5.0 Mustang & Super FordsProject Vehicles
Mustang T-Top LX Project Car - Full-Throttle Meltdown
Our T-Top Coupe's Supercharged 347 Detonates To Kingdom Come At The Worst Possible Time, But We Bring It Back To Life In A Hurry
Horse Sense: Every once in a while, we experience an occasion where the negative outweighs the positive - by a lot. This is one of those times.
"Magazine projects never have catastrophic problems. If they do, we never hear about them." The opinion that a magazine editor's world is, well, perfect is a misconception that unfortunately is shared by more than a few readers of this and many other car enthusiast mags.
Sure, most of our content focuses on good-and cool-modern (Fox thru S197) Mustang parts, technology, events, and opportunities that we experience each month. Unfortunately, for all of the good, there are certainly times when things go wrong. When the problems occur, they're sometimes big enough to completely dispel the notion that mag projects know no evil.
You might recall reading about our prized '86 T-top LX's triumphant debut in our Aug. '07 issue ("Final Exam," p. 164). The article summarized the coupe's initial dyno numbers and cruise-mode performance. We also gave you the all-important timeslip data, detailing how quickly our Fox-Rod 'Stang motored down the 1,320-foot racing surface at Auto Club Dragway in Fontana, California.
While the T-top coupe scored high marks across the board (600-plus lb-ft of torque, good street manners, and low-11-second e.t.'s), there were a few new-car bugs at the track that we felt were setbacks. A slipping blower belt limited the Paxton Novi 2000's boost production, and spinning 17-inch tires almost certainly had a hand in keeping our Fox Rod out of the 10-second club.
A few months after making changes and correcting the glitches, we decided to give the car another workout, participating in the test 'n' tune segment of the West Coast Hot Rod Association's summer event at Auto Club Famoso Raceway in Bakersfield, California.
Despite our high hopes and good intentions, disaster struck our coupe roughly 800 feet into our first pass off the trailer. Although the rear drag radials didn't bite as hard as we hoped they would after launching with the transbrake (we changed the strut and shock settings for better weight transfer and traction), our 'Stang shot out to the eighth mile, tripping the clock for midpoint speed at 102 mph-about 6 mph higher than the 347's previous best speed (96.11).
We credit the gain to a taut blower belt and the big boost it helps create, achieved by a new larger-diameter pulley on the belt adjuster that our friend Marc Rubin made for us. Unfortunately, the coupe's best-ever eight-mile speed is the lone bright spot for the ill-fated pass.
Shortly after clearing 800 feet-and with your tech editor trying his best to bust his right foot through the floorboard and out to the bellhousing-the engine suddenly laid over, which is akin to someone unexpectedly putting a pillow over your face as you're inhaling. It belched what appeared to be white smoke through the exhaust and cut off just before the finish line.
Our initial thought was that a head gasket had let go. We later learned that the smoke was a lot darker than we thought. As you'll find out when you read further, we'd probably welcome 10 head gasket failures over the carnage we found inside our stroker. By the way, our Fel-Pro multilayered steel gaskets weren't blown.
The blame for this disaster falls solely on the shoulders of your tech editor and not any of the parts manufacturers or service providers we used to complete the coupe's 347. As a matter of fact, we're going to use the same brands (Scat rods and SRP pistons) to replace those that were destroyed.
Mistakes happen. Thankfully, we learn something from them in most cases, in addition to finding out how expensive they can be. The lesson of our engine mishap teaches us that while 91-octane pump gas served our street/strip supercharged engine well under 8- to 10-psi boost conditions, pump gas is no match for the heat and cylinder pressure of a 17-psi blast of forced air. Detonation is definite, and heavy damage is the result.
You may recall we worked valiantly to build our T-top Fox in time to participate in Hot Rod's Drag Week event in 2006. We fell short of making it, but in the spirit of challenging event deadlines, we're currently faced with an urgent need to get the T-top coupe back in action right away. We're not going to tell you where the thrash effort is taking us, but be sure to check out future issues for a better idea of why we're going all-out to fix our project ride.
Read on and learn more about the problem we encountered and the measures we're taking to make things right. Thanks to Federal Mogul, Moroso, Paxton, Royal Purple, Scat Cranks, SI Valves, Sportsman Racing Products, and VP Racing Fuels for turning product orders around for us in record time. Major props to Extreme Automotive and Big Terry's Engine Shop of Simi Valley, California, for going the extra mile and keeping the lights on late for us during an intense two-week thrash.
The first indicator of really bad news was the sizeable dribble of oil that Saul poured out of the runner for the No. 1 cylinder in the upper intake. Theoretically, an engine with proper ring seal and crankcase ventilation shouldn't have that much oil this high.
Our detective work brought us this second clue. Notice the light gray and dark black colors on two halves of the wideband O2 sensor. We assume the darker color confirms the engine's air/fuel ratio was rich and safe at the beginning of the run, but as boost increased, insufficient-octane fuel caused the ratio to shift toward the lean side, causing harmful detonation. The silver specs mixed in with the gray told us we would find damaged pistons once the engine was out.
We swung out the coupe's engine and transmission in a one-shot deal...
...and had our engine bolted to a cradle and ready to transport to Big Terry's Engine Shop in Simi Valley, California. There, Rocco Acerrio would disassemble the engine and hopefully repair any damage, if it's repairable at all. We should also let you know that it's important to have the turbocharger or engine-oil- lubricated blower inspected whenever a major engine failure occurs. Despite filtering screens designed to protect an oil-fed adder's critical internal pieces, fine metal particles from broken pistons, rings, and other parts can sometimes slip beyond the screens and damage the blower or turbo. Technicians at Paxton's Oxnard, California, headquarters inspected our Novi 2000 while Rocco handled the engine's needs.
With only two days before our deadline, Rocco delivered our fresh engine for its installation at Extreme. Although our engine failure was centered on insufficient fuel, we're not taking any chances on the oil side, either, so we added Moroso's aluminum Eliminator 7-quart oil pan (PN 20514) to the new bullet.
Taking engine protection one step further, our 347's oiling system is now supplemented with Moroso's new 3-quart oil accumulator (PN 23902). The accumulator is huge, and finding a suitable mounting location for the extra oil reservoir was somewhat of a challenge. The accumulator gives us peace of mind that we probably won't incur major engine damage if there's a sudden drop or loss of oil pressure.
Since the engine's Holley SysteMAX II upper plenum will block these babies from full view, here's a better look at our step-up in valve covers. Moroso makes these super-bad carbon-look covers for small-block Fords in gray/black (PN 68451), blue/black (PN 68452), and red/black (PN 68453). We repositioned the breather/oil-fill holes in each cover, and we're using Moroso's new screw-in AN -12 bulkheads (PN 22635). The bulkheads are cool because they don't require any welding on the nice covers. AN -12 braided lines will vent blow-by gases into a catch can (PN 85465) mounted along the frame.
Thankfully, the engine went back in as easily as it was removed, taking about half a day. We have to credit that to the thought that went into designing and laying out the engine compartment and drivetrain for the project car.
It was built to come apart and go back together with minimal effort whenever necessary. We just didn't plan on it being so soon.
Rocco To The Rescue
There's a lot that can be said about best-kept secrets, especially when talking about engine builders.
Big Terry's Engine Shop of Simi Valley, California, isn't one of the more popular engine shops in the country. Nor is its owner, Rocco Acerrio, noted as one of the nation's top performance-Ford builders. Rocco has been at it since before he could drive legally, so to say he knows a thing or two about making horsepower is an understatement.
Some things can't remain a secret forever, so it's time to let you know about Big Terry's and the incredible assistance Rocco and Nathan Hall gave us at the 11th hour.
With our project car down with a blown engine and your tech editor facing a deadline that was fast approaching, Rocco and Nathan took complete control of what seemed to be a dismal situation and delivered a fresh 350ci engine for us in record time.
Our engine suffered through a detonation episode and damage was severe. The block required a sleeve; a full 0.020-inch overbore; a rack of eight new pistons and rings, among other things; and two new connecting rods. We used the same brands for the hard parts, as none of the damage was due to failure of the original pieces. As the saying goes, "the best thing to do is dance with the one that brung 'ya." The forged pieces by SRP (pistons) and Scat (rods) more than proved themselves in the T-top coupe's original engine.
While almost all the engine's components were reused-with the exception of an oil pump and pickup, Fel-Pro gaskets, and an intake and exhaust valve in one of the cylinder heads-Rocco added a new aluminum oil pan from Moroso and a pair of off-the-hook fiber valve covers. The project ride's new bullet has a wicked look that we're sure matches the power it's capable of producing once our freshened Paxton Novi 2000 starts blowing boost down its neck.
The engine is ready to rock. More importantly, while it's close to the wire, it looks as though we're on course for attending a major race event, which we'll tell you all about in an upcoming issue.
With our coupe's engine mounted on a stand, Big Terry's Engine Shop owner Rocco Accerio got down to the task at hand, uncovering the mystery of what went wrong.
Our early diagnosis and hope of a blown head gasket was quickly disproved. The Fel-Pro multilayered-steel gaskets weathered the inferno without any sign of damage, so we rebuilt the engine with a fresh set of the same sealers (PN 1134), including a Remainder to Assemble Complete Engine (RACE) gasket kit (PN 2718) that will cover all the other areas requiring solid seals.
Here's a look at some of the additional piston damage that the stroker endured during our ill-fated pass.
Due to a lack of sufficient octane, the pump fuel detonated and instantly created high pressure in the combustion chamber (imagine smacking the top of your pistons with a sledge hammer), which proceeded to do a number on our pistons.
A closer look shows exactly where piston failure begins. Note the crack at the intake-valve pocket. This area is the closest point to the ring land, and it's the thinnest area of the piston surface. When they go, it all begins right here. This is the best looking slug we found. The other seven pistons were either broken, ventilated, melted, or all of the above.
Here is the No. 3 cylinder-the hole that took the biggest hit from detonation. Rocco initially thought all the cylinders would clean up with a good honing and not require any overboring. After measuring the cylinder and assessing how deep the burn is, the call was made to install a sleeve in No. 3 and bore the block an additional 0.020 inches.
The AFR 205 cylinder heads escaped with minimal damage: Only two valves were bent and burned, and the heat didn't cause severe cracks in either head.
All the Comp Cams valvesprings and pushrods checked out. We replaced the broken valves with stainless steel: 2.08-inch intake and 1.60-inch exhaust valves from SI Industries.
NGK's BKR 6E spark plugs show signs of lean, as well as damage from making contact with pistons.
The oil-pump pickup features a screen designed to protect the pump from foreign matter, such as the piston chunks shown in this photo. While the screen can catch some things, material does pass through. Always replace your engine's oil pump and pickup when this kind of catastrophic failure occurs. We went with the same Melling unit we originally installed (PN 10688).
Nathan Hall removed the camshaft from our wounded engine. Neither the cam nor the lifters suffered any damage, so they were cleaned and reinstalled.
A flat spot on the bearings is a true indicator of detonation. Nearly all the bearings in our project car's bullet had flat spots and were replaced with another set.
Two connecting rods were obliterated. The pin bushing was moved on one rod, and we found piston material imbedded in the side of another. "I've never seen that happen before," Nathan says. He's been working at Big Terry's for the past eight years.
Here, our coupe's engine block is now ready for the long, but hopefully fast, road to recovery.
A fresh rack of eight new SRP-forged, dished pistons highlights the rotating assembly again. Damage was severe enough to warrant a 0.020-inch overbore of the block, so we once again installed SRP's finest (PN 231574) in a slightly bigger diameter. Each piston features a -15cc inverted dome and will make a 9.6:1 compression ratio with our AFR 205s.
All the parts, including the Comp valvetrain, Aussie Muscle Parts beltdrive, and Scat 3.250-inch crankshaft (PN 4-302-3250-5400-2123) were thoroughly cleaned and laid out for engine assembly.
We lucked out, as the crank wasn't damaged to the point of requiring any undersizing.
Rocco pressed a Darton sleeve into the No. 3 cylinder of our damaged Ford Racing Performance Parts R302 engine block. We initially thought the block's original 0.125 overbore could be retained with a simple hone, but the damage proved to be too severe.
The unfinished sleeve and seven other cylinders were bored 0.020 inches beyond the engine's original 4.125 bore size. The additional cylinder diameter increases the cubic-inch displacement of our stroker to 350.
After decking (milling 0.003 inches from each cylinder bank) the block to ensure it's square, the cylinders were honed with a torque plate in place to simulate the weight of a cylinder head on the block. The technique, better known as torque-plate honing, facilitates optimum ring seal, which will maximize the performance potential of the new bullet.
Big Terry's Engine Shop had our T-top coupe's "bigger-bore" engine block fresh and ready for reassembly in less than a week. This kind of service is awesome and appreciated, especially considering they also had to have another customer's complete 'Stang ready to participate in the same event that we're thrashing to attend.
We mentioned earlier that only two of our Scat H-beam rods (PN 2-302-5400-2123A) sustained damage rendering them unusable. We replaced the pair of 5.400-inch rods with the same part number, and Rocco added new pin bushings to the reused original rods.
Cylinder-head repair was limited to welding on one head, then milling 0.004 inches from the surface of both heads to ensure they're straight. Rocco gave each head a five-angle valve job before installing them on the short-block. Now they're better than new-and we intend to keep them that way.
Rocco entertained the idea of swapping our Comp hydraulic-roller camshaft with a solid bumpstick, which would all but guarantee an 8,000 rpm redline for our fresh engine, but we weren't feeling the idea of adjusting the valves frequently. After polishing and installing the original 0.608-intake/ 0.612-exhaust cam, a degree wheel was used to dial in a few additional degrees of advance.
A distributor, wires, spark plugs, a fresh pour of Royal Purple XPR 20W-50 oil, installation (with exhaust, starter, supercharger and air-inlet plumbing), and tuning are all that stand in the way of this new engine and our T-top coupe's miracle comeback. Thanks, Rocco!