i've just started a pinto for a very special customer
the brief is for an engine with some poke, but is fuel efficent, and thus needs to be nice and flexable and pull tall gearing, its going to be an efi, but would work on a suitable modified carb.
now the budget isnt very big so the money has to be spent wisely, we need the most bang (torque) for least bucks, i'dealy i would of built a big capacity engine but its staying a 2.0 for reasons i'll list later
if you want economy you need an engine which has lots of torque low down, therefore you dont have to rev it,
high compression helps, thermally the engine gets more efficient the higher the cr to a point, but high compression demands high octane fuel, in practise a high compression engine on dearer high octane fuel will be cheaper to run the extra efficieny offsets the extra fuel cost, and you have extra power if you want it, or you go low c/r worse economy and power and can run cheap fuel,
this engine is going high c/r route
more revs = more internal friction, i.e less economy
so the cam will be a "caravan" cam, which is pretty mild but will give more grunt than the std ford cam and from very low revs, the mild cam will also keep to a minimum the fuel that goes in the inlet and straight out the exhaust without ever being burnt, again maximising economy
cams and compression go very much together a 320 degree race cam and a 10.1 compression wont work well, on the other hand a 12.1 compression and a 270 degree cam is likely to lead to a dead engine, to get the most from the engine im looking at a 10.25:1 cr which is high for the 260 degree caravan cam, so i'm going to build the engine as smaller squish as possible ( squish is the gap between the top of the piston and the flat psrt of the cylinderhead chamber) this will reduce the chance of detonation
the head is an injection one, which i will mildly port and install some oversize inlet valves, this will help the engine breath throughout the rev range, its not going to make masses of power so we dont need big exhausts.
mgp is heavily dependant on driving style, but my target aim is an engine in a fully trimed car which will return 35mpg without driving at snails pace and will give 130-135bhp if asked
DISCLAIMER, i have to say this is how im approaching this engine is build based on my experience, i never went to an engineering school or whatever to learn this stuff, so whilst it works for me i cannot say everything im doing is 100% right by the book, i am writing this as a "show whats involved guide", rather than a diffinative how to
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