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which is only in place to honor a German car manufacturers “gentleman’s agreement” between Audi, VW, Mercedes and BMW (originally made to forestall autobahn limits mooted by the Green Party).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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18 Comments on “Dinan Cold Air Intake and ECU Software Review...”

  • avatar
    Virtual Insanity

    And the Dinan snare snags another one. Always stood back from Dinan parts, to much money for to much nothing. I had a carbonio CF CAI on my 3, it cost me 200 shipped, install took fifteen minutes in my drive way. Looked the exact same as the Dinan CAI, just a different sticker.

    • 0 avatar

      Funny how the losers commenting on this site complain that Dinan stuff is “to expensive(sic)”. Those of you who know how much time Steve and his engineers put into a cold air intake, for example, so that it doesn’t allow your engine to gulp down rain water during a storm and blow itself to smithereens (good luck getting BMW to pay for THAT warranty claim!)

      If the only thing you can afford is cheap crap parts from China, you need to get back on the porch, boys. Cuz you can’t run with the big dogs. Go buy a Honda and soup it up.

      I’ve owned several Dinan BMWs and they ROCK. No other sedan can touch a Dinan M5, in my experience. Fortunately I can afford to buy the best, because I work my ass off to do so.


  • avatar

    Nice info. I generally drool at the Dinan letters on the back of a bimmer, then immediately wonder what options the person purchased in order to get enough Dinan points to earn the badge. You can no doubt spec out a “Dinanized” car and earn the badge without much increase in performance over stock. Or, you could spend the big bucks and spec the car out with all the chassis tuning they offer (it’s all Koni, Brembo, etc. anyway) and have a real screamer. I’m glad Dinan does what he does, but for the money I’d be hard-pressed to go that route. Maybe TC Kline. Still pricey, though.

  • avatar

    how does it sound?
    the only reason i’d put a CAI on anything is for the noises.
    i don’t really buy the whole hot air in the engine bay thing. on a cold day when you can see exhaust, look how big of a cloud you make and how fast; that’s all air that went through your engine. engines suck so much air that intake air doesn’t spend enough time in the engine bay to heat up significantly. when you’re at the absolute limits in a race engine, maybe a degree or two is the difference between detonation and not. for street cars, i don’t see the point. but if it sounds good, it’s easily worth the $200 for entertainment.

  • avatar

    Dinan is a huge scam. Overpriced garbage for little to no gains – pretty much everyone in the BMW community knows this.

    Steve Dinan is also a huge jerk.

    • 0 avatar

      BTW, I’ve met Steve several times. He is one of the nicest, most humble people I’ve ever met. He worked himself from nothing to be THE leader in BMW performance.

      Once I had a problem with one of his sales people — the guy was just not super friendly — and I complained. Steve’s wife talked to me for about 45 minutes to assure me that the problem would be fixed (and it was, the guy was fired not long after), and Steve wrote me a personal apology. TRUE STORY.

      People on this forum are the jerks — not Steve Dinan or his company.

    • 0 avatar
      Tom Martin

      Perfectname!! You are a cretin. Dinan equipment is the real deal. Obviously you don’t have any real experience with Dinan. I have a 2012 BMW 335i Xdrive Dinan 3. It has Dinan exhaust system, Dinan computer download, Dinan suspension. Dinan claims 361 HP and 401 foot pounds of torque. It’s faster than hell and handles beautifully!! In sixth gear at 60 mph it accelerates faster than my 2012 Corvette Grand Sport till the GS rpms get up some.
      Stupid people shouldn’t announce their stupidity to the world like you did!!

  • avatar
    Virtual Insanity


    I disagree. Many people in the Mazdaspeed3 Community, and most turbocharged cars, can show very noticable gains at the wheels from nothing more than a simple Open Element filter. Using the Speed3, for example, people have dynoed upwards of a ten wheel horsepower gain from just cutting up the stock box, and almost 20whp and good torque gains from an intake.


    I agree 100%. I read his white paper about underdrive pullies, and had to laugh. The only reason he doesn’t like UD pullies is because UR wont sell him theirs, and you can’t charge 200% mark up for them.

  • avatar

    Dinan’s products are of high quality, IMHO. I like the fact that they are engineered to work with the car. Many aftermarket companies seem to lack the commitment to actually test their products and ensure they don’t degrade the reliability of the vehicle. However, they are way overpriced for what you get. I did install the Stage II suspension on my car because it offered the spring/stabar tuning I was looking for, and I love it, but I would never blow this kind of cash on a CAI or the $1200 their high flow exhaust goes for. Also, there are aftermarket companies who do engineer and build their products very well, like Active Autowerke, and sell them for much, much less.

  • avatar
    Virtual Insanity

    Active Autowerke, Rogue Engineering, ESS, etc. There are a tonf of companies that make parts just for BMW and blow Dinan prices out of the water. UUC is ok, but they tend to be on the pricey side.

  • avatar

    Someone please point a few things to me.

    1. Where is the dyno results of the M Roadster BEFORE the CAI and ECU were installed?

    2. Was there any mention of Dinan’s warranty? Dinan products do not void the BMW factory warranty (unlike most aftermarket products) and they backup their products for two full years after the product is installed by an authorized Dinan dealer. Go to the Dinan website and read the details.

    Yes, Dinan products are generally more expensive than their competitors, but Dinan puts more R & D into their products than most other BMW/MINI aftermarket parts manufacturers and they fully support their products.

    I interviewed Steve Dinan and spent several hours with the man touring his Morgan Hill facility. Most of the negativism towards Dinan is because few people understand the company’s philosophy and the amount of work to produce a product that improves the performance of a car with ZERO compromises. How many aftermarket performance parts have you installed that have some ill effects along with their claimed benefits?

  • avatar
    Virtual Insanity


    No aftermarket product will void a warrenty. Ever. The only way an aftermarket part will cause your warrenty to be void is if it is directly associated with the failure of the part. There’s a federal law for it. And no, Dinan doesn’t match that part.

  • avatar

    I really don’t see the point of writing this article without a baseline dyno run.

    The 17.5% dyno correction factor you used is purely arbitrary, so saying that your modded car makes 244 crank HP is misleading, at best.

    Would you review the results of a botox injection without a “before” photo…and tell your readers that “I feel a bit younger?”

  • avatar

    Virtual Insanity :
    If they’re getting horsepower gains just from cutting up the box (I’ve seen this in the VW world), it’s because of increased air flow, not lower air temperature.

  • avatar

    Couple of points:

    I am assuming Dinan’s CAI kit is actually routed in the engine compartment to not be a hot-air intake, but I’ve seen plenty of CAIs that don’t seal the conical filter from the hot engine bay. Just wanted to make sure Dinan isn’t making a carbon fiber version of the CAIs you can get at WalMart for $25. :)

    As mentioned before, a baseline dyno of the car is really necessary to show before and after improvements. This could be a good thing, maybe the (before) test vehicle is not performing to its SAE-blessed ratings, and the increase in power (after) is more impressive. But from what I’ve seen in the M5 crowd, the baseline would show the same thing: 10-20 more horses, no governor, higher rpm, etc.

  • avatar

    10-20 HP is optimistic for the E39 M5 CAI. Dinan makes a quality sealed piece, but 5-7 HP is more like it, ie not a significant gain.

  • avatar

    Dinan’s CAI is routed into the bumper/front apron area. On some BMW models (E36 M3), it is fed by the brake duct cooling.

    I had the CAI and software on my previous M3, the primary benefit was sound. At wide open throttle the car just ROARED.

    On my current BMW 540, I purchased their software during their 1/2 off sale 2 summers ago, so I paid $150. The difference in the car was dramatic, not so much at full throttle, but more so at partial throttle, where most of us spend most of our time driving. Dinan advertises a peak torque gain of 25 tq @ 2500 rpm. I don’t know if that is the number or not, but it sure felt different after the software. The downside is the requirement for premium fuel.

  • avatar

    To all:

    I like the fact that i can rest at night nowing that my investment is covered by dinan’s promise. yeah its more money but you trully get what you pay for, we all know that. Turns out you all are right. Dinan’s performance increase has a high sticker, considering the small improvements. but that only goes for BMW naturally aspirated engines. BMW turbocharged engines are a different Dinan world.

    I have 2008 335i coupe, stage 2 turbo charge upgrade, and free flow exhaust, about $2,100 for the software and another $2.700 for the exhaust. there is a tremendous difference with the software, not so much the exhaust, my car went from a stock 300 hp/ 300 ft. tork to 385 horses and 414 ft. tork. a substantial difference you can definatelly feel, I ridicule Ford mustang GT’s and recently a late model Trans Am (pontiac) that made you feel intimidated just on sound alone.

    CAI (Cold Air Intake): someone i know had the CAI installed the test revealed 14 hp increase with the stage 2 software and free flow exhaust (just like mine). what’s more amazing is that the CAI pushed an extra 36 horses @ 6300 rpms. that’s a total of 421 maximum horsepower output. The Infamous 2010 M3 pushes a max of 419 horses with a sticker price exceeding $30k more than my 335i. Is it worth it yet?

    I CANNOT WAIT TO GET MY CAI. if you want the best out there with piece of mind; it has a price sticker you must be willing to pay. Or if you want to spend money on different parts from different manufacturers, well that kind a’ sounds like an automobile version of a Frankinstein and a mutt.

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