Hemi engines are notorious for working the valvetrain hard, so there are no cutting corners here. Stage-V provided the stainless-steel roller rockers and special stands for their Millennium heads. These rockers provide oil directly to the pushrod cups, so oiling through the pushrods is not required. Rocker shafts are upgrades (thick wall) from DeChellis Machine, and the camshaft and lifters are from Comp Cams. Camshaft specs are 280/288-degrees duration at .050 inch, with .720-inch lift at the valve, and a 112 lobe separation angle. This is the same camshaft that was used when the engine was normally aspirated, and it doesn’t really stress the valvetrain. The Pacaloy 1247 valvesprings have pressures of 300 pounds closed, 730 pounds over the nose, and are set at 2.075 inch installed height. These will hold things stable to over 8,000 rpm.
The oiling system is a 10-quart pan with a dual line and a swing-arm pickup, feeding a high-volume Titan pump and remote two-quart Wix oil filter.
This is a 16-bolt EFI manifold from Indy Cylinder Head. This engine will be injected, and we will be running injectors both above and below the blower. Injecting below the blower adds difficulty in regards to plumbing and tuning, but it pays dividends. It’s a world of difference on a street engine because of improved drivability. But, even on a race engine, it helps minimize distribution differences, and it increases charge density. The injected methanol that doesn’t go through the blower cools the intake charge rather dramatically. It’s like nitrous without the bottle.
Roots blowers displace a fixed volume of air per rotation, so a 572-inch Hemi is technically a little too large for a blower rated at 10-71. But we don’t need much boost to meet the goal, and we’re willing to overdrive it if need be. Besides, we already had the blower.
The EFI System
We chose the FAST XFI system with internal data logging. The internal data logging is needed, since there’s no way to carry a laptop in the dragster. The data log function is critical to view what the engine was doing during the pass, and see the actual A/F ratio every 1⁄10 second. There’s just no better way to tune an engine.
Since this engine doesn’t use a distributor, we used the FAST XIM ignition controller to drive the eight ignition coils. A distributor would work fine, but we did this to show that it could be done, and to minimize the electrical noise that could be created by the sparks inside the distributor cap. Sequential fuel injection and coil-near-plug operation both require a cam sensor, which was easy to acquire with the exposed Jesel beltdrive. This would also be a good test to see if the standard MSD LS-style coils have enough energy to fire the super-rich Methanol charge under boost conditions.
Methanol is almost an ideal race fuel since it carries some oxygen and cools everything it touches. About the only drawback is that it’s corrosive. This has to be considered, since contamination of fuel systems cannot be taken lightly. But if you do your homework, you can learn to not only live with it, but love it. Here are some characteristics and considerations:
- Methanol (Methyl-Alcohol) (CH3OH), has a specific gravity of .78 - .79, and weighs 6.5 pounds per gallon.
- It is non-edible. In fact, it is poisonous.
- It’s a clear liquid that also burns with no visible flame.
- It mixes with and absorbs water, so it must be stored in sealed containers.
- You burn twice as much as gasoline.
- Ethanol is derived from renewable sources such as corn. In its purest form, it is drinkable, so it is combined with other liquids to make it not suitable for consumption. If this was not done, many ethanol racers might never make it to the track. E85 is 85 percent ethanol and 15 percent gasoline.
All of the fuel system components must be alcohol compatible. That should be obvious, but even the normal stainless steel braided hose is still just rubber hoses with a braided cover. You need to use hose that is rated for alcohol, such as Earl's PTFE-lined Ultra-Flex, and all fittings must be anodized. The fuel pump must be up to the task of not only the higher fuel pressure needed for EFI (greater than 43 psi), but also the higher volume requirement (2:1). Fuel filters cannot contain a paper element when using alcohol. Once complete, an alcohol fuel system will last for years. As an additional precaution, many racers add a lube to the Methanol, which coats aluminum surfaces. But some Methanol blends come with this additive already blended in.
As already stated, Methanol is a great fuel. If you didn’t change anything else, you would pick up about 10 percent in horsepower, and also gain consistency at the track. It has a very high latent heat property, which means it evaporates very quickly, and thereby cools everything it touches. This increases charge density and makes the engine less susceptible to detonation and environmental changes.
But your engine will consume twice as much as compared to traditional fuel. With a carburetor, this means you need to run huge main jets, which usually results in very rich idle conditions. With EFI, this can be controlled so that overly rich conditions don’t occur. Methanol engines are known to “milk the oil” (excess Methanol actually gets into the oil pan and makes the oil look like chocolate milk), but EFI can minimize that characteristic.
Methanol is very forgiving in regards to tuning. It has a much wider air to fuel ratio (A/F) range than gasoline. With a blown gas engine, the tune must be dead on, and would use a very high-octane (read: expensive) fuel. Methanol tolerates being on the rich side, and since it doesn’t produce carbon, it won’t foul plugs. You also won’t find an Octane rating for methanol, because of its different characteristics. Try building a blown gas engine that starts with a 13.0:1 static compression ratio. It’ll detonate and destroy itself during the first pass, but this is a normal, static compression ratio for a blown alcohol engine. Dynamic compression ratios with a boosted alcohol engine approach 30.0:1. So we have to change how we think about Octane and compression ratios when using Methanol.
For what it’s worth, many racers with a blown, alcohol engine don’t even know what their A/F is, since the only way to measure it mechanically is to weigh the fuel and the air (hard to do during a race). But a modern wideband O2 sensor works great to about 3:1 and it comes free with EFI. Wideband O2s are becoming more common in the racing world, but just like anything else, change takes time.
This is only the first of a three-part series that will show you exactly what goes in to building an injected and blown Hemi. This first installment covered the objectives, component selection, and design considerations. The second installment will cover the machining and assembly procedures, and show the differences from a “normal” street Hemi. Finally, in the third installment, we get this beast on a dyno, make some pulls, tune it, drop it in a car, and make some runs.
So we have our targets, and we have a handle on the rather interesting characteristics of Methanol as a fuel. Next month we’ll build this beast and see some special assembly techniques.
|Coated Main Bearings
|Coated Rod Bearings
|Rocker Shaft Supports
|Adjuster studs and nuts
||Stud# 823, Nut# 851
|Oil Pump Internal Pickup
|XIM coil controller
|Main Stud Kit
|L19 Head Studs
|Crank Support Cradle