ChumpCar 1992 Lexus SC300

During Greg's stint, he called in to say the car was a little down on power, but otherwise good. He did three or four laps at speed then came in for a driver change.

After that, we started cycling through the drivers with everyone doing shorter stints of 20-80 minutes depending on how long they wanted to stay in.

We found pretty quickly that the car started to loose power after about 3 laps. I behaved as an ignition issue (bad coil for instance) with break up at high load and high RPM that progressively became worse spreading to lower RPM. It felt very different to me than the fuel issue. We swapped out the coil, ignitor, AFM, and some other parts we had on hand, but to no avail. So, we would just pit every 5 laps or so. Let the car cool down for a few minutes, after which it returned to normal. Then we'd send it back out. Around dusk we removed the hood to try to increase cooling to the under-hood electronics, but it made no discernible difference.

Despite this issue, we managed to keep turning laps for the rest of the race and cycled through all the drivers a couple times.

When the final 45 minutes of the race came, I pulled my gear on again and went out for the last stint.

I managed to pull off a 1:55.2, despite power loss and after a couple quick stops for cool-down, I pulled out onto track for the last time. I made a few more laps and heard that we were into the last minutes of the race over the radio. I came over the crest into turn 12 and saw the flying checkered. The car powered across the line and down the front straight. Still pulling well 14 hours after the green.

In reply to pinchvalve:

Haha. I actually have a big tub-o-hand lotion because my skin does get really tore up when I'm working on cars for weeks at a time.

So yeah. That's about it for the race. At the end of the day we put down exactly 100 laps, placing in 79th out of 109 entrants. It was a blast. I had a great time and it was an epic struggle that we ultimately won. I think the other guys on the team all enjoyed it too, which is great.

After the race we spent some time talking with the Flatout Racing guys about their SC300 and found that other than headers and fancier wheels/wider tires, we're running nearly an identical setup. Also, the 1:50.X I set in the sprints put us just a couple seconds behind the fastest cars in terms of lap times - and that being my first time ever driving Road Atlanta. So, there should be hope for us to improve significantly in the future.

Wait, that's not it. You have to fix the problem for the next race and then tell us about how you fixed it with a broken beer bottle and a roll of masking tape.

I will only be happy when you solve this round of problems and head out again. The car is fast. Your team seems to work well together. Success is coming!

In reply to mazdeuce:

That's the plan. Might be a little while before I can do another race, but I'll keep you all posted.

Special thanks to everyone at GRM - I've been getting messages all day about the "Hot Builds" piece on the Wrexus. I didn't think you'd have it out so quickly, but the timing couldn't have been better!

I just got my car weighed today. Race weight with 15 gallons of gas is 2840lbs. That includes 140lb roll cage, gutted doors weighing 82lbs for both, a 42lb gutted hood, 25lb trunk, 12lb battery, single Sparco Sprint seat, currently 275/40/17 front and rear wheels and tires 55.5lbs each. Like I wanted, it's under 3,000lbs with me in the car ready to go.

The car handles amazing I was at a PCA DE event this weekend and the car cornered as well as any car on the track. The steering quickner is amazing and makes correcting any issue easy. I ran in the soaking rain and 40 degrees on no tread pattern race tires and could correct huge oversteer, understeer, brake lock up's with no abs, anything that happend the car felt amazing.

I have 18X11 and 315/30/18's ready to go on the car for next track. I'm confident the car will out handle almost any stock frame/suspension car on the road.

Some places and series I can run without the doors or hood, so that takes off another 120lbs. Subtract the cage, gas, hood and doors and you're under 2500lbs.

Revisiting this thread because my cousin is looking at a 93 with no start/gas in oil issue for $700 today.

I need to post up some more updates. Maybe later this week.

In brief: clutch is fixed, took the car for a nice long drive and this mysterious power-loss issue that surfaced during the race is still there. Probably try to figure that out this weekend.

DuctTape&Bondo wrote: Revisiting this thread because my cousin is looking at a 93 with no start/gas in oil issue for $700 today.

Sounds like it could be a sweet deal. You know if it's a manual or auto?

JohnyHachi6 wrote:

DuctTape&Bondo wrote: Revisiting this thread because my cousin is looking at a 93 with no start/gas in oil issue for $700 today.

Sounds like it could be a sweet deal. You know if it's a manual or auto?

Auto, if it was manual I'd be on my way over there to get it for myself. (he's still on the fence about it)

Ok, time for some updates!

Been super busy with my research since the race, so it's been kinda slow going, but I've been able to get a few things done on the weekends recently.

First, some pics of the car post-enduro.



Special thanks to Grand Turismo East, here in Atlanta, who did a great job taking care of the alignment on the car. It's the only shop I ever take my cars to and I can always trust them to do a great job.

Here's the window net setup we completed in the rush before the race. We used the quick-release from an old Hutchens neck restraint device and it works great. Pretty easy to put up and very quick and easy to release by pulling that yellow strap.

Pull handle mounts for the fire system. One for the driver or driver-side safety workers, one for passenger-side safety workers.

Better shot of the rear bulkhead. I shot some matte black paint on all the tape and aluminum to keep the glare down.
Decals for the kill switch, as required.

That shot of the number panel reminds me to share the logic behind the #136. It's a throw-back to the #36 Castrol Supra; winner of the 1997 Japan GT500 series.
If I ever paint the Wrexus, it'll be hard not to do this livery.

So, as you'll all recall, we had serious clutch issues during practice and the race, ending with a direct-drive (welded p-plate to clutch hub) setup. First order of business was to get that all fixed up for good (hopefully).

Transmission had to come out again - man I'm getting fast at that after doing 3 clutch repairs on this car!
Here's the pressure plate/clutch hub. It's been through ~7 hours of racing with no clutch. Held up pretty well with no noticable damage.

I picked a spare flywheel on Craigslist - these are tough to find and I got a great deal on this. Paid $100 for the flywheel plus a spare SC300 manual trans ecu that had been professionally rebuilt (new caps).

Here you can see the flywheel that was in the car - notice the dark ring around the center of the friction surface - the clutch was only touching there and that's what caused our second clutch failure. Too bad we couldn't get it in to be resurfaced overnight before the enduro...
I took both of these in to Clutch Specialty Auto Parts to be resurfaced. Those guys know this stuff really well and have good prices - total was $60 for resurfacing both units.

Here's a shot of the inside of the transmission bellhousing. Notice the shinny ring around the edge of the housing - that's where the clutch bits were dragging against the housing. Fortunately, nothing more than minor scrapes!
While it was out, I power washed the transmission and cleaned the input shaft, clutch fork and pivot really well and greased everything up. It all appeared to be in excellent condition though. Got a new Sachs clutch kit off ebay and got that installed with the resurfaced flywheel and get everything put back together. Really hoping that will be the last time in quite a while. FYI, the Sachs kit was pretty nice with a higher quality clutch hub than the parts store special we had to use during the start of the race.

With that all done, it was on to the hydraulics. We had totally removed the slave/master cylinders and clutch pedal assembly during the race, and while it was out I took the opportunity to weld up a tiny spot on the back of the dash bar that I had missed previously and one of the tech guys kindly pointed out during the inspection.

Man it was a PITA to get in there, even with the pedal out, and doing this with a hand-controlled TIG torch was crappy.

Pedal went back in with a new slave cylinder. While I had the pedal out, I cut off the helper spring, which reduces the force required to keep the pedal depressed. It's kinda an old-lady feature and it makes it really difficult to bleed the clutch, as it keeps the pedal on the floor when there's little/no hydraulic pressure.

I completely disassembled the master cylinder, cleaned and inspected it and decided it was in great condition so reinstalled it after lightly honing the bore. Was pretty pissed for a few minutes when I couldn't find the banjo bolt for the master cylinder. It's a pretty specialized part and I don't know where I'd find another one, but it turned up in the bottom of my spare bolts jar that I took to the race.

Used up some of the last of my ATE Super Blue bleeding the system. It's a real shame that you can't get it any more. I really liked being able to switch up the colors to tell when you'd totally flushed the fluid.

I also pulled apart the original slave cylinder, inspected, cleaned and reassembled that to have as a spare. It was in good shape too, but a new replacement was only $18, so it didn't go back on the car.

Anyway, got that all put back together and took the car for a test drive. Everything is working well with the clutch and I think that's finally squared away.

And that's where I'll stop tonight. More to come...

So, on with the story...

When I had the transmission out I took the opportunity to inspect the exhaust. I hadn't been ambitious enough to do anything fancy other than cut off the OE mufflers and make some down-turns, so the car was still running the cats. In the frantic prep before the race, I had noticed that the main cat was badly cracked and falling apart, so I had welded in some patch panels. I took a good look at it while it was out of the car. Not the prettiest welds, but holding up well.
I do have plans to make a better (more free flowing and lighter) exhaust at some point, but it hasn't been too high on the priorities yet. I did however, pick up a header for the car on ebay ($66 shipped). So that will be installed once I figure out some O2 sensor adapters and make a flange for the y-pipe.

Not really expecting a lot of extra power from this, but the headers are considerably lighter than the cast manifold/cat, so why not?

While I was working under the car, I also noticed a pretty good bit of Road Atlanta that we had brought home with the car. I had one quick agricultural excursion during the sprints and I think one of the other drivers did too. I cleaned out all that dirt/grass, which was mostly lodged around the rack and crossmember.

During the race we had also removed the hood during the night in an attempt to alleviate our power loss issue, which I had theorized might have been ignition bits getting too hot. One of the hood hinges was pretty rusted and had been poorly welded in a few spots at some point in the distant past and we had just loosely bolted everything in place when the car went on the trailer at the end of the race. So, I decided it was finally time to cut out the rest of the support metal on the hood, remove the hinges and put in hood pins, which had been on my to-do list for a long time anyway.

While I was working in that area, I took the opportunity to remove the cowl and wiper motor assembly along with the hinges.

The wiper assembly was surprisingly heavy and included this big chunk of cast aluminum to support the arms - a little silly.

Hood hinges and hardware.

With hood pins going in, the middle of the radiator support and latches wouldn't be needed, so that came out too (with a little persuasion from the sawsall).
As mentioned, the rest of the sheetmetal supports and latches were cut off the hood to save some more weight. It does make a pretty floppy hood, but with the pins, it should be fine. I was still disappointed in how much the hood weighed when I was done - very spoiled by the aluminum on the Miata and RX-8... Here are the hood pins I ordered - the cheapest aluminum ones on ebay! Cost was $18.14 shipped for 4 pairs (enough for the trunk and hood).

The blue wouldn't be my first choice, but hey "is racecar". The quality seems decent and they're quite light.

Drilled the holes after some careful measurement.
I used some short lengths of coolant hose instead of springs under the hood to get the height where it should be. I have found in the past that the springs like to rattle around and get lost when the hood is off.
Everything finished up. This was actually a big pain and took a lot of time to locate everything well. The hood is also enormous and taking it on and off frequently, with one person, is a pain.

Alright, so with the hood secured and the clutch fixed, it was time to tackle this weird power loss issue that came up during the race.

As you might recall, we had a power loss issue during testing, which turned out to be fuel pressure loss and I attributed to the leaking fuel supply line in the fuel tank. Replacing the tank seemed to fix the problem, but during the race something similar came up again.

The car seemed good during some last minute testing, during the sprints, and during the first stint of the enduro. However, in the afternoon/evening of the race (after welding up the clutch) the car would go out on track and after about 15 minutes, the power would slowly start to drop and the engine wouldn't rev past a given RPM, which would become lower and lower.

I was pretty convinced that this was not a fuel issue, since I had replaced almost every component in the fuel system. However, during the race we replaced most of the electrical components that we had spares for, with no effect.

I bought another ECU on craigslist (mentioned above) and tried that a couple weeks ago, and it had the some issue as well. So, running out of other options, I decided to put a fuel pressure gauge back on the car and see if this was the problem again.

I tapped the end of the rail and installed an old gauge on it, as such.


Then I mounted a GoPro on the front bumper and with the hood off, went out for a test drive. After about 15 minutes, the issue came up and I brought the car back home. Review of the video showed that it was, in fact, loosing fuel pressure still!!
For your entertainment, here are some short clips of the gauge during that test drive. First, what it's supposed to do: about 35 psi under vacuum and about 45 psi at WOT.
http://youtu.be/oDK05XbGdMs
And here's what was happening after driving around for 15 minutes: about 35 psi at idle, but at WOT the pressure quickly drops from 45 psi down to 10-15 psi, at which point the engine cuts out.
http://youtu.be/vrh1bsDzdDA
So, at least I figured out what was happening. But, I wasn't sure why this was happening. After mulling it over for a while I decided that it wasn't the pressure regulator, which had been swapped out, or the fuel filter, which was new. I decided that it must be a problem with the pump itself not putting out enough flow after running for a while, and that must be either a problem with the pump itself, or the wiring to it.

I left the fuel pump on for about an hour or so after taking this video, then measured the voltage at the fuel tank bulkhead and it came in at 12.1 V or so. So, I decided that this was all probably an issue with the pump itself, which aggravates me because it's a brand new Bosch (supposedly) unit.

This evening, I popped out the pump (getting quick at this too, just like the transmission).

Everything looked fine, though there were some little metal shavings stuck to the body of the pump.
I went through my stash of fuel pumps and found a couple possible candidates - a Walbro 255 and a Denso unit from a '00 Lincoln Continental (just under 300 hp, factory). The Walbro didn't really fit the mounting setup, so the Denso went in. I was also hoping to put on a bigger strainer (had a nice one from a WRX, pictured), but it was a slightly different size, so I rinsed off the one from the Bosch pump and used that again.

That's all back together now and I ran the pump for about 10 minutes with no issues, so I'll take it out for another spin soon and see if this finally fixes the problem.

While I'm messing with video, here are a bunch of clips from the evening/night hours of the enduro. For reference, this is all after the clutch was welded and the fuel pressure issue came up. You can watch our hilarious pit-lane starts with the starter motor - worked surprisingly well, and even the shifts aren't too terrible, for the most part.

Clips from the other drivers:
http://youtu.be/nhLNdGtwdWY
http://youtu.be/3Iv4nnevsYI
http://youtu.be/VS4srEpN_F4
http://youtu.be/Dgzijkzqiso
http://youtu.be/ewcMda_oxWc

Part of my last stint:
http://youtu.be/B6exrOIz0gs
http://youtu.be/B5fhv_i0Xrc

You can see the lights are really bad during the night - that was OE high- and low-beams. Definitely need to get the LED lights installed for the next race and get everything aimed much better.

Thanks for the update, progressing nicely! My cousin didn't end up picking up the SC due to flaky CL seller. The search continues.

DuctTape&Bondo wrote: Thanks for the update, progressing nicely!

Thanks!

DuctTape&Bondo wrote: ...due to flaky CL seller.

Tell me about it. Was just about to pick up a nice set of wheels for $20 posted on a CL ad last weekend (different project), but the guy flaked out. Oh well, can't complain too much about a free service I guess...

JohnyHachi6 wrote: That's all back together now and I ran the pump for about 10 minutes with no issues, so I'll take it out for another spin soon and see if this finally fixes the problem.

Alright! Looks like that fuel pump was the issue. Not too happy that a brand-new Bosch unit immediately crapped out... I double checked when I pulled it and it definitely says "Bosch Made in Germany" on the pump body.

In any case, the car is running and driving the way it should now.

Next, I've got a long list of projects to take care of that are aimed at increasing competitiveness and driver comfort. Some of these include:
- Installing a better tach (the OE tach needle doesn't light up any more).
- Figuring out a better headlight setup/installing the LED lights.
- Getting the header and exhaust sorted out.
- Replacing side mirrors with cage-mount ones.
- Installing new, OE replacement rear shocks.
- Additional lightening (trunk area, etc).
- Heating/ventilation work.
- Center/cage net setup.
- Additional hood support.
- Clutch pedal return spring.
- Check engine timing again.
- Fix or remove ABS.

I'm really hoping to get the car out to some track days this summer and I'll probably take it to an auto-x or two as well. I've been thinking about using it as a sometimes daily driver too, but not sure if I want to do that or not.

As far as additional enduro races, I'm definitely planning to be at the November ChumpCar race at Atlanta Motorsports Park. I've also been mulling over making the haul to VIR for the 24 hr enduro in August. Looks like spots are still available, but it's a bit of a long haul.

So, taking the car to its first autocross this Sunday, barring any unforeseen issues. SCCA Points 5 at Turner Field, here in Atlanta. Bunch of other guys from Wreck Racing will be going too with a couple of the team's cars.

In preparation I've been tinkering away with some of the smaller items on the list. It appears that the fuel issue is now resolved entirely (hoping it stays that way!). I installed the center/cage net the other day and put together another nice quick-release for that. Pic to come.

I also put in a center support for the hood to keep if from flapping around where the plastic cowl would have supported it originally. Again, pics to come.

After that, I wanted to check the timing again, since I hadn't ever messed with the distributor, other than to replace the cap and rotor. I found that the base timing was somewhere around 20 degrees BTDC. Should be at 10 BTDC. The idle was probably a little high when I checked though because the idle air control valve hasn't been working well (hardly working at all actually). I loosened the distributor and rotated it to retard the timing, but I hit the stop on the adjustment slot before I could get down to 10 degrees. Hmmm, figured maybe it had been put in 1 tooth off by the PO, so I took it out and flipped the rotor to the next tooth on the gear and put it back in. Then, it was really retarded and I couldn't advance it enough! Ahhgg!

Long story short, after messing with this for a while I decided I must have put the timing belt back on with a tooth off on one of the cams or something. Despite the fact that it all looked ok. So, I tore it down and carefully checked everything, only to find it was all OK. I even counted all the teeth between the cam and crank sprockets and it was just right.

So, I don't know what's going on with that, but ended up just putting a washer between the distributor housing and the head to pull it ~0.1" away from the head. This clocks the rotor slightly since you're pulling the worm gear/distributor shaft away from the cam gear. It worked great and I set the timing with the idle just where it should be, the engine at correct temp and the diagnostic terminal jumpered.

Car seems a little happier as a result (maybe a little more power), so that's nice.

While I was out test driving it after setting the timing, the IACV crapped out and hot stuck open. Need to fix that at some point. After ~5 minutes of driving around it came back to correct idle.

I also noticed a cyclic squeaking/crunching (bushing sound) when slowing to a stop, so I'll probably pull the wheels for a quick inspection before the autocross.

Lots of stuff to keep after....

More pics/updates later in the weekend (hopefully).

Its a Toyota, shooting TB cleaner through the IACV when it idles funny is routine maintenance.