![]() As for the "next best part" for your engine, I really don't think along those lines. When you stop seeing an improvement in the elapsed time in between your 2 set mph points, then go back to the best setting. Do 2 runs per setting over the same track distance. I would go 2 camshaft degrees at a time starting with the intake cam, since it also determines the reference baseline ignition timing as well (connected to the distributor). Variations in performance can occur simply from minor differences in assembly at the factory, engine break-in procedures (if any) by the owner, and owner maintenance. Just because someone has the exact same model Integra and parts as you, does not necessarily mean that their engine and yours behave identically. It's only sensitive to changes in the early part of the rpm range.Įach person's engine will have a different optimal cam gear setting for it. ![]() ![]() A change of 1 tenth of a second or more consistently is good.ĭon't rely on the butt dyno. You want a higher number if the cam gear setting is good. Acceration is the change in speed over the change in time. You want an objective measure ,like an acceleration time, to tell you if the setting is good for your particular engine. Have your friend time how long it takes you to go from say 30 mph to 90 mph. The point here is that, for each cam gear setting, do your timing over the exact same stretch of road and over the same exact distance. Do some wide open throttle acceleration runs at the 1/4 mile strip on a test & tune day. On a tuning session on the street or at the strip, I suggest that you do the cam gear tuning by going with a friend in the passenger seat with a stopwatch, if you don't have a datalogger that records speed and elapsed time. Have you checked to make sure that INTAKE 0 degree and EXHAUST 0 degree markings on those cam gears were indeed set at TDC? Decreases Piston-to-Valve Clearance Obviously, widening the LSA (decreasing overlap) does the opposite to these. Idle Vacuum is Reduced and Idle Quality Suffersġ0. Increase Cranking Compression and Effective Compressionħ. SUMMARY OF THE EFFECTS OF TIGHTENING LSAĦ. The idle suffers as you add more overlap since there's not enough vacuum at idle rpm. Less LSA is better for a racing engine than a high performance street engine. Less LSA increases intake and exhaust valve opening overlap which creates more scavenging and a stronger upper rpm powerband. Narrower lobe separation angle (with dots) produces more high rpm range and peak torque but with a loss of midrange. Wider lobe separation angle (no dots) produces more midrange torque but with a loss of upper rpm and peak torque. Hp and Torque Curves with Dots = Tighter LSA EFFECT OF TIGHTENING THE LSA WITH ADJUSTABLE CAM GEARS The trick is to find the best overlap for your particular engine's package of parts and unique way of breathing compared to everyone else's. If you want a higher powerband location, you tighten the LSA by rotating the intake and exhaust cam gears in opposite directions from one another in steady precise increments. When you tighten the LSA, you increase cam overlap duration. ![]() You do this by tightening the lobe separation angle (LSA) between the intake cam's and exhaust cam's lobe centers with your aftermarket adjustable cam gears. improvement), you need to increase the overlap. To shift or move the powerband up higher along the rpm range (for 1/4 mile et.
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