Engle HEV 3945AS Camshaft
TO the OP
Where you install that cam is gonna depend partly on your Static Compression ratio, and partly on your intended usage, and mostly on your combo.
>If you have a low compression engine, you will want to increase the Dynamic pressure by advancing the cam well past it's straight up position.
> if you already expect a high dynamic pressure, you may have to close the intake later, to keep out of detonation on pumpgas.
>Of course factors such as Quench/squish and chamber desin will plasy key roles.
> and finally; a light street car, operating at sealevel, with a high stall and a higher than average second-gear ratio is gonna need a different set-up than than a heavier car, at elevation, with a crippling factory stall and hiway gears. It's all in the combo.
I like that cam. The first thing I always look at these days is the total of compression degrees plus power-extraction. A good target for a streeter is more than 227 degrees. If it has that, it's gonna have the potential to be fuel thrifty on the hiway. This cam has 132.5 before compensation for loss of duration due to lashing. This number cannot be changed, because it is a function of the grind. You can trade compression and extraction back and forth, in a modest window, to solve for tuning issues, for operation targets, or for fuel-economy.
For instance In at 104*, the compression degrees are (working off the advertised, is 121 degrees. leaving 111.5 for extraction. If at this number of 121, your engine detonates on an already fudged ignition timing curve, your next move is to reduce the cylinder pressure. You can do this, in the field, by retiming the cam up to several degrees later, stealing them from power extraction. Say you take 3 addition degrees from extraction, leaving 108.5 back there, and getting 124 degrees of compression. Those 3 degrees might represent up to 9 psi. and say your engine now stops detonating. All is good right?
Yes and no.
It's very good to not have detonation at WOT, so maybe at the New lower pressure, you can put the Power-timing back.
But
let's not forget the loss of extraction time. The WOT torque and power will shift to a new slightly higher rpm, and the loss of extraction at low rpm usually translates to a couple of things; 1) reduced fuel economy, which will be readily apparent in city use because of, the loss of torque down low. and 2) a drop in steady-state fuel economy, usually due to there still being useful energy in the expanding gasses release by the earlier opening exhaust valve. thus,
It behooves you to engineer the Static compression ratio, to achieve the highest Dynamic pressure ratio, working with a preselected Intake closing event, so that the Power-Extraction event can also be properly engineered for street fuel-economy, in these days of the ever increasing cost of fuel. and so, you get the exact right cam timing, the first time.
Now;
I know that I can get very high mpgs with as little as 110* of Power extraction, but it's gonna take a cruise rpm lower than 2000. But in your case, with this cam, the advertised (in at 104*) is 111.5, allowing a bit more hiway rpm. I also know that in the zone of 106 or less, fuel economy becomes atrocious even at 2200 rpm. And, I know that at 116* (what a 318 runs), economy can be off the charts at 65= sub 2000rpm. So the window, working off the advertised, is somewhere between 106 and 116..... so half way is exactly where this cam drops in at, when installed at 104*.
One thing I can tell you is that with an Ica of 57* or less at actual lash. You might have to reduce your Scr, to drop your Dcr out of the detonation zone with open chamber non-quench heads, so hopefully, you already engineered for that.