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Old 02-02-2013, 02:04 PM   #1
MaddMax
Scooby Specialist
 
Member#: 9264
Join Date: Aug 2001
Vehicle:
2016 BMW M235i 6MT

Default What this noob has learned from owning his first turbo car

This post is merely to state my personel findings of owning my first turbo car after 27 years of car ownership and possibly give perspective WRX owners an idea of what to expect with respect to the stock turbo power delivery of the 09+ WRX.

Over the years, the only other turbo cars I had driven were a Stage I 06 WRX, stock 02 WRX, and turbo diesel Golf. The Stage I 06 WRX was what ultimately got me interested these cars.

Prior to this car, my last three cars were all NA, modified to some extent (suspension and motor), and all made around 10% to 15% more power than stock. The cars included a 94 Z28, 96 Maxima, and 03 G35 sedan. Most of my modding experience over the past 14 years has centered around toying with Nissan's awesome VQ motors. These motors have great low and midrange power while pulling nicely to their 6600rpm redlines.

In late March 2012 I got my WRX. I was pleasantly surprised by how powerful the WRX felt above 2000rpms. It makes the car fairly easy to drive around town once you figure out the quick revving motor and the nature of the clutch. I was really worried the car would feel a bit boggy like the 02 WRX I had driven previously. Even in 100 degree temps, I feel the power is acceptable and the car doesn't feel nearly as affected by heat soak as my VQ Nissan cars or the Z28.

Over the past 10 months, I've become very aware of load dependence of a turbo. Simply put, you've got to be a bit hamfisted with the accelerator if you want the acceleration you expect. You can't drive them like an NA motor. Period.

Once broken in and fully stock (still is), I finally started getting a feel for the power delivery in these motors. To say the turbo power delivery is different from an NA motor is an understatement. After driving decently powerful NA motors for so long, these turbo motors at full tilt feel foreign to me. Gone is that snap you get from an NA motor when rolling in 2nd at ~3500rpms, punching it, and having it immediately takes off with a fury. Doing the same feat in the WRX results in the pedal going to stopper the floor, the car softly accelerates intially, and then a split second later the motor winds up with a quick rubber band effect. While it feels powerful once going, it doesn't have that immediate snap in power and frankly makes your brain think the car is a bit slow because you were expecting an immediate response in relationship to the movement of the pedal. With a turbo car, it's simply not happening. I have no doubt that while the WRX doesn't "feel" as quick initially, it would slowly walk my G35 and Maxima (both 100mph trapping cars) from a roll.

Punching it from 3000rpms in 1st and rapping it out to around 80mph is fairly impressive, even for stock and is probably where the car feels the quickest. Each shift in 2nd and 3rd is met with a very slight delay and followed by tidal wave of thick power.

The turbo spool between 2500-4000rpms is really fun, especially in the lower gears, and like nothing you'll feel in an NA car. However, this quick and rather strong ramp up in power fools the butt dyno as the power continues to build into the upper rpms. If you've seen a dyno plot for the EJ25, you'll see the power ramp up quickly to ~4500rpms and then power curve becomes broader (flatter). Over 80% of peak power is made by ~4500rpms, peaks at ~6000rpms, and about 90% of peak power is sustained right up to 6500rpms. It's a really effective powerband and every gearhead knows that power under the curve is what truly makes a motor perform and turbo motors are generally really good at this. An NA motor on the otherhand builds power through displacement and rpm; therefore, the power is usually linear and continues to climb to peak power with less of a broad power delivery.

From the seat of the pants, the NA motor can sometimes feel quicker because it starts off with less power, but that power continues to build and build whereas the turbo delivers much of the power in an initial wallop and then sustains the power over a large useable rpm range. That initial wallop in power is what can fool the brain. You fall in love with the turbo surge and expect it to last the entire way to peak power rpm or fuel cut, much like an NA motor. When that doesn't happen, the acceleration can feel a bit muted. I've fallen sucker for this quite often only to look at the speedometer to see I'm going much quicker than I thought.

Lastly, turbos are like mufflers, both on the intake and exhaust side, and these motors rev quite smoothly. It reminds me very much of my ultra smooth revving VQ30 in my 96 Maxima. There is hardly any induction noise like that of an NA motor. Less noise and NVH generally equals a reduced sensation of speed. About all you hear is a light turbo hiss, some faint BPV/wastegate noises, and the imfamous rally-like gear whine in 1st and 2nd.
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