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Old 07-08-2013, 03:49 PM   #1 (permalink)
Jack-Lee
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Join Date: Jun 2013
Location: Germany
Posts: 126

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Engine mod (BJ 1991)

Hi,

my project go forward.
Beside the aerodynamic mods i modified the engine.
Currently a 55PS Mono-Injection 1.3l assembly are installed.

New Engine:
modified "3F" 75HP Multipoint 8V

Modifications:
-new DIY Manifold (oscillating tube charging)
-new DIY Exhaustsystem
-higher compression ratio
-modified head ("Back Cut" Valves, polished exhaust port)
-modified controlbox (no wide-open-throttle enrichment, deceleration fuel cutoff from 1200U/min [currently 2000U/min], mached to "super" gasoline)

Result:
-114Nm at 2000U/min !
-Max 131Nm at 4500U/min
-Peak Power 71kW (95Hp)
-BSFC 256g/kWh at best point (about 2500U/min), 265g/kWh average from 2000-4500U/min

Stock 3F:
-97Nm at 2000U/min
-Max 99Nm at 3200U/min
-Peak Power 55kW (75HP)
-BSFC 263g/kWh at best point (about 2000U/min), 275g/kWh average from 2000-4500U/min

currently Engine (AAV 55HP)
-88Nm at 2000U/min
-Max 95Nm at 3500U/min
-Peak Power 45kW (55HP)
-BSFC 272g/kWh at best point (about 2000U/min), 280g/kWh average from 2000-4500U/min



So i save only 5% fuel, but the engine is almost new after the rebuild, so the difference is bigger.
Also i could drive with a looooonger gearbox
by the way, ive double the output power

The picture show the difference between stock and mod.
Sorry for the grid, the two diagramms had not the same y-axis.


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Last edited by Jack-Lee; 07-08-2013 at 05:13 PM..
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