So in STOCK trim, is the WRX top speed limited by the ECU? I've had mine up to 130 exactly, seemed to be getting a LOT of drag.

 

I'm at TXS stage 2 plus a coulple of other mods.

I hit 135 pretty fast then I crap my pants and slow down but I can tell it has a way to go beyond that point. I should invent the speed diaper!

Stability is good, I'm lowered a bit and my crappy knock-off C-west fiberglass wing looks like its about to ripp off. Looking in the rearview reminded me of aircraft wind tunnel test footage right before the wings ripped off the little plane. It was oscillating like crazy. It has cracks in it now, at the stress points. NICE!

 

145 @ 6100 rpms had a nice tailwind could have kept going to redline, by my self open road. Its not crazy its fun.

 

I wish I had the *****/room to top it out. Here in Hawaii we have precious few places to open it up. I've hit ~125 late at night on H-1. Still had plenty of tach left, just not enough ********* (or road, for that matter).

 

When the WRX first came out several of the magazines gave a top speed of about 148 mph (drag limited).

Tevia-boy has it right - drag limited means you run out of horse power to go any faster. Air drag is your biggest power requirement at high speed.

Now you need to keep in mind that power required to go faster increases at the cube of the speed so to double your top speed you need 8x the power. What that means in the real world is very small variables will change the top speed "your car" can go by several mph.

Consider 2 identical cars both on a level road, one running into a head wind of 5 mph and the other with a tail wind of 5 mph. 5 mph is about the breeze you feel when you walk fast inside a building -- not much at all. Yet those cars would have an apparent difference in top speed of 10 mph due only to that small wind.

A fair number of people have reported top speeds of 150+ and a handful have given what appear to be reliable reports of 160+. These cars were all modified. This checks out in that Subaru set a land speed record for a stock station wagon at 167 mph here in Colorado using a turbo legacy with the larger turbo that came on the cars in Japan (TD05h-16G).

Unmodified somewhere in the mid 140's is pretty solid and low 150's if you have looooottts of time to wind it out.


Mario:

As far as the holding boost for a long time. The Subaru engine has a history of breaking during long 4th and 5th gear pulls at top speed. The cylinder that dies is usually #4 (driver side rear). It usually breaks a piston. This appears to be due to detonation at high rpm. The stock ECU is deaf to detonation at rpms above about 5700 rpm. For normal street use that is not a problem because the engine is normally most prone to detonation in the 4000-5500 rpm range. What some of us think is happening is during long duration high rpm heavy load pulls, the engine temps rise enough so that the engine starts detonating slightly. Were not sure why the #4 is most prone but there are a bunch of folks trying things to see if they can get rid of it. Any way the stock pistons are of cast aluminum alloy and do not tolerate a lot of det. What happens is the pounding hammers the top compression ring so hard that it breaks the ring land below it . Then that breaks the the ring and the next below that. Result #4 cylinder has a compression of about 60 psi when all the others hold 140 -160.

Larry

 

You can go to www.oakos.com they have a wrx section with a spread sheet (xl) that you can play with.

If I remember correctly the pure rpm limited top speed is (assuming enough power is available) about 180 mph on stock tires.

Larry

(edit just got a chance to load that spread sheet, and check the top speed)

 

Always appreciated Larry, those are some great explanations!


*Computer dorks unite*

 

So im guessing the WRX has no ECU top speed limiter? Is this correct?

 

The cylinder closest to the turbo is #3, Subaru uses a convention that is opposite to american V-8. On the Subaru right side odd, left side even.

Larry