Finalize my 3.5 specs

[Samujr]

Hello everyone, I've been lurking/reading this forum for long and followed many interesting projects. Most knowledgeable Porsche people here! Even there is a lot of information available I need your help to finalise my engine build specs. Aim is to build reliable high performance 911 engine. This is additional engine - I still have 3.2 running until this build is ready. Old engine needs complete overhaul soon.

Target chassis: 911 -87 with only small modifications to suspension at the moment (bilsteins/ARB), but well balanced. 964/951 brakes. Will have 22/29 bars, camber plates, ER PB bearings this winter (thus not bought these parts yet). Has bucket seats, rs door panels, no radio, Odyssey battery, duck tail etc minor weight modifications.

Current part list:
-3.2 case, spigots bored to 105mm
-964 oil pump
-3.2 crank, std
-pauter rods with ARP bolts
-Capricorn/Perfect Bore cylinders 100mm
-Wossner pistons, cr should be around 10.5:1
-Twin plugged 3.2 heads, new guides, std turbo intake/exhaust valves
-993 twin dis
-993 exhaust manifolds flipped flanges, (m&k muffler on shopping list)
-964 plastic intake or std 3.2
-3.2 Motronic ecu

Main usage will be DE/autocross but it's street legal car. I need to be able to drive to and from track as minimum. Surely not daily driver. No Cal type smog laws here in Finland. But it's really difficult to register 3.6 on 3.2 chassis here hence I have chosen this route.

I need your help to choose rest of the parts/machine work:
With the valve set (bought from PP member) I received set of retainers. These are 9 gram each, but material is unknown. See photo below. Do you think these are usable with performance springs or should I buy complete set (does the shape on these variate)? What is your recommendation, should i use racing springs like Aasco, EBS, Dougherty? I have understood that higher wear on valve train and some power loss is fact with these.

Relevation to this is camshaft profile what is my next question. Considering my intake and car usage will the dc20 or 993ss be safe choice? Or should I have more aggressive? G50 transmission with std euro gears will be used. Piston valve pockets you can see below. Or should I just ask recommendation from camgrinder as he will be used any case.

As case, crank and heads are still in machine shop I can still ask them to do needed modifications. Not sure if I should have crank crossdrilled for this build? At the moment only inspection (magnaflux) and micro polish is ordered. Case main webs will be chamfered (boat tail), but I did not order shuffle pinning or dowel pinning as I tought it's not required for this kind of long stroke build (save some money also). Without shuffle pinning/crosdrilling what will be max rev limit recommendations? In case this engine will be used in the future with throttle bodies/high cam/ECU on purely track car, will I miss these mods?
Do you recommend to chamfer cylinder heads as cyl/piston size will increase 95->100mm? Does piston top shape matter as there is ~3mm "band" around the piston as seen on photo?

Sorry that I have so many questions, but I hope you can guide me to have perfect setup.
Samu

[BURN-BROS]

Here are a couple to start with.

Choose a different oil pump, A 996 turbo or the cast iron turbo would be my choices. The mag 964 pump starts to move and bind as it ages.

Cams determine what springs to use. So verify with your favorite cam guy before you buy.

Get an opinion from your favorite cam grinder(s) on a what cam to use.

[Samujr]

Thank you Aaron. Actually I've been looking for 930 oil pump for long, but second hand ones Ive seen only there in US. Maybe I still need to try my luck if you think that 964 pump will be weak link. Is 996 turbo pump similar to gt3 pump?

Regarding the valve springs and cam, does hi-performance valve springs have very negative effect for the engine with e.g. 964 cam profile? Is the rocker arm/cam wear only issue or something else also? I believe it's not best combination but at least it wouldhave better possibilities to survive possible over rev.

How about main/rod bearings, Are the ones from Porsche best ones? Some people use coating on these, good benefit? Other options?

[BURN-BROS]

996 turbo is very similar to a gt3 pump. The only difference is the extra pickup for scavange.

If you cannot find a turbo or GT3 pump then the next step down would be a 3.2 pump. It has a smaller scavange, but work well. I avoid most magnesium pumps.

Springs,

You can run a aftermarket spring with 964 cam. You could even set the stock springs stiffer as long as coil bind is avoided. Your cam guy can give you what his recommendations are for seat pressure and pressure over the top.