Originally Posted by dynamicS
Ok folks, here's my real complaint about the Sprint Booster. It's a decent attempt to fix the throttle lag which it does well. And I can't put any blame on the 1st gear ratio on the 6 speed, that's not the problem.
The problem I am experiencing is that the throttle is not linear when pressing the pedal. I don't have any realistic way to measure it, but it feels like within 1/2"-1" of pedal travel I'm getting power that I used to get at 80%-100% throttle. I just wanted to remove the lag.
I tried resetting the throttle, but it's still taking off too quickly in 1st. Now maybe I didn't do it correctly, so I will try disconnecting the battery over night and reconnect it in the morning. I'll see if this works but I doubt it.
The Sprint Booster is actually improving throttle response by giving disproportionately wide throttle openings for small initial pedal movement. This obviously improves the initial response but can do very little to improve the response over the latter portion of the pedal travel since the throttle butterfly will run out of movement. Exactly like you explain it is giving you the 80% throttle for the first 10% of pedal movement, it can never give better response over the whole pedal travel. This is why I have my doubts that HDDP will pick up any more time on the track; it may feel better out of the slow corners when winding up through the rev range but on the track you tend to be running at higher revs and using a much narrower rev range. I will happily be proved wrong if he reports otherwise though (Good Luck at the Weekend Derek!).
I actually looked into making something similar to the Sprint Booster some time ago but decided against it. I checked the throttle butterfly movement in response to the pedal and there does not appear to be any delay. I think the lack of response is largely a function of the inlet design which is where I am focusing my attention. The other thing that put me off is that the fact that the ECU’s throttle algorithm is still in play and will still modify the throttle response. It would be yet another layer of software between me and the car and decided it is better to fix the inherent problem (not that I have ever had a really big problem with response) rather than try and mask it.
Just for further information here is the service manuals description of the throttle algorithm:
The PCM recognizes how the accelerator pedal is being pressed and switches between a few characteristic curves.
Eighty percent of the engine’s power is achieved for a pedal travel of about 50% for an aggressive driver and about
40% for a conservative driver. There is no further difference felt above a pedal travel of about 90%.
The characteristic curve for a conservative driver is active after a long drive. Then the accelerator pedal must be
pressed down unusually hard to obtain a higher acceleration level.
I don’t mean to dismiss the SB as it appears to be a well engineered device that does what it claims and I know there a many owners who are very happy with them, I just don’t think it completely addresses the problem. Just my .02.