Selasa, 22 Juli 2008

1971 Datsun 240 Z- Power Shift

A Blown L28 Leads This 240z To Godzilla's Mighty RB26

all contributors: John P. Roper

Longtime Austin, Texas resident Mark Rolston has become a bit of a legend in Texas road racing circles lately, thanks in large part to the car you see before you. When it first hit the track with its new powerplant late last year, it took quite a few Vipers and Ferraris by surprise. But the story of this car is a lot longer than those two sentences. It's taken over ten years of trial and error (lots of error) to get it to where it is now (much like Super Street but with a better end result - JN).

Mark's been into Z's of all types since he got his driver's license, his first high school car being a '78 280Z (so very disco!). He bought this particular '71 240Z 11 years ago as a fun weekend toy. Having had lots of experience with autocross, he wanted to try his hand at something more serious and competitive. A plan was hatched to prep the car for regional NASA road racing.

The first version of this car was basically what you see in most street Z's: a firm suspension, a bit more power and a gutted interior. Version one featured a mostly stock L28 (from a newer 280Z) replacing the torquey but somewhat anemic L24. With the associated suspension mods the car was very fun on the street and at the local autocross, but was not quite as competitive as Mark wanted it to be.

Feeling the need for more power, the plan was to build a race-prepped L28 to take the place of the first one. After lots of machine work, time and plenty of money, Mark had his dream engine. After extensive tuning, the car made just a shade over 250hp. Not too shabby for a naturally aspirated, two valves-per-cylinder, single-cam engine first designed and engineered some time in 1967. This version certainly proved to be fairly potent out on the track. While still not able to beat up on the truly fast cars, it at least took Mark from the back of the pack to somewhere in the middle. And then the unthinkable happened; while doing well in a race late in the season, a sudden oiling problem caused that engine to self-destruct in spectacular fashion. As he coasted into the pits with the same powerless end as a Super Street project car, Mark was determined to not have it happen to him again.

He decided to stop messing around with the old school bits and get into something stronger, more powerful and more reliable. Not wanting to stray from the Nissan family, the choice was abundantly clear. Mark had to have the heart of Godzilla itself, the almighty RB26DETT. For the uninitiated (or you Honda heads), this engine is the very powerful inline-six, dual overhead cam, twin-turbocharged beasty found in the late model Nissan Skyline GT-R. But such a swap would not be without its roadblocks, either.

Needless to say, since the GT-R was never officially imported into this country, RB's aren't exactly growing on trees. Mark got on the phone with a few importers and finally found a lightly modified engine set from a wrecked R33 and then proceeded to have it shipped over. Somewhere along the way, some silly J-dude pressure washed it and filled one of the cylinders with water. By the time it got here, that cylinder was wasted. The replacement engine itself wasn't exactly in tip-top shape, either.

Instead of trying to get it running in stock form Mark opted to do it "right" the first time. He had already spent heaps of money on it, so why not go all the way? The internal guts were replaced with basically everything Tomei offers for the RB. And while most opt for the single-turbo conversion for maximum power, Mark wanted to keep it simple and tractable for road race duty. With that in mind, he simply upgraded the stock twin snails with rebuilt GT2871R turbos. While not making the big numbers that the monster single turbo setups make, these Garrett compressors are no wimps. After tuning the Autronic SM4 stand-alone and changing the stock injectors out for whopping 1,000cc units, the engine pumped out a staggering 612whp at 8500rpm. But don't let that high RPM number fool you. It makes plenty of power all over the rev range. Torque is massive and everywhere. With the custom front mount intercooler and piping, it keeps its cool amazingly well, even in the tough Texas heat. And keep in mind the car still only weighs around 2,500 lb.



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