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Tuning for bigger cams
Posted by 85Turbosled [Email] (more from 85Turbosled) on Sun, 13 Sep 2015 12:17:21
Just looking for insight on tuning my recent install of some custom high(ish) perf cams.
Engine is an '85 with '88 pistons with slightly ported & matched 2.1 head and 2.1 manifold, FMIC, bigger injectors, 3"DP, 2.5" exh and many other little things.
compression check before cams was 180psi even in all 4, now its 150psi! Now im aware of course that cams can affect cranking pressure, but I didnt expect this much! Idle vacuum went from 21" to 16" so thats not horrible I suppose.
whats bothering me is the amount of timing I am now needing in this engine to get it to knock under stock boost is crazy. Old timing numbers around stock boost levels are as follows:
BTDC AT 11PSI
with the new cams installed in order to get repeatable knock the timing numbers look like this:
BTDC AT 11PSI
Initially without remapping timing, the car was an absolute dog, but after remapping the entire timing map, the car seems very nice, and on boost it absolutely rips your face off, especially +4000 revs!
has anyone experienced this happening on their Saab?
I of course realize that in order to make the best of any cams, especially aftermarket cams, I WILL need adjustable timing sprokets, and I will also have to phone back the person who made them for more specs so that Im able to correctly time them (LCA, Lobe sep, installed lifts, timing events ETC) but for now I just want to go fast and have fun (safely)
cam specs that I know:
Primary lobe, Duration @.050": 218Deg, .365" (9.3mm) lift
Secondary lobe, Duration @.050": 220Deg, .340" (8.65mm) lift
Duration @.050": 218Deg, .365"(9.3mm) lift
any feedback about tuning for more power and the odd timing amounts is appreciated, and yes I have checked that the cam marks line up exactly at TDC to the marks on the caps
posted by 70.69.16...
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