Braymond

I'm starting a research project to help me determine what cam specs I want for an upgrade I'm planning next year. I'm hoping to recruit some help with the standard camshaft specs for the 944S and 944S2 cars. I've done some searching and found a lot of info on the 8v cars including the 951, but not much on the 16v cars.

For context, I have an '88 944S and use the car for autocross and HPDE and spirited driving in good weather. It's not a daily driver. I have no plans for Spec or Cup racing, so I'm not worried about "rules." I will not consider swapping the engine. I've already upgraded all of the suspension to Koni Sport adjustable. I may add a new fully adjustable front sway as an upgrade to my existing 26mm front sway bar.

I've started a top-end engine refresh this year and have plans for more upgrades this year and next. Some of these upgrade decisions will guide the cam specs and some cam specs (off-the-shelf) may guide my upgrade decisions. On the short list (Level 1) of upgrades:
- rebuilt head with the larger 968 intake valves and beehive springs
- adjustable cam gear
- 944S2 intake manifold (extrude honed)
- VEMS or chip (undecided)
- all new exhaust from headers back
- New ignition coil - MSD Blaster
- reconditioned fuel injectors

Level 2 upgrades
- bored throttle body
- upgraded EV6 injectors
- new camshafts

Level 3 upgrades - bottom end stuff (2021+)
- 968 crankshaft, rods, pistons
- bored cylinders
- offset ground crank??

The cams are an expensive upgrade, so I'd prefer to upgrade only once. As you can see, I've pushed the BIG changes out on the schedule and these displacement upgrades will need to be considered in advance when selecting the cams (no pun intended). Without going full custom, I've found 3-4 sources for OTS 16v cams and I've started to compile the specs.

I'd love to hear from anyone who has some experience with these well-known vendors and with similar engine builds on what worked for them with regard to lift, duration, timing, and overlap.

I have found timing specs for the S and S2, but no lift info. I saw someone has created a very nice pdf with cam timing curves for the 924S/944 NA cars. I may try to created something similar for the 944S/S2.

-Bill

Braymond

I got the head back from Lindsey last week with the larger 968 intake valves. There's an attached pic below, but I'm not sure it's being displayed in the post.

V2Rocket

going off memory but pretty sure.
S cams are 216 intake duration and 212 exhaust at 1mm (0.039") lift
S2 has basically same intake and exhaust is basically the same but ground maybe 4-8? degrees advanced vs the S exhaust cam.
max lift is 11mm intake and 10mm exhaust for all. these are tiny baby cams by any measure.

skip the "upgraded" ignition coil; stock is more than capable of what you want or just wait until you get your new ECU and go waste spark or coil-on-plug.
if you are upgrading ECU in stage 1 might as well get new modern-type superior injectors vs the ancient stockers, even if they are reconditioned they don't have as good spray patterns and are very small flow wise.
DEFINITELY get a bigger throttle body, 60-65mm should do it for the airflow you're looking for. stock S is 55mm like a basic 2.5 8v. it's too small on a stock S2 so a turnt-up S will suffer similarly. either bore the stocker or adapt to a Ford 65mm 4.6L TB (or whatever you want since you have a new ECU)

buy the 16-valve Stahl header set (Racer's Edge) and pair it with a new 2.5-3" exhaust system with a low-restriction muffler and a cat if you need to run one for emissions.

Braymond

Thanks for the reply V2! That's some good info.

I had read in several threads that the 944S cams are "hotter" than the S2 cams, but as I said before, I haven't found any specs to back that claim up. I'll use your numbers as baseline.

I already bought the Blaster, so that's going in. I may upgrade further if I decide to go with VEMS.

I may just try the injector upgrade now. I've been researching options. It's currently clear as mud.

I have the S2 intake manifold already back from Extrude Hone in SoCal. I also have the S2 throttle body. I believe this is 59.5-60mm stock. On the MaxBore website it appears I can get 63.5-64mm final. This should work well.

As for the header, there are a few options i'm considering. I'm leaning toward the new header from Lindsey. It's not SS but can be ceramic coated and significantly fewer $$.

But, this thread is about cams

V2Rocket

Make sure you get the coil/dwell/etc setting specs and plug them into VEMS when you get it going.

Modern 4-hole or 6-hole injectors are superior in all ways to stockers. You can go to five-o motorsports and pick any injector you want and configure VEMS to run it. High impedance is no problem and generally less expensive. For a Hot 16v some 4-hole Bosch 36lb injectors should give you plenty of head room (these should work i think but check with fiveo to confirm fitment https://www.fiveomotorsport.com/0280155767-36lb-cobalt/)

Page 86 for cam specs. IIRC the "S" exhaust cam is regarded as hotter but its only a few degrees retarded relative to S2. S2 intake cam actually looks better than S at first glance.

(download this doc it has everything you want to know for specs of S/S2 engines)

http://www.uriarte.dk/porsche944/gar...uals/vol1a.pdf

IMO i would skip Lindsey's headers (MSDS brand) and go straight for the Stahl. More expensive but Stahl is a proven piece with actual data from users about output gains. MSDS does not have any dyno info whatsoever and neither does LR about these headers.

harveyf

Just my 2 cents worth on something I think people miss. Any and everything you do to make the engine breath better will require more fuel, to match the increased airflow, and thus unleash some horsepower. Chips are worthless in this regard because they are somebodies idea of a fixed air/fuel map that probably is not even close to what you will need. I have no experience with VEMS but have spent a lot of time looking at Megasquirt and feel that gives you the flexability you need to optimally tune the engine at every stage you obtain. Also, to evalute your improvements, you need to establish a test protocol (unless you just happen to have access to a chassis dyno at low or no cost). With a little bit of simple datalogging (speed vs time, rpm, air/fuel ratio, ambient air temp) and knowing the cars weight, you can do some acceleration runs in a single gear (probably 2nd but maybe 3rd if you have the open road to do so) and develop horsepower curves. It won't neccesarily be the actual horsepower but it will be a good A to B comparison. V2 and I have discussed this, as I want to do something similar with my 2V engine but it takes time and it takes money. I have an old internet thread on calculating horsepower based on time vs speed, and also a way to calculate drag losses using a coast down test. I can scan it and post if you are interested.

Another thing I have considered as valuable is hooking up a shop vac to my exhaust pipe, coupled with a simple manometer. Again, this will be for A to B comparisons of the entire air flow system from filter to tailpipe. You should be able to see differences as you do the various steps you have described. For instance I would be shocked if you can spot any appreciable change after extrude honing. But I do bet getting a bigger throttle body and, with Megasquirt, not having any sort of air flow meter, would give you a noticable change. It all adds up.

Of course, the cheapest horsepower of all in obtained through lightness (Google Colin Chapman). There is a lot of lightness that can be added on your car, especially if it's not a daily driver. Search my website for "weight loss".

Good luck, keep us posted!

T&T Racing

Rule of Thumb - Every 10lb of mass removed is adding effectively 1HP.

Braymond

Thanks for the input, Harvey. I would like to see that old internet thread. Yes, please go ahead and post it here.

Basically, I'm trying my best to get the most air flow with commonly available bolt-ons. I may decide one day to jump to ITBs, but that's a big jump in $$. There's a nice setup available from Hayward Performance for the 16v head and it's very tempting, but I figure that I can bolt everything back together right now with the S2 intake and rebuilt head and it'll run at least as good as before with no other changes. I'm just trying to spread-out my spending a little bit. Everyone has a different budget to work with and that's often the biggest influence on upgrade decisions.

I had a microsquirt setup that I just recently sold. It was just too much for me. I need something a little easier. Even VEMS is a big jump for me. I'm comfortable with the mechanical stuff, but the tuning part comes with a big learning curve and I'd prefer to flatten that curve as much as possible to start. I can learn some stuff and evolve the tuning and engine management. If I have a good mechanical baseline to start with, it's just a matter of learning over time how to get the most out of it.

With regard to the comments about losing weight, that project is still in work and I am struggling a little bit with it. Before I purchased the car, it was my intent to strip it down and make it a track car. After enjoying the car now for 3+ years, I'm torn. It's such a nice car and in pretty good condition. There are no cracks/splits in the seats. There are only a few small cracks in the dash and only around the defroster vents. Everything works (the AC will work when I reassemble the engine) and I know I won't drive it nearly as much if it's just a stripped-out track car. So, without sacrificing some comfort, weight reduction comes with some cost too. I've already installed the euro front (composite) bumper. The stock power seats weight almost 50lbs each. The rear bumper will likely get swapped soon. Replacing them is on my list. I will not remove the AC or stereo. I will be removing the rear seat. I'm not ready to take the plunge and start removing anything else - carpet, power windows, power rear hatch, power sunroof, power mirrors, power rear wiper, power front wipers and wiper fluid, li-ion battery, lexan replacement windows, fiberglass/carbon fiber hood and body panels, etc.

If your statement about 10lbs nearly equals 1hp is true then I know where I can get at least 3 more hp without removing anything from the car

harveyf

It sounds like you have a realistic attitude. It is a sad fact that beyond the typical base value of an average 944, any money you put into it will never be recouped. So spend what is reasonable for you and hold it at that.

But that weight thing. Seats, rear hatch, bumpers are certainly low hanging fruit. The doors are suprisingly heavy I suspect due to internal crash protection. Having to do it over again for a track car in the south, having AC would sure be nice.

Good luck.

Braymond

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.

<<Edited to remove some incorrect data. The new table is attached with corrections below.>>

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.

harveyf

I have a couple of general comments. First, there are practical iimits to total lift and lift at TDC. You will want to check your valve clearance, especially at TDC, to make sure you have enough. What is enough? There are some rules of thumb out there if you look. There is also a concern about what happens if a valve floats a tad? So the spring package you use comes into play. At some point you are really going to be pounding the valve train and longevity can/will be sacrificed.

As you increase duration and overlap, the engine will be more peaky. When they say "race" I imagine it is a clue that the engine won't idle worth a damn. And you will get great horsepower results but only at high rpms, over a narrow band. In general, you will sacrifice torque at lower rpms, like you typically drive on the street, in return for better high rpm numbers. So with the cams you have highlighted, you are really moving away from a "steetable" engine.

Not as much of an issue with fuel injection, but your "vacuum signal" is also going to go into the toilet. Review any part of your build that monitors vacuum and make sure you are not headed for trouble there. At a minimum, your fuel pressure regulator may get confused.

Several "names" in the field of 944 racing are out there. I would not rule out calling them up to pick their brains. Some are more approachable than others. A consulting fee might grease the skids and save you money in the long run.

T&T Racing

Harvey, i'll pick up the tab 😃
I believe to take advantage of aggressive cams, the cylinder head, in particular, the intake should be ported to take full advantage of the lift, ie more air flow.

T&T Racing

Deleted, duplicate

V2Rocket

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.

Jay Wellwood

Maybe michaelmount123 will chime in here on the subject of cams...