X1 xDrive 28i Sprint Booster installation & review

[Ja Gio]

However it works, it works - and it doesn't just barely work, it very obviously works. It delivers more, earlier. Not only is the green setting noticeably quicker than stock, but the red setting is noticeably quicker than the green. Clearly, there are differing acceleration curves the car is capable of achieving.

I don't profess to know how it's done, but I can attest it is done.

[PrematureApex]

Originally Posted by Ja Gio

However it works, it works - and it doesn't just barely work, it very obviously works. It delivers more, earlier. Not only is the green setting noticeably quicker than stock, but the red setting is noticeably quicker than the green. Clearly, there are differing acceleration curves the car is capable of achieving.

I don't profess to know how it's done, but I can attest it is done.

yes, it does deliver more, earlier in the pedal travel. That's the point. Your old 50% throttle is now 70%, your old 10% is now 30% (or whatever the actual shift is).

But your 100% throttle is still 100%. You flooring your car is no faster than when you floored it before.

It's like the much-lamented "sport" button on an E46 M3. Yes, your throttle response has sharpened, no, your car isn't any faster.

Any speed you're achieving can be achieved all the same in a non-booster equipped car by simply pressing down on the gas harder.

Of course, the benefit is that you like the way it drives. But you haven't gained any performance, you've simply altered the pedal travel need to obtain a giving amount of it.

[Ja Gio]

I hear what you're saying, but I don't think it's quite as simple as a new throttle equals 1.25 times old throttle - but maybe it is... That said, it feels as if it's doing things it couldn't do before, even when flooring it. I had a Merc c400 chasing me home tonight, and I out accelerated it every time.

[Mtpisgah]

Originally Posted by PrematureApex

yes, it does deliver more, earlier in the pedal travel. That's the point. Your old 50% throttle is now 70%, your old 10% is now 30% (or whatever the actual shift is).

But your 100% throttle is still 100%. You flooring your car is no faster than when you floored it before.

It's like the much-lamented "sport" button on an E46 M3. Yes, your throttle response has sharpened, no, your car isn't any faster.

Any speed you're achieving can be achieved all the same in a non-booster equipped car by simply pressing down on the gas harder.

Of course, the benefit is that you like the way it drives. But you haven't gained any performance, you've simply altered the pedal travel need to obtain a giving amount of it.

I was getting ready to ask if this was as good as, better than or in any way similar to a Burger tune. Premature Apex's post has cleared it up very nicely. I hope to order a Burger soon.

[PrematureApex]

Originally Posted by Ja Gio

I hear what you're saying, but I don't think it's quite as simple as a new throttle equals 1.25 times old throttle - but maybe it is... That said, it feels as if it's doing things it couldn't do before, even when flooring it. I had a Merc c400 chasing me home tonight, and I out accelerated it every time.

It is absolutely is that simple. There's a potentiometer in your gas pedal that outputs a voltage signal proportional to throttle position. This just amps up the output signal, how much depends on what setting it's on. IIRC, they clearly state this on their website. Not to be blunt, but you spent hundreds of dollars on something and you didn't even look into what it does?

You installed it right? Did you notice the only thing you were interfacing with was the pedal? Given that fact, obviously there's no mode by which you could have gained power at 100% throttle.

BTW: A C400 is running 13.3 at 107+. And again sorry for being blunt, but if he was trying to outrun you, he could...as in, very, very easily. You car isn't even remotely in the same league as that car. You'd need a tuned N55 X1 (like 380-400 BHP) to keep up.

http://www.caranddriver.com/reviews/...ic-test-review

[PrematureApex]

Originally Posted by Mtpisgah

I was getting ready to so if this was as good as, better than or in any way similar to a Burger tune. Premature Apex's post has cleared it up very nicely. I hope to order a Burger soon.

You can certainly run both, but this simply ups the throttle response. It does nothing to add power like a tune or a piggyback.

[Ja Gio]

Be blunt all you want. Out on the highway in heavy rush hour traffic it's not all about 1/4 mile or top end speed, it's about seeing opportunities or gaps and being able to hit them quickly (and under control). As I said in the beginning more, earlier...more, earlier... I can operate the car within a broader band of high acceleration rates (other than just flooring it).

And, yup, I spent $289 without fully understanding how it works - so what? I think I'll order an Apple Watch today...oh, wait - I can't...that forum character says I shouldn't own one until I understand how it works...

Have a nice day!

[PrematureApex]

You too!

Enjoy all that extra power!

[Ja Gio]

More, earlier...

[PrematureApex]

Originally Posted by Ja Gio

More, earlier...

Yeah, that .02 (or whatever) seconds it takes for me to depress the pedal the extra 1/3" to get to the same effective throttle position is going to make all the difference!

As I stated before, it's an absolutely fine modification. The most important thing being that you like how it feels.
Getting to 70% throttle in .04 vs. .06 seconds is hardly going to be reflected in any kind of tangible performance increase, and as such, touting the modification as any kind of real performance enhancer isn't exactly fair. It's much more of a feel thing than anything else.

[improvius]

So you've never tried it, and you're not sure how it works, but you're certain that its benefits are illusory.

[PrematureApex]

Originally Posted by improvius

So you've never tried it, and you're not sure how it works, but you're certain that its benefits are illusory.

Are you talking to me?

I'm not the one who doesn't know how it works. I explained exactly how it works in post #27. As the owner of an E46 M3, I have a built-in "sprint booster". The other guy, who bought it, admitted to not understanding how it works.

Read this white paper on its function and resulting performance (aka lack of performance increase):

http://www.crosslake.net/~dbipes/spr...intBooster.pdf

Again, it simply shifts the output signal level of the throttle position potentiometer. The last 1/3 or so of your pedal travel is now dead, as 100% is at ~2/3rds. That's ALL it does. There is no increased power, just the ability to achieve whatever power you desire hundredths of a second sooner.

Also, even the quickest google search will reveal several tests all concluding the same thing. No measurable performance increase. If you understand how it works, you'd know why that is the case. Here's one, for example only:

http://www.clublexus.com/forums/perf...0-60-data.html

These devices aren't new guys. What I'm saying isn't any different than what has been explained on literally thousands of car forums for over a decade.

They're fun, the car's throttle is snappier...but you're not gaining any kind of tangible performance benefit. It's a feel thing.

If you do think your car is actually tangibly faster, than as this guy admitted above, you simply don't understand how it works.

[PrematureApex]

From that white paper (I wasn't far off with my .02 seconds estimate!)

OK, so what about those times when I do mash the pedal to the floor? If you examine the TPS curves carefully, you'll see that with or without Sprint Booster, when mashing the accelerator pedal the throttle butterfly valve moves equally as fast for about the first half of its travel.

It's only when the throttle is more than half open does it actually move a bit faster with Sprint Booster. The Sprint Booster speed gain when mashing the throttle is 0.07 second, so 0.07 x ½ travel is 0.035 second. With Sprint Booster, the throttle is open wider for 0.035 second.

How much wider? Only a small fraction wider than the stock case at any given point in its travel. In theory, that would translate into a faster 0-60 acceleration figure of something less than 0.035 second. In actuality, the increase is so small that it is not measurable.

[improvius]

Yeah that's great stuff but we're talking about late model BMWs here. The problem is a lag in the stock accelerator pedal response that, from what I can tell, is unique to our cars. Now go find someone with an 8-speed automatic transmission and N20 engine doing similar "debunking" and I'll be happy to read it. But I've been reading up on the various pertinent BMW forums, and everyone I've seen is very happy with the results.

[PrematureApex]

Originally Posted by improvius

Yeah that's great stuff but we're talking about late model BMWs here. The problem is a lag in the stock accelerator pedal response that, from what I can tell, is unique to our cars. Now go find someone with an 8-speed automatic transmission and N20 engine doing similar "debunking" and I'll be happy to read it. But I've been reading up on the various pertinent BMW forums, and everyone I've seen is very happy with the results.

Edit...see my post below.

And just as a side-note, you do know that the factory "throttle delay" (like standing still and punching it) is programmed into the car's DME, and not the pedal position sensor (you know, the only thing the spring booster affects) right?

So, beyond reducing the throttle delay on the scale mentioned above, how are you suggesting the amplification of the signal from the pedal position sensor eliminates that programmed factory delay?

Any reduction in delay beyond the few hundred thousandths of a second from the booster can be achieved with more aggressive throttle inputs on an otherwise stock car. If you're going to say that's not true, you're going to have to explain the mode by which that is achieved.

[zeevette]

I bought one knowing that in no way would it increase performance. All I want, is to reduce/eliminate the lag in the throttle, especially at tip-in. I do deliveries in my X1, with lots of stop and go traffic, so the lethargic throttle response drives me crazy, and even unsafe. It's all about response. That first 1/2" or so of dead throttle is unacceptable. I'm hoping that it'll also help with another peeve; trying to keep a steady speed while cruising. (not accelerating or braking) without resorting to using cruise control.

[PrematureApex]

Originally Posted by zeevette

I bought one knowing that in no way would it increase performance. All I want, is to reduce/eliminate the lag in the throttle, especially at tip-in. I do deliveries in my X1, with lots of stop and go traffic, so the lethargic throttle response drives me crazy, and even unsafe. It's all about response. That first 1/2" or so of dead throttle is unacceptable.

And I fully agree with all of that.

Rest not directed at you:

People are acting like I chimed in saying it was useless, and that people had no reason to be happy with them.

I said nothing of the sort.

I merely responded to the guy claiming his car was now outrunning much faster cars as a result of his spring booster.

I'm finding it hard to believe that anyone with half a brain would even attempt to defend such a position. And if you aren't defending it, then stop coming at me, because that's the only thing I've been saying.

Not that better throttle response can't/isn't an enjoyable thing for an owner. In fact, I said that multiple times.

[improvius]

This should be pretty easy to test. I can literally mash down the pedal and immediately let up with zero change to the throttle. I assume I'm not the only one here who can do this. So the question is, if I install a SB, will I still see this result?

[PrematureApex]

Originally Posted by improvius

This should be pretty easy to test. I can literally mash down the pedal and immediately let up with zero change to the throttle. I assume I'm not the only one here who can do this. So the question is, if I install a SB, will I still see this result?

That delay will be reduced, but don't see how it could be eliminated (that delay is programmed into the DME). Well...let's explore that a bit further.

From my understanding (IIRC, it applies to the N20 and eight speed like it does on the old 6 speed) is that delay is somewhat of a moving target based on learned driving habits (how heavy/light your throttle inputs are). Hence the procedure to reset the throttle adaptations if/when your response gets really lazy.

So maybe, as the booster is constantly making your throttle inputs seem, say, 30% more aggressive than they would otherwise be...will help keep that delay to a minimum via the (more aggressive) "learned" throttle behavior?

Does that make sense?

[Ja Gio]

From the Car & Driver review you cite..."Forget the 400 nomenclature; this engine is 2996 cc, and it feels every bit down the two cylinders until the boost comes on. Benz’s engineers have done all they can to shorten the wait, but it’s still possible to catch the engine napping in awkward situations, such as when diving into a lane of fast-flowing traffic."

So, it's utterly impossible that I could "out-quick" him in rush hour highway traffic? Of course, driving skill and vision come into play, too.

[PrematureApex]

Originally Posted by Ja Gio

So, it's utterly impossible that I could "out-quick" him in rush hour highway traffic? Of course, driving skill and vision come into play, too.

Will you stop posting already?

No one said you couldn't out drive him in rush hour traffic.

What was said was, the hundredths of a second you gained via your Sprint Booster IS NOT THE REASON you were able to do so.

BTW, in case you forgot...your original post said this:

and I out accelerated it every time.

This implies...you know...OUT ACCELERATING. Like, your car accelerating faster than his. The only way that occurs is if he wasn't trying to out accelerate you.

So what's your point? You out accelerated a car that wasn't trying to out accelerate you? OK...terrific! I out accelerated a 458 today! How the hell is that AT ALL relevant to the topic at hand?

You know very well you said something silly. Stop trying to backtrack out of what you implied: that your Sprint Booster made your car faster.

Originally Posted by Ja Gio

From the Car & Driver review you cite..."Forget the 400 nomenclature; this engine is 2996 cc, and it feels every bit down the two cylinders until the boost comes on. Benz’s engineers have done all they can to shorten the wait, but it’s still possible to catch the engine napping in awkward situations, such as when diving into a lane of fast-flowing traffic."

BTW: Your engine has a bit of turbo lag too, you know. It doesn't feel like an N/A 6 on throttle tip in, just as that 6 doesn't feel like an N/A 8. Reading comprehension!

[Ja Gio]

At the risk of upsetting PA, here's another post. Looking at the white paper, figure 1, at 1/2 pedal position, the TPS is reading about 50% of the accelerator pedal sensor. While figure 3, at 1/2 pedal position (with SB) the TPS is reading at about 140% of the accelerator pedal sensor. So...at 1/2 pedal position, isn't the difference between stock and SB 140/.5 - okay, say, 130/.5 - rather than the 30% you cite? 30% amplification vs. 50% de-amplification.

Whereas stock, TPS didn't meet the accelerator pedal sensor output until full throttle, with SB TPS was well above accelerator pedal sensor from 1/4 pedal position until full throttle, and SB TPS was far above stock over the entire range, until full throttle.

It's a shame the writer didn't overlay these two charts, and use identical scales.

So, no doubt I'll be told I'm reading it wrong, but it looks to me that with Sprint Booster TPS is well above stock, unless I have it floored - and since I don't drive around with "pedal-to-the-metal", I'm getting much greater response using SB than with my stock set-up.

Thanks for sharing that white paper...