Turbo Car vs. Turbo Bike: 1978 Porsche 930 Turbo vs. Kawasaki Z1-R TC

From the August 1979 issue of Car and Driver.

It is quiet at Road Atlanta. Too quiet. Summer is invading the hills and hollows, and afternoons tend to move slowly in this part of the country, but the stillness today is unwelcome. We are dead in the water, staring at a car and a motorcycle that have agreed to function no more. Danny Ongais has been here before, in this situation, and in this place, too. Ongais has a reputation, right or wrong, for caning his engines until they retch their lubricants and their moving parts right out onto the pavement. Herb Porter says it’s an undeserved reputation. Porter is Indianapolis’s own wizened resident builder of racing engines, and he says Ongais is too smart of a racing driver to overwork his engines on purpose. If they let go, there is probably an internal fault. The mechanical seizures suffered in Georgia today are certainly not of his doing. Call it fate. And just when Ongais was starting to cook. Damn.

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The Kawasaki arrived two days ago in a truck from California, accompanied by Wayne Moulton, president of Turbo Cycle Corporation, and Lou Nauert, vice-president of American Turbo Pak, Inc. The two companies are engaged in a partnership to provide a turbocharged, fully pack­aged motorcycle for sale through authorized Kawasaki dealers. Additionally designated TC, and based on the production-model Kawasaki KZ1000 Z1-R, this street motorcycle is the fastest thing on two wheels this side of Kenny Roberts. It is a rocket.

The Porsche 930 Turbo is King of the Hill among production cars. Except for stops at Gettysburg and Antietam, I have brought the car from New York in a sensory rush through New Jersey, Pennsylvania, Maryland, Virginia, and the Carolinas, and quickly into Georgia. The 930 Turbo has given speed the way a moped gives economy, but the two-wheeler it has come to face off with at Road Atlanta is anything but a moped.

Danny Ongais calls it The Scooter, a wonderful sort of endearment for a 145-mph motorcycle. The turbo people are leery of letting Ongais run free on the bike. They know he is magic in cars, but it’s been a while since he straddled a motorcycle with serious intentions. A stock Z1-R is reason enough to get very serious. Boasting dual front and single rear cross-drilled brake rotors, it weighs in at 555 pounds, and its 1015cc (62-cubic-inch) engine rips out 90 horsepower at 8000 rpm in stock form. By the time Turbo Cycle turns it into a Z1-R TC, it has sprouted smoothly integrated new plumbing for the turbocharger, a Rajay 370F40A unit with a dual oil-feed center bearing, and a 38-mm two-stage carburetor, bolted to the turbo as a draw-through unit. The carburetor features an accelerator pump and a very large-capacity float chamber, which is fed fuel by a 4.5-psi solid-state electric fuel pump. The waste gate is an American Turbo Pak design with a relief valve that can be set anywhere from almost zero boost up to more than 20 pounds, although the normal recommendation is 8.5 pounds. An oil-pan hinge-type baffle is added to keep the oil from rushing away from the oil-pump pickup tube under the tremendous accelerative forces the Z1-R TC generates. A turbo-oil drain block encourages the free-flowing return of oil from the turbo itself, and an all-chrome exhaust system incorporates a newly developed spyder header, a connector pipe, and a tailpipe, complete with heat shield and center stand bumper. The inside of the engine is normally left untouched except for special racing applications. A glycerine­-dampened 15-psi boost gauge is mounted in a cast bracket to the handlebar bolts. After a black paint job and yellow and red striping by Molly Designs, the bikes are recrated and shipped off for eventual sale through Kawasaki dealers.

Our bike for Danny O. has a little something extra. Ostensibly added because of the anticipated hard usage on the road course, but a good idea for any fast roadwork (and what other kind could there be?), an air-boost fork kit and Freon-filled rear shocks with 120- pound coil springs have been installed by S & W Engineered Products. The Kawasaki’s stock rubber has been chucked for the very latest Goodyear Eagle HST­ series tires, sized 350-18 (ML90-18) front and 450-18 (MP90-18) rear. Designed to run either tubed or tubeless, the Eagles our Z1-R TC is wearing at Atlanta have tubes inside. We hear howls of rage and cries of Foul! among you already, but remember that the Porsche 930 is anything but a stock 911 chassis with a turbo motor stuffed in. The spirit of sportsmanship, and even common sense, say you don’t bump up a monumental horsepower increase without adding ten-league boots to the chassis. Not upgrading the chassis is dangerous, and besides, we’re playing by our rules, so there.

The Porsche 930 has pretty much established its own rules and called its own shots since Day One. By comparison, other cars seem to pop out of the muzzle like a cork on a string, but the Turbo is truly shot out of a gun. Porsche’s continuing policy of constant improvement has added further intricacy to an already complex mechanical package, and last year’s intercooler and running-gear changes have done their part to kick the duffs of the competition harder than ever before. The 3299cc (201-cubic-inch) flat-six produces 253 horsepower at 5500 rpm, and transfers it to the ground through Pirelli P7 tires. The 930’s 3040-pound bulk is brought to a stop by brakes originally developed for the 917 race cars. The huge four-wheel discs are ventilated and cross-drilled for maximum cooling and braking consistency. The rock-solid, superbly finished unit body is suspended on front MacPherson struts with longitudinal torsion bars, and semi-trailing arms with transverse torsion bars at the rear. Anti-roll bars are 20mm thick in front and 18mm in the rear.

The specifications for the two combatants indicate that the only similarities are turbochargers, disc brakes, rubber tires, and great gouts of horsepower, but they share more than coincidences on a list of particulars. We have brought these two together because each represents the zenith of its own brand of performance, and because the classic rivalry between fast cars and fast motorcycles has existed since the driveshaft and the chain were invented. Each does what it does with more terrifying and icy efficiency than anything else you can get your hands on. To string them out as tautly as the string can be drawn, we have asked in the master of icy efficiency, Danny Ongais.

Ongais slows to a crawl on the vertigo-inducing rise that follows the dogleg left up to the rock-’em-sock-’em mineshaft plummet to the right. This heart­-stopping drop has its beginnings under Road Atlanta’s famous pedestrian bridge. It is butted on the outside by earthen banks mildly padded with old tires.

“See those black marks?” Ongais says. “Those are mine.” They run straight off the pavement and swirl smack into the wall. The 930 Turbo is idling smoothly as he tells me he went in too deep trying out new, better brakes on his Porsche 935 two weeks ago. There are ugly marks on the barrier tires and gouges in the red clay, and somewhere deep in the part of my mind that I don’t want to know about right now, I know we’ll be flying next time around. Swell, Danny. Do you do this to all your dates?

I unlimber my little recorder as he schusses the Porsche from the shade beneath the bridge into the swoop of unbroken sunlight, down the terrifying unseen drop I choose to call Pitfall. Ongais rushes us out of the right onto the pit straight with a fierce, neck-tugging whoosh. A year ago, I rode around this place with David Hobbs in the McLaren Turbo BMW at a good-for-third-on-the-­grid 105-mph average. In spite of the fact that I have stretched the string tight on the Turbo myself, I am appalled by the violence Ongais is able to create and form to his will in this street car. The Goodyear racing technicians say that he is tremendously perceptive and very articulate. He is preparing his lesson plan for us. The textbook is opening:

“The Porsche is a compromise between what you need to run on a race car and a street car, I suppose. If you don’t allow it to take a set before you attempt to drive it hard, it’s very sensitive and it unloads. It wants to go from an immediate understeer into an over­steer, which is almost uncontrollable because you only have three wheels on the ground. You need to get the weight transferred very smoothly; then it will set and bite very nicely. It’s very sensitive to the throttle on slow and intermediate corners. It does very well in the high-speed situations…You turn in gently and apply the power and it works, it’s pretty neutral.”

This is wonderful. Ongais is confirming my experimentation back in the mountains yesterday. The car is a struggle to drive quickly through successions of tight comers, a cranky difficulty compounded when you are not sure where the road goes in another 200 yards. It is a seesaw battle between boost lag, understeer, oversteer, and solid doses of kickback through the steering wheel. Getting the boost to come in at the right moment is an art best learned on your favorite closed course. Danny Ongais has a 930 Turbo of his own. He says the first time he drove it, he decided never to go fast in it, except in a straight line. Hello, hello, is this the real Danny Ongais?

“I wouldn’t say it changes direction very well. You have to be very much on your tiptoes, but it’s more stable in faster corners. It may be that the aerodynamic influence of the rear spoiler helps considerably, a lot more than we would think, but we’re approaching speeds out here that you don’t normally see on the highway.”

Amen. The inherently gentler high-­speed transitions make a big difference, too. In any case, the 930 is a classic case for In Slow, Out Fast. “That’s about what it seems you have to do,” he says with a laugh.

When prompted, the World’s Bravest Man admits the brakes are the best thing about the car. “Well, at the moment, it seems that way.” He is smiling inside his helmet.

“It’s for sure not the same car that we race.” Going over the oh-God curving rise on the hyperfast back straight, Ongais says, “Here, we’d be going into fourth gear in the 935 and the car would get a little light, but the 935 uses up maybe half as much road as this does. It’s very much more precise. In tighter corners, the side bite would be very good, with no roll, except from the tires themselves.”

As we hurtle down through the esses toward the tight, uphill left at the bottom, we compare notes on the height mismatch of the brake and throttle pedals. Ongais says, “Yes, for a heel-and-­toe application, yeah, I agree with you, it’s not ideal here. That’s odd, because mine is very comfortable in that respect.” We also agree there is probably a built-in adjustment that could be made in the pedal or the linkage to smooth out the downshifting process.

Amid ferocious alternating tire squeals (which we are later told were heard all the way down in the pits, on the other side of the cloaking hills and forest) and the whistling shriek of the turbo, our talk turns to horsepower and what it can do for you. My contention is that having willing, predictable power adds another element that makes a proper car easier to drive. Power allows you to make corrections and attitude adjustments, and power in a good chassis is reassuring rather than frightening. “Yes,” he says, “you can set the car, you can turn the car, you can do an awful lot, just by having a little more suds to play with.” He pauses …. “You know, there’s something small, but something wrong here. We’re not getting the proper amount of boost.”

Ongais is right, the car is down on power. It has lost the explosive surge of boost that causes the eyes to get all wet. Or all bright, depending on the lady. It started yesterday, with no apparent provocation. All at once it just wouldn’t deliver full boost, either on the gauge or to the seat of my pants. It still pulls revs like a greased rabbit out of a Teflon hat, but the sudden violence is gone. There is nothing to be done about it, so we go on rearranging my lunch, a meal Ongais always skips when he has work to do.

The seats are holding us snugly, but my lower back has developed the same dull ache it developed from New York all the way to Flowery Branch, which is just up the road toward Gainesville. The instruments are doing their usual efficient and legible job of keeping Ongais apprised of the multi-thousand-dollar Turbo innards. Nothing seems amiss except the boost. The air conditioning is switched off, of course, and the power windows are closed tight. We are sweating fiercely. The deep shag carpet is almost clinging to our humidity.

“This handling would suggest,” says Ongais, unmindful of the heat, “that someone who has some proper training, who has perhaps been to driving school, would be able to get onto one of these much quicker than the person who walks in cold-turkey off the street. He would begin to be able to appreciate it. Otherwise, uh…a gentleman could be in a lot of trouble.”

Ongais has a point. I have it on good authority that more than 40 percent of the Turbos sold by one West Coast dealership have been crashed backwards. No mean average, that. Today, Ongais has demonstrated car control beyond compare. We have been, intentionally and unintentionally, thoroughly sideways at speeds hovering on both sides of 100 mph more times than a heart specialist could count on an electrocardiogram. But, through it all, there has been one thing on my side, pushing aside my doubts and concerns, and that was a placid, functioning Danny Ongais. The man is a marvel, hardly a man at all in his level of skill, and therein lies the catch. He is a one-off and you will notice that his 930 Turbo is not among that errant 40 percent. Danny Ongais decided not to drive his Turbo fast except in a straight line, remember? Where does that leave the rest of us? Where does that leave the legend of the Porsche Turbo? Sooner or later backwards, most likely. Eternal vigilance and constant practice are the only salvation.

As we ease down Mineshaft #2 into the pits for a cold drink, Ongais notes a definite softness in the throttle. Popping and wheezing ensue, and he cuts the engine as we roll up to the Turbo Cycle truck. He thinks maybe it sounds like a fuel pump gone bad, but the rest of us are more skeptical. All immediate attempts at restarting fall on uncooperative combustion. The chances that Ongais will be able to get in some really hot laps by himself appear deep in jeopardy. Our attention turns to The Scooter, as he calls it.

The Z1-R TC has been sitting quietly under the adjusting ministrations of Nauert, who is complaining because someone back at the shop in California forgot to put Loctite on the waste-gate bolts and a couple have unwound themselves during Ongais’ early-morning familiarization run. A baffle has been removed from the exhaust system in the interim, and the firmer rear-suspension setting Ongais requested after his first outing has been dialed back to its original, full-soft position.

Ongais says: “It induced some wheel hop, so we went back to the softest setting, where it gets the power to the ground very well. We were getting hop under braking, trailing throttle, and downshifting.

“I find the use of the rear brake these days is almost nonexistent. They seem to do it all with the front, and then carefully and very smoothly downshifting.”

I run two easy laps, riding behind Danny on the Kawasaki, watching over his shoulder as he arcs his way smoothly right, left, right, left, over the hill and down into the esses. On the back straight we are over 100 with never the uncertain stumble of a missed beat. Up and under the bridge, I am aware of the concrete whuffiing past my head as he arcs the Kawasaki down the hill, squarely on the line.

Then, as we watch from the pits, Ongais dispels any lingering doubts among the motorcycle crew. Within a couple of laps he settles into the rhythm of the machine and the course. His speeds rise near vertically on the scale.

“Shoot, we don’t have anything to worry about,” says Wayne Moulton.

Ongais is a ringer natural on anything he touches that has wheels connecting it to the ground. Later, he says: “The bike rides quite nicely, surprisingly, in fact, and it handles well. It turns into the cor­ners very well, doesn’t have to set twice or anything. You get it there, you lean on the throttle, you use some body En­glish, and when you’re smooth, it seems to get around very quickly. It gets to its top speed very quickly and it seems to hold it. It takes a bit of muscle to get it turned in at something over 140 mph, but when you do, it holds a very good line and is very stable.

“I would have to say the motorcycle is quicker than the car, if only because it is able to attain the speed quicker. Whatever you feel with the bike is what you have. The power builds very smoothly, early on, somewhere around 4000 rpm, and it probably has full boost on at around 6000. The highest I’ve run it is about 8500, and it seemed to want to go a little more. It holds it, and when you shift it, it immediately picks up the maximum boost you’ve had previously and continues on its way. There is no lag between the gears.”

Compared with the Porsche, the Kawasaki seems to have a greater consideration for its operator. When Ongais stops for a swallow of Gatorade, his enjoyment is fairly bubbling through his Bates leathers. “At no time does the bike try to carry the front wheel or do anything violent. When we stiffened the rear end, it had a tendency to break away a lot quicker, but that was the only thing that happened. I am able to adjust into any position I want. The saddle allows you to do an awful lot, and it seems you would be comfortable over a long distance. It does seem to be a good touring machine.”

He likes the tires, says they are precise and easy to read, but he opens a necessary discussion on the merits of the contact area.

“The car does stop much better than The Scooter does, I think because you’ve got maybe ten times the amount of rubber on the ground.” The effects of weight transfer are also accentuated by the motorcycle, whereas the rear-engined Porsche takes maximum squatting advantage of its massive P7s and simply stops moving, properly allowing the locking of the fronts first, with sufficient, easily modulated pressure. Ongais notes that the rear brake on the bike is touchy, tending to upset the machine too easily.

He is carving a slot around Road Atlanta now. The bike is smoking some, but Ongais is honing his approach, not yet doing anything unbecoming to a master wheelsman. The lean angles and cornering speeds are moving into a realm that would toss most street riders off into the fences. He is running over 145 at the bottom of the back straight, 20 mph faster than the weak-­running Porsche. Then the bike packs it in, a cylinder gone. Until now it has been stunningly fast, in a league even a healthy Porsche couldn’t get a whiff of.

“I never was able to extend the bike, or the car, because our day was cut short here. With the bike, I never felt I should try without becoming friendly with it first.”

There, sir, is a truth. You treat either of these stupefying creations like a large, strong, and cunning wild animal you’ve had no truck with before. Any other approach is foolhardy.

Lying on the grass beside the guard­rail, Ongais sums up the two. “I don’t know if it’s a fair comparison at the moment, because we don’t know just how well this Porsche was working, but I’ve driven other 930 Turbos that come on a lot better. In overall performance, I’d have to say, at the moment, that the bike will run off and hide from it.”

Both turbos have broken, the bike with a gone cylinder attributed to insufficient break-in, stock pistons, and the unrelenting and unexpected road-course gaff Ongais was able to deal it. The Porsche’s problem will later be diagnosed as a nut that backed off the end of the right-bank camshaft, shearing a drive tooth, allowing the cam to stop turning altogether, and bending two valves.

For the moment, a look at the accompanying performance tables will have to satisfy your need for comparative times. My thanks to editor Cook Neilson of our sister magazine Cycle for providing the bike’s quarter-mile numbers. Ongais has indicated that he remains available for further judgments. We may yet make an attempt to settle this eternal debate with these ultimate debaters and our ultimate referee. But, according to the very educated seat of the Ongais pants, the inescapable truth is that the bike can blow past the car and be gone from sight anyplace where there is a moderate straight stretch with which to work. From that point, it’s Sayonara, Porsche 930. Hello, Kawasaki Z1-R TC.

As we pack up the remnants of a fascinating day, loading the bike for the return trip to California and leaving the Porsche for an ignominious ride to a dealership on a salvage truck, Danny Ongais leaves it in perspective.

“There was quite a bit in hand.”

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