corral article: edo 1998 season

Going to Milan Dragway on 8/19/98, ran a best pass of:

18.090 seconds at 56.46 mph with a 2.338 seconds 60 ft time

Once again, a major disappointment. The FEAD belt shredded, so we installed a shorter belt and tried to run naturally aspirated, but flowing the air through the nonrotating Vortech. Then we discovered the engine was running way too lean. This was due to a calibration error on my part. In an attempt to get more power this time at the track, I had retrieved an old calibration file that had more spark advance. Unfortunately it was also set up for higher fuel pressure, but I was now using stock fuel pressure. I didn't notice that error until running the car at the track. So far, the problems this season were mostly due to not having enough time to work on the car and being too anxious to run some fast times.

The next day, I looked over the supercharger installation and noticed that the belt had wedged in between the Vortech housing and pulley, damaging the shaft's seal and causing oil to leak when the supercharger was turning. Due to these problems I missed out on taking the car to the Superford Magazine 4.6L shootout in London Ontario on 8/21/98. There seemed to be no point in going if the car would only run naturally aspirated (and poorly at that).

Since I had to call Vortech in order to send the supercharger back to them for repairs, we discussed the situation and concluded it was likely my manual belt tensioning method that was causing the problem.

So, off came the Vortech, its plumbing and big Pro-M air meter. On went the production Cobra air meter/filter once again.

I decided that I really needed some bigger injectors too, since I had been running near the ragged edge with the A/F ratio. Since I went with the biggest available air meter when I installed the 107 mm Pro-M and was very happy with it, I also decided to try some really huge injectors. Well, as it turns out, Ford natural gas powered vehicles use unique injectors that are physically the same size as any other Ford injector, but flow 165 lbs/hr when used with gasoline. One injector flows more fuel than all 8 of the stock 19 lbs/hr injectors combined. These have become quite popular with the 5.0L crowd when they are making big power numbers, but I wasn't aware of anyone using them when idle quality was a concern. So I installed a set and changed the calibration in the EPEC to match them and the stock air meter. To my amazement, the car started right up and ran fine, except for some instability below 1000 rpm, so the idle was increased to just over 1000 rpm. However, the injectors create a very loud clicking /knocking noise that is most noticeable from the vehicle's interior. If you ever listened to the stock injectors ticking under the hood, then think of that sound amplified by a few orders of magnitude, as these almost sound like a rod knock.

Going to Milan Dragway on 8/26/98, ran a best pass of:

13.608 seconds at 102.05 mph with a 2.031 seconds 60 ft time

The ET was not too bad, but the mph was still disappointing for no supercharger. However, since the engine has a rather low compression ratio and the calibration was just a best guess and I'm not interested in naturally aspirated performance, it didn't really bother me because nothing broke for a change.

The T-trim came back from getting a new shaft seal, so it was reinstalled along with the big Pro-M 107 mm air meter, and the EPEC calibration switched over to match. Also, went back to using the normal Vortech belt routing instead of the manual tension method I started using this season since that seemed to be the cause of the belt problems.

Going to Milan Dragway on 9/16/98, ran a best pass of:

11.689 seconds at 126.02 mph with a 1.945 seconds 60 ft time

While it still was not the best the car had ever run, it was nice to feel the power once again. However, two more familiar problems surfaced. The 3.73 axle ratio combined with the 1st gear of the Tremec was creating severe traction problems with the Hoosier Quicktime street tires I had been using for the past two seasons. This wasn't unexpected, since the ratio was chosen for roadracing instead of dragracing, but the traction was much worse than anticipated. The other problem was the Vortech discharge tube kept coming off the throttle body. I had installed screws radially around the tube to hold it together last season, but they would no longer keep it together with the T-trim’s increased airflow. The highest boost seen was about 19 psi at 6000 rpm, as that was about the highest rpm I ran the engine to.

Deciding a better fix was in order, I asked a mechanic familiar with Vortech installations on Cobra engines for advice. He fixed it by removing my screws and installing some big rivets through the hose clamp, rubber coupling and plastic discharge tube at both ends of the tube.

The Ford Motorsports Enthusiasts (FME - a group of Ford employees with a passion for performance) rented Milan Dragway for an evening so I got another chance to go out on 9/17/98, ran a best pass of:

11.642 seconds at 127.81 mph with a 1.996 seconds 60 ft time

The traction problems still existed, but the supercharger discharge tube gave no problems at all. However, what really pleased me was breaking the 130 mph barrier with a pass of:

11.873 seconds at 130.71 mph with a 2.089 seconds 60 ft time

The engine was surging a bit when I tried to lower the idle from just over 1000 rpm to something closer to stock, so a bit of time spent with the EPEC calibration seemed to fix that problem. The EPEC can be a very powerful tool (and fun) when used properly, but you also must be careful using it because it gives you complete control over the engine. It is a computer after all, and will do what you tell it to do, whether that is right or wrong, so just make sure you think about what you are commanding and you will really enjoy it.

Well, that same Ford Motorsports Enthusiasts group was busy again, but this time it was a dyno day at Paul's High Performance in Jackson, Michigan on 9/19/98. It seemed like a good time to see what numbers the car could make, so here is what it ran on their chassis dyno:

529 ft-lbs at 5200 rpm and 569 hp at 6100 rpm, which was the maximum rpm I wanted to try on the first run.

I was very pleased and several other people were quite surprised at what the 4.6L SOHC engine could do. However, due to not really planning ahead and not being able to buy Turbo Blue race gas at the local gas station this day, we were only able to make one run on the car, as the fuel gauge was reading empty and it started sputtering on the second run.

The following graph shows the very progressive torque curve that the Vortech produces. You can also see that the peak power had probably not been reached, but I didn't want to go very high on the first run.

Paul's is an excellent facility and one trip there is all it takes to find out why the FME group goes regularly. Paul's is also gaining notoriety for Modular Mustang tuning with considerable magazine coverage of the cars belonging to Jerry Green (DOHC Cobra), Barry Shepard (naturally aspirated SVO equipped SOHC GT) and Roxanne Shepard (SVO supercharged SOHC GT).

Another point of interest is that Barry's engine and mine have similar modifications, except the Vortech on mine gives me at least a 250 hp advantage. For those people who get bored with their cars not long after a modification, it is hard to beat the potential of the Vortech to keep you happy.

After that dyno pass, there was a noticeable amount of belt dust from it slipping on the 2.5" diameter supercharger pulley. I was still using the 6 rib belt and there was just not enough grip. Taking a tip from several people, I had the blower pulley sandblasted in an attempt to get more grip to reduce belt slip. This would be tested the next time out.

I wanted to play with the spark calibration a bit next time I got a chance to run on the chassis dyno, since it is a much more controlled environment than the track. So I created some new EPEC calibrations ahead of time and just saved the files in a laptop computer. That way it was just a matter of opening a file for each calibration change while on the dyno, which saves a lot of time.

Ran on the chassis dyno at Paul’s High Performance again on 9/23/98:

Saw no gains whatsoever with the other calibrations over the one I had been using, so I was both disappointed and happy. It meant that there would be no simple free gains, but it also meant the "best guess" calibration I had been using was actually quite good. I didn’t try changing the A/F ratio since I choose to be safely conservative with that by running about 12.5:1 at 2000 rpm and tapering off to 11:1 at 5000 rpm and above.

There was no noticeable boost increase from sandblasting the blower pulley, and after just one dyno run it looked very polished. The belt appeared to be slipping so badly that a "quick fix" just wouldn't be enough. If slippage is not too severe, then sandblasting for better grip probably works quite well, but the limits of the 6 rib belt and stock belt tensioner were really being pushed on this application.

Paul thought he heard some detonation during one of the runs with the spark advanced. Detonation at this power level on 110 octane race gas can damage parts in a real hurry and I was glad he was listening that closely, so I wasn't tempted to try another calibration with even more spark advance.

Looking at the Air/Fuel ratio and also the fuel pressure showed no problems with fuel flow. This is still with the stock fuel lines, fuel rail and regulator (no FMU). The car had a 190 L/hr in-tank pump and the normal Vortech T-rex in-line pump. The T-rex was being powered by a Kenne-Bell Boost-A-Pump set on max. The biggest advantage was using large enough injectors so that really high fuel pressures were not needed, since fuel pumps can flow a lot more at a lower pressure than at higher pressures.

The Cobra R radiator worked great, as the car never came close to overheating even though we made 7 dyno runs in 15 minutes.

However, there was a misfire anytime we tried to run above 6000 rpm. It would occur anywhere in the 6000 - 6200 rpm range. I had noticed this while running at the track and just figured I was hitting the rev limiter (I had it set at 6500) by accident. But since I was now on the chassis dyno, it was easy to look at the EPEC inputs in realtime mode and I noticed the air meter signal was just about maxed out. When I originally got the meter, I had asked Pro-M to calibrate it for 42 lbs/hr injectors because I wanted good resolution through the whole power range of the engine. Since I was using the EPEC, it didn't really matter what they calibrated it for as long as I knew what the output voltage was for a given airflow through the meter. They had done a very good job, since all I had to do was type in the volts/airflow curve and the injectors I was using and the EPEC took care of the rest to produce A/F ratios that were very close to the commanded values. I took the air meter back to Pro-M and got it recalibrated so it would measure more airflow and hopefully get rid of the high rpm misfire.

Also decided it was time to alleviate the traction problems but without spending a lot of money or losing the "stock" appearance. I bought my first set of slicks - Mickey Thompson 26 x 8.5 x 16" slicks mounted on stock 16" wheels. And, since the trans had a bit of time on it now, a B&M Ripper shifter was installed and I could feel free to shift more aggressively.

Going to Milan Dragway on 9/30/98, ran a best pass of:

11.011 seconds at 129.57 mph with a 1.659 seconds 60 ft time

Now running on slicks was a whole new experience for me with this car. I could actually launch above an idle and have the throttle open quite a bit. This took a few passes to learn since there was still enough torque to cause wheelspin if the launch was too aggressive, but the traction was so much better than before. I started out using 20 psi and then kept lowering it a little after every couple passes until reaching 15 psi. That is still rather high for many people using slicks, but it created the wildest ride of my life. Way down the track over 100 mph, the car headed for the guardrail. I really found out how sensitive it was to steering inputs at that moment and had to back out of the throttle to get it under control. I came back to the pits and promptly raised the air pressure to 18 psi in the slicks. It was still a bit wavering, but was no longer frightening.

Also noticed it still had a misfire above 6000 rpm, so the problem seemed like it may be the same as what plagues the Cobra people running high boost - the ignition system is just not up to the task. The engine was still using the stock coils and wires. I was getting better at driving on slicks and was very close to running a 10 second timeslip, but it was not to happen this time out. On the 9th pass I noticed the oil pressure gauge (stock one) just suddenly dropped to zero when I pushed in the clutch after going through the timing lights at the end of the ¼ mile. This was rather scary, so I shut off the engine and coasted to a stop on the return road. I looked under the hood and made sure the wire was still attached to the sending unit. There was no oil sprayed anywhere and the dipstick had oil on it. Tried starting the car and it idled okay, but with no oil pressure registering on the gauge and a little valvetrain clatter just seemed to be audible. Got a ride back to the pits with another racer and then put the car on the trailer and towed it home.

Still not knowing for sure what was wrong, I started looking looked into it. Attaching a mechanical oil pressure gauge showed that there really was no oil pressure when cranking the engine over. Draining the engine oil revealed no problems as the oil was very clean. Since the oil pump is behind the front cover (and timing chains) and I didn't feel like removing the engine if there was a simpler in-vehicle fix that could be done, I removed the front cover for a look. There were some metal particles in the front of the oil pan. That seemed odd because there were none in the oil that was drained out. I removed the pickup tube from the oil pump and then removed the oil pump and took its rear plate off. The pump was broken inside. Looking at the crankshaft flats that drive the pump, I noticed that the flats had rather severe contact marks on both sides of each flat and the edges were rounded over from when the pump stopped turning. The contact marks on both sides of each flat should not happen, since the pump should only load it in one direction. The metal particles I just saw in the front section of the pan were from the oil pump, but since the pump stopped flowing oil when it broke, there were no damaging pieces carried throughout the engine.

Well, now the engine had to come out in order to just have a look at the bearings and to install a new crank, since there didn't appear to be an easy fix for the crankshaft flats. I took the pump, some bearings and the crankshaft in to work for some opinions. The viewpoint was that the crankshaft had some severe torsional vibrations that the damper was not controlling. There were two reasons for this, with one being that since there were much higher firing loads on the crankshaft, the stock damper was no longer tuned for the system. The second reason was that since the outer ring of the crank damper is also the pulley for the whole FEAD system including driving the supercharger, the belt load was too severe to let the damper properly dampen out the crankshaft torsional vibrations.

The bearings were still in amazingly good shape. Apparently I was really lucky in seeing when the oil pressure dropped and shutting the engine off at that point. If the pump had broken a second or two sooner, the engine likely would have scattered at the dragstrip, so some things did go right this season.

Also noticed on disassembly that the head gaskets had been leaking a little around the exhaust side of several combustion chambers. That may have started when detonation was heard on the dyno. I was a bit concerned about the pistons too, but they didn't seem to care what they had been through, as they still looked good.

Overall, the improvement from last season was .26 seconds and roughly 3 mph in the 1/4mile. It would have been significantly greater if there had been enough time to get the belt slippage under control, but I did learn that switching to the T-trim with a smaller pulley was certainly a worthwhile change. We'll see what happens next season with more improvements already planned.

I'd like to thank the many people at Ford (Modular Engineering and SVO along with others) for their continued interest in this project. And a very BIG thanks goes to Matt Sweet for the tremendous amount of time he spent working on the car, as I would probably not have had it running this season without his help.

Ed Olin (EDO)
5/17/99