Category: Chipping

By on December 20, 2007

dyno2.jpgSay the name Hartge or Alpina to a BMW fan and you’ll get instant nods of understanding and respect. While Dinan doesn’t get the pistonhead props afforded these German uber-tuners, they’re rightfully considered America’s foremost BMW tuner. Steve Dinan’s mob has been modifying BMW cars since 1979. His Morgan Hill California-based company offers upgrades for Bimmer engines, suspensions, brakes and wheels. Like the Germans, Dinan also sells “Signature Vehicles” and creates special Factory Works programs. We concern ourselves here with an ECU upgrade and a cold air intake. 

Until the introduction of the sublime twin-turbo 335i, BMW prided itself on the fact that it relied on naturally aspirated engines to reach vaunted performance levels. Increasing performance of turbo-charged engines by modifying their Electronic Control Units (ECU) can lead to fairly dramatic performance upgrades on the order of fifty plus horsepower and foot pounds of torque. I tested Dinan’s ECU upgrade on a naturally aspirated inline six to see if similar gains could be found.

As stated in my previous review of the APR ECU upgrade for an Audi A4, ECU tuning is a difficult task. A tuner must examine thousands of lines of code to find areas where changes in parameters can add to performance. They also have to balance potential gains against potential engine damage.

BMW rates the 3.2-liter inline six in my '00 M Roadster at 240 horsepower. In its original state, the engine is relatively detuned; the same engine with variable timing and separate throttle bodies (as sold in Europe) produces over 300hp. This should mean lots of head room for Dinan to wring-out some extra power– without fear of dreaded engine “issues.”

The Dinan software is sold in various stages, partially tied to other Dinan products. I tested the Stage II software with the Dinan Cold Air Intake (CAI). In addition to increasing horsepower and torque, the software has two additional benefits. First, it removes the 155mph speed limiter, which is only in place to honor a German car manufacturers “gentleman’s agreement” between Audi, VW, Mercedes and BMW (originally made to forestall autobahn limits mooted by the Green Party). Second, the rather low redline limiter is lifted from 7000 to 7400 rpm.

Dealer installation is required; the software is transferred via an installer’s computer directly to the Bimmer via the BMW’s data port. (The leading competitor is the Conforti Shark Injector, which is user-installed via the OBD-II port, saving a trip to the dealer.)

The Cold Air Intake system can be fitted by both friends and foe (dealer). The CAI replaces the [allegedly] more restrictive factory air box with a long carbon fiber tube and a large cone-shaped air filter. In theory, moving the air intake away from engine heat improves performance. In practice, cold air simply allows the engine to produce more power. Unfortunately, many systems that advertise gains do so without merit, and car websites are rife with claims that CAI systems actually decrease horsepower. 

Dinan’s website claims that their CAI system adds 12 hp and 11 lb-ft of torque. They also claim a gain of 10 hp and 10 ft.-lbs. of torque for their software. However, they caveat the CAI claims by stating that “a Stage 2 version of Dinan's Engine Software is available for optimum performance from the High Flow Cold Air Intake System as well.”  Take it from a lawyer: it isn’t clear if Dinan’s claiming a combined gain or a cumulative gain for the two systems.

Measuring engine improvements requires both objective dyno-based tests and a subjective seat of the pants test. I went to a local BMW tuner, Road 'n Race. to check my installation's gains on their Mustang dynometer. Dynos measure wheel horsepower, not the crank horsepower manufacturers advertise. Therefore a correction factor must be applied. Also, the two most common dynos produce different results and are not directly comparable. To measure current performance of the M Roadster, I used a 17.5 percent correction factor. 

On my best run, the car produced 208 peak hp, or 244 hp. That's four more than factory. Torque was up five foot-lbs over stock. While a large fan was used to simulate air movement, some power is lost compared to real road driving.

On the open road, the car felt slightly faster than stock, with better pedal feel during acceleration. These improvements were, at best, slight. The redline limiter was definitely raised, but since peak power is produced earlier, the benefit was limited. 

The Dinan CAI sells for $649.00 and the Stage II software is $299.00. Add in a dealer charge for installation and you’re looking at over a grand for a very small gain. Therefore, except for bragging rights the Dinan name entails, I would not recommend this upgrade, though the CAI does look good in the Bimmer’s engine bay.

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By on November 16, 2007

apr-chipset.jpgEnthusiasts have been tuning vehicles since the first car coughed into life. Back in the day, performance-minded pistonheads could enhance their car’s fun factor by putting stiffer springs on the distributor advance, or changing the top dead center degrees. In fact, there were hundreds of relatively simple ways a clever wrench could wring more performance out of his [formerly] humble four-wheeled steed. Today’s cars are too heavily computer-dependent for such simple tricks. Enthusiast-oriented entrepreneurs have created a whole new market of electronic modifications to fill in the void.

The ECU (electronic control unit) regulates various elements of the modern car’s activities: fuel delivery, spark plug detonation, etc. Manufacturers program the ECU’s software to balance the car’s performance with fuel economy, emissions, safety and reliability. In almost all cases, carmakers leave a large margin of performance on the table. If nothing else (cough warranty costs cough), the extra oomph would sacrifice some of the car’s commercial appeal.

Third party tuners download and disassemble the ECU’s source code (i.e. hack), and then recode portions of the software to unleash unused performance. Some chip tuners can dramatically increase horsepower and torque. In other cases, where power increases are limited, chip tuners improve the overall power delivery, remove top speed limiters and raise the car’s redline.


Until recently, ECU tuning required a hardwire modification. If the ECU software was socketed, a user could remove the factory programmed ROM and replace same with a new chip from the tuner. If the ECU software was soldered, then the pistonhead usually sent the ECU to the tuner for modification. Thanks to OBD-II access (now required by federal law) and the use of flashable ROMs (which allow for reprogramming by the manufacturer), tuners now can simply reflash the ECU without hardware modification.

APR offers several ECU options for Audi, Porsche and VW enthusiasts seeking extra oomph for their German-made, well-designed whips. In addition to modifications that remap the power delivery, customers can pay for the ability to switch between stock and “enhanced” modes, a valet mode (to reduce power below stock), and a 100 octane mode to accommodate race track gas. I tested APR’s competitively-priced 93 octane program upgrade ($599), with one mode ($100), on a 2006 Audi A4 2.0T.

Our local APR dealer performed the installation in about 1.5 hours. Once the software was installed, he showed me how to switch between no-go and go modes using the cruise control set button. Liberating the hidden horses was a bit tricky, and not always successful. In one case, I couldn’t start the car for a few minutes after activation.

APR promises a 41hp increase and a whopping eighty-five pound-feet more torque. The change in the car’s performance was dramatic. In real world testing, I dropped over a second from my normal zero to 60mph sprint time. Equally beguiling: acceleration was notably stronger throughout the entire power band.

APR improves performance in the Audi [in part] by increasing the turbo’s boost pressure. From the factory, turbo pressure at maximum acceleration is about twelve psi. APR ups this pressure by five psi. APR insists that the Audi engine can easily handle twenty psi. As long as you use 93 octane fuel (hence the product’s name), APR claims their upgrade remains safely within this margin. Long-term effects are unknown, but I noticed no engine issues over a ten-thousand-mile test.

This brings us to the thorny side of these mods: their effect on your warranty. Some owners worry that an APR or similar upgrade will void their factory coverage. While some dealers are quick to use modifications to deny a warranty claim, the Magnuson Moss federal warranty act specifically prohibits denial of coverage unless the modification actually causes the claim. But do you really want a protracted court battle with your car dealer?

The chip tuners offer no guaranties– which is worrying. The ability to turn off APR’s modifications and “hide” them from the factory technicians (“valet mode”) offers some peace of mind. HOWEVER, should the factory update your car’s software, the APR software will be overwritten. And this is occasionally done as a matter of “routine” during scheduled maintenance.

Now, some more good news…

The APR upgrade didn’t reduce the Audi’s fuel economy; in fact, I measured a slight increase in fuel efficiency. The ECU upgrade also works well with other engine modifications, such as cold air intakes, headers and larger diverter valves.

Overall, the APR ECU modification is an impressive effort. It greatly improves engine performance with only a slight, ongoing financial penalty (due to its need for premium dino-juice). Outside forced induction, no other modification gives as much bang for the buck as an ECU upgrade. For those looking to increase performance on their Porsche, Audi or VW, the APR program should be on the short list.

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