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euro 1982 turbo with 964 cams question

anyone put 964 cams in a euro 930 with 1.46mm timing at overlap
Old 12-17-2007, 02:10 AM
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Macht Schnell
 
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Hello,
Surprised nobody has answered you yet. When I was looking up CAMS for my EFI conversion, I was told that the overlap of the 964 CAMS caused Low end Issues with CIS and was not recommended for a CIS 930. Hopefully some more folks will pipe in here.

Les
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---Les Garten---85 930, Andial IC, GHL Headers, Fabspeed Dual, K-27 HF2, 3.4 JE Full Finned 7.5:1 CR, 964 CAM'd, Carerra 3.2 Manifold Cut/Flipped, Tec3r, Siemans 55#, GSF Fuel Rails, Clewett Crank Trigger, Clewett Cam Trigger,Dual Plugged, ARP Head Studs/Rod Bolts, Clewett Wires.Tial 46mm WG, Tial 50mm BOV, WEVO Shifter,934 Boost Gauge, Wideband EGO Sensor/Gauge, C2T Head Gaskets, '88 MB 300TE,BMW R100RT
Old 12-17-2007, 02:11 PM
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Several cams will work with CIS, the 964 is a popular grind. The timing setting is partially dependant upon where you want the torque to come in.
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Old 12-17-2007, 05:01 PM
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thanks for your respones, I am trying to get a bit more down low so I thought to try aroun 1.4 to 1.46 at overlap
Old 12-17-2007, 11:57 PM
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Have you talked to any of the big race shops or Dougherty Racing Camshafts?

I have a feeling they're going to tell you the best overall setting is at 1.26mm.
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Old 12-18-2007, 07:34 AM
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The 964 cams will make a significant difference just on their own, I think. Probably should use the recommended timing for them.

You could time SC cams where you asked, but camgrinder gives a specific timing for the 964 one - no leeway on it. As they're higher lift than SC, that might be a factor?

That said, interestingly, I note that the DC-15 (Super SC) and DC-19 cams he lists totally different timing for, despite the fact that the cam profiles are very similar, with the DC-19 having even more lift than the 964 (DC-15 has SC lift)...

I think you really need to talk to someone who knows.

I have SC cams from Camgrinder, timed @ 1.4mm IIRC - less hot than 964, nice and tractable off-boost. Both are quite a long way from stock 930: http://www.drcamshafts.com/911profilesprint.htm

IIRC, John (camgrinder) Doughery said elsewhere on Pelican that SC cams are identical to Carerra cams, and that the 993TT cams are pretty much exactly the same, modulo some ramps for the hydraulic tappets. Can't find that post now, but I did find the following looking for it:

In this thread 964 Cams On an SC or other HP upgrades, John said:

"Charlie,
The SC cams work very well with turbos.
A 964 cam has more overlap than the SC cam. It will work in a 930 with an upgraded turbo, but the low speed "off boost" performance can suffer"

and in this one [url]SC cams in 930 Turbo he said:

"The 964 cams would have less power off boost. The 964 cams will move the point where you build boost higher in the Rpm band verus the SC cams. They will also have more power on boost.
Porsche specs for the SC cam range from .9mm to 1.7mm depending on the year and model. 1.4 mm is a good number for a turbo. The higher the number (1.7) the further advanced the camshaft is.
The Sport-SC cams is more aggresive than the stock SC cam. It has more lift at top dead center. Thats why we specify 1.8-2.0 mm."
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Old 12-18-2007, 08:49 AM
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Hello,
I won't re quote the whole thread above. I've had SC cams in my 930 and they are really nice cams.

When I was looking into EFI Richard Clewett advised me to look into 964 Cams. I told him I thought I couldn't use them on a 930 because of Low end performance. He said, that they were high overlap and that CIS did not work well with high overlap cams. He also said they would be good with direct port EFI. I believe he said the reasoning for this is that the EFI could "Tune up" the low end response for the CAM profile.

I think there may also be an interaction between the high overlap and the metering plate in the CIS fuel head that does not respond well to back pulsations into the manifold. Don't quote me on this though.

I would look into this carefully if you are thinking of running this cam and CIS. Talk to people who are living with the combination. The cams are great on my car, but mine and yours are different.

Les
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---Les Garten---85 930, Andial IC, GHL Headers, Fabspeed Dual, K-27 HF2, 3.4 JE Full Finned 7.5:1 CR, 964 CAM'd, Carerra 3.2 Manifold Cut/Flipped, Tec3r, Siemans 55#, GSF Fuel Rails, Clewett Crank Trigger, Clewett Cam Trigger,Dual Plugged, ARP Head Studs/Rod Bolts, Clewett Wires.Tial 46mm WG, Tial 50mm BOV, WEVO Shifter,934 Boost Gauge, Wideband EGO Sensor/Gauge, C2T Head Gaskets, '88 MB 300TE,BMW R100RT
Old 12-18-2007, 09:16 AM
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Quote:
Originally Posted by les_garten View Post
I think there may also be an interaction between the high overlap and the metering plate in the CIS fuel head that does not respond well to back pulsations into the manifold. Don't quote me on this though.
Heh. Sorry Les, I quoted you. No trouble mate..

The above is perfectly true for N/A cars, I've read. And the main reason the old 'S' cams are a lot hotter than SC cams.

But it doesn't apply to a turbo I'm told - as there's so much distance between the intake valves and the plate that it's not a factor in the same way.

I think the issue here is that they're high-overlap cams, and don't work well out of the powerband - an effect that you can offset somewhat with EFI.

So it comes down to whether you want top-end performance at the expense of lower/off-boost (964 or hotter), or good low-down, off-boost response - and still improved on-boost power over factory (SC).

My tuner told me "your car would make more power with 964 cams". I told him I thought the car was very streetable, and that I didn't feel like I was exactly hurting for top-end...

It seems to me like the original poster doesn't like the characteristics of the 964 cams in everyday driving and would like to trade some top-end for better low- to mid-range. Especially given camgrinder's comments that the 964 cams move the boost point up the rev range as well as giving less low end response than SC.

TURBORS930, can you comment on that? What turbo are you running and what other mods do you have?

Also, I see that camgrinder gives 1.26mm for 964 cams, and you're asking about using 1.46mm as though that would be retarding them, whereas that would appear to be advancing them 0.2mm?

Whose cams are these, and what did they recommend they be timed at? How do they compare to camgrinder's profile?
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Old 12-18-2007, 12:03 PM
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Hi Spuggy,
Interesting about the N/A vs Turbo and 964 CAMS. Thanx for that.

Les
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Old 12-18-2007, 12:12 PM
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Originally Posted by les_garten View Post
Hi Spuggy,
Interesting about the N/A vs Turbo and 964 CAMS. Thanx for that.

Les
Actually, I just re-read what I wrote there, and I don't think the length or volume of the intake even matters (although it's a factor for the pop-off valve - or lack thereof).

As far as the intake reversion wave problem with lumpy cams and CIS is concerned, I think the big spinny thing between the intake valves and the metering plate takes care of it for 930's...

Oh, and just in case it's of interest, I saw somewhere else that SC cams were factory fitment on the 930S models.
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Old 12-18-2007, 12:42 PM
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My question is why would Porsche go thru the trouble of designing a special turbo grind cam if the SC cam would have worked fine or even improved performance in the first place. The turbo and SC came out in the same time period of the early 70's as far as development was concerned so there must be a clear benefit of one cam versus the other with regards the SC versus turbo cam in the turbo application.
Now the turbo will alleviate the intake revursion issues to a large extent so that I think you are less likely to experience trouble with more aggressive cams and CIS in a turbo versus an SC.
I have just sold my 1979 911SC which I built with 964 cams and it ran great. The idle suffered oh so slightly from the switchover, and I gained alot of high end power versus the stock SC cams which ran out of power around 5500rpm. With 964 cams it pulled till 7000rpm!
I would think the same would follow suit with the turbo, but remember in that car you need low end response improved more than high end since the turbo is cramming in the air at high revs where lots of valve overlap may actually hurt you.
This is very involved theory and we need a cam specialist to chime in.
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Old 12-18-2007, 01:25 PM
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Originally Posted by fredmeister View Post
My question is why would Porsche go thru the trouble of designing a special turbo grind cam if the SC cam would have worked fine or even improved performance in the first place. The turbo and SC came out in the same time period of the early 70's as far as development was concerned so there must be a clear benefit of one cam versus the other with regards the SC versus turbo cam in the turbo application.
Now the turbo will alleviate the intake revursion issues to a large extent so that I think you are less likely to experience trouble with more aggressive cams and CIS in a turbo versus an SC.
I have just sold my 1979 911SC which I built with 964 cams and it ran great. The idle suffered oh so slightly from the switchover, and I gained alot of high end power versus the stock SC cams which ran out of power around 5500rpm. With 964 cams it pulled till 7000rpm!
I would think the same would follow suit with the turbo, but remember in that car you need low end response improved more than high end since the turbo is cramming in the air at high revs where lots of valve overlap may actually hurt you.
This is very involved theory and we need a cam specialist to chime in.
Hi,
I've had the SC cams in mine and have 964 Cams presently. I agree with what you state about the RPM and where the SC's run out of Breath. Now I have 964's, I don't think I gave up much to the SC's on the Bottom, the midrange and 5500 plus are much more robust.

Les
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Old 12-18-2007, 01:49 PM
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I installed the 964 cams in my street motor over the sc cams after much research and user feedback. My motor is CIS, cams are timed at 1.26mm and full boost comes on at 3000 rpm with a K27 HF. I have been in a similar but SC cammed vehicle and the low end difference is measureable. It did run out of breath 5500-6000 rpm where as my motor continues to pull right to the rev limiter.
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Old 12-18-2007, 03:04 PM
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I have been in a similar but SC cammed vehicle and the low end difference is measureable. It did run out of breath 5500-6000 rpm where as my motor continues to pull right to the rev limiter.
Sounds right.

With stock headers, 3DLZ and SC cams, my car made max power @ 5700 RPM.

With GHLs, K27/HF and the same cams, it makes max power (and about 30% more of it) @ 6100 RPM. It also develops .5 bar @ 2500 RPM on the rollers.
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Old 12-18-2007, 04:00 PM
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Porsche used the 964 grind on the 1994 Turbo S model that made 381hp. These cams along with all the usual mods(K27, headers, etc.) are a very nice setup and have more low end than stock and have more top end than an SC cam. I run this cam on my car for 3 years now. Turbos' sweet spot is in the upper rev range where the turbo is at full boost so having a cam that complements that works well.
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Old 12-18-2007, 06:28 PM
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