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camshaft selection advice

I am going to remove my cheap headers to try to "fix" my exhaust leak and also have small oil leak at drivers side cam chain cover. Car is driving GREAT!! but the "psst", "psst" noise from the headers is annoying. SO,
I was thinking of upgrading the cams. I was reading on SC cams and 964 cams but the mechanic who will be doing the cam replacing recommended I get a "custom grind" for my set up from "ELGIN"
What is a custom grind about? who is or what is ELGIN?
With my bolt on mods listed on my signature below, what cam configuration would you guys recommend. This is not a track car but I "enjoy" it as much as I can on the street.
Thanks for the help
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1984 ROW 930 turbo with rarly8 exhaust, waste gate pipe and HEADERS
K27HFS TURBO, B&B IC, 1 bar spring,LEASK WUR with rpm solenoid, fab speed intake filter, front strut brace rennline. MOMO wheel, Innovative afr 16-1 gauge, custom 930 ELGIN cam
Old 04-18-2010, 05:45 AM
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Contact Doughtery Racing Cams (DRC) at Dougherty Racing Cams and ask for John. He is a regular contributor here and he is one of "us". His website has a great table to help you decide what you want (get smart about what is out there) then call John.

Not sure about ELGIN.

No affiliation, etc.

Mark
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Old 04-18-2010, 06:00 AM
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i filled out his(doughtery) website's info request page. Thanks for the link. I'll see what he says. The mechanic here seems to have worked with this guy Elgin from elgincams in cali but said its a bit hard to get a hold of him cause he does them all himself.....www.elgincams.com
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1984 ROW 930 turbo with rarly8 exhaust, waste gate pipe and HEADERS
K27HFS TURBO, B&B IC, 1 bar spring,LEASK WUR with rpm solenoid, fab speed intake filter, front strut brace rennline. MOMO wheel, Innovative afr 16-1 gauge, custom 930 ELGIN cam
Old 04-18-2010, 01:09 PM
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John started his cam career at Mr Elgin's shop. That should tell you something right there. Dema Elgin is extremely well known in the performance world of most motor sports. Do some research on him for yourself - you'll be impressed. John left Dema years ago to open his own shop.

Your mechanic might be on to something with a custom grind, but if its mostly stock, there is not much need for custom. If you are looking for some specific performance gain, then that's a different story and a custom grind might be in order.

Do not buy custom grinds from cam shops - buy them from motor builders like Performance Developments or JB Racing or Jerry Woods for example. These guys design, grind (or have ground) cams, then test. They know motors and the cams that go in them. They know the results first hand. Again, if you're going to keep your motor mostly stock, its probably a good idea to get a 964 or GTII cam grind - ALWAYS buy cams ground from billet, not reground and buying these from a cam shop is ok. My advice is based on personal experience.

Talk to the builders for solid advice, then come up with a plan with your mechanic.

Good luck.
Old 04-18-2010, 05:24 PM
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thank you. Id like to get a cam that will help improve my low end but still pull hard to redline. Also a cam that I can continue to use in the future when inevitably the engine needs a rebuild and better performance internals are added to the already bolt on upgrades.. May be asking too much perhaps
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1984 ROW 930 turbo with rarly8 exhaust, waste gate pipe and HEADERS
K27HFS TURBO, B&B IC, 1 bar spring,LEASK WUR with rpm solenoid, fab speed intake filter, front strut brace rennline. MOMO wheel, Innovative afr 16-1 gauge, custom 930 ELGIN cam
Old 04-18-2010, 06:51 PM
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Quote:
Id like to get a cam that will help improve my low end but still pull hard to redline.
Me too.

Quote:
May be asking too much, perhaps.
Yep.

I have S cams in my 2.7 RS spec engine and it only wakes up above 4500. It is nice to tool around town with a docile kitten and then unleash the tiger through the canyons just by winding it out. The sound! The acceleration!

With a turbo, you can use less overlap to increase dynamic compression ratio at low revs without boost and then when boost comes in you still get top-end pull. That is your only real way to that goal of ours.

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Old 04-18-2010, 07:20 PM
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Most cams seem to support efficient operation over about a 1500rpm range so the question becomes where do you want to make your power?

I think this range can be moved about 500rpm going from stock 930, to SC to C2 and a little bit more if you play with the timing of the cam you choose. With every cam the effective compression ratio the cam makes goes down and this can effect your off idle pre-boost power some (say 1000 to 2000rpm boost onset).


For your drive-ability goals it is hard to beat an SC cam which is why it has been the go to cam for so long.

Might be best to find a used one in excellent condition and have Elgin, Web, or The Cam Grinder install a drive block on it for the turbo savaging pump. This way you get a factory hardened cam with full diameter lobes that keeps the rockers at the correct angle to the cam. New rockers or rebuilt so as to retain the stock geometry is a good idea. You need to reset your spring heights or go to proper sport valve springs.

I suspect a custom cam if it has to stay in the rpm limit of stock rod bolts , CIS and or be smogable if needed is not going to show much improvement on a stock displacement 930 over an SC or C2 cam.

Not an expert.
Old 04-19-2010, 07:26 AM
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Quote:
Originally Posted by 911st View Post
you get a factory hardened cam with full diameter lobes that keeps the rockers at the correct angle to the cam.
Keith, almost all production cams are made of chilled iron. In other words, they are thru hardened. When the new base circle is ground into the cams, they are just as hard as when they came from the factory. Then the only worry is if there is enough adjustment with the jack screw. According to those who re-grind 911 cams, there is.
Now if a cam is cut from steel billet material, it will need a surface hardening treatment.
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'91 964 Turbo
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Old 04-22-2010, 03:11 PM
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Thanks Paul.

I surely am not a cam expert.

I had heard from one source that even though the there is enough screw travel, if the cam is not built up or a fresh billet is used that maintains the same size base lob circle that it has an effect on cam, rocker, valve geometry. I do not remember the effect but is was one of thouse Ah Ha moments.

However I suspect it is very livable as many have probably done it and we are not building 300k motors like the factory.

There is just is not much meat to work with on a stock 930 cam so at a minimum it would probably have to be welded up anyway.

Not sure about the hardened thing. This used to be a concern many years ago with most the re-profiled aftermarket cams as there were no billets so most were weld up or they had to grind a lot off the base circle to get the bigger lobs they wanted.

Factory Porsche cams were at that time considered superior to most all the aftermarket cams.

I know the last set of cams I had to have repaired because I lost a lob because of a spray bar issue, the grinder was very specific about lube and brake in procedure. Not that that says anything.

I'm still learning.
Old 04-22-2010, 03:58 PM
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Zaidi,

You already have a lot of what you need. When you change headers go with 2 5/8 primaries, do the 964 Bov mod, regrind your cams to SC spec,. sell the K27 HFS, or trade for a K27 7200 or K27S and some cash, use the cash to buy a MSD 6Al-2 programmable ignition. Get the timing set up and you'll be able to run high 11's, low 12's shifting at 6000 rpm on the street.

Cole
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Mods: TurboKraft Custom IC, 934 Headers, GSX 61, Zork, Port Work, SC Cams, Air Mod Fuel Dist Relocated, Water Meth Injection, BL WUR, MSD 6530, Greddy EBC, Synapse Bov, Short 2nd & 3rd with 8:37 R&P, Wevo Shifter, Coupling, and Mounts, MTX-L SSI-4, Big Brakes, Rebel Coilovers, Bilstein Sports.

Last edited by cole930; 04-22-2010 at 05:50 PM..
Old 04-22-2010, 05:48 PM
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thanks everyone. I just had the car dynoed to compare the effect of swapping cams. Not sure yet what cams it will be.... But even with the small cheapo header leak and my hit and miss afr adjustments on the DWUR, It dynoed at just over 335rwhp! Very surprised! The car would most likely do a bit better if the DWUR was set up right by someone more experienced than I but.......
I will try to post the dyno run and type of dyno it is soon....Never actually had a car dynoed before.
Thank you

Cole,
why ditch the k27hfs for a 7200 or an S? I thought the hfs would be better since this is an ongoing process that never ends so the hfs would be able to support further upgrades to the rest of the engine down the road. Im new to this stuff.......Thanks again
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1984 ROW 930 turbo with rarly8 exhaust, waste gate pipe and HEADERS
K27HFS TURBO, B&B IC, 1 bar spring,LEASK WUR with rpm solenoid, fab speed intake filter, front strut brace rennline. MOMO wheel, Innovative afr 16-1 gauge, custom 930 ELGIN cam
Old 04-22-2010, 06:32 PM
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also, can someone direct me to the 964 BOV mod thread? how to do it.


more work to do.................

thank you
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1984 ROW 930 turbo with rarly8 exhaust, waste gate pipe and HEADERS
K27HFS TURBO, B&B IC, 1 bar spring,LEASK WUR with rpm solenoid, fab speed intake filter, front strut brace rennline. MOMO wheel, Innovative afr 16-1 gauge, custom 930 ELGIN cam
Old 04-22-2010, 06:42 PM
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Ziadi,

The K27 HFS is a great Turbo but not necessarily for what you want. Your going through what all of us have done. First thing to do is decide how the car is going to be used. Road car or Street car, Track car or no track car. You said street car.

On a street car your looking at quick spool, tune for the engines torque curve, no lag, lower to mid range cams, modified timing, and good fuel control. The K27 7200 and K27S are good reliable Turbos with quick spool up and will give you all you need if your using the torque curve and shifting around 5600 - 5800RPM. You'll hear everyone raving about shifting at 7500 RPM but once you have exceeded the torque range the extra RPM is just creating noise not power. There are better Turbos out there but the K series are plentiful, easily rebuilt, reliable, easy to install, and reasonably priced.

You don't need to go 160MPH on the street. Your K27HFS is made for big boost all the way to whenever you shift, for that you need large headers, higher rpm, higher torque range, mid to high range cams, more fuel, head work, better pistons, on and on. You'll make good HP but boost won't even start until past 3500 - 4000 RPM, and you'll be running 7000 - 7500 RPM to optimize what you have. And the engine needs to be built to handle the high RPM, HP, and Torque, if it isn't built correctly for the power you'll have a 4 wheeled hand gernade.

With my set up the only timed run I ever did was 12.13 @ 126 MPH. No hole shot, street tires, and shifting at 5,600 RPM.

Cole
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Mods: TurboKraft Custom IC, 934 Headers, GSX 61, Zork, Port Work, SC Cams, Air Mod Fuel Dist Relocated, Water Meth Injection, BL WUR, MSD 6530, Greddy EBC, Synapse Bov, Short 2nd & 3rd with 8:37 R&P, Wevo Shifter, Coupling, and Mounts, MTX-L SSI-4, Big Brakes, Rebel Coilovers, Bilstein Sports.

Last edited by cole930; 04-22-2010 at 07:49 PM..
Old 04-22-2010, 07:45 PM
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thank you Cole. I am beginning to understand.
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1984 ROW 930 turbo with rarly8 exhaust, waste gate pipe and HEADERS
K27HFS TURBO, B&B IC, 1 bar spring,LEASK WUR with rpm solenoid, fab speed intake filter, front strut brace rennline. MOMO wheel, Innovative afr 16-1 gauge, custom 930 ELGIN cam
Old 04-22-2010, 07:54 PM
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dyno run results as it is now, without any cam work




dont know if this will show but it says 345 hp, 322 tq
max hp around 5600 and max tque way before

dont know what the O2 x 10 number is about
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1984 ROW 930 turbo with rarly8 exhaust, waste gate pipe and HEADERS
K27HFS TURBO, B&B IC, 1 bar spring,LEASK WUR with rpm solenoid, fab speed intake filter, front strut brace rennline. MOMO wheel, Innovative afr 16-1 gauge, custom 930 ELGIN cam
Old 04-22-2010, 07:56 PM
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Zaidi,

Really nice numbers. See how the torque starts to fall after peak, any RPM after that point is just dangerous noise. Thats also where you have more Turbo than what's required. That also tells you your making great HP at a
safe RPM which keeps a motor together much longer.

Cole
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Mods: TurboKraft Custom IC, 934 Headers, GSX 61, Zork, Port Work, SC Cams, Air Mod Fuel Dist Relocated, Water Meth Injection, BL WUR, MSD 6530, Greddy EBC, Synapse Bov, Short 2nd & 3rd with 8:37 R&P, Wevo Shifter, Coupling, and Mounts, MTX-L SSI-4, Big Brakes, Rebel Coilovers, Bilstein Sports.

Last edited by cole930; 04-22-2010 at 08:31 PM..
Old 04-22-2010, 08:28 PM
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I see how my hfs may b " too much" for what it needs. If i were to keep the hfs and cheapo headers for now, would sc cams still be the best choice?
Old 04-22-2010, 08:35 PM
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Is there a rev limiter addon that can keep me from going over 6 k? Is that part of the msd setup? Will msd switch mess with the dwur?
Aahh??!!! More and more questions!!??
Sorry
Old 04-22-2010, 08:42 PM
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MSD 6AL will have rev limiter chip.
Regarding interference with dwur, guess you have to ask unwiredtools
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Old 04-23-2010, 03:38 AM
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Quote:
Originally Posted by zaidigonzo View Post
thanks everyone. I just had the car dynoed to compare the effect of swapping cams. Not sure yet what cams it will be.... But even with the small cheapo header leak and my hit and miss afr adjustments on the DWUR, It dynoed at just over 335rwhp! Very surprised! The car would most likely do a bit better if the DWUR was set up right by someone more experienced than I but.......
I will try to post the dyno run and type of dyno it is soon....Never actually had a car dynoed before.
Thank you

............................snipped............... .............................
zaidigonzo,
Is it possible you could show us your recent dyno results? It would be interesting to see your curve to determine how the HFS turbo is performing with the factory cams and if the AFR's are with the DWUR. ( stable/flat-lining) OOOPS!!! My Bad. I just spotted the curve! Sorry, just woke up.
I agree with the "Cole-Meister" that your cams, turbocharger and heads are not matched up that well. Determine what your entertainment target is and match up the pieces accordingly.
Thanks. I look forward to your continued progress.
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'85 930 Factory Special Wishes Flachbau
Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P

Last edited by WERK I; 04-23-2010 at 05:01 AM..
Old 04-23-2010, 04:57 AM
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