blnemec

High Speed Cruising - Poor? Does the RDX need to use turbo boost to maintain a 70 to 80 MPH highway cruising speed? - with moderate loads? - with moderate hills/inclines?

One poster indicated the engine needs to rely on the turbo boost to maintain speeds on moderate inclines - additional opinions / experiences would be appreciated.

Joe Fixit

Not sure what you mean but consider this.

Most turbos do not provide much boost at low RPMs. This is because if it spins the spindle fast enough at low RPM to provide high boost it will spin the spindle even faster at high RPM due to the additional exhaust being generated. Spinning the spindle even faster makes even more boost which sounds really good but the physics of it is that at some point the spindle will fly apart. That is why the RDX has a dual gated turbo.

The turbo has two variable gates that control the spindle speed. The flow control gate directs the flow of exhaust through the spindle. The waste gate dumps the exhaust gases directly to the exhaust pipe bypassing the turbo spindle. The goal of both of these gates is to maximize the turbo boost at low RPM's when in most turbos there is not enough exhaust gas to turn the spindle fast enough to generate high boost. The gates also decrease the boost at higher RPM when the engine is producing much more exhaust and will cause spindle to turn to fast and be destroyed.

crazymjb

If your asking if the turbo is in use... Turbos are always producing some amount of boost, regardless of speed. There is never uncompressed air going into any type of mechanical Forced Induction System.

Mike

RSXster

When you are driving and are accelerating (press pedal down) the boost will increase and that will allow for more torque. If you are going uphill just like any car you will press more on the gas in order to keep the same speed or else you will slow down, the turbo will spin to increase your speed (tho it may not boost as high depending on conditions).

When you are driving and are cruising at a constant pedal pressure the boost will be at 0 or less.

When you are driving barely on the gas or are off the gas the Boost will drop below 0 into what is known as Vaccum. Once you press the pedal more it will go back up, eventually past 0 and into boost.

Dont worry about boost when you are cruising on the highway, the only time you will need to worry about boost is when you want to change lanes QUICKLY. If you are not boosting you will have to wait for the lag, so just make sure you are aware of your RPMs, Boost, and surrounding traffic before attempting quick lane change or emergency manuever.


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05 WRX 276 whp, 263 lb-ft

orbitwhite

I want to believe the RDX market pitch for a vehicle good for urban city driving and out of town road trips. I dont know what to expect for the RDX on 5-6 hour drives up/down hills and windy roads?

RSXster

I dont understand what you are asking? Its a car, it will drive you where ever you want to go. a Turbo allows you to use a smaller engine to get the same output as a larger one. The RDX will drive perfectly fine up and down hills and it will outperform vehicles in its class on windy roads thanks to the SH-AWD.