333pg333

It's 4.30am and I can't be bothered to fight the search section. Who has swapped out to an n/a cam and what sort of results did you see? I'm just thinking this might be a cheap mod for my 2.5L motor.

thanks

MAGK944

I thought they were the same. I have a turbo cam in my na and haven't notice any difference.

333pg333

Copied and pasted so too much info however you can see the difference in the 2 here:


From the Parts & Technical Reference Catalog 1999 Edition, we have the following part#:
944.105.155.05 CAMSHAFT for 1983-85/1 944 and 1986-88 944 Turbo
944.105.155.09 CAMSHAFT for 1986-88 944 / 924S
From the Service Information Technical Manual Ô88, we have the following cam specs @ 1mm/0.039Ó clearance:
Combining these two tidbits, we can derive the following additional information:
HereÕs a picture of what these cams are doing (lift not drawn to scale):
Copyright©2001 Dan Nguyenphuc <danno@thevine.net>


944 / 924S
Intake opens: 1¡ after TDC
Intake closes: 49¡ after BDC
Exhaust opens: 47¡ before BDC
Exhaust closes: 1¡ after TDC


944 Turbo
Intake opens: 1¡ after TDC
Intake closes: 49¡ after BDC
Exhaust opens: 43¡ before BDC
Exhaust closes: 3¡ before TDC

TDC 0¡ TDC
360¡
TDC
360¡
BDC
180¡
BDC
540/180¡ 944 Turbo cam # 944.105.155.05
exhaust open
43¡ before
BDC
3¡
115¡ LC
intake duration 228¡
intake closes
49¡ after
BDC
113¡ LC
exhaust duration 220¡ 1¡
intake opens
1¡ after
TDC
power stroke exhaust stroke intake stroke compression stroke
ignition
BANG!
exhaust closes
3¡ before
TDC
lobe-center angle / separation
228¡ crank rotation / 114¡ cam
exhaust stroke
TDC 0¡ TDC
360¡
TDC
360¡
BDC
180¡
BDC
540/180¡ 944 / 924S cam # 944.105.155.09
exhaust open
47¡ before
BDC
1¡
115¡ LC
intake duration 228¡
intake closes
49¡ after
BDC
113¡ LC
exhaust duration 228¡ 1¡
exhaust close
intake open
1¡ after TDC
power stroke intake stroke compression stroke
ignition
BANG!
lobe-center angle / separation
228¡ crank rotation / 114¡ cam
I got some emails with these additional cams measured at 0.050Ó clearance (lift not drawn to scale):
TDC 0¡ TDC
360¡
TDC
360¡
BDC
180¡
BDC
540/180¡ cam # 944.105.156.09
exhaust open
43¡ before
BDC
???¡ LC
intake duration 223¡
intake closes
49¡ after
BDC
???¡ LC
exhaust duration 223¡
power stroke exhaust stroke intake stroke compression stroke
ignition
BANG!
lobe-center angle / separation
228¡ crank rotation / 114¡ cam
944NA & 944Turbo
cam-timing profiles PORSCHE 944
944 / 924S cam # 944.105.155.09
int. duration: 228¡ (-1 +180 +49)
int. lobe-center: 115¡ after TDC (228/2 +1)
exh. duration: 228¡ (+47 +180 +1)
exh. lobe-center: 113¡ before TDC (228/2 -1)
944 Turbo cam # 944.105.155.05
int. duration: 228¡ (-1 +180 +49)
int. lobe-center: 115¡ after TDC (228/2 +1)
exh. duration: 220¡ (+43 +180 -3)
exh. lobe-center: 113¡ before TDC (220/2 +3)
exhaust stroke
TDC 0¡ TDC
360¡
TDC
360¡
BDC
180¡
BDC
540/180¡ cam # 944.105.155.9R
exhaust open
???
???¡ LC
intake duration 223¡
intake closes
???
???¡ LC
exhaust duration 215¡
exhaust close
intake open
???
power stroke intake stroke compression stroke
ignition
BANG!
lobe-center angle / separation
220¡ crank rotation / 110¡ cam
0.434Ó lift 0.472Ó lift
0.473Ó lift 0.473Ó lift
exhaust close
intake open
???

blown 944

IMO
Not a lot of difference. It just felt better on the top end.. slightly.

I changed some other things (S2 trans) shortly after so it was hard to compare for an extended period of time.

The early NA and turbo are the same the late na has a little more lift and duration on the exhaust

MM951

I have an N/A cam and notice virtually no difference

gt37vgt

Konstantine had one in his land speed record 951 what more evidence do you need

333pg333

Link?

gt37vgt

yeh I've been saying that but you said you can't get it off the other engine ...

I know this NA cam thing is a bit cheap for you how about i ingrave a fancy name on it and take heaps of your money would you feel more confident then ??

CarbonRevo

I plan to go with one in my 951 until I can afford an aftermarket cam. What are the specs for the 2.7 cam? (that list is too hard to understand).

piper161

I put a N/A cam from a 2.7 in my car just because the PO had damaged the cam trying to install a new seal and i happened to have a 2.7 cam laying around. Not much difference. Felt like it may have had a little more top end power if anything.

333pg333

What 'other engine' ?
It's not a matter of it being too cheap or custom or whatever. Thought it might be a good idea to actually ask if people had done it and what they thought. Doesn't seem like much of a reaction from those that have it? It doesn't look much different to the turbo cam in spec, but as you say if there is a small increase vs how cheap you can pick up an n/a cam, it might still be worth doing it.

EDIT: Sounds like the late model n/a cam can be picked up really cheaply so I might do it anyway. Sean says that he has done this and it allows more rpms up top but must be at the expense of a bit of lower down tq?

JohnKoaWood

+1 an additional 8 deg of exhaust valve open SHOULD add some power (read few HP) but could be a cheap few HP, are the lift the same between the 2 cams? If no difference in lift, the extra duration should help some (instrument the change, we will all benefit).

V2Rocket

if im reading it right the intake and exhaust valves overlap for 1 degree! lol

Olli Snellman

Turbo cam is the early N/A cam. From 1985½ N/A cam was changed; there's 1mm more lift on exhaust side. Otherwise it's the same. You can identify cams easily; three last digits on 951(old N/A) cam are 05R and new N/A cam they are 09R.
Patrick, can you PM me your email address. I have lost it. I have some cam info you might be interested of.

Duke

It's little bit more duration as well, but that has been stated earlier in this thread.