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Jack-Lee 07-08-2013 03:49 PM

Engine mod (BJ 1991)
1 Attachment(s)

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

-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)

-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 :D

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

Jack-Lee 07-10-2013 06:30 AM

1 Attachment(s)

i modified the engine again.
Smaller! runners
smaller valves
shorter Manifold with smaller diameter

136Nm! @ 4500U/min
better enginie efficenty

In the picture: comparation between my currently and the next enginie

JasonG 07-10-2013 08:01 AM

Looks promising, keep up the good work Jack.

Jack-Lee 01-16-2014 02:26 PM

7 Attachment(s)

latest Version with 141Nm@4500U/min and 92HP@5000U/min

And a few Pics from the first "real" steps.
The engine are now by the tuner.

-new pistions (incl. drill and honing)
-new valves
-new bearings
-new sealing
-higher compression
-other cam
-other alternator
-DIY intake manifold
-DIY exhaust

renault_megane_dci 01-16-2014 03:14 PM

That's way cool but could we get more pics of oily parts and namely your DIY parts, assembled engine and such.

So you have the facility to dyno run the engine or is it an engine simulator ?

I would really enjoy more details like valve size before and after and such.
Also, what is the cam duration ?

Jack-Lee 01-16-2014 03:17 PM


my english is bad, so i doesnt write all the think that i could write.

Name the Parts? There's normal Motorparts (Pistions and so on)

I clean the Head and mill a little "combustion chamber". Without sharp edges the pinging risk is lower (other changes at the pistion)
The Exhaust is finished, but i had no photo on my PC :/

The Valve are standard, but the valveseat is changed an the valves milled to be lighter (lower springstiffness -> lower losses)

The data in my last post are simulated. But the Motor (when finished) are fine-tune on a dyno.

renault_megane_dci 01-16-2014 03:22 PM

You little teaser ;-)

If your english is not good (not buying it any second) that gives you more of a reason to post more pics !
Also, cam duration, valves diameter and CR you can write in german ;-P

RustyLugNut 01-16-2014 03:52 PM

What are the units for your BSFC.
Those are very low numbers.

Jack-Lee 01-16-2014 03:52 PM


Cam Datas:
CAM from a Polo 6N with ABU Engine
111.5° ATDC
Duration @ 1mm 211/215
Max Lobe Lift 9.4/9.6

Standard from "G40" (exhaustvalve with natrium)
Intake Valve:36mm (Port 30,5mm)
Exhaust Valve:29mm (Port 26,8mm)
Valves polised and the ports are aerodynamik tuned

Intake Manifold:
Length 300 (standard about 130)
Runner Dia: 30,5mm
Made of Alu or CFK, im not sure what material i use.

Exhaust "Fächerkrümmer" 4:2:1
Section 1 (from each cylinder): 32mm (the "step" from head to exhaust minimized the reflow in the cylinder)
Section 2: (for 2 cylinder) 45mm
Section 3. (for all) 50mm

@rusty lug: What numbers you mean?

RustyLugNut 01-16-2014 04:11 PM

The chart you posted for bfsc.

Originally Posted by Jack-Lee (Post 407430)
@rusty lug: What numbers you mean?

Gasoline engines usually come in at right about 0.48 pounds/horsepower*hour in British units. A very good gasoline engine or a basic diesel will dip down to 0.42 lb/hp*hr. Large diesels used in power generation or ocean going power plants can dip down to 0.28 lb/hp*hr.

Your simulated engine is below that at just below 0.25, but it may be an issue of unit measurements. I just wanted to clarify.

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