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Driveline, Engine & DME Tuning
Talk about driveline improvements, NA tuning and DME tuning your E46 BMW here. This includes diffs, intakes, exhausts, chips, software and OBD tuning.

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Old 04-18-2009, 12:59 PM   #41
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That's a lot of conjecture. I can offer more conjecture...

It is true that an engine is more efficient the hotter it runs, that's basic thermodynamics. That doesn't really mean more power because you are also more likely to detnonate and timing is retarded to compensate, which obviously reduces power.

It's also true that hotter means closer to having mechanical problems. Aluminum heads on an alumninum block are exteremely sensitive to overheated and even a small, local hot spot can spell trouble.

I can tell you what head bolt threads look like after getting too hot!

As far as the thermostat, it doesn't communicate anything to the ECU. It has a small internal heating element that melts some wax when the ECU wants additional cooling.

With your setup, I would take the cooler thermostat anytime!
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Old 04-18-2009, 01:48 PM   #42
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Yup, already have the new pump and the thermo in now, it is nice. Maybe with the pump and thermo together I am noticing just a bit more power, like 3whp or maybe 4, but it is just running really clean and consistent. Problem is now, everything feels slow compared to my new Jeep SRT8 which is laying down 398 to the wheels and 0-60 in 4.4 and soon 3.9, so now I have to think of more mods. Here we come tranny mods, anyone know of a good stall/torque converter with higher stall to get some more launch on the low end, my 60 foot times are crap right now.

Jason Hrissikopoulos

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Old 04-18-2009, 01:48 PM   #43
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The electrical connection is there to power a heater element in the thermostat. This enables opening of the thermostat by the engine management system. The engine management system needs to open the thermostat when the engine is under heavy load. Modern engines run at very high temperatures, with a conventional thermostat the coolant around the cylinders would boil under hard acceleration before the water at the thermostat got hot enough to open it and cool the cylinders. With a heated (map) thermostat the engine management system can look at the power requirement and predict the heat build up, therefore it can switch on the thermostat heater and get the thermostat open in time to cool the cylinders.

That said, with the OEM radiator, Stewart Water pump, OEM thermostat, my engine runs between 85-89 degrees under regular driving and at 75-80 under WOT or with a lot of engine load

Last edited by paraklas; 04-18-2009 at 01:56 PM.
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Old 04-18-2009, 01:54 PM   #44
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Yeah, it's pretty interesting to watch the coolant temps drop under WOT... even with the TS... and then climb back up at cruise or idle.
04 IR 330i ZHP | ESS TS2+ SC | MagnaFlow "headers" | KMS 3.64 LSD | AST 4100 550/650| APEX ARC-8 18x9 | H&R front sway bar | Vorshlag camber plates, RTAB limiters | TMS subframe & swaybar reinforcements | UUC SSK & DSSR | UUC TM & TME | BW motor mounts | Dinan strut & shock tower bars | vaio 4-bolt oil pump
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