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les_garten les_garten is offline
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Join Date: Jun 2003
Location: PSL, FL
Posts: 861
Originally Posted by NathanUK View Post
You quote in red was my point. If the WG is open then the turbos hot side is not strangling the engines out flow?
Unlike the smaller turbo which will have WG tightly shut.

This comes back to the air pump, getting air in & out of the engine = power.
Xactly! You can do a few things with a Turbo change.

1) Get a More efficient Turbo that is a newer design and spools quicker and more linear, maybe more HP or not. This by itself may not be a big TQ or HP producer, but may make the car more tractable by itself.

2) Get a Turbo that moves your RPM band around with changing the Hot and cold housings characteristics. Give up low end for high end or vice-versa.

3) Or Bolt on a Turbo to suit current or planned mods to make a high Torque- High HP motor. This is the "Air Pump" principle. If you want more TQ and HP, it really needs to work with other mods that make the motor a better "air-pump" and the turbo as a facilitator, given equivalent boost levels when comparing before and after scenarios.

If your Turbo over feeds your air pump, you get more wastegate dump. If your Turbo under feeds your air pump you get less or no wastegate dump and may not make the required boost level.

If your Turbo can't make the required Flow and boost, that's a scenario where a Turbo change could get a Big HP and TQ increase.

A Turbo change can make a hell of a difference if you are using it to make lots more boost(That your current Turbo can't make), or are making lots of mods in reference to how your motor moves air in and out.

I think the thing that starts these type of threads are when you go to a PowerHaus page or whatever and you see the Phase I-IV kits and they make reference to how much HP the Different Turbo's make at each phase. In Isolation those Turbo's can't do that HP by themselves. They work with the CAM, Valves, Manifolds etc.
---Les Garten---85 930, Andial IC, GHL Headers, Fabspeed Dual, K-27 HF2, 3.4 JE Full Finned 7.5:1 CR, 964 CAM'd, Carerra 3.2 Manifold Cut/Flipped, Tec3r, Siemans 55#, GSF Fuel Rails, Clewett Crank Trigger, Clewett Cam Trigger,Dual Plugged, ARP Head Studs/Rod Bolts, Clewett Wires.Tial 46mm WG, Tial 50mm BOV, WEVO Shifter,934 Boost Gauge, Wideband EGO Sensor/Gauge, C2T Head Gaskets, '88 MB 300TE,BMW R100RT
Old 07-18-2008, 11:50 AM
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