Guys (and girls)

I intend on making a megajolt setup on my 2l pinto (will eventually when funds allow go for the full megasquirt)

Currently a standard (i believe - the engine was in a westfield, now back in a sierra) carbed unit, but wont be staying that way for long, so i want to get a megajolt setup working before modifying anything

the engine currently is a points setup, but i want to go dizzyless, i have the coilpacks and edis modules (as well as a full loom etc from a cvh cfi to hack up )

Does anyone have a base map for the ignition on the pinto that the megajolt (when i purchase one) can use - and im assuming that MAP would be a better take off than TPS for the system as MAP would be a indicator of actual engine load?

here:

http://www.cate1.co.uk/megajolt/mapping.php

(not my site)

For a baseline map this may help (from the megasquirt site)

For timing, we don't have a generator written yet (it's on my list, but unfortunately not near the top!). The basic principles are to determine a maximum advance for your engine and work backwards from there with heuristics:

- older engines (1960s up to 1990 or so) with two valves - max advance = 36°
- newer two-valve engines - max advance = 30°
- three or four valve engines - max advance = 26°

then adjust for bore size:

- under 3.5" (89mm) - subtract 3°
- between 3.5" and 4.000" (101.6mm) - no adjustment
- over 4.001" (+101.6mm) - add 3°

then adjust for the fuel:

- regular - subtract 2°
- mid-grade - subtract 1°
- premium - no adjustment

That gives us a maximum advance figure. It you have an aftermarket combination with a good squish area and optimized quench, subtract another 2°. If you have a flathead, add 3° or 4° or more.

We will use this to fill in the table at 100 kPa from 3000 rpm to the redline.

From idle to 3000 rpm, we want the advance (@100kPa) to increase fairly linearly from the idle advance to the maximum advance. idle advance is really a matter of tuning, but assume 8° to 16° in most cases, with stock engines being on the lower end, and 'hotter' engines being on the upper end.

So if we have a hot engine with 36° maximum advance and 16° idle advance (at 800rpm), the spark table might look like this for 100kPa:


100 16° 16° 18° 24° 28° 36°

rpm 600 800 1000 1500 2000 3000



Below 100 kPa, we add 0.3° per 1 kPa drop. So for example, if our total spark at 100kPa and 4000 rpm was 36°, the advance at 50 kPa would be:

36° + 0.3° x (100-50) = 51°

and the advance at 45 kPa and 800 rpm would be:

16° + 0.3° x (100-45) = 32.5°

However all of these would need to be tuned, and it often helps idle stability to limit the advance at idle to under 20°.

Finally, for boosted engines, you subtract 0.3° of advance for every kPa above 100 (it's not a coincidence that this is the same factor as for the 'vacuum' adjustments). Because 101.3kPa=~14.7psi, this works out to ~2° per pound of boost. It is often the case that you want to limit the retard under boost as well, typically so that it takes out no more than about ½ of the maximum advance at 100 kPa.

None of these will give you the 'right' values for your engine though, and like the VE table calculator, are just a relatively safe starting point. They should be somewhat closer than starting with an empty table, though!

Lance.

*puts dunce hat on*

whats kpa?

kpa = Kilo Pascal = 1000 Pascals

It's a unit of pressure and 1 bar = 1 x 10^5 Pascals (approx' ).

[Edited on 15/5/06 by JAG]

If you are going for multiple carbs then a TPS may be better than MAP. MAP gives a good indication of engine load provided you can get a constant vacuum. This means either using a standard manifold or tapping each manifold pipe and feeding to a common plenum to balance out the pulses.

I would also suggest using more than 36deg of advance as the combustion chamber has a major impact on burn speed and the Pinto chamber is not a particulary good design. I am currently up to 39 deg and may still get to 40 at certain points in the range.

ok,

im now seriously considering going for the full squirt and jolt V3 setup - as its not a huge amount more and for the use i have appears perfect - but (and this is the big one)

using a standard pinto EFI manifold, cylinder head etc - can you use standard injectors in the engine as well? and are they low or high impedance?

should be ordering the megasquirt soon