Any issues with running at 110mph for 50 minutes?

Yes, you can drive 110mph (and much faster) legally in an event held in Nevada called the Silver State Challenge Classic (http://www.sscc.us).

I plan to enter my 2006 Legacy GT 2.5 automatic wagon. The car has new W rated tires (168mph), performance down pipe, remapped ECU, higher performance brake pads, and thoroughly inspected specifically for this event.

My mechanic mentioned the possibility of adding a transmission oil cooler? Any thoughts on this or any other possible issues?

I haven't driven this particular vehicle at 110mph much. In testing, where I briefly hit 110mph, the car was in 4th gear at about 5000 rpm. I suspect it was still in 4th because of the throttle position. Will it shift into 5th when it reaches a steady state (less throttle)?

The car felt more floaty at 110 than at 100. Is this the consensus? If so, I'll probably move down to the 100mph class and not push the car so much.

Finally, under load, I found the A/C turned off. I'd like to confirm that this is normal behavior. If so, at what threshold does it shut down?

If anyone is interested in being a navigator (my wife won't do it ), I *may* be looking for one. PM me if interested.

Thanks,

Deven

Check out ClimberD @ HEXMODS for a tanny upgade.

I'll bet you'll need a bigger radiator too.

You'll want to get catless DP and up pipe and a tune.

Without those as a minmum I see a major FAIL coming your way.

I doubt the engine has enough oil capacity to run that long at that rpm.

If you have to ask for advice here, about that, your already in trouble.

Do you really have any idea the stress that will put on a stock 7 year car ?

Oh, Welcome to the forum.

Damn....I can't imagine a boxer engine running a sustained 110 m.p.h. for 50 minutes straight, let alone the turbo spooling for that long straight. Imagine how those tiny little bushings in the center section are going to take that kind of abuse. There will be noise and it won't be nice noise either.

The failure issue is absolutely real and much likely way before you reach your destination. I would bet that this will be an "expensive" endeavor, no matter if you finish or not.

I don't think the engine will have an issue, and I'm wondering why you'd mention specifically a boxer engine would have an issue with that. The turbo? Maybe, but there are a few things that play a part in that. I think, if anything fails, it's likely to be the transmission.

Anybody know what the RPM is at ~110K in the 5EAT?

Is it a fact that at 100+mph the engine will be under boost? I'm not sure that's the case. Under acceleration yes, just cruising at 100mph I'm not so sure.

Same thing I was thinking.

OK...so elevation changes mean harder acceleration to go up hills, which means on the boost, which means turbo.....

And with the car running at say 4500 rpm for a sustained period, the exhaust is still going through the up pipe, through the turbo, and out the downpipe. Turbo is spinning irregardless of on boost or not and most likely the go pedal is going to be pushed on hard, so that will put it in boost for any downshifts.

The differentials ratio are 3.272

automatic transmission 4th gear is 1:1 ,5th is .834:1

so you can figure up the math with the tire size and stuff to figure out your rpms

Thanks for all the feedback!

The car does have a catless DP and has been retuned. 57K miles on the odometer. My mechanics do a lot of autocross and track events and specialize with Subarus.

The 90m course is straight enough that you don't have to let up too much with the exception of one short section where speeds can drop to 80mph. The goal is not the highest speed, but to hit the target speed for your class. So if your class speed is 110mph, then figure you're going to be going 112mph most of the time.

What I am hearing here is that 110mph is pushing it, which, frankly, I agree with. So how about at 100mph or 95mph?

Deven

They sell turbo Subarus in Germany right? And what speeds do they travel at on the autobahn?

I'd think 100 is sustainable.

My 1.8L turbocharged car doesn't seem to mind extended cruising at 115mph, and I do that pretty regularly anytime I get on the highway.

For 50 minutes? What RPM are you running at that speed?

They do. I've seen a few STi's running around.

I got my doors blown off while cruising at 185kph, by an RS6 Avant. On the unlimited sections, 170-190kph seems to be the "spirited" norm, but there are always guys flying past at 250+. I wouldn't have been surprised of that Audi were going near 300kph, and it did NOT sound stock.

For 50 minutes? What RPM are you running at that speed?

115 in the unlimited sections, 60 in the limited ones. I don't pay attention to RPM, I pay attention to the road and traffic.

Lots of 'theories' here.

I've regularly sat at 110-120 mph out in South Nevada. 50min to 2 hours at a time. The car was only stage 2, tranny cooler was put on but not for the run, for the added power.

The temp was around 105-108 during my last two runs. The stock rad works just fine and there was no signs of heat related issues.

What's most impressive is how comfortable the car is, motor wise, at those speeds.

Your two biggest problems are:

1. Braking - stock anything but a full kit upgrade will be shit. Don't talk to be about better compounds or rotors. The stock calipers are horrible above 80mph.

2. Suspension - some close calls with poorly designed suspension (OEM) make the car unstable on uneven road.

Re boost - you're not in boost while cruising. Car returns a respectable 18-20mpg at 110.

Second thoughts here too.

You need to keep in mind that at 110 mph the world is going by you very quickly. Should a problem arise on the road, with your tires or in your car you're traveling nearly 2 miles/minute or 161 feet/second.

Remember stock braking from 70 is 190 feet. While I've never panic stopped from 110 you would be looking at a very long stopping distance.

God help you if you blew a tire. I will be running tire sealant in the future to reduce the risks of a blow out.

There isn't much greater danger of a tire failure at 110, than there is at 65mph. Remember that even though you might be traveling at 110mph, where the rubber meets the road the relative velocity is still zero.

Inspect the tires frequently for damage to the sidewalls or any debris/punctures, and you should be fine. The tire itself is structurally sound to it's speed rating.

Running sealant isn't going to prevent a blow-out.

They sell turbo Subarus in Germany right? And what speeds do they travel at on the autobahn?

 

I'd think 100 is sustainable.

A LOT of diesel Subaru's in Europe, as a matter of fact, I would bet there are at least 2 to 1 diesel to gas there. Diesel cars in Europe get about 60-70 m.p.g. so they're the most economical way to go. I have a friend with a Rover Cars diesel wagon (about on par with a BMW 5 Series in size and quality) and he regularly achieves over 60 m.p.g. with his.

100-110 doesnt seem that wild.

If you were trying to go 150 for an hour...