Choosing an Aftermarket ECU

Competition engines and ancillaries - general discussion
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petert
Posts: 61
Joined: July 13th, 2006, 12:38 pm
Location: Sydney, Australia
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Choosing an Aftermarket ECU

Post by petert »

I spent some more time on the dyno today fine tuning my new engine. It's a 2L 16V Peugeot, 86x86mm, 11.8:1 CR, 100 ron fuel. I spent condiserable time holding at each load point (the important ones anyway) and confirming the mixtures. After that I decided to do a power run vrs mixture to see the outcome. To my surprise there was still a nasty rich - lean dip at 5000-5500 as it came on the cam. Inspection of the fuel table at 100% throttle opening shows 5000 had a value 85 to produce 12.9:1 and 5500 had a value of 102 to produce again 12.9:1. Hold them steady at those points and the mixtures were fine. However, on the power run, where you move through the points, there was spike to 13.4:1.

The only way to solve the issue was to add another axis at 5250. If your software doesn't allow you to add an axis, then there's no chance of ever improving on that type of situation.

Then take a look at the ignition table, in particular from 2500 to 4000 at 100% load. Load in this case is by manifold pressure. Those values were originally 24 degrees. However, while I was watching the torque readout, I used the + and - keys to adjust the timing. It was surprising how much the torque INCREASED by a decrease in a few degrees. The resolution for a highly tuned engine is important. Notice in this case it's to a tenth of a degree. Again, that's what you pay for.

I also concentrated on 3500 - 80%, to check the cruise timing. I had this value originally at 30 degrees. As I held the + key down the Nm just kept on climbing, until they peaked at 36 degrees. I didn't have time to do the full table, so I filled in the rest at 36.

Maximum power was 123kW at the wheels (approx. 220hp) at 7400. It was still climbing but discretion being the better part of valour, I imposed a safe rev limit.
Attachments
Autronic Ignition Table - load sensing via manifold pressure
Autronic Ignition Table - load sensing via manifold pressure
ignition table.jpg (45.56 KiB) Viewed 4129 times
Autronic Fuel Table - load sensing via throttle position
Autronic Fuel Table - load sensing via throttle position
fuel table.jpg (44.91 KiB) Viewed 4129 times
Last edited by petert on May 25th, 2007, 11:53 am, edited 1 time in total.
petert
Posts: 61
Joined: July 13th, 2006, 12:38 pm
Location: Sydney, Australia
Contact:

Post by petert »

Here's the full spec. of the engine, originally an S16/Mi16 Peugeot:

36.5mm inlet, 29.5mm exhaust valves
inlet cam 243 deg. @ 0.050", 0.362" total lift, 106 LCL
exhaust cam 226 deg. @ 0.050", 0.350" total lift, 109 LCL
forged flat top pistons
0.7mm gasket
11.8:1 CR
48mm throttle bodies, 320mm total length
Autronic ECU
M&W Pro14 CDI (an amazing bit of black magic)
4-1 exhaust, see ( http://guy-croft.com/viewtopic.php?t=302 )
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