Last week we had the pleasure of dyno tuning Eric Straw’s magnificent 1969 Datsun 2000 Roadster. Eric is a long time friend of Z Car Garage and we  first dyno’d this roadster in 2012 while a few years later we enjoyed tuning his RB26DETT powered DR30 Skyline. In addition to being a talented fabricator it is clear that Eric has a penchant for white paint, red valve covers…and turbocharged Nissan powerplants!

 

SR20 Roadster: Version 2

 

After restoring his roadster with an S13 SR20DET drivetrain a decade ago, Eric started working on the next evolution with a totally revised chassis and new engine (the previous setup sold for a customer’s roadster).  The new drivetrain consists of an S14 block (JE pistons, K1 rods, P12 oil pump) with a P11 VVL head (Kelford turbo cams, Tomei cam gears, Taarks VVL relocation kit, R35 coil packs) all mounted to the roadster frame using a Spriso Motorsports HD motor mount kit.

 

Providing boost is a GTX3071r turbo with Tial exhaust housing mounted to a Straw-fab’d custom tubular manifold with CNC 1 piece collector. On the cold side is a custom intercooler with Garrett core and custom intake manifold. It’s both pretty and functional considering the roadster’s tiny engine bay:

 

Backing the SR20VE-T is a 6-speed (CD009) transmission normally seen in the Nissan 350z. The SR mounts to the tranny via a Mazworx bell housing with an OS Giken Twin disk. The shining star in Eric’s craftsmanship is the chassis preparation with a heavily modified frame with tubular x-member and bolt-in reinforcements.

 

It would take another blog post to dive into the suspension but if you are curious about the restoration and more please check out Eric’s roadster featured in this Speedhunters article by Naveed Yousufzai HERE.

  

Dyno Tuning

 

The tuning session was conducted with driveability and longevity in mind. Outright peak power numbers were not a priority. Eric’s hometown in Salem, Oregon is where this car would be enjoyed with premium fuel and the occasional 100 octane splash.  Surely more power could be extracted with E85 but Eric is 50 miles from nearest station. Rob comments on the choice of engine management for the SR20VE-T:

“When Eric contacted us about about building the SR20VVL we discussed EMS, and ZCG is a Haltech Pro Tuner. We really like how user-friendly this product is for a tuner. It’s perfect when you need to map out all of the different phases, complete control of ignition/fueling, cam control, idle air…everything to take this car you’ve dreamed of and make it drive like it came from an OEM factory.”

 

Rob dyno tuned the SR equipped with a Haltech 1500 Elite. Initial passes were performed on 92 octane. The plots below show without a boost controller (387hp/287tq) and with a boost controller, making 425hp/331tq to the wheels:

 

Of note is Nissan’s wonderful variable valve timing (VVL) at work with a very flat torque curve and incredible, spine-tingling cam changeover sound. See video below! Eric and Josh drained the fuel tank to add 100 octane for the next passes.  Fueling is supplied by a custom stainless tank (Aeromotive hangler/bladder), custom stainless lines all dash 6, 1300x Injector dynamics and a Radium Fuel rail:

 

On 100 octane the SR20VE-T made 491hp/393tq at the wheels. That is roughly 570hp at the crank. Keep in mind this little Datsun roadster weighs 2250lbs with a hardtop and 14 gallons of fuel!

 

Driving Impressions

 

Following the dyno session we had to take the roadster out for a drive. This video shows multiple dyno passes and test drives, volume up!

 

 

Here are a few driving impressions from the three of us, enjoy!

Eric

“The car went from being an impressive car to completely coming alive and becoming a rocket ship that just keeps pulling. The VVL is like another level of performance. The power comes on very progressive and linear to give the chassis the best chance of getting as much as possible out of it. We made multiple setting to help with driving goals based on the roads and situations we are in.”

 

“The suspension has been a lot of work and has really paid off many times over be able to get this power to the ground and drive the car like it was intended. The rear suspension is so predictable and precise that immediately I had a lot of confidence to be able roll some power out of the corner. Rob had truly made this dream come alive and make this car so very impressive.”

 

Rob

 

“The cam control and air flow from the VVL is staggering, just really super cool. I’m not surprised…from being around the DR30 and seeing all the cars Eric and Michael Spreadbury have built over the years.  This roadster continues to evolve as they continue their craft with each chapter revealing a new level like a boost controller: 5 years ago was 10lbs of boost, 2 years ago 12lbs,  and now 22lbs (this roadster should only be driven on high!) Eric Straw isn’t just one man. He seems to be a mass of people to not only design an engine bay and make it work efficiently but also bolt a non-matching transmission, and then that rear end suspension….obviously one of the biggest things when modifying a 50+yr old Datsun with high power levels is trying to put it down. His engineering accounted for enough tire, brake and balance. The setup Eric built for this roadster I could not believe how we could deliver 500+hp/almost 400ftlbs of torque, and yes we were lighting off the tires but…I still felt like I was in control. We were on ice, but I felt like I was on Speedvision from back in the day of World-rallying Championship..with just a slight motion of the steering wheel I could rotate that car wherever I wanted. 

 

Alvin

 

“As a passenger and long-time roadster owner…it’s not easy for me to ride shotgun in a high-powered car but I still can’t fathom how smooth it felt under intense acceleration. These are super tiny cars and to see both Eric and Rob harness it was a testament to Eric’s chassis engineering. I’ve been in other Datsuns with turbo SRs and they will pitch sideways under full throttle but this one was planted even on our rough downtown roads. Watch the video. It’s epic.”

 

All of us concluded and shared similar sentiments: Eric’s suspension enabled this roadster to manage all that power. When boost hits and the tires break loose it can be seemingly glide controllably with steering input…no hopping or skittering. The rear suspension consists of a hybrid rear axle built by Moser based on a Dana 44 with a Torque arm and 3-Link Watts with Ridetech coil-overs. Up front are custom Ridetech coil-overs and sway bar.  R33 GTR Brembo brakes provide stopping power. The Watanabe wheels are wrapped in 225F/245(!)R tires which are massive for a stock-flared roadster body.

 

We had blast spending the day with Eric and tuning his roadster. We can’t praise him enough for the ingenuity and execution of his build. Eric would like to thank Julie Straw, Michael Spreadbury and Rob Fuller.  More pictures in the gallery below and Enjoy The Boost Eric!