Ivhdude,
I have had an Accusump in mine for about 9 years. I have never had it loose pressure, even after weeks (maybe a month?) I run the electric type and it works great. Its wired to open when you turn the key to power on (it also has an off switch on the dash) Its very nice. Turn the key and hear the click, and hear
oil flowing and charging the system. Wait a few seconds for the
oil pressure gage to come up (25-30 lbs, it was 40 9 years ago! lol) give it a couple of squirts of fuel and it fires right up.
Compression for 91 octane: That depends on so many things it hard to throw out a number. Many things contribute or detract from detonation resistance. Combustion chamber shape, squish, valve overlap, ignition, vehicle weight, trans, load…. It goes on and on. IMHO, you’re pretty safe @10.5-1 with Alum heads in a Cobra. I wouldn’t get too concerned about trying to squeak every last point of static compression out of a street motor. Set a power level and work towards it keeping in mind want you want it to do.
“Too much” cylinder head flow: It easy to get caught up in the “More is better “mentality,
But on a street motor, the short answer is yes.
500+cfm race heads are cool…but they require huge cross sectional area and lots of port volume to flow those big numbers . Sadly coming off idle, those huge columns of air are moving slowly and resist changes in velocity(read crappy throttle response).Couple that with the fuel falling out of suspension and puddling on the port walls and valves (read hard to tune, snotty, stinky idle and generally unhappy) is not what most people look for in their “FUN CAR”
Those heads are great at pushing dyno needles into the nether regions, But they suck at performing mundane street tasks.
In a street motor, drivability is important with Fun being the primary goal, not 10/10ths performance.
The ability to lug away from a stoplight or creep along in traffic on a congested highway is worth more than most would realize. The smaller ports of “street heads” will serve a street car so much better when cruising around town, or playing up in the canyons or mountain roads.
Remember, street heads like the Ford/Kaase SCJ and P51 regularly make 750-900hp (with known builds of the P51 exceeding 1000hp on race gas). That kind of power gets it done for most people. But if your needs exceed that, race heads ( TFS “A”, Ford “C”, Thor, etc) are where you should be looking.
I do believe that a good port EFI system will help to tame a big race head.
Jason