Enthusiasts’ Thoughts – Fall 2019: Adventures In Throttle Response


By Ron Acher

My Journey From American Iron to The Ultimate Driving Machine

When I bought my first BMW 11 years ago this month, the seller, Mike Perrino (owner of the late lamented Beverly Hills Auto Spa in Basking Ridge, the best auto detailer in NJ) told me that the throttle response on BMWs is different from what I might be used to from driving large cubic liter American V-8s.

It was, and is, a 1996 E36 328 automatic convertible, with a removable hardtop (which was the main reason I bought it, thus being able to drive it year round in New Jersey, though regrettably not on any NJ BMW CCA track).

He was right. It is a very fast car, capable of a speed-limited 124 MPH. But boy, do you have to lean into the pedal to get it to pick up! And it does, if you do.

But you have to know that I was coming off more than 30 years of driving two specific American cars, a 1970 Mopar 440 high performance unmarked detective car, and a 1977 440 high performance state police highway pursuit vehicle. Both of these cars were specifically designed for “spirited” driving in excess of 80 MPH (shifts out of second at 98 MPH), but they were also great for everyday driving between 30 and 70 MPH because they had gobs of torque at the low end. (For a long time in America after about 1971, you could only get real performance in a family sedan by buying a police car.)

I drove these cars in a very relaxed way, even at high speeds, by having the seat as far back as possible, being very light on the throttle, but expecting and getting instant response from the slightest “curling of my toes” on the throttle pedal, let alone actually depressing the pedal to any noticeable degree.

My 328 was different, and I’ve only recently come to realize why.

Firstly, all BMWs that came to America up through the 90s were routinely detuned at the factory (because BMW AG maybe thought that Americans didn’t know how to drive — after all, they drink coffee while driving!).

Secondly, European sports cars are designed for people who like to continuously take corners and shift gears, so throttle travel is designed to be much longer in general, thus providing more precise throttle control, especially when cornering hard under power.

And thirdly, I was forgetting that my beloved American big iron automatics had never heard of overdrive. Top gear was 1:1 – which is only 3rd gear in my 328. My 328 goes into 4th gear (overdrive) at 30 MPH around town. Even though the 328, at 192 HP, is probably quicker through the gears and at the top end than either of my beloved old Mopars (at 250 corrected BHP, down from the factory-claimed 350 of the 1970 car), I shouldn’t really have ever expected comparable throttle response under similar driving conditions.

So I set out to fix all this.

The first thing I did was to flash the DME with Jim Conforti’s Shark Injector, which made an immediate difference to power, torque, and throttle responsiveness.

The second thing I did was to learn to drop a gear when desiring to pass fast above 80 MPH – which made an astonishing difference at the top end. The car leaps like a shot out of a catapult if you drop a gear and floor it between 80 and 90 – precisely because power and torque are designed to be all the way up there, rather than having big torque at the low end.

But neither of these things really affected pickup in Drive between 40 and 50 MPH, where there is to be found the notorious BMW 6-cylinder torque “flat spot.” (Intake VANOS in 1996 helped, but it wasn’t until the 1999 TU and later E46 engine when exhaust VANOS was added, that this was relieved.) But only recently, and purely by accident, I discovered the final and most effective performance improvement technique of all for this car. And it’s totally free.

I just happened to be giving a ride to some friends with the top down, one of them tall enough that I had to move the seat considerably forward to give him sufficient room in the back seat behind me. It was then I noticed that, while my leg was a little cramped, the car was suddenly performing MUCH better, even with the weight of 3 extra people.

And so it hit me! If your leg is more tightly angled when you drive, your foot movements on the throttle pedal are sharper and more aggressive, and even a light touch produces more pedal travel. And presto! Much snappier performance!

Dear Mike, I love you. But when you told me about the pedal response, you forgot to tell me how to solve it.

Move the seat forward!

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