High tech turbo design plans
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From: Simi Valley, CA
You might fail emissions with the cat that far back - if the cat doesnt get hot enough, it wont work. Might as well plan on ditching it.
Teching In
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From: Clarksville, TN
Originally Posted by Terry Burger
Personally I think any turbo will work like crap back there, but from the looks of it they just have a normal T60 size turbo, probably a tighter ar ratio for more response (due to the lack of exhaust pressure).
However, in the STS location, the enthalpy of the exhaust stream will be lower due to (according to Rick@ STS) about 500°F lower exhaust temps in the remotely mounted location compared to on the manifold.
I am still curious how well the STS kit works out with a ~T76 mounted out back...someone will try....it just won't be me first. That is when we will find out how much the lower enthalpy really increases lag (maybe a little, maybe a lot).
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Just to nitpick a little. There will not be a lack of exhaust pressure with the STS kit. In fact, the entire pre-turbo exhaust is suppost to be ~30 PSI on the LS1 kit (i forget at what boost).
However, in the STS location, the enthalphy of the exhaust stream will be lower due to (according to Rick@ STS) about 500°F lower exhaust temps in the remotely mounted location compared to on the manifold.
Teching In
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From: Clarksville, TN
Originally Posted by Terry Burger
Did they measure that on GTech too?
Low enthalpy = low turbine speed = low boost, right?
Low enthalpy = low turbine speed = low boost, right?
No, I believe they had to use the GTech Pro to measure the exhaust backpressure.
enthalpy = internal energy + Pressure * Volume.
The internal energy, pressure, and volume are functions of temperature. When the exhaust is 500°F cooler the volume is less (lowers enthalpy) the pressure is likely somewhat lower (lowers enthalpy) and the internal energy is much lower (lowers enthalpy).
The turbo is getting ALL of its energy from the enthalpy change in the exhaust stream before and after the turbo and converting it to mechanical energy used to accelerate the turbine/compressor and compress the intake gases.
Translation: There is significantly less enthalpy (energy) available to operate the turbo in a remotely mounted configuration compared to a manifold mounted setup. However, since there is so much energy in the exhaust stream (this is why the wastegates have to bypass some of the exhaust) even at a lower temp, this might be only a very mild real world difference (say spool 100-300 rpms later than a manifold mounted system) or it could be more significant and annoying.
Time will tell.
Last edited by Cld12pk2go; Dec 11, 2003 at 07:18 PM.
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