Top Speed STI

Anyone know what the top speed is on a stock STI? I've heard its a little pathetic. Is their anything that can be done to boost this up to the competition. And don't say horsepower. because I know this can only be so effective due to aerodynamics. how much does the huge spoiler slow down the car at top speed?

the spoiler doesn't slow dow the car...if anything the help add speed and control at high speeds

Remove the speed limiter in the software. Theoretically, it's artificially limited to 147, but would probably be in the 170 range without the speed limiter. The spoiler lowers the top speed a bit, but not much.

the spoiler doesn't slow dow the car...if anything the help add speed and control at high speeds

Downforce=lower top speed

Downforce=greater stability at top speed.

It's a small trade off, but it's all in the name of control.

'specially since the STi wasn't really designed with top end as a priority. Fast top end was just a byproduct of good handling & high acceleration

I don't think top speed is important at all. Really, how often do you even get over 100mph, much less 150?

Really, how often do you even get over 100mph, much less 150?

Every time there's a track day?

yep, I was over 120 MPH in 2 different Subarus and over 100 in the Miata on Mon and Tues, though I can't think of any road courses that a stock STi would hit 147 on. (Mosport)

Well 100 is understandable, but complaining that 150mph is too slow?

Yeah, only on a wide-open road course straightaway (like, say, Monaco or Laguna Seca) would you ever need that top end.

Monaco and Laguna have nowhere near the top speed that Mosport does. I'd be surprised to see over 115 at either Laguna or Monaco. The highest speeds I would expect to see would be about 140 at Daytona (road course) or Road America, and possibly getting over 135 at Road Atlanta, Watkins Glen, VIR, Mont Tremblant, and Sebring. There may be a few tracks in Europe and South America that are that fast, but the USDM STi isn't available there (Monza and Interlagos come to mind).

I would think that on any wide-open straightaway with R-comp tires and a good suspension (ie, high exit speed), one should be reaching up into the high 120's and 130's rather quickly. 115mph is still third gear, after all. Given a really long straight, I would think that the 140's would be easily attainable. I get up to 110-115 on the entrance ramp to the interstate (and then realize what I'm doing and slow down).

In the STi, 115 is the middle of 5th, not in 3rd, and it's well into 4th in the WRX. Subaru speedometers are notorious for reading 5-10% higher than actual speed.

The back straight at Mosport is 3/4 mile long, though it is uphill, and the corner leading on to it is about 40MPH. The STi I drove had Toyo Proxes RA-1's on it. I have spoken with someone who had the same setup except with an aftermarket spring an shock package who ran the car at Laguna Seca, and about 115 was all it was good for on the front straight. Remember, there the front straight has a very slow corner (about 35 MPH leading onto it, and it is also very steeply uphill.

The longest straight at Monaco is about 1/4 mile long, and though it's downhill I seriously doubt that a relatively stock (i.e. still street driveable) STi would be able to go flat out through the tunnel.

You have to remember, a highway entrance ramp would generally be a very fast corner on the track. The formula I use for how fast a street corner would be on a track is to take the reccommended speed, double it, and add 15 MPH. If you look at the tracks I listed, they all have straights over 1/2 mile long, but with the exceptions of Road America, Daytona, and Watkins Glen, the corner leading onto the longest straight is in the 50MPH range in a good handling car with track tires and a good suspension. Also, measure the length of the on ramp you go onto next time, I'll guess that from the time you get full throttle until you merge onto the highway is at least 0.3 miles.

silver state classic perhaps


speed might be a factor



P.S. On second thought, dying in an impreza is probably not the best way to go

This is true... road courses do tend to be a lot smaller than they feel like when you're on them. I generally don't look down at the speedo when I'm racing; the tach is in the middle on the '04s. And you're right, I generally don't get out of third while on a road course. Is the speedometer so far off that I'm reading 115 at the rev limiter in third, and I'm only doing 103?!? This speedometer reading has only been tested in the dead of night on barren, straight, empty roads that are well-lit, mind you. Not while racing or doing anything more stupid than speeding on a really huge interstate or really long straight Texas road (see "This one time..." thread). But, that being said, I did actually go out and look at it the other day while I was speeding. Third gear goes up to approximately 115 on the speedometer before the rev limiter kicks in. I'll have to bring my friends with the BMW M3 and the 3000GT out there to help me test (they can actually keep up at those speeds).

And since the server is not letting my upload my post right now, I'm going to continue to put my musings in print. I was at TX Motor Speedway's infield this weekend on the road course, and the end of our autocross was at the beginning of a good long straightaway. I was pegging the rev limiter of second gear at the finish line, and that was with a defined turn (no chance to drive a good line). I'm sure by the end of the straight, if I'd had good brakes/tires/suspension, I could have gotten it up to the redline of third. I may have been able to shift into fourth if we were running the road course as a road course instead of an autox. I'm thinking an STi should go faster than my WRX. Maybe not 150mph, but then again the infield of TMS isn't all that huge; there are longer straightaways.

PS-Mosport is way bigger than I thought it was.
PPS-The next question: What's top speed on a WRX, since its gearing is longer than the STi's?

It is possible, the speedo on mine and pretty much everyone elses STi reads about 10% high. Also remember that a slight change in tire diameter will affect the speedo reading as well.

When I was at TMS 3 years ago (not driving), the Porsche 996 Cup car I was working on (415 HP, 2800 lbs) was about 140 at the end of the front straight before braking for a goofy chicaine that was set up at pit exit after running the infield. Top speed in the infield was about 115.

The gearing in top gear is very similar between the WRX and STi (5th WRX, 6th STi), and I think that there is a chance that top speed in the STi (assuming removal of the top speed limiter) would be gear limited rather than drag limited. At Mosport, the WRX was consistently 1 gear lower than the STi pretty much everywhere, but all the shift points were close (modded WRX, stock STi, my guess is that the WRX would have been about 2 sec/lap faster with equal drivers).

Also remember that the drag is inversely squared to the speed of the car. Aero drag at 120 requires 4 times the HP (and more than 4x the distance) to overcome air resistance as it does at 60.

One other track I forgot about that's probably faster than any other road course I've mentioned: Nelson Ledges.

it doesnt matter how fast it goes...its how fast you get there.