ChumpCar 1992 Lexus SC300

The injector flow rates (at ~30 psi, or 2 bar) were:
1. 240.8 (cc/min)
2. 229.5
3. 238.8
4. 241.7
5. 236.0
6. 245.6

I'm looking at these numbers again for the first time since taking the data a week ago. Interestingly, injector #2 is significantly lower than the others. That also happens to be the cylinder that was steaming with the plugs removed and had a very clean cylinder head roof. It's possible that it wasn't functioning properly and was causing some of the smoking that started this whole head rebuild project. Some of the variation is also probably due to my timing with the stop watch and any fuel droplets that splash out of the jar, etc.

In any case, I'll test another 6 injectors that I have kicking around and pick the 6 best-matched set to put back in.

So, that brings things up to date for now.

Tomorrow I might try to wrap up the fuel system BS and get the manifolds and wiring back on and start the engine. Would be nice to be able to get it in and out of the garage again.

Why not just send the injectors out to get cleaned?

JohnyHachi6 wrote: In reply to Petrolburner: To clarify, those PCV covers did go back on after cleaning.

You had asked opinions on the timing belt cover, I'd put it back on for reliability's sake. If a car kicks gravel onto the track, or gravel in the paddock, it's not worth the chance of ruining the day.

In reply to amg_rx7:

I could have, but I wanted to test the fuel pump anyway, and I don't have a big budget for the car or racing. Injector cleaning for 6 injectors is something like $100-150 and a week or two of time (for the companies I'm familiar with). I did this in about two hours for free.

In reply to Petrolburner:

Ah, yeah. I've been talking about too many covers!

Thanks for the input on that. I'm certainly inclined to agree that having the timing cover on is preferable.

Debris can cause belt to break or come off -- with engine running. That usually ruins a lot more than just your 'day'...cover on is a good call.

Great thread! Thanks for documenting everything so well.

A bunch of us are starting a Chump team and we need a Toyota or Lexus platform. If this were the only criteria, would you chose the SC300 again?

Good question...

I would think about what your goals are as a team. The SC300 is a good platform, but it's not the cheapest (to buy or run), nor is it the easiest to source parts for. Additionally, with one of the top teams in Chumpcar running one (Flat Out/KSR), it's not unlikely that it gets a bump in value (MPV) in the next year or two.

If you just want something fun and cheap, I'd look at something that is lighter and runs smaller diameter tires. A ratty AE86/AE85 corolla or an older RWD Celica or supra. Something like that. Also, the FWD celicas have been pretty competitive and have slightly lower MPV then contemporary supras.

The 2nd gen MR2s have also been very successful, but I think they end up being big projects.

The benefits of the SC300 are that it has a nice, reliable engine that puts out a good combination of power and economy, it has a huge fuel tank, and very good suspension geometry. On the downside, no LSD definitely hurts on corner exit, particularly with a car this heavy, and there isn't a lot of room for upgrades because of the higher MPV.

Personally, I probably would have run a MkII Supra if I could have found a good one for cheap. It has the LSD and a good engine/manual trans, good suspension as well, and is much lighter.

I don't regret choosing the SC300, though. It's a good platform, generally, and fun to drive.

Excellent read...used up a free morning reading it! As far as your fuel pressure issues, did you replace all the O.E. rubber fuel lines? They can constrict when they get hot when they are old and it can cause a random low pressure issue. I'm sure its a PITA but a cheap fix...Good luck and keep updating!

In reply to zracre1:

Thanks! I need to do some more updates, but it looks like it's just another bad fuel pump! I ordered a replacement today, will post more on that when I have time. Hope to have everything put back together and get the car running again in the next few weeks.

Great read johny. I am really enjoying all the detail your putting into everything.

Looking forward to see how you do this season racing.

Well, we picked up a really nice SC300 with 5 speed. One owner and well maintained, 80,000 miles. The MR2 would have been a little tight for some of our team members. I've owned a MkIII Supra but it never seemed like a lightweight. Surprisingly enough, there aren't any decent RWD Toyota Celicas or Corollas around here. Heat and humidity mean mucho rust in Florida.

I'll be removing the interior and I hope to get decent money for it as it is just about perfect, door cards are really nice as well as front seats, armrest and an untracked dash. It's so nice, I almost want to keep it as a toy. However, it is destined for the track and that means a clean interior has to go!

I'll attempt a build thread as we get going. I wish posting pictures was more intuitive. Pics on the IPad are too big and the phone requires that I transfer the pictures to a computer...

In reply to maj75:

Sounds pretty cool. Yeah, the MkIII supra is a little on the heavy side. I was thinking of the '82-'85(?) supra - the MkII, I think. They're about 500 lbs lighter than the SC300, if I remember correctly and are pretty decent all-'round.

Anyway, good luck with the build. Keep us posted.

Btw, the distributor issue you are having. I think its related to the throttle position's IDLE switch. if you have access to the manual, there is a specific way to reset. We had the same exact issue as you did with not being able to retard/advance enough with the distributor. Once we set that idle switch back, the car idled great!

Now our current issue is IAC related. Since the IAC is, I assume, a stepper motor, when we kill the car with the kill switch the IAC valve never resets its position and the ECU assumes an incorrect position on startup (kinda sucks that lexus assumes the IAC is in the correct position on startup, rather than SETTING it to the position it wants). We figured this out by disconnecting our kill switch and running it off a normal ignition switch again. After a few start ups like that, the IAC went back to normal and the car idled fine. What helped is our first shut down without the kill switch, you could hear the IAC trying to do its two normal clicks. Next startup/shutdown cycle we got the 2 clicks and it started fine after that.

Sorry if its confusing, just don't want to be in tech and not be able to get the car to run after testing the kill switch.

What belt did you use for the power steering and a/c delete? I can figure it out eventually, but since you have already done it was hoping you could help me with a shortcut.

Just saw this. looking at an SC400 for a challenge car.

In reply to rodgerhome:

The belt was P/N 390K6 from Advance Auto. I'd probably try one size smaller next time - there was a little bit of slipping when it was really cold out (if I remember correctly), but that worked OK.

FYI, the part numbers are typically the nominal belt length in mm(?) or cm (?). So I'd go back in to one of the parts stores and see if they had a 389K6 or 388K6 belt hanging on their wall in the back.

In reply to singleslammer:

Cool. It's a fun car, and a very capable chassis. It's pretty damn big for an auto-x course though. If you lower it a bit and get 2-3 degrees of negative camber dialed in, you'll be able to pick up a lot of time in the auto-x. That's one of the best things about the car; the amount of suspension adjustability from the factory.

Also, when I was lead engineer at Wreck Racing we managed to get 223 hp and 230 lb-ft of torque out of an early 1UZFE with only some jenky home-made headers and a megasquirt to tune fuel and spark. That was measured on a Dyno Dynamics chassis at the rear wheels. Most Lexus owners who have has stock engines on the dyno report 175-195 rwhp, so I expect there's a lot to be gained from tuning fuel/spark.

I know some of the recent GRM LS400/SC400 owners were mentioning looking at LSD options. Let me know if you figure out something that works well. As far as I know, there aren't really any good, inexpensive options. I have plans for a welded diff in the not-to-distant future.

JohnyHachi6 wrote: In reply to rodgerhome: The belt was P/N 390K6 from Advance Auto. I'd probably try one size smaller next time - there was a little bit of slipping when it was really cold out (if I remember correctly), but that worked OK. FYI, the part numbers are typically the nominal belt length in mm(?) or cm (?). So I'd go back in to one of the parts stores and see if they had a 389K6 or 388K6 belt hanging on their wall in the back.

I think it is in tenths of an inch effective length, in the cases you say it would be 39.0" or 38.8" effective length for K profile and 6 grooves. That is what I was looking for, thanks and maybe see you at Road Atlanta in Feb.

In reply to rodgerhome:

Yeah, could be. I don't remember the details of the P/N. Sounds like you've got it figured out though. Good luck!

So, what happened to the car after the last update?

In reply to Harvey:

Yeah, long story short: life. I have some updates, but basically haven't had much time to mess with it as I've been finishing my grad degree.

I'll try to post more in the next couple weeks. Also, expect some big updates about it being back on track (hopefully a lot) in 2016.

Stupid life.

Tell me about it...