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4.0L Conversions for 981 and 991 3.8L Models

ralphmusic

ralphmusic

PCGB Member
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DeMan in the USA have released more information on their 4.0L engine upgrade in this Rennlist thread.

http://rennlist.com/forum...-deman-motorsport.html

DeMan Motorsport 4.0L Engine Upgrade Package consists of 4.0L stroker kit, 82mm Throttle body, Fabspeed Headers and appropriate DeMan Motorsport custom tune using Pro tuning software by Cobb on our Dyna Pack dyno. With this specific setup, gains of 45+ horsepower and 36 ft/lb of Torque at the wheels over the stock car. The torque increase is vastly improved throughout and the 4.0 conversion is available for any 3.8L 981/991 based cars.

- Stock GT4 Grey #1 - Highest Stock (357.7whp / 303.8ft/lb) Average Stock (348whp / 299 ft/lb)
- GT4 Grey #1 with 4.0L stoker, 82mm throttle body, Fabspeed header, stock exhaust, DeMan Motorsport custom tune using Pro tuning software by Cobb - (403.1whp / 339.9ft/lb) The graphs below are labelled Fly Wheel Power/Torque but are Wheel Power/Torque.

DeMan%204.0L%20GT4%20Dyno.jpg










 
One has to admire the US can-do approach Ralph - jump straight in. Not a cheap conversion though at $18,950, while the stand-alone price of the Cobb Access Port DME upgrade is $1,295 (are there any UK agents yet?). It seems as though the X51 Powerkit is the next item on their list (£9k+).

The graph's too small to get any detail - does the longer stroke restrict the maximum revs compared with the standard 3.8L? I seem to recall that Porsche reduced the red line revs on the 991 GT3 RS 4.0L by 200rpm compared with the standard GT3.

Interesting to note that DeMan's approach to the GT4's high gearing is to fit 18" wheels along with a different caliper, disc and wheel combo.

Jeff


 
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