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Posts: 1,057
Join Date: Apr 2016
Car: 2008 E93
Default 08-22-2019, 03:35 PM

Originally Posted by codesx
I'm in the process of further dialing in my tune, with Payam. I'm freaking loving it.

I've read posts talking vaguely about launching/accelerating in such a manner as to not snap crank-shafts or bent rods.

I'd like to fall within the maxed out, but not snapping things category.

Please share your knowledge with me!

-I'm an Auto. Convertible, fat and heavy. (<- car)
-Map 6, 19PSI Flat (from 1500 RPM)
-Meth injection (ensuring clean timing all the way through)
-My rear tires are 275 wide, Indy 500, slick-like treads, grabbing great in the dry hot (and terrible when wet)
-I can spin my rears (easy enough), but can switch into second by 4500 RPM to minimize momentum loss
-Second gear holds (traction off) with just a mild singing if there is any mild deviation in the road
-I'm sure I'm under 4 seconds to 60mph, calculations to come (logs show 3.5 seconds to 60mph from a 40' roll start, hammering at 10mph, zero boost at 'go')

Launching: Given the specifications; Out side of the A/T, is this enough power to damage the drive shaft (or other) if I brake-boost for 1 second? Should I strictly roll launch? Should I reduce boost in 1st to 15 PSI rather than 19? Should I graduate the currently Flat 19 PSI quickly rather than full 19 at 1500 RPM?
For yourself, and anyone reading this, this is why logs are needed. 19 psi flat from 1500 rpm. Your car, as most others, will not hit 19psi at 1500 rpm. Not without anti lag or something anyway. Yes, I would and I do use, boost by gear limit. Everyone will use a different limit. . Many people have different set ups, turbos, different fuel, different tunes, etc so some may use 10 psi max, others 15psi, etc. Meaning not everyone is making the same torque or whp at 19 psi. Hope this helps.
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