Quote:
Originally Posted by DorkMissile
Unfortunately so much emphasis is put on the idle sound. Yea, 8-10 degrees of overlap will get you a lot of attention when you putt around at cars & coffee, but you are going to trade drivability and cruising power for it.
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Guilty as charged, BTW the car runs and drives fine with no lack of power. I had to embrace the new world order. Cams are ordered for sound now by many people, they are sold and marketed that way. I was a bit strange at first, but true.
Also a centri's boost curve further up in the RPM range can take more overlap vs a roots. Cam Motion makes completely different grinds based on the type of supercharger. The higher RPM and bigger overlap helps keep the torque flat and stable to the upper RPM ranges 6000 to 7200 rpm. Boost NOT being blown out the exhaust at 6000 RPM BTW. This lower (in terms of ft-lbs), longer torque curve allows the drivetrain to live, helps with traction on street tires and at least for my m6 adds to power under the curve, a 7200 RPM shift puts me into 5000 rpm range during the shifting where the centri is building more than enough boost to send the car into the weeds. I believe the M6 is rated at 500 ft -lbs engine... so at least to my mind limiting torque and bringing it further in the RPM is a easy way to have the HP (torque x RPM), and save the drivetrain. I figure I'm anywhere between 1000 to 2000 full throttle run thru the gears now and just started on my 4th set of back tires in 20K miles with no burnouts, just running through the gears
I think I'll do some runs today on my way to Yoga... and quite meditation, puts me in the Zen mood. I don't have a roots or an auto so got no idea what works on the street for either. M6, centri and summer tires it is HP between 6000 to 7200 RPM that can be applied gently to the ground, well at least in 3rd... I bet my 0-60 already in the 3.6 range is better now cause I don't have to shift.... LOL
Nutshell with stock CR forged pistons and a centri, more overlap can be had I'm at 5.6 degrees (less than I thought but my lobe lift is less), I'm sure if this was a standard Texas Speed lift spec I'd be at 8 degrees or so.
https://www.tremec.com/anexos/TREMEC_TR-6060_1017.pdf the M6 has a 1.78 2nd gear.
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Forged short block, large duration sub .600 lift Cam Motion cam, 7200 RPM fuel cut, Pray Ported Heads, 3.85 pulley D1X, stage II intercooler, DSX secondary low side, DSX E85 sensor, Lingenfelter big bore 2.0 pump, ported front cats, 60608 Borla, LT4 injectors, ZL1 1LE driveshaft and Katech ported TB, ported MSD intake, BTR valvetrain, ARP studs, ProFlow valves, PS4 tires.