I'm planning a holiday build for my old 998 block, my main goal is driveability but I do enjoy spirited driving and I do have a track in my city.
I found a 12G295 head with 80thou skimmed off and I was planning on going for a CR around 9.5 - 10.
I'm considering going as far as stripping and installing:
Cam: 250°-255° since I do enjoy some low end and a stable and silent idle, piper magnum or kent (maybe sw5 since I've heard marvels and read so much about them here!)
Pistons: Flat top circlip +60
Head: Port, angled valve seat cut
Lightening existing crank and rods.
Adequate intake and exhaust.
A good quality harmonic dampener (any recomendations?)
Although I more or less have a general idea of what I want I want to measure twice and cut once and make sure I have no oversights in my build, and this is where I have a few questions...
Should I remove the 5-6cc's I need to achieve the CR from the chambers or the pistons? I don't think I'll find any good dished +60s for the 998[Answered: Upping the CR to 10.5 means only a 2cc dish needs to be machined in the pistons] Are 1.5 rockers beneficial to a fast road car? I've seen them paired with the SW5 but I'm not sure they don't wear the cam and valve guides too much. [Answered: No]
- I've read about the 1100 crank and the exensive benefits it provides, but I've also heard it provides a very noisy, shakey and thirsty ride, balancing and lightening should take care of that, right? Since it's expensive and hard to come upon I was wondering if it was worth the effort.
- Vizzard goes wild about Hepolite 20950 KR pistons, I know this book isn't exactly modern so have modern developments left these pistons in the dust in comparison to what minispares offers or is it worth the hastle to hunt these down?
- The 12G295's valves are stock at 1 7/32" intake and 1" exhaust, will these be a limiting factor in my build? Is there any benefit to go bigger in a small bore?
- I was considering lightening my crank but then I can also pick up https://www.med-engi...econ-crankshaft since I'm not sure my machinist will be able to heat treat. On the other hand I can always pick up https://www.minispor...haft.html?qty=1 wich is wedged and I hope will run smoother, Thoughts?
Hopefully these aren't too many questions but I really want to get this build right and not simply throw pieces at a block and expect them to run smoothly.
Thanks for all your help ♥
Edited by chocobochan, 10 October 2020 - 07:32 AM.