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Hello everyone,
In my search to understand camshafts for older 2.0L turbo saabs, I came across many differing data sheets which describe the duration, and degrees, of certain cams. Mainly there were discrepancies about older model camshaft degrees.
I'm going from cam information I found from a saabnet post from Simon, which shows the actual saab documentation of the camshaft degrees... which the image should be at the bottom of this page, original post linked as well.
I was lead to believe that putting an NA 2.0 or 2.1 intake cam on, coupled with an 85 turbo exhaust cam was the "best" setup for a 2.0L turbo engine wanting to make lots of power.
After My own research I'm not convinced, although I know a lot of you have tried it, and liked it, I've also talked to a few who didn't.
I guess it depends on what else you're running, and what you're trying to do.
Currently, I have a 2.1 NA intake cam on, and a 86-89 2.0turbo exhaust cam on, and I'm not entirely happy with it. (haven't found an 85 exh cam yet to try)
However, I'm running a 2.1 ported head and intake, t3/t4 turbo, jak's stage 2 ecu chip, Group9 APC chip (brads maybe), 34# redtop injectors, 3.0bar FPR, open intake, full 2.5" stainless exhaust (abbott racing oldschool) and a few other mods... on an 1988 9kt with airflow kit.
I'm finding that I'm making way too much torque in the low RPM range to help the turbo do anything in the mid to high rpm range... and I think the power curves of my hardware are sort of overlapping or working against each other. I get nothing in first gear, feels like boost is limited, then I get a lot of wheel spin in second around 2500 to 3000 rpm unless i baby the gas pedal, then 3rd is nice if i baby it a litle, but by the time my turbo is in full swing, it just feels a little off...
timing is 22degrees BTDC as recommended by dave from group9 (i'm using his AID)
This is MY data that I've come up with, Using this information coupled with a camshaft calculator at this website
http://www.rbracing-rsr.com/camshaft.html
also i read this post to understand lobe separation benefits, and overlap benefits, but it looks like his tables were messed up in the post
http://www.saabnet.com/tsn/bb/performance/index.html?bID=57165
HERE IS MY CAMSHAFT COMBINATION DATA.. all the combinations you would want to do... (lobe separation calculations shown)
THE FIRST ONE BEING THE ONE I WANT TO TRY, due to larger intake duration, overlap, and a better lobe separation angle. The second one, with STOCK CAMS, appears to be better for higher RPM than using the NA intake cam... but we can argue about that later...
_______________________________________________________________________
86- early 89 Turbo intake cam / WITH 85 turbo exhaust cam
Intake Duration of 252.00 degrees.
The Exhaust Duration is 252.00 degrees.
Overlap of 32.00 degrees
The Inlet Cam has an Installed Centerline of 110.00 degrees ATDC.
The exhaust cam has an Installed Centerline of 110.00 degrees BTDC.
110+110/2 = A lobe separation of 110 Degrees
________________________________________________________________________
86-early 89 TURBO intake cam / WITH 86+up TURBO STOCK exhaust cam
Intake Duration of 252.00 degrees.
The Exhaust Duration is 254.00 degrees.
Overlap of 29.00 degrees
The Inlet Cam has an Installed Centerline of 110.00 degrees ATDC.
The exhaust cam has an Installed Centerline of 114.00 degrees BTDC.
110+114/2 = A lobe separation of 112 Degrees
_______________________________________________________________________
NA intake from all 2.0i, 2.1i, and 89+up 2.0TURBO / WITH 86+ turbo exh cam
Intake Duration of 240.00 degrees.
The Exhaust Duration is 254.00 degrees.
Overlap of 29.00 degrees
The Inlet Cam has an Installed Centerline of 104.00 degrees ATDC.
The exhaust cam has an Installed Centerline of 114.00 degrees BTDC.
104+114/2 = A Lobe separation of 109 degrees
_________________________________________________________________________
NA intake from all 2.0i, 2.1i, and 89+up 2.0TURBO / WITH 85 turbo exht cam!
Intake Duration of 240.00 degrees.
The Exhaust Duration is 252.00 degrees.
Overlap of 32.00 degrees
The Inlet Cam has an Installed Centerline of 104.00 degrees ATDC.
The exhaust cam has an Installed Centerline of 110.00 degrees BTDC.
104+110/2 = A Lobe separation of 107 Degrees
Based on what I've read...
CAM duration is an "overused" specification when deciding which cams to buy, but certainly when you see performance cams, the "higher performance" cams have LARGER duration numbers...
This is what confuses me about anyone wanting to use an NA cam on a "high performance" saab engine... you're lowering the duration... and you're also lessening the OVERLAP unless you use it with an 85turbo exhaust cam...
but even when you use the 85 turbo exhaust cam with an NA intake cam, you're LOBE SEPARATION isn't as wide as using that same 85 exh cam with an 86-89 stock turbo intake cam... which pushes the lobe separation to 110
I'm looking for some people to explain why exactly putting an NA intake cam on over a 86-89 stock turbo intake cam would be beneficial if you're trying to make more power.
Let's discuss...
-Gavin
http://www.saabnet.com/tsn/bb/performance/index.html?bID=112206
, Fri, 9 Jan 2009 18:50:33
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