INDUCTION
Feeding this engine may seem like an easy task, but this is not so. We have a very efficient intake port in the AFR head, and feeding it becomes quite a task at low rpm. As we mentioned earlier, the proper size port was the goal, and we were leaning toward a 190cc port to ensure good velocity. We chose the 210 for increased power potential upstairs and knew feeding it right off-idle may be a challenge. Also, knowing our cam of choice may be a bit choppy until it gets past 2,500 (or so) meant an efficient intake/carb combo was in order.
We looked over all our research and decided on Edelbrock's Performer RPM Air Gap intake. This super-efficient piece has all the features we want in a performance intake while maintaining streetable manners. We also like their new Perma Star finish, so we ordered PN 75012 (right). The "as-cast" finish is shown on the left; also a Performer RPM Air-Gap. This tall dual-plane design delivers torque down low without losing anything in the higher rpm bands, and since our redline will be in the 6,500 rpm neighborhood, the RPM Air Gap is a good match with the rest of our performance package. We'll run it untouched, just like the heads. The chrome-like Perma Star finish looks great without the maintenance polished intakes require, and looking good never hurts, especially when you can back it up with serious performance.
We've chosen a BG Demon carb with removable venturi sleeves so we can test different carb flow rates to find the best-possible scenario. Many tuners know how running the carb a bit rich can help keep detonation at bay, and should we encounter issues the Demon is flexible enough (through its wide range of fine-tuning adjustments in addition to the venturi sleeves) that we should be able to tune away any potentially damaging problems. We'll also test a series of carb spacers to see how they affect the results and if we can find more streetable power by using them. Both HVH Super Sucker and BG Fuel Systems spacers will be tested.
We like carb spacers for many reasons, and with the variety of designs available, power always seems to be found when the correct design is used. We'll be testing open, four-hole, and tapered four-hole designs on this project. We've seen increases in off-idle response and general power gains at most rpm levels when spacers are added (versus not running any spacer at all). Also, the fact that spacers isolate the carb further away from the heat of the intake manifold is always a plus, as any technique that keeps heat form the carb and therefore the incoming air/fuel charge offers a denser mixture to the port. A denser mixture carries increased oxygen, which is what burns in the chamber. More oxygen means more power, and that's not in question.
Spacer research is one of the hottest areas of innovation and development at this time, and hopefully our research results will help solidify which design is best for street enthusiasts using the popular Edelbrock Performer RPM Air Gap intake atop good-flowing cylinder heads like our AFRs. Dual-plane intake designs react differently to spacers than open single-plane intakes, and we're anxious to see how much can be gained, and which design is responsible for the greatest efficiency increase.
IGNITION
An MSD ignition system will be utilized so we can fine-tune our timing curve to achieve the best-possible results. It's possible to add a few degrees of timing and add to the detonation avoidance in some cases, especially when a well-designed combustion chamber is part of the program. Having a surefire spark is an absolute necessity to try and burn as much of the 87 as possible, and having the multiple firings MSD is named for will assist in this further, especially at the critical lower rpm levels we expect the worst fighting to occur at. Having a tried-and-true MSD 6AL box and coil attached will give us plenty of ignition power and the accuracy to fire it when we want, instead of when it feels like it.
Many enthusiasts run this basic MSD ignition system, and rather than choosing a more expensive digital or programmable setup, we felt it would be in the best interest of our readership to base our research on an ignition system many of our readers already know well.
COOLING
Keeping temps down is a huge part of fighting detonation. We've added a Weiand high performance water pump to the engine to work in concert with the many other aluminum components we've got and the teaming of these aluminum components will act as an efficient heat sink.
We'll plug in a 160-degree thermostat and we'll be cooling through an aluminum high-flow radiator in the car, but for the dyno test-and-tune sessions we'll keep temps in the 160-170 range, like we hope the engine will maintain in the car. We will experiment with temperature ranges, but we're confident cooler will be better here.
THE OILING SYSTEM
The lubrication system is also being treated like a cooling system, since in many ways, it is. Adding additional oil to the system (by using a deep-sump Milodon pan/pickup combo) is a big part of that, but also paying careful attention to windage control is a big part of our oil system design. While not directly cooling-related, it is still a power tip. An effective windage tray serves to pull oil off the spinning reciprocating assembly (which is also smoothed to encourage this action) and not force the crank to carry this additional weight around every turn. A lighter crank means more power to the flywheel, and that is precisely our goal.
Like the crank/rods/pistons, we chose to run a "system" of parts designed to work perfectly in concert. The Milodon oiling system (consisting of a matched pump, pickup, oil pan, and windage tray) is engineered to provide outstanding performance in applications like ours. The pan is deceptively stock-appearing, which means fitting in our street-based chassis will be no problem. Engineered inside are the oil control devices we've mentioned, and the "kit" aspect saves time and headaches.
SUMMARY
So, that's our theory. We've done plenty of homework and have come up with a battle plan to fight for true street performance using the least-expensive fuel possible. We want to be able to rely on this engine to get us around town, and we've built in plenty of durability for weekends at the drags or on the road course. Should we encounter heat and/or detonation issues in the depths of the hottest summer heat or during heavy towing or racing, adding a bit of premium or relying on tuning information gleaned from our time on the dyno should clear everything right up. This has got to be a better daily driver option than a lifetime commitment to pricey 92-octane. We have done our best to design a detonation-fighting powerplant capable of serious performance on bottom-dollar gasoline. We think this is the kind of story readers want to see, and hopefully the tips and tricks we've shared will help make 87-octane performance less of a misnomer and more of an honest goal for the future. Unless gasoline prices begin to drop dramatically, we genuinely feel this route may be our future, and we're preparing for it now. Let us know how you feel about it.
AFR 210cc HEAD SPECS: PN 1050
Basic Package Components:
100% CNC Ported Combustion Chambers
100% CNC Ported Exhaust Ports
70% to 100% CNC Ported Intake Ports
3-angle Valve Job
Intake Valve, 2.080" x .050" long, AFR #7018
Exhaust Valve, 1.600" x .050" long, AFR #7057
1.550" OD Roller Valve Spring, 220 lbs. on seat,.670" maximum lift, AFR #8000
10o 4140 Chrome Moly Retainers, AFR #8510
10o Valve Locks, AFR #9005
7/16" Rocker Studs, AFR #6405
5/16" Guide Plates, AFR #6105
Valve Seals, AFR #6611
Hardened Shims, AFR #8045
Intake Valve Seats, AFR #9060
Exhaust Valve Seats, AFR #9070
Bronze Valve Guides, AFR #9050Special orders available on request.
Specifications, Features, and Supporting Components
Head Torque 65-70 Ft. Lbs.
Rocker Stud Torque 55-60 Ft. Lbs.
Intake Port Gasket, 1.310" x 2.180" w/ 3/8" radius, AFR #6820
Important: Do not port match your intake manifold to this Fel-Pro gasket, as they do not exactly fit AFR heads.
Intake Gasket Option, 1.280" x 2.090" Fel Pro #1205, AFR #6810
Exhaust Port Gasket Fel Pro #1406, AFR #6835
Head Gasket 350cid Fel Pro #1003, AFR #6800
400cid Fel Pro #1014, AFR #6802
Head Bolts & Studs Standard ARP, AFR #6310 & #6305
Head Bolt Washers Manley, AFR #6320
Stud Girdle AFR #6201
Spark Plug Starting Range Autolite 3910
Combustion Chambers 76cc
Spring Pocket can be cut to 1.750, no deeper.
Valve Spacing Standard
Rocker Arms Standard
Valve Angle 23o
Angle Mill (milling available) .008" per cc
Flat Mill (milling available) .006" per cc
Pushrods 5/16" Hardened, AFR #6601 thru #6604