Hello to one and all, I am converting my pinto engine to Megajolt, it has the following spec, big valve head, Kent FR32 fast road cam, twin Dellorto 40's. I would like to use the option to have two maps, one to give best tractability etc for around town and to give easy starting ( zero advance at cranking speed) and one for best open road performance. If I use the supplied "safe" map as the basis for the round town map what changes should I be looking to make to the second map. I am betting that someone has done this before and can set me on the right track,
microx
pinto 2.1 question
Moderators: JeffC, rdoherty, stieg, brentp
I don't think this is the way you think about it.
Your 2 maps shouldn't be used to get "good driveability" for one & "good performance" for the other.
That's exactly the point of MJLJ: To get both with one map.
Low load (= low TPS or low MAP reading) & low rpm = good mileage
medium load & medium rpm = driveability
high load = Power
All those zones are part of one unique map. What I've written above is just to get the idea.
2 maps are for 2 different fuels for instance such as E85 & 98 octane gas, or valet mode (rpm limiter for instance) & regular mode.
To start, I would try to:
- set the max timing where it was before you've switched to MJLJ at the right rpm up to red line.
- set initial timing to where idle is best: increase timing at idle until you've got highest rpm
- get a linear approximation between max timing & timing at idle.
Now you should get what a distributor with no vacuum should do.
Next step is to advance timing where it would help the most to get best driveability with cells lower than max load.
On the road, get the car on a steady state (load, rpm) at regular speed limits (such as 50kph in town, 130kph on highway, etc.), at that particular state, you should advance timing until you notice no more improvement.
You should do this operation with an iterative process.
To acess some cells, you might have to find a road going up to create higher load at some rpm. You could also play with gears.
That's the theory, in reality it is not so obvious to feel improvement. The best way to do it is on a dyno / rolling road with braking capability (eddy current type usually). It would allow you to measure precisely torque.
Inertia dyno are good only for max hp / max load. That would cover only high load tuning.
With brake dyno, you can get a steady state for every cell on the map you'd like to set up, you change timing until you've got best torque with min timing.
Some conditions are also not so obvious to get but you'll get them on the roads at some specific conditions (high temp for instance, max load at very low rpm, etc.)
Something good to get also is a detcan to allow you to track detonation while tuning for max hp. I did mine for 10€ with noise cancellation head set, some copper tubing, some hose for gas. You just bolt the end to the engine to listen to it while tuning.
Other advice would be to read some books. I did read the following ones maybe 3 times each + many books on carb tuning. They are easy to read.
Designing - tuning High Performance engine
Performance Fuel Injection Systems
So much stuffs to learn, my MJLJ should be in my car during winter, I can't wait to see how it will perform
Do not hesitate to react to my message, I'm nowhere near a tuner, I'm also here to learn.
Good luck with your project!
Your 2 maps shouldn't be used to get "good driveability" for one & "good performance" for the other.
That's exactly the point of MJLJ: To get both with one map.
Low load (= low TPS or low MAP reading) & low rpm = good mileage
medium load & medium rpm = driveability
high load = Power
All those zones are part of one unique map. What I've written above is just to get the idea.
2 maps are for 2 different fuels for instance such as E85 & 98 octane gas, or valet mode (rpm limiter for instance) & regular mode.
To start, I would try to:
- set the max timing where it was before you've switched to MJLJ at the right rpm up to red line.
- set initial timing to where idle is best: increase timing at idle until you've got highest rpm
- get a linear approximation between max timing & timing at idle.
Now you should get what a distributor with no vacuum should do.
Next step is to advance timing where it would help the most to get best driveability with cells lower than max load.
On the road, get the car on a steady state (load, rpm) at regular speed limits (such as 50kph in town, 130kph on highway, etc.), at that particular state, you should advance timing until you notice no more improvement.
You should do this operation with an iterative process.
To acess some cells, you might have to find a road going up to create higher load at some rpm. You could also play with gears.
That's the theory, in reality it is not so obvious to feel improvement. The best way to do it is on a dyno / rolling road with braking capability (eddy current type usually). It would allow you to measure precisely torque.
Inertia dyno are good only for max hp / max load. That would cover only high load tuning.
With brake dyno, you can get a steady state for every cell on the map you'd like to set up, you change timing until you've got best torque with min timing.
Some conditions are also not so obvious to get but you'll get them on the roads at some specific conditions (high temp for instance, max load at very low rpm, etc.)
Something good to get also is a detcan to allow you to track detonation while tuning for max hp. I did mine for 10€ with noise cancellation head set, some copper tubing, some hose for gas. You just bolt the end to the engine to listen to it while tuning.
Other advice would be to read some books. I did read the following ones maybe 3 times each + many books on carb tuning. They are easy to read.
Designing - tuning High Performance engine
Performance Fuel Injection Systems
So much stuffs to learn, my MJLJ should be in my car during winter, I can't wait to see how it will perform
Do not hesitate to react to my message, I'm nowhere near a tuner, I'm also here to learn.Good luck with your project!
Mathieu
Thanks for your reply, much of what you say is true. Perhaps I should have said that I have a kit car and some of my objectives are toward solving some special problems like overheating in a hot climate and, oddly, problems starting in the winter, it's all a bit of a comprimise. The car is set up now using methods that you suggest and I will use what I have already found to be best as a basis for my map, it will just be nice to get rid of the problems by having more control over the advance curve. It took me AGES to get the jetting for the carbs right and I may still have to correct it further after I have the Megajolt fitted. I dont go any great distance in this car so I can always use 98 fuel, I think I will have two maps if only to compare changes made.
I like your cans, I made some with an electret mic capsule on a magnet and a little amp, lent it to a friend and never saw it again, what are friends for eh!
microx
I like your cans, I made some with an electret mic capsule on a magnet and a little amp, lent it to a friend and never saw it again, what are friends for eh!
microx