Help needed ASAP

[LeonV]

Rich? Hmmm, I always thought that hot exhaust meant lean. Makes sense, I guess.

Yes, the mix up may come from the fact that combustion chamber temps reach a maximum just above stoichiometric and exhaust temps are a max below stoich.

And yes, we are still using the stock rail. I guess it's time to ditch that too. It's still bolted to the head in the stock four locations.

There you go, that's 4 paths of conductive heat transfer right from your engine to the fuel lines. No amount of heat shielding will stop that. Hopefully, eliminating the stock rail and routing your lines in a way to limit heat transfer into them will alleviate if not fully cure your vapor locking problems.

Out of curiousity, did you try running the car with the hood propped open to vent heat?

[Jeff G 78]

No, we didn't try anything with the hood this time. We did try it in the past, but that was before any of the recent changes. We don't have a hood latch and we run hood pins, so we'd have to remove it and we have lights mounted to the front of the hood, so we'd have to unhook the wiring to those as well. We did consider taking a cutoff wheel to the hood and cutting a big hole over the carbs. I'm pretty sure I still have a vented '78 hood, so we might paint that one up and use it instead for future races.

[cygnusx1]

+1 on the L28ET swap. How big is your shoestring budget for the swap? I can detail the swap for you if you want.

[Jeff G 78]

Dave, I need to research the rules and see how much a turbo is worth to the budget. Then I need to spend the winter searching CL and ebay ads for cheap Z cars. ChumpCar uses a system called AIV or Average Internet Value. We have to produce ten ads for cars like ours and the average ASKING price is your AIV. The cars must run to qualify and they must be the same make, model and option list. For old cars like the Z, they allow us to use all S30's even though they might have different engine sizes than the car we run. For this race, I came up with an AIV of $415. That means I could have $85 worth of mods for a $500 max value. Keep in mind that COST never factor into AIV. It's all about VALUE. In other words, if I buy a Rebello stroker motor from a friend for $85, it's not going to fly. They have value assigned to many common upgrades. Have aftermarket bars? They are worth $50 each. Springs, camber plates, and other mods have similar minimum VALUES assigned. I say minimum because the value can go up if they are more than cheap aftermarket parts. Chinese ebay coilovers are worth far less than real race coilovers, for example. I have never seen turbo values listed, but a junkyard turbo motor can be had for what, $150? That means I'd have to get my AIV down to roughly $350.

[cygnusx1]

Running, turbo motors are probably more than $150. I would say that a greasy, well used, running, turbo motor with its ECCS injection system, would average around 500-1000. It will make the car much, much, quicker, so I suspect that you will take a pretty large penalty from the race organizers. Then brakes and tires become an issue as well. Considering your great placement at the end of this last race, you may already be sitting on the correct formula. Maybe you just need some spit and polish.

[beermanpete]

Awesome! It sounds like you guys had a great time overall.

Are you using the Falken Azenis RT-615? We have been thinking of trying them.

[Jeff G 78]

Yes, that's what we run. We still use the old RT-615, not the new RT-615K.

[Captain Obvious]

Hi Jeff,

Thanks for the fantastic race report. Congratulations on your finish position, and your Mr. Clean award! Sounds like a load of fun, although frustrating at times. That's the problem with not being able to test under the actual use conditions.

I know it's way out of your budget, but could you run a wideband? After the stuff you describe, it's unclear if you are running too rich or too lean. Your 5:00AM discussion buddy thinks it rich, and backfiring on decel and your glowing manifold would corroborate... You could use it for test and practice laps, but then take it off for the actual race laps? Would that count against your $$ ?

So what's the bottom line on performance...

When it's cold, it runs great. No stumbles at all and no restart issues. Makes power all the way to 6500 RPM.

When it's hot, it stumbles out of turns (right turns only?) and is hard to restart hot. Breaks up above 5000 RPM.

Are you running any of the original emissions controls? I assume you've already nuked EGR and air pump, but are you still running AB valve or throttle opener controls? I'm thinking that the elimination (or non-functioning) of those two might load up the plugs and exhaust manifold with unburned fuel on deceleration.

And I agree that a vented hood would be a good idea in the future. Probably won't do a whole lot once you're up to speed, but could help a whole lot at low speeds and when you are stopped completely like at pit stops and driver changes. Especially if you've got to keep the engine running for five minutes while sitting dead still.

[Jeff G 78]

You are on the right track. We will probably install a wideband O2 sensor to see what's going on. It doesn't count against us as it's considered information only and doesn't affect the performance. One suggestion I got from a fellow CC racer is that we are cooking the fuel due to the use of the stock fuel rail which is bolted to the head in the original four locations. All of that head heat is transmitted right to the metal rail and is then captured by the OE heat protecting wrap. I'm sure the rail was probably too hot to touch, so it makes sense.

We don't run any of the OE emissions equipment. The EGR and air pump are gone as are the rest of the stuff. The "spillover" theory that a racer told me makes the most sense. It's when the car goes rich mid-turn due to high float heights and then sputters off the corners until the plugs dry off. I will talk to Steve and Bruce at ZT and see what they say.

Our biggest problem is that even at night when the car ran damn near perfect and we turned our fasted race lap, we were STILL 12 seconds off the leader's best lap and the slowest "fastest lap" of any car. Granted, there was only a 10% spread through the field, but we are still too slow. I'm thinking that we could improve the overall running and eliminate the lost laps due to vapor lock, but it won't be enough to even be a mid-pack car in lap times. We need more HP. We can either try to eek out what we can with the L26, swap in a L28ET, or go radical and swap a V8 or other motor in the car. I would really rather not go the V8 route, but I am not against a turbo swap. After a quick CL search, I found a <100k turbo motor for $500. I'd rather find a whole ZX Turbo, but those aren't exactly common in the rust belt.

Thoughts???

[Jeff G 78]

After a few emails back and forth to my teammates, it sounds like in 2012, we will be sticking with the L26 and tuning it better after getting all of the fuel issues worked out. If it's still too slow, then we will upgrade next off-season.

Any recommendations for a Wideband O2?

Edited October 12, 2011 by Jeff G 78

[Captain Obvious]

I've never personally messed with a wideband, so I'm not qualified to provide suggestions there.

I did come up with a question about the problem in the turns though... You said that it goes rich mid-turn. Are you already on the gas at that point when it starts acting up?

I, for one, am glad that you are sticking with the L26. Frontrunner or not. You're period accurate, and I think that adds class to your team. Of course, that doesn't add any speed, but I think it adds credibility.

[Jeff G 78]

Yes, it acts up under hard throttle. The explanation I got is that the plugs get wet while leaned over hard and then it takes a few seconds for them to fire properly again.

I would love to see us keep the L26 AND be competitive, but I'm not sure we can do that without spending big bucks on the engine which we won't do.

I went through the lap report today and if I remove all the lost time stuck in the pits due to vapor lock alone, we'd gain over 100 laps. That would have moved us up from 30th place to around 13th place. Fix the other fuel delivery issues to make the car run better and we could have been a top 10 car without actually being much faster than we are now. We still would have been down close to 100 laps to the winner, but it would be a respectable finish.