Originally Posted by
fyrstormer
Stock header (looks to be about 2" from the exhaust port to the tuned-pipe inlet if the header were straightened-out), Novarossi EFRA-2601 high-RPM tuned pipe. (I had to buy the freaking thing from Austria; Novarossi USA never officially carried the one that fits my car.) The header is port-matched to the engine, something I took care of when I first built the car.
If increasing the compression further were going to produce any benefit, wouldn't I have seen at least a slight speed increase from advancing the ignition timing with the hot glowplug? I didn't see any change at all, at least not on the GPS speedo.
Would I see any benefit from replacing the steel crank bearings with ceramic? I have no problem doing that, I've replaced crank bearings with ceramic before to protect against rust, but I don't know if it would make any difference in terms of performance. It seems like all the popular racing engines use ceramic bearings nowadays, but maybe that's just a gimmick to sell more expensive engines.
After compression the manifold is the next most critical...no matter what you do to the engine the RPM range of the powerband wont change much without a manifold change...So to find the sweet spot you would need to test multiple manifolds, likely needing a shorter one then the RTR manifold...As for compression you likely still have more to go, if the hot plug didn't lose power there is probably more in it.