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Vi-PEC V88s ensure NZV8 TLXs achieve parity

New NZV8 TLXs are achieving parity thanks to engine management by Vi-PEC
Vi-PEC V88s ensure NZV8 TLXs achieve parity

Even playing field – Holden, Ford and Toyota battle on the track

Performance parity – they’re two words that come up often in motorsport circles and which, together, cause more angst than perhaps any others.

With the new NZV8 TLX cars getting into their stride around the country and three manufacturers involved with the series, parity is more important now than it’s ever been in a MSNZ-sanctioned series.

Based on a control chassis manufactured by Hamilton’s MRX Engineering, this year’s TLX field includes Toyota Camry, Ford Falcon FG and Holden Commodore VEII all running V8 engines from their respective manufacturers  with different performance ratings. Andre Simon, owner and director of Wellington-based Speedtech Motorsport Ltd (STM), is charged with the task of ensuring an even playing field by creating engine parity between the three manufacturers.

“Many people doubted we could get parity between three completely different engines but with modern technology and with electronic throttle bodies, we can match power right through the rev range,” he says.

This is done by installing a custom-developed electronic control unit (ECU) into each car, which controls fuel delivery, ignition timing, cam control (if required) and throttle to allow equal tuning and mapping right across the rev range."

“We can map the throttle opening on the engine, irrespective of pedal position. Basically, the driver can have his foot pinned to the floor, trying to push it through the firewall, and we can do whatever we want with the throttle,” Andre explains.

“Back in the old days, when they were trying to get performance parity, they’ve done it with air restrictors, ballast and rev limiters, but none of that worked because you had two engines with vastly different torque curves. Strangling engines with a restrictor doesn’t solve the torque disparity”.

The mechanics of it

STM conducted a series of pre-season tests on a 5-litre Lexus-sourced TRD quad cam fitted to a Toyota Camry and a 6.2-litre Chevrolet LS3 push-rod in a Holden Commodore.

“We tuned the LS3 to 560 hp (418 kW) but when we got the Camry engine on the dyno, its peak power was 530 hp (395 kW); if we were trying to match peak power, there’s only 30 hp (22 kW) in it. It’s not massive.

“However, what you lose track of if you’re concentrating on peak numbers is they peak at about 6,400 rpm. If you come back to 5,000 rpm, there’s a discrepancy of almost 100 hp (75 kW) between the two engines.”

To negate the problem – and to bring the engines back to something approaching parity – Andre mapped the throttle openings relative to the RPM, so that the output curves of each engine are not only comparable, they’re almost identical.

“The NZV8 Category asked for 2% variation in engine performance curves and we actually got closer to 1%.

“We can do all of this and, basically, the driver doesn’t even know it’s happening – it’s so smooth and seamless at the engine that he doesn’t feel it. We basically end up with two engines that are identical in power delivery and torque curve.

“The Coyote (5-litre quad cam Ford engine) came out with almost exactly the same peak power as the Camry engine – I think there was about 4 hp (3 kW) in it. With the advantages of variable cam control and the fact it’s not such a wild motor as the Camry, it made quite a lot of mid-range torque, which we again detuned using the throttle body.”

With such accurate and effective engine parity being produced in the workshop and confirmed through dyno testing, Andre says a neutral chassis could be fitted with any of the three engines and performance between them would be so close that a driver wouldn’t be able to discern the difference. However, he does point out that each of the engines will have different weights and different centres of gravity, which may have an influence on chassis dynamics and affect the handling of the car.

To back up the testing done in the workshop, the STM team generated data at the racetrack to further reinforce their success in ensuring a fair and even playing field.

“The dyno is great for proving power parity, but it’s still just numbers on a piece of paper. Obviously, we’re interested in what the cars are doing on the track.

“What we’ve been doing at each of the round so far is overlaying the data logging from all of the cars. The easiest place to look is a section of straight and then we can overlay the GPS speed traces just to confirm we have power parity in that respect.”

Is there a way to cheat the system?

“No,” says Andre. “The mapping in the ECU is locked, so that teams don’t have access to it. We also have ways of confirming through the data logging that no cheating’s going on and that everyone’s playing by the rules.”

Could TLX and SuperTourers be tuned for engine parity?

One of the hottest topics in NZ motorsport is the development of the two separate V8 categories. While parity between the TLX cars in the NZV8s is one thing, Andre is also confident he could achieve similar results between the current TLXs and the V8 SuperTourers, despite the SuperTourers’ larger 7-litre LS7 GM-sourced engines.

“Absolutely – the LS7, to all intents and purposes, is very closely based on the LS3; they’re all the same family of engines. They basically run the same electronic throttle body arrangement, so we’d do it in exactly the same way. We could definitely get better than 2% power parity.

“If we look at the test that Tulloch Motorsport did with Jason Bargwanna at Ruapuna before we’d done any parity tuning, Jason put in a 1:24.10 lap, which would have put him near the front row of the SuperTourer field.

“At that point, the LS3 was still a little underpowered compared to the LS7, but it would suggest to me that they’re probably very, very close.”

TLX parity dyno graph for Toyota Camry

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