Complete engine rebuild: Anything to consider for max efficiency?

[bandit86]

It is a single cam, no advancing the intake cam

A fluidampner (sp?) will balance your rotating assembly

Or just get a 1l kubota or tankard engine and run that

[serialk11r]

Originally Posted by bandit86

It is a single cam, no advancing the intake cam

A fluidampner (sp?) will balance your rotating assembly

Or just get a 1l kubota or tankard engine and run that

Oh derp, thanks for pointing that out. I missed "SOHC" lol.

[oil pan 4]

Low tension rings will help reduce friction, low tension rings will need the cylinders to start and stay very round and finish the bores with at least 800 grit.

[JRMichler]

We used to have a 95 Neon with the base engine and AT. That engine has peak torque about 4000 RPM, but ran about half that RPM on the highway. The car got almost the same mileage at 80 MPH as at 60 MPH. It ran noticeably better at the higher speed because the engine had so much more torque.

It would really benefit from a cam that moves the best efficiency point down to about 2000 RPM, followed by transmission shift point recalibration if you have the AT. And get the torque converter to lock up sooner. That car had way more power than it needed, anyway.

[straight5]

I've also been considering rebuilding another engine. I thought I understood making an engine more efficient with some of the tricks that performance engines use, but the more I think about it, the more I wonder if that is correct.
Example:
If you polish the back of the valves, and do a 3 or 5 angle valve job, clean up any sharp edges ect, those things are normally done to improve airflow.
More airflow + more fuel = more power.

As to coatings, apparently there are some good ones on the market that are diy. Friction and heat reducing.
I'll thow these out just for sake of discussion:

[smokey442]

I've written a soon to be published book on this very subject. Too much to list here but I'll give you a few highlights. Ring selection there is only one Total Seal. I like the second position gapless. You can get almost as good results by file fit at wide open throttle only. When you throttle back for low power demands or idle speed the gaps open in the lower temperature and blowby goes way up. Expect a minimum drop in fuel consumption of 4%. Do not bore the block oversize. Rigid hone it. If your budget allows consider custom rods and pistons. Longer rods reduce cylinder wall side loading (less friction) Hone the block till the cylinders "clean up" and order your pistons accordingly. Keeping cylinder wall material at the max reduces heat rejection rate into the cooling system. Paint coolant cavity in block with rustoleum primer and color slowing the heat rejection rate even more. Use a dished piston .030-.060" depth that mirrors the squish pad(s) in the head. Have top ring groove .075-.100" from top of piston head. Place the wrist pin hole so that the assemble piston to head clearance at TDC is .025" Also have the top of the piston diameter as large as possible. That along with the ring placement will reduce the crevice volume and the unburnt fuel and air that gets trapped there. Gets the unburnt hydrocarbon emissions down also.

[straight5]

I wonder what stock engines most closely match those disirable qualities?

[drmiller100]

Originally Posted by smokey442

I've written a soon to be published book on this very subject. Too much to list here but I'll give you a few highlights. Ring selection there is only one Total Seal. I like the second position gapless. You can get almost as good results by file fit at wide open throttle only. When you throttle back for low power demands or idle speed the gaps open in the lower temperature and blowby goes way up. Expect a minimum drop in fuel consumption of 4%. Do not bore the block oversize. Rigid hone it. If your budget allows consider custom rods and pistons. Longer rods reduce cylinder wall side loading (less friction) Hone the block till the cylinders "clean up" and order your pistons accordingly. Keeping cylinder wall material at the max reduces heat rejection rate into the cooling system. Paint coolant cavity in block with rustoleum primer and color slowing the heat rejection rate even more. Use a dished piston .030-.060" depth that mirrors the squish pad(s) in the head. Have top ring groove .075-.100" from top of piston head. Place the wrist pin hole so that the assemble piston to head clearance at TDC is .025" Also have the top of the piston diameter as large as possible. That along with the ring placement will reduce the crevice volume and the unburnt fuel and air that gets trapped there. Gets the unburnt hydrocarbon emissions down also.

i'll bet it is a pretty good book. let us know when it publishes - I'll buy a copy.

[tortoise]

Some 95 and 96 SOHCs came with aluminum rather than plastic intake manifolds. Racerboys look for these because they're easier to port-match.