| RACE GAS RESULTS |
| RPM | TQ | HP | BOOST PSI |
| 3,800 | 1,075 | 778 | 17.6 |
| 4,000 | 1,078 | 821 | 17.6 |
| 4,500 | 1,079 | 924 | 17.7 |
| 5,000 | 1,075 | 1,023 | 17.6 |
| 5,500 | 1,017 | 1,065 | 17.4 |
| 5,800 | 971 | 1,073 | 17.3 |
| 6,000 | 938 | 1,071 | 17.3 |
| 6,200 | 906 | 1,069 | 17.3 |
EFI Rev-Limiting With Boosted Applications
One of the many benefits of EFI systems is their built-in rev-limiting abilities. At a preset rpm of the tuner's choosing, the system will randomly drop cylinders by cutting off fuel and/or ignition. Who knows how many engines have been saved by this technology, but there is a potential problem with engines under boost, especially the higher boost pressures this engine could see with racing fuel.
Wheeler Dyno Service recommends limiting rpm by dropping the ignition only, not by randomly shutting off injectors. This way the fuel is there once the cylinder gets spark again, so there is less chance of the cylinder firing lean and damaging the engine.
Yes, ignition-only cutout will cause some random rich cylinders, but that won't hurt anything, and the extra fuel will instantly clear once the power is back on.
| HPP ENGINE BUILDUP WORKSHEET |
| Engine Displacement: | 505 CID |
| Horsepower: | 920, pump gas; 1,073, racing fuel |
| Torque: | 829, pump gas; 1,079, racing fuel |
| Bore/Stroke: | 4.350x4.250-in |
| Bore/Stroke Ratio: | 1.02:1 |
| Rod/Stroke Ratio: | 1.57:1 |
Behind the throttle body is...
Behind the throttle body is the air-temp sensor and three vacuum/boost ports: one supplies both wastegates, one is for the 3-bar MAP sensor (attached below), and the third boost references the fuel pressure. One psi of fuel pressure must be added for each pound of boost so that injector consistency is maintained as pressure increases in the manifold-45 psi is standard.
The Target Air/Fuel ratio...
The Target Air/Fuel ratio table tells the FAST ECU what A/F ratio the tuner wants the engine to be running at every rpm and load condition that it could encounter. This program will compare the actual A/F ratio, as measured by the wideband O2 sensor, to this table and then attempt to add or subtract fuel to get them to match. It's critical that the tuner knows what these numbers need to be for the engine so there is a safe place to begin tuning.
Many of you may remember a...
Many of you may remember a recent European car commercial that, in part, went something like, "300 horsepower is fast; 400 will take your breath away." If that's the case, then 920 hp will cause a seizure and loss of consciousness. What's a little surprising is how flat the power curve is on this thing and how much power it makes down low. The engine is also unexpectedly smooth and quiet, even at max power. At idle, you can tell that it has a cam in it, but no one will ever suspect what's really going on with this one-until it's too late.