Chris cost shouldnt be an object as youll save it in fuel

Sodium filled valves are cheaply available from e15t turbos, jet coating and ceramic coatings are now cheaper and will help high comp ratios.

difenetely dont overlook the brakes touching.

[

I have always read that achieving high compression with "pop up" or domed pistons is not such a great idea, as the piston dome impedes the flame travel. Can anyone suggest a way to achieve 14 or even 15 to 1 compression with a flat top piston? I know the E-series 15M head has tiny 17.9cc chambers, but there aren't any A-series heads with a chamber that small are there?



I think that in an old pushrod 2V engine, even with a stock cam with minimum valve lift, trying to get up to 15:1 compression just by shaving head/deck height will see valves way too close to hitting pistons, unless u get them with the valve recesses.

I aggree with all the above, high compression ratio, small a-series (A10,A12) small carb etc. Use 0w20 synthetic oil in the engine. (low friction) How about the rest of the car. A datsun 5spd with the greatest overdrive ratio in 5th gear. Low ratio rear end gears. EG 3.9:1 or 3.08:1 or better. Run 75w90 synthetic gear oil in the diff. & trans. I'd run 12" rims and tires, as thin as possible 145sr12's etc. and run them at somthing like 40psi or higher for (less rolling resistance.) Run no front or rear spoilers (drag). Remove the outside mirrors, wipers & antenna (again drag). You could also tape all the seams with racers tape (hood edges, door gaps, etc (again, less drag).

Quote:
Careful not to stop the flow of air through the engine bay by blocking off the back of the bonnet.

BlownB210 will confirm or deny, but I thought that this engine was for temproary use in occasional club fuel economy trials, so it would take a very long time to recoup the expenditure on fuel savings.

While sodium filled valves are wonderfull in extremely high heat applications, like the truck engine I described earlier, or in blown/turbo applications, & haven't yet caught onto how they would help to extend the distance traveled on a given quantity of fuel.
Lean mixtures burn much hotter, but at the low engine speeds & low throttle settings that are envisaged, exhaust valve temperatures should still remain well within limits.

While the suggestion is to push the 'static' compression sky high, in reality this is really just a number. The actual compression ratio/pressure that the cylinder sees is dependant on many things including valve event & the actual volume of gas in the cylinder [% of cylinder filling] If an equivalant of 8 or 9 to 1 is achieved in economy cruise mode, it would be way above what a stocker would see at the same manifold pressure. [That's 'pressure absolute' or pressure above zero]

I don't know how much benefit that taping over the seams would provide as economy runs are usually done at surprisingly low speeds to minimise the parasitic drag. This drag, & therefore the power required to overcome it, rises exponentially with speed.

Double the speed= 4 times the drag & the power [fuel consumed] needed to overcome it rises sharply too. Slow is economical, ... within reason, so tape over the seams may not provide much of an edge, if any.
The heat output from an engine that is producing the minimum power needed to keep moving should be well within the cooling systems ability to cope, even with the bonnet/hood fully sealed with tape as most of the air from the engine bay passes under the car anyway.

This has to be the most intresting thread that i have come accross. I have never really looked into making a car more economical than standard before, so all these ideas are intresting to read about.

This forumn is constantly a source of new mechanical information for me to add to my memory for later use.

Nice works folks

And you wanted me to put Bigger Jets in the Weber Rubin.. ha ha...

I didnt say that I would go down this path....

dont tell me that you dont want to feel the raw power of the kitchen table special. I know you do, you know you do, so lets just agree that it needs to be done, and just accept that fuel economy edging 20l/100km is acceptable for a 655kg car with a 1.2l motor....

Quote:Yes Dodgeman is correct. I'm not going to spend a fortune on this engine that I'll use very infrequently, BUT it is still important and very much appreciated to hear everyone's ideas even if they don't apply directly to my project. I'm with Reuby, this is a very informative and interesting thread.

Now I'm looking for a set of A14 flat top pistons. Even used ones will be fine. I'll have to check with the racers on these as I think these will be custom units.

Still looking for a water heated round port intake too!

Mike

very hard to get high comp without losing P-V clearance but you will have a very small cam
what about an e 13/15 motor?
dazza