Nissan 300zx SR71 details for those who wanted it
The Motorsport International 300ZX Twin Turbo, also known as the SR-71, is the Japanese equivalent of a Callaway Corvette. Actually, it's more than equal because it is both quicker and faster. Engineering Editor Peter Albrecht tested the Godzilla Z.
The trouble with being a celebrated gunslinger is that somewhere, there's somebody faster. Just a few months ago, on the dusty Pomona dragstrip, the Callaway Twin Turbo and Corvette ZR-1 raced each other down - and came away with a draw for the fastest on the street.
Now there's a new gun in town. And it just blew the two Vettes right out of the saloon. The new top gun is the Motorsport International SR-71. Just as the Callaway is based on a production Corvette, so the SR-71 is based on Nissan's own supercar, the 300ZX Twin Turbo.
The SR-71 package is put together by Motorsport International of Waco, TX, at 817-776-0330. Randy Ball of Motorsport has been developing Nissan Turbo Zs in various forms for several years. Ball and HKS representatives met at an industry convention, where HKS offered to do a Twin Turbo Z for his personal use. Ball, though, saw a larger market on the horizon.
He commissioned a study to see if a Callaway-type production operation could be done. The result, the Motorsport International SR-71, will be built on an assembly line in Waco. The car will be sold through Nissan top Merit Award dealers who choose to participate, as well as Motorsport International. Ball plans to build 500 cars per year through 1993. One hundred orders are already in hand. The car will carry the same warranty as the stock ZX Turbo, 3 years/36,000 miles, through the Nissan dealer network. The SR-71 will carry a price similar to the sticker on the ZR-1, and be pegged considerably below the Callaway Twin Turbo. (By the way, ZR-1s can now be bought below sticker).
Motorsport bills it as a "serious car for a modest price." The first serial-numbered customer cars will roll out of the Waco plant in November, 1990.
The hard-core engineering work on the SR-71 has been done by HKS USA Inc., of Torrance, CA., a subsidiary of Tokyo-based HKS, a large engineering and manufacturing company that specializes in aftermarket performance. Todd Gartshore of HKS brought out the prototype SR-71 for performance testing at Pomona and Mrs. Orcutt's ever so bumpy Driveway.
The HKS mods on the 3.0 liter Nissan engine boost power on 92 octane premium unleaded pump gas to 464 horses at 17 psi of boost. (The stock car makes an even 300 ponies). Todd Gartshore points out that those 464 horses are representative of what the car will do on the street. Over 400 dyno runs were made with the complete street exhaust system and all emission control hardware intact and functional. Oil and water temperatures were regulated to higher than what the car would eventually see during our speed runs at Mrs. Orcutt's: 225 degrees for water, 205 for oil. The outlet temp from the intercooler was held at 195 degrees, while only 165 degrees were observed at Mrs. Orcutt's on a 100-degree day. HKS did one dyno run with short exhaust stubs behind the turbos and 105 octane racing fuel. The result was a 500 horsepower pull at 6,500 rpm.
The finished SR-71 package will include the HKS-built intercoolers and a street-legal free-flow exhaust bolted behind the stock catalytic converters. HKS and Motorsports International are working on California Air Resources Board certification, and expect the car to be 50-state legal when production begins.
The engine's torque is as impressive as its power numbers. It developed more than 400 lbs. ft. in a broad band between
4,000 and 5,500 rpm. Torque peak on pump gas was 433 lbs. ft. at 4,750 rpm. On racing gas, it saw 462 lbs. ft.
Gartshore thinks the engine has more left in it. "In the dyno run, we made for flash power. We were running very rich. We did not maximize fuel curves to take advantage of the fuel. We believe that if we optimize the mixture, we could run a legitimate 535-540 horsepower."
This is the quickest street legal car we've ever tested. Of all the cars that have carried our test gear, only three race cars - the McLaren M1A, Shelby 427 Cobra, and Shelby GT 350 - could out-accelerate it. And the SR-71 could probably take the Shelby, given slicks and shorter gearing. (The Shelby GT 350 would redline at only 142 mph.)
Gartshore emphasizes that all of this was achieved with no internal engine mods whatsoever. HKS took the engine apart,
put in new bearings and rings, and bolted it back together. The factory cam with its variable valve timing is retained.
Changes are limited to the induction, fuel, and exhaust systems.
HKS and Motorsport are building a more radical motor. With balancing and blueprinting, cams, larger turbos, as well as
extensive bottom end and head work, Gartshore hopes it will put out a reliable 650 horses. "I think that should give us
enough to push the envelope to maybe 220 mph."
The turbochargers have custom housings cast by HKS. The entire rotating sections are taken from production Garrett
AiResearch T25G turbos. As their sole Japanese distributor, HKS has a direct line to Garrett AiResearch.
To use the output from the larger blowers, Motorsport adds HKS' PFC - Program Fuel Computer. The PFC raises the factory
fuel cut point from an indicated 7,200 rpm (which HKS found to be a true 6,500) and the rev limit. The PFC eliminates the stock speed governor, which limits top speed to 157 mph. HKS removes the air mass sensor from one cylinder bank, replaces it with a relocated single sensor feeding just the left bank of cylinders. The right side is wide open, with no air mass sensor restriction. HKS found that the factory airbox was just too restrictive to meet their ultimate goals, so a pair of Power Flow air filters complete the intake tract changes. Gartshore: "Just moving the air mass sensor and adding the free-flow filters adds an easy 35 horsepower."
The PFC controls new 600 cc/minute injectors, replacing the stock 430 cc/min. injectors. The stock injectors in effect
limited boost to 11.5 or 12.0 psi. With the 600 cc/min. units, a realistic 18 psi boost is available, with a maximum of 19 or 20 psi.
The HKS package includes an electronic valve controller (EVC). Unlike factory wastegate controls, the EVC microprocessor does not signal the wastegate until 90 percent of the desired maximum boost is reached. Most street units begin opening well before that. As an example of its effectiveness, the addition of the HKS EVC on a Porsche 930 Turbo, with no boost increase or other engine mods, improves 0-60 mph times by 0.6 seconds and quarter mile times by 0.9 seconds over stock.
The EVC on our test car incorporated another neat little three-letter acronym, the Scramble Boost Controller (SBC). The SBC is an outgrowth of recent Formula One technology. It has three user-controlled functions: 1) Temporary increase in boost over the nominal EVC wastegate setting, from 10 to 100 percent, in 10 percent steps. So the driver can select a
temporary "emergency boost" of, say, 50 percent over normal; 2) Time of overboost, in 3.0 second steps, from 3.0 to 30
seconds; 3) A driver-controlled trigger to activate the SBC, located in an easily accessed location such as a door panel or on the shifter. A small alarm tone warns the driver that the SBC is activated, and a warning light on the trigger goes from green to red. The SBC was not used for our steady-state top speed runs. It would be useful on the drag strip or in passing traffic. Under racing conditions, the SBC helps to economize on fuel, but makes passing power available on demand. Alternatively,
it allows the car to be set up for low boost in corners for smoothness, with bursts of driver-controlled high boost available on the straights. The SBC will not be part of the standard SR-71 package, though. If you want one, call HKS or Motorsport for details.
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The bad thing is I don't think they producd the hundreds that the article says they did. To my knowledge there are only 5 cars with the SR-71 name plate. One of which (seriel#000) was for sale recently.
As far as I know it was the fastest Z ever made with a full warrenty, the GTZ with 465HP was next and the SMZ with 365 was just above stock.
http://sportscarforums.com/printthread.php?t=3330
