Ignition and VE table M20 Alpha-N

[digger]

seems like you should have kept the CR a little more mild so you could run more timing on pump fuel.

out of curiosity what do you get on a cranking compression check?

any plans to run on higher octane fuel and see what it has?

you would want HD rockers (or peened and inspected rockers) and uprated springs and it should be fine to 7000rpm, it probably is now but power has peaked already by 6100rpm

[ForcedFirebird]

Nice numbers!

Surprised the timing had to be that low, those are as low as a stock m20 running 1bar of boost. Glad you got it sorted, though.


I didn't see mention of what type of fuel you are using (or what's available there).

[Schlander]

Digger: Yes that could have been an idea, but as it is I'm loving. It has never been a HP focused engine, but I'm very surprised it did 260 The high torque from the buttom and throughout the entire band was the idea.

I run 98/99 Shell V-power, the highest pump gas we have here en Denmark. Next step would be E85 or racefuel.. Thats not gonna work on a daily...

It peaks at 6100 because the limiter in the ECU is set to 6.500revs with soft limiter with 300revs to do it.. So its the ECU that keeps the peak at 6.100.

The next step is a bigger cam, 304 Schrick or something like, according to the wizard who dynoed the car. Ofcourse springs and rockers also.. But with more lift, I either need to make deeper pocket in the pistons or buy a new set.. So I'll keep as it is for know :D

The fuel table is not as Rama explained it should be, but it works and runs fine for know. I'm thinking about changing it with the wizard and try it out. He said that for Alpha-N it should be very detailed in the bottom with tps percentage like 0,1,2,3,5,7,10,13,16,20,25,30,40,50,70,90..

As promised, the new fuel and ignition tables.

[ForcedFirebird]

Yes, Alph-N needs more resolution in the lower RPM's, specially on a street driven car.

Since you have a wizard, you can watch the VE changes the ECU will want in different gears at the same RPM. In other words, since you are basing fuel only on RPM and throttle, there's no way for the ECU to indicate true load variables. So if you travel on a road at 2000rpm in 1st gear vs 2000rpm in 4th gear, the ECU will be using the same map locations for both situations. I have found there will always be a compromise when using pure Alph-N because of this.

Does your ECU allow dual maps based on user inputs? With Megasquirt, we can have it reading MAP sensor, then switch to Alph-N when certain criteria ar met (such as over 70% TPS etc).

[Schlander]

According to the log, theres almost no map pressure change at all..

He'll know, he works primarily with EMU ecu's :)

The next thing to do, must be try to make another more resoluted map for it :D

[ForcedFirebird]

Yes, the resolution needs to change for the MAP/kpa readings as well. With that cam and ITB, you are probably idling at 80-90kpa. So, if you look at kpa in 1-2kpa in the graph, then you would see more movement in the maps. Instead of 0, 10, 20, 30....100kpa, you would do 80, 82, 84, 86, 88....100.

[digger]

Digger: Yes that could have been an idea, but as it is I'm loving. It has never been a HP focused engine, but I'm very surprised it did 260 The high torque from the buttom and throughout the entire band was the idea.

I run 98/99 Shell V-power, the highest pump gas we have here en Denmark. Next step would be E85 or racefuel.. Thats not gonna work on a daily...

It peaks at 6100 because the limiter in the ECU is set to 6.500revs with soft limiter with 300revs to do it.. So its the ECU that keeps the peak at 6.100.

The next step is a bigger cam, 304 Schrick or something like, according to the wizard who dynoed the car. Ofcourse springs and rockers also.. But with more lift, I either need to make deeper pocket in the pistons or buy a new set.. So I'll keep as it is for know :D

The fuel table is not as Rama explained it should be, but it works and runs fine for know. I'm thinking about changing it with the wizard and try it out. He said that for Alpha-N it should be very detailed in the bottom with tps percentage like 0,1,2,3,5,7,10,13,16,20,25,30,40,50,70,90..

As promised, the new fuel and ignition tables.

the other dyno i saw of the 3.1L with schrick 288 and RHD ITB was 277 bhp @ 6875 and 326 Nm @ 5345 on a Maha Dyno in the UK so similar numbers.

the pockets might even be deep enough for a schrick 304? maybe the dome makes them look deeper. you should have the depth measurement on the form that comes in the box with the pistons

if you end up pulling the head it probably needs some more port work, you can never have enough with a 3.1L

i ran my ITB on alpha N with 0,7,14,21,28 load sites. it chewed through
alot more fuel that was the biggest difference compared to now running much smaller steps at low throttle. since my ECU doesn't allow load site changes i had to fudge a non linear TPS vs voltage curve to fool it

was the cruise rpm and load tuned on the dyno? my map runs about 30* more timing at 2500rpm 14%tps

[Schlander]

I've heard about that, believe its in a cab?

If the cam is set in the middle, the theoretic gap should be 0,2mm on the intake.. At the moment it is 2,03mm.

It drives beautifully with the resolution, but I'll see if it will make it better when i get the time.. And when I make a tool for the pedal to rev through the specific loads so I can tune every little point in the map with a fixed throttle percentage.

Every load line was tuned in.. First 100% and then down to 7% :) So at the moment it is spot on, hitting the afr target.

We've also activated the oxygensensor to EGO correct if there are any fall outs.