No More Lag — Redefining Torque And Response With Nissan’s RB26DETT

Located in the beautiful southern Puget Sound area of Washington state, there’s an inconspicuous tuning shop that goes by the name of U.P. Garage. Founded thirty-six years ago, the shop began by wrenching on Datsun Z-cars and racing them in SCCA ITS. Over the years, they shifted their focus away from anything Datsun, to swapped S-chassis cars, to focusing almost entirely on the Skyline GT-R and its legendary RB26DETT powerplant.

Doug Smith and Eric Rittscher, the two men responsible for this shop, are arguably some of the most fastidious, ethical, and straightforward mechanics I’ve ever met, and their obsession with this platform has taken them down an unusual path. While many Skyline owners and tuners focus on attaining higher levels of peak power, U.P. Garage prioritizes response, tractability, reliability, and cost-effectiveness. Once their customers experience a wider powerband, more power under the curve, and a generally more tractable motor, they rarely look back.

The Nissan Skyline R32 GT-R, now legal in the U.S., is the shop’s most popular platform.

 

“We want our users to get the most smiles per dollar. It might not be the best approach to solidifying my retirement, but we believe in giving our customers something that is tangible,” says Smith. By optimizing the stock components, keeping the car reliable, affordable, and usable, they’re thinking of their customers and the environment which they’re affecting.

Their early GT-R builds used large and laggy twin-turbochargers, which left them wanting for something. “The power was wild, but I found you’d spend too much time waiting for the power, which usually arrived shortly after 5,000 rpm,” Smith says. Massive single turbochargers were the next big trend in tuning. Though it’s possible to make 700 horsepower with an RB26 and a watermelon-sized snail, they found the resulting turbo lag, reduced area under the curve, and worsened transient response detracts from the overall driving experience.

Though the prominent single turbo makes a bold statement, it doesn’t make the kind of accessible power a well-sized set of twins will.

 

“I found I was too busy to enjoy those high-horsepower builds; too busy watching the revs and dealing with wheelspin. The cost of consumables went up, and so did the repair bills. Our customers were getting frustrated by the higher running costs and a lazy powerband,” recalls Smith.

This situation dredged out an almost masochistic side of the tuned car owner: the need to convince themselves that the cost is justified. Oftentimes, that’s done through desperately chasing more power and unwittingly worsening the situation.

It’s no wonder then that so many owners wound up selling their cars after a costly year of chasing the dragon. To combat these discouraging mistakes, U.P. Garage began pursuing sustainability. They shifted their tuning philosophy towards keeping the costs minimal, prioritizing response before peak power, and ensuring the power made is manageable in all situations.

Nearly every customer who’s been exposed to this tuning philosophy has jumped the high-horsepower ship.

 

Minor Tweaks Provide A Major Return

From minor adjustments to boost, timing, and fuel to variable-cam systems and upgraded turbochargers, U.P. Garage has devised some of the more sensible, cost-effective, usable tuning theories for the RB26DETT. Due to the significant bumps in performance between each of their tuning steps, they recommend the user move sequentially through all three steps to appreciate the improvements each makes. The first is fairly basic, but—due to their tuning approach, it realizes the potential of the factory components.

The modifications in this stage are a simple cat-back exhaust, cleaned injectors, boost controller, and Link ECU. Though the Link ECU might seem excessive for some, it more-than-future proofs the build. A manageable torque curve is a must — and the options offered by the Link ECU make that possible. “In the end, performance is realized by tuning,” asserts a resolute Smith. “There are no hard and fast rules to tuning, since each engine, tuner, and selection of modifications change the situation.”

Here, you can see the initial power levels compared to the basic Stage 1 modifications.

 

Most engines will see a gain of 75-90 horsepower here, though a very healthy example might yield 110 horsepower and an additional 120 lb-ft of torque. In other words, as much as 380 horsepower at a 7,500-rpm redline and 300 lb-ft of torque at 4,000 rpm can be had.These modifications will take a stock R32 GT-R up to the standards of modern performance vehicles, but for those who desire more, Stage 2 addresses one major shortcoming of the RB26.

More Torque With More Efficiency

Historically, the high-revving RB26 has been criticized for a lack of low-end torque; the motor in stockish trim only starts to come on-song past 4,000 revs. U.P. Garage designs their Stage 2 package around the addition of HKS VCam, a variable cam system which modernizes the RB’s powerband. This offers the nearly instantaneous torque and response expected by modern drivers.

The installation of a VCam system in progress.

 

This variable cam system allows for 30° of movement in the intake cam. With the right recalibration, the engine now becomes more efficient at the lower end of the rev range without losses in peak power. A more efficient engine allows for higher cylinder pressures without detonation, so more boost is now possible. But, with higher adiabatic efficiency and more oxygen (boost) comes a greater demand for fuel. They sate the straight-six’s thirst with SARD 850cc injectors.

That telltale silver spool valve on the side of the cam over signals VCam in place.

 

At 20 pounds of boost, the Stage 2 engine produces 300 lb-ft of torque at a mere 3,200 rpm. This represents an additional 80 lb-ft over the same point in the rev range of the breathed-on Stage 1 engine. It continues to ramp up quite quickly, peaking at 350 lb-ft of torque at 4,300 rpm. Clearly, the ramp rate is high, but the linear curve makes this power manageable. Very quickly, one gets comfortable exploiting all of this surprisingly controllable wave of life-affirming thrust.

Here, you can see Stage 2’s big effect on low-RPM torque.

 

The variable intake cam system allows for the fitment of a larger exhaust cam—usually an HKS 272°—to further widen the powerband without a loping idle or any low-end losses. Funny how so much power is available without even considering what some consider to be one of the first steps in modifying this motor: upgrading the turbochargers and internal block components.

Raise the Roof

In order to grow beyond what’s offered by the second stage, replacing stock turbochargers is necessary. In their place go a set of Spectrum Motorsports‘ DR500 turbochargers. These drop-in items are appealing not only for their flow numbers, but also for their packaging. They use the same frame as the standard T25s, and as such, work with the factory oil and water lines as well as the stock exhaust. For such a simple and cost-effective addition, they raise the ceiling significantly. As Smith sees it, they’re a godsend. “There aren’t any turbochargers which maintain boost as consistently across the entire RPM range as these. They’re truly tailored for the RB26,” he raves.

A set of DR500s bolted snugly to the factory manifolds.

 

Despite sporting larger compressor and turbine wheels than the standard turbochargers, the DR500s don’t compromise the low-end response. To complement the greater top-end, they further modify the variable cam system. The second phase of VCam tuning requires some clearancing of the pistons, but that’s all that’s needed to allow the intake cam a full 50° of camshaft movement to broaden the powerband even more. Now, the engine pulls frighteningly hard from 3,000 rpm and doesn’t relent until redline.

Stage 3 not only produces decent peak numbers over the stock RB26 numbers, but has power in all the right places for something that actually gets driven.

 

Lag is nearly nonexistent, and once it crosses the boost threshold, it simply pulls the horizon towards you. The bonus is there aren’t any flat spots in the curve, which is broader than anything most 2.6-liter turbocharged engines should be able to produce. In fact, its low-end delivery is like that of a normally-aspirated engine with greater displacement, but the way this sonorous straight-six screams all the way to its stratospheric redline and keeps pulling is something a little alien. Once you’ve had a taste of this surreal concoction, you can’t forget it.

So, while it’s very easy for someone to get lost in the sea of peak numbers and big dyno graphs, at the end of the day, we need to remember that an engine’s main purpose is to move a vehicle as efficiently (efficient power delivery and acceleration, not Prius “efficient”) as possible, not just make pretty lines and numbers on a computer screen. Once Smith and Rittscher realized that, their whole paradigm shifted and the results speak for themselves.

A ‘clincher’ comparison between a similar-sized single turbo at the DR500 twins. While the big single gives you a larger peak number, look at the difference in power and torque from 1,200 rpm all the way up to about 6,800 rpm.

 

 

By TOMMY PARRY AUGUST 11, 2020

Engine Labs