exhaust back pressure that it will tolerate before the wastegate opens on its own accord. Basically the wastegate blows open, wether you want it to or not. If you really want to max out the turbo, you wire the wastegate actuator shut. Not recommended for long turbo life of course :lol:

Thats one reason why external wastegates are nicer, they usually have an ajustable spring or different spring rates available, and have a top port. The top port actually pushes the wastegate closed when pressurized.
 

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What octane level is the guy running? I didn't read the article btw haha.
Im also a little curious as to how it is only a ~15% drivetrain loss when power has to be sent through THREE differentials.

I agree with CloneGTS, must be more hp at the crank.
 
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