One thing Steve Dinan can’t figure out about the competition: How do they come out with parts so soon after a car becomes available?
“It takes us four to five months of just analysis before we get going developing parts,” he said. “It always shocks me when people come out with high-performance upgrades and I’m still taking the car apart.”
Actually, taking the car apart is the second stage. The first is driving it.
“BMW has a recommended break-in procedure of 1,200 miles where you are supposed to keep it under a certain speed,” said Dinan. “I’m not very good at keeping it under a certain speed.”
Regardless, those first 1,200 miles are prescribed for note taking, “getting a feel for what I like and don’t like about it.” Then the team will disassemble the car and “come up with as many strategies as we can to address things we don’t like.”
The first thing that became apparent in disassembling the BMW M6 was bore and stroke. “It was just sort of begging for stroke.” How about a little bore, too? Dinan stroked it to 83 millimeters and bored it to 93 millimeters. Boring the V10 from the stock 5.0 liters to 5.7 took some delicate maneuvering, since the cylinder walls were lined with silicon-impregnated aluminum alloy. Dinan’s CNC bore machines were up to the task. “The silicon’s impregnated deep enough into the block that you can bore out into the aluminum and still have the silicon. We had actually perfected all this technique on the racing engine.”
The racing engine is the one Dinan puts into the Grand-Am cars, one of which won this year at Laguna Seca, just down the road from the company’s headquarters in Morgan Hill, Calif.
To accommodate the extra power and torque, he added his own forged crank and lightweight forged pistons and con rods, balanced and blueprinted the whole thing and managed it with matching electronics and software. At $39,995, it isn’t cheap, but it gets you 65 more horses.
Another 55 hp comes from high-flow intake assemblies, throttle bodies, rear mufflers, middle exhaust and 13 percent underdrive pullies. Peak output is 628 hp and 480 lb-ft of torque, as opposed to stock output of 500 hp and 383 lb-ft.
That’s just the engine. Dinan has been known in its 30 years of business for suspension improvements. Again, these came from disassembly of the car.
BMW “wanted to leave room for the convertible, which compromised the amount of shock travel,” Dinan found. He designed new upper-shock mounts and bump stops at all four corners, increasing shock travel and ride compliance. Caster and wider front tires take out some of the stock understeer. The result is much better grip and steering feel: “It feels more like a 3-series than a 5-series.”
We drove an M6 in the hills one afternoon and felt all of that. A back-to-back run would have been better to gauge the understeer Dinan says is on the stock M6, which we didn’t notice at that car’s intro in Spain. The added power was most welcome, particularly at midrange passing speeds. Lack of roll was also impressive, but again, it would have been helpful to gauge it against the stock M6, on a racetrack, with somebody else paying.
We could imagine getting only the suspension stuff plus wheels and tires for a little more than $9,000. Who wants 628 hp, anyway? Well, everybody. But it’s nice to have the option.
And speaking of options, you soon may be able to invest directly in Dinan, which is planning to go public--“if there’s still a stock market to go into,” Dinan said.
And if there isn’t, why not raid the retirement fund now for one of these? You may go out with a bang, but you’ll arrive at the poor house in full opposite lock with 628 hp.
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