2001 Impreza Wagon FWD Dirt Track Racecar

Just dropping by for a quick update.  It's been a busy couple months!

Since our feature was canceled at the car's first race, they ran a make up feature the next race weekend.  It was the first race of the night.  Right off the start, the car felt down on power.  After 3 laps, the temp gauge was 3/4 of the way up, so I decided I'd pull off the next time by the pit entrance.  By the time I made it to the pit entrance, the car stalled, and the temp gauge was maxed.  I let it cool down for a bit, got out, and found the plug wire for cylinder 1 hanging in the engine bay.  It had come off when I first got the car together, but I assumed I didn't have it snapped on completely.  Now I know it's probably a bad wire.

I pulled the car into the pits, let it cool down, checked the coolant and oil.  Everything looked okay.  I started it again, and heard a bit of a rattle as oil pressure came up.  I heard some definite rod knock while revving the engine.

So, that was pretty short lived.

That was at the end of June, and I haven't even had a chance to get the engine out.  Hopefully in the next couple weeks I'll get a chance to find another engine.  I don't know if I should be worried about addressing the oiling system or not - the car was .5 qts overfilled with Rotella T6.

Nice cage work, man.  Came here following the link you posted on the LeMons forum.  

I'm somewhat local to you, and we have been running LeMons for 10 years now.  Feel free to PM me.  I know a few other teams in the area as well.

After spending all spring deciding if I should Lemons this car or try to keep it from starving for oil, I bought a 300k mile Outback with a 100k mile engine and swapped the engine into the dirt car.

Yes, that's a 300k mile car.  It looks great for it's age / miles.

I'm really, really glad that Subaru engines are so easy to pull.

Same deal as last time - valves adjusted, new valve cover gaskets, and it was back in the car.

It runs great.  For months, I had planned on buying an Accusump to help with the oiling issues.  I heard an old engine builder say that the sump will still suck air and oil when the pan is low, even while the Accusump is supplying oil pressure.  The result, he said, was foamy oil and lower than normal pressure.  That had never occurred to me, and I don't even know how true it is, but it made some sense and I didn't like the sound of it.  I just decided to do a Moroso oil pan for now.  It has a better baffle, a deeper sump, and holds 6 quarts vs the factory 4.5 quarts.

Oil pan is on.  I'm going to let the RTV dry and put some oil in tomorrow, as well as replace a diff seal that is leaking pretty bad.  Hopefully going racing on Sunday.  There's a smaller track nearby that hasn't had many cars showing up, and I'm hoping I can use it to test the car out again.

Good news!  The car made it through an entire race and a heat of another, and is still running great.  And by great, I mean I'm really excited about it's performance.

Last weekend, I went to Roaring Knob Motorsport Complex to "test" the car.  It was an actual race, but the track has (sadly) been struggling with car count this year.  I have never been there, and it's much smaller than the tracks I'm used to.  Their rules are also much more open to modification in the 4 cylinder class, so most of the cars that race there are nicely prepared.  They also allow you to use different size tires. 

I made an educated guess on tire sizes, opting for a 205/50-16 Federal 595 on the RF, 205/55-16 RR, and 205/45-16 on the left side.  The 205/45-16s I had were old and almost bald, but gave me the front stagger I wanted to help pull me through the turns on the tighter track.  Based on the right front tire, this would give me a top speed in 3rd gear of 87.51 MPH at the 6500 RPM rev limit.  According to Subaru, my engine makes peak torque at 4400 RPM and peak HP at 5600, which puts my speeds at 59.24 MPH and 75.4 MPH respectively.  I didn't have much to go on, but a friend who has raced there said I should gear my car for "maybe 75?", so that's what I went for. 


I also made some aesthetic changes to the car with a flat black RS hood and a hatch and roof spoiler.

I started last in my heat of 4 cars, but was in P1 by the first turn, and continued to pull the field for the 6 laps of the heat.  I quickly noticed that having one good tire on the right front of the car wasn't the best setup, and the car was really loose.  Still, it seemed to run great, and I think the gearing was spot on, as I was turning about 6000 RPM before I got into the brakes for the turns.


These were probably a good tire - 6 years and 8k miles ago.

They inverted the field for the 9 car feature race, so I started in the middle row, inside line.  I settled into P4 pretty quickly, but struggled to find a way around the 3rd place car.  I finally got around him with 2 laps left, and quickly caught P2, but didn't get around him.

This past weekend I went back to Cumberland.  I tried out some new 205/55-16 tires, which should have gotten me close to the gearing I wanted.  Somehow, I was way off.  The car was into rev limiter about halfway down the front straight, meaning I was above the engine's HP / TQ range for the majority of the lap.  Regardless, the car handled well and still outran some fast Cavaliers that have won at that track before.  I started in last place, P9 for the heat race, and worked my way up to 2nd.  I tried running 4th gear on the last lap, just to see how much it lowered the RPMs, but I was only turning about 3800 RPM when I got in the throttle in the turns. 

The feature was canceled due to rain, which was okay with me because my gearing was so far off.

So I'm doing some maths this morning to try to find out a good tire size.  Here's the gear chart for my trans:
TY754VA1AA 3.545 1.947 1.366 0.972 0.780    FD 3.900
It looks like my 4th is an overdrive and is really far off 3rd, which ruined my thoughts of running a smaller wheel / tire and using 4th gear.

I have this trans available to me for free, from an 06-07 NA Impreza:
TY754CV7AA 3.545  2.062 1.448 1.088 0.780   FD 3.900

BUT, it seems like the best trans I could run at Cumberland with a reasonable tire size is any 5 speed from a ~99+ Forester, Legacy, or RS, which has the same gearset as the 06-07 Impreza, but with a 4.11 final drive.  I could pair it with a 205/50-16, which is a common performance tire size, and be geared to run just under 100 MPH at the 6500 RPM limiter.

I think the car should be a top performer with the gearing figured out.  I'm ready to win some races, but I guess this is all part of developing a new car.

I found my error with the gearing calculations.  My ECU hits rev limit at 6250, not 6500.  Oops.  So, this week I picked up another trans and got it FWD converted.  It's a TY752V2DCA, with the following ratios:
3.545 2.111 1.448 1.088 0.871    FD  4.111

I paired this with some new Falken Ziex ZE950s in 205/45-16, which should have geared me for 96 MPH at 6250 RPM in 4th gear.  Saturday was Cumberland's highest paying 4 cylinder race of the season, at $1000 to win.  There's a pair of good running Cobalts that frequent our track, and big payout races bring some Sentra SE-R Spec Vs from Pennsylvania that run very well.  I know I can run around fairly modified 2.2 Cavaliers, but have yet to line up in a race with a Cobalt or Sentra.

I knew right away during practice that my gearing was wrong.  The car felt worse, but I was running the same lower line I ran the week prior.  I got passed by my brother in an almost completely stock 2.2 Cavalier, so that had me pretty bummed.

For the heat, I started in the 2nd row on the outside with 3 Sentra SE-Rs and a few Cavaliers.  The track had dried and tacked up some, and the outside line was starting to get worn in.  I pulled out around a Cavalier right away, then took the lead around the outside of a Sentra on the second lap.

The car definitely ran better on a higher, faster line.  It's obvious in the video that my car starts making peak horsepower a little over halfway down the end of the straight, though.  Oddly, my data log from a Bluetooth OBDII on the Torque app (here is the .xls log if you'd like to check it out) does not line up at all with the gearing calculations I did.  However, if I substitute the 4.11 R+P for a 3.90, it almost lines up exactly.

So, I think the car can perform even better with some smaller tires (again).  I may take a set of 205/50-14 to the next race and try them out. 

That just looks like a ton of fun. I should get involved with my local track and see what I can build.

In reply to maschinenbau :

It is so much fun, and really pretty cheap. Find a local track with a stock 4 cylinder class, and you can pick a car up for a little over $1000!

This is a really cool and unusual build. I wish the track near me ran this class. Sadly their lowest class is Sportsman which is basically Street Stocks hopped up on steroids until they look like Late Models.

I checked another local track and they run 4cyl cars but they had, uh, 4 cars in their most recent race. Oof.

So, I think the car can perform even better with some smaller tires (again).  I may take a set of 205/50-14 to the next race and try them out. 

Gear it for your torque peak RPM near the corner exit and use over-run to finish the straight going into the next corner on the limiter.

This will give you the best acceleration off the corner where you need it, and that carries down the straight.

Been a bit.  I've been too bummed about the car to post anything.

I did end up swapping the trans for a 4.11 and doing a set of 205/45-16.   I also got rid of the stock WRX cat and resonator I had on it, and made a short piece of straight exhaust with a muffler tip that angles toward the ground directly behind my seat.  The car sounded great, had to breath better, and it probably lost 15 pounds.

So after some really promising heat races (features kept getting rained out) at Cumberland, the good guys and race car enthusiasts at Peer's Used Auto Parts offered to paint my car. Shameless plug for some guys who have helped me a ton - if you're in the western MD, WV, PA area, give them a call if you need a junkyard with tons of inventory.  Anyway, the car looked sweet.

Looked sweet.

First lap, first turn of the biggest 4 cylinder race Cumberland has, and I thought I had a good line down the inside until the car outside of me came down into the front of my car.  I'll let the video tell the story:

Off the start, I thought the clutch was slipping, but the car was just spinning.  That's why I let off going down the straight and how I ended up way on the inside in the first place.

The car shut off.  Tried restarting it, no compression.  Timing belt was broken.  I got drug off the track, winched the car onto my trailer, and towed it home.  I looked at it long enough to snap that shaky, dark picture you see above.  My wife and I had to get to sleep, as we were waking up at 5 AM to fly to the other side of the country to drive a beater 95 Civic back.  Needless to say, I was pretty bummed.  The Civic trip was mostly fun, though.

When we got home, I took a more serious look at the damage.  The front right wheel has a small crack and the tie rod is bent.  Both frame rails are bent, with the passenger side being back into the timing belt.  The driver's side is bent worse though, and it's bent outward.  The main thing I'm worried about is the fact that the driver's side is bent in between the two subframe mounting bolts.  The front subframe bolt is severely bent.

The car has just been sitting for the last couple months.  I was able to get another engine, but I'm just deciding if I should try to pull this frame back straight or cut the frame rails off one of the parts cars.

Man what a bummer! I think cutting the front off a parts car is going to be easier....

Yeah, unless you have your own personal frame machine you'd probably be time ahead cutting the front off of a parts car.  

Great thread btw. 

Thanks!

I think both of you are right.  Just trying to decide if I should hack up a parts car or build a tube front.