natehall
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| posted on 14/5/06 at 09:37 PM |
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MegaJolt
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?
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givemethebighammer
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| posted on 14/5/06 at 09:54 PM |
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here:
http://www.cate1.co.uk/megajolt/mapping.php
(not my site)
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GeoffT
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| posted on 14/5/06 at 11:22 PM |
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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.
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natehall
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| posted on 14/5/06 at 11:49 PM |
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*puts dunce hat on*
whats kpa?
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JAG
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| posted on 15/5/06 at 07:53 AM |
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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]
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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TangoMan
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| posted on 18/5/06 at 11:21 PM |
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What intake
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.
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natehall
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| posted on 23/5/06 at 11:10 PM |
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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 
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