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So, I've consolidated some of cam specs here. The 944S and 944S2 lift figures are from V2 (above) but the durations are from the Porsche manual. The CatCams website claims that the S2 OEM cams are the same spec as stock S2 cams from Porsche. Differences not withstanding, the lift numbers are close.
I'm leaning toward the CatCam highlighted in orange here. Based on my planned upgrades, that's probably the most aggressive option. I highlighted slightly milder options in yellow.
The Cat 12mm lift requires clearance machining of the cylinder head.
It's also the top level cam you'll be able to get away with hydraulic lifters.
CAT is pretty unresponsive from my experience, I went though a UK dealer that was excellent.
PM if you want a contact.
The cams are hollow and weigh substantially less that solid billets or reground factory.
Center mass, but still mass.
Custom header for a custom engine will always be beneficial but that's moot if you will be constantly changing format (stages in your earlier post)
Think this through and go for it once or you'll be buying a lot of parts, for instance, if you recipe for max power @ 7500 revs, go to the stroker crank, you may only see 7200 safely.
I think another source is necessary for the LSA of the stock cams; that seems way too tight for an OEM emissions-focused engine.
BTW your numbers are off, going by the manual S cams are 216/212 and S2 are 224/212 (you are adding when you should be subtracting) there is 0 overlap on these cams.
So I plugged in the valve timing info from the Porsche Manual you linked me to and plugged them into an online calculator. I see the mistake that I made - needed put negative numbers into the calculator for intake ATDC and exhaust BTDC. Thanks for that! This corrects the differences between the Stock S2 (from the Porsche Manual) and the CatCams Stock S2 numbers.
I'd better go edit my old post and remove that misinformation!
Like all, threads of this nature will end with discussion on oiling unless you are already planning on dry sump...or not spending much time at max power.
The cam I linked is close to just the CAT sport, peak power at 7000 revs, dry sump "highly recommended".
I have a ~243 duration cam in my big 8-valve and it rips.
I bet it would make a 16-valve travel through time.
Well, I only need to get up to 88mph for time travel. We just watched the whole Back to the Future series last week with the kids.
Thank you for the link, T. I just sent JME a request for more info about two of their 4v hydraulic cams - the N11/N10 and the N11/N9. It appears from the description that JME takes your cams as cores, hard welds them, and then machines them to spec. I'll add these two cams to the list and update this thread when I get the details added.
Neither increasing the redline or moving to dry sump are on my planned list. I've found that autocross usually has me in 2nd gear for the whole course. I can't remember ever needing to upshift to 3rd, but I am often in the 5-7k range for a good portion. For track days, I really don't "need" more rpm either. As I mentioned, it's really just for fun and to satisfy my butt dyno. I am considering some oiling upgrades without going to dry sump. I may cross-drill the crank, add a scraper, baffles, coated bearing, etc, but not until I open up the bottom end. But, I will keep this info in mind when researching cams.
I saw a 2.5L 16v road race motor on FB Marketplace for sale recently. It mentioned some custom cams so I asked the seller if he would share his build sheet and cams specs with me. He was very helpful.
I've added these custom cams specs to my spreadsheet for comparison to the others. These custom cams appear to fall somewhere in between the two highlighted Catcams - Hot street and Race 1. Based on the build specs for this engine, it's similar to the build I'm planning buy slightly more race-oriented and higher revving. I'm planning to keep the redline at 7k. I will be doing some oil mods to protect the rod bearings, but not planning to add an Accusump or go to dry sump.
I'm thinking maybe I will choose the cams and then build the engine to best match those cams. Right now I'm leaning toward the Catcams Sport or Hot Street. I may also just bite the bullet and rebuild the bottom end now too and get all the mods done at once.
I sent a request for info to JM about a month ago and got no reply, so some of that data is still missing here.
I think I saw that motor was it the 2.5 16v for like 8-9k, he had like 20k in the build stated in the ad? That Hot Street cam has me tempted a bit.
I haven't had much to update lately. Lots of changes going on here at home and moving to a new house (nearby) soon. I'm not looking forward to moving this project, but I won't have it finished in time for the move to the new house.
I did finally place my order for the Catcams 944S2 PN 5220212 - Hot Street as shown in the table above. I did get some positive feedback from Michael Mount about Catcams and these specific cam profiles, so that made my decision a lot easier. Lead time is 4-5 weeks, but I'm checking this box as done. I will update this post with a couple of pics of the new cams when them arrive and I'll be posting the stock 944S cams for sale here and maybe on FB marketplace too.
Not much progress recently I'm afraid. This year started off with a lot of obstacles, but I think we're back on track () now.
I thought I order these cams back in December, but as it turns out I only really paid for them back in December. When I contacted the local distributor again a few weeks ago, they discovered that they had not actually placed the order at Catcams. They have corrected the problem and I have an order confirmation now, but there's still a 4-6 week lead time so I'm still waiting.
I'm also still waiting for the crankshaft. It's been even longer at the crank shop - mid-Sept 2020! I spoke to the crank guy a few weeks ago too and he promised it was almost done with just the cross-drilling and polishing to be finished. He did give me final numbers and it looks like 94.7mm stroke, so that brings me to 2975cc displacement with the stock bore size.
I knew this build would take some time. My goal now is to have the car ready for 944Fest, but that may be too close if I don't get the crank back soon.
07-11-2020, 12:08 PM
We just watched the whole Back to the Future series last week with the kids.
) now.
