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An in-tank fuel system is recommended for a number of reasons. First, a Chevrolet production in-tank system will ensure
that no vapor lock issues arise. Vapor lock is a common problem with in-line fuel pumps. In high ambient temperatures the
fuel in the fuel line can vaporize. An in-line fuel pump cannot move this vapor at the levels required by the fuel injection
system. As a result, the fuel pressure at the fuel rail drops, and a number of problems arise. These problems include a
stumble or sag to a worst case of a stall and no start condition. Using a Chevrolet in-tank fuel system will ensure that this
problem does not occur on your vehicle. Second, the in-tank fuel delivery system will have a return line plumbed into the
fuel sender unit. This return line is required for proper operation of this system. The fuel regulator, mounted at the fuel rail,
maintains the correct fuel pressure being fed to the injectors, based on intake manifold vacuum. In general, the fuel pump
will supply fuel at a pressure greater than required at the rail. The regulator then bleeds off this extra fuel to maintain the
correct pressure. The fuel that is bled off needs to be carried back to the fuel tank, via the fuel return line. Third, the fuel
tanks used with in-tank fuel systems have baffles in them. These baffles ensure that the fuel pump will have fuel available
as long as a sufficient amount of fuel is in the tank. The baffles keep all of the fuel from collecting at one side of the tank
during hard cornering, or at the rear of the tank during hard accelerations.
If you are installing this package in a vehicle that was originally equipped with a carburetor, the fuel lines will need to be
upgraded as well. The lines must be able to handle the increased pressure required by the fuel injection system. Do not
use barbed fittings or worm clamps to secure the pressurized fuel lines. Also, ensure that the rubber lines are removed
and replaced with fuel lines of sufficient strength, Aeroquip AQP fuel line hose with a stainless overbraid and AN style
fittings for example. Finally, use caution in routing the fuel lines to ensure that the lines are not located too close to the
exhaust system and are protected from road debris or obstructions.
The fuel filter recommended for use with this system is part number 25171792 (AC #GF626). This filter is a 10-micron
filter with 3/8" fittings on each end. The fuel filter should be installed between the fuel tank and the fuel rail, typically
located close to the fuel tank.
Headers:
A RAMJET 350 engine should be equipped with a header exhaust system for maximum performance in applications
where a non-production exhaust system is legal. All of the calibration development work was done with a header exhaust
system installed on our development engines. Installing production style exhaust manifold may increase backpressure
and alter the performance of the system. The recommended header configuration is 1-3/4" diameter primary pipes, 32 to
36 inches long, with 3" diameter collectors. Use 2-1/2" diameter tailpipes with a balance tube ("H" pipe) and low restriction
mufflers.
350 RAMJET Operating RPM Ranges
Thinking about the intended usage of the vehicle you will be installing your RAMJET engine into will allow you to make
good decisions on your total vehicle package. To get the most effective usage from your crate engine, you should
attempt to design the rest of the vehicle to complement the effective engine RPM range. Consider the weight, gearing
(transmission and axle) of the vehicle, as well as the vehicle speeds and geography (hilly or flat) that you will most likely
be driving in the majority of the time.
The RAMJET 350 engine makes peak horsepower at 5100 RPM. A good rule of thumb would be a highway cruising
speed that places the engine at an RPM in the range of 60-70% lower than peak. Using this example would place optimal
highway engine speed at 1500-2000 RPMs. Heavier vehicles (over 3500 lbs) would perform better using a combination at
the higher end of this range and lighter vehicles (under 3000 lbs) would be better suited near the lower end of this range.
Things that impact final gear ratio are:
•
Tire Size
•
Axle Gear Ratio
•
Transmission Gear Ratios (with or without overdrive)
•
Torque Converters (stall speed selection and/or with or without lock up feature)
Some handy formulas are included below to help make informed decisions. Insert your numbers into these formulas to
help you decide what will work best for your application.
Tire Diameter = Measured in inches
Ramjet 350 Engine
TITLE
ALL INFORMATION WITHIN ABOVE BORDER TO BE PRINTED EXACTLY AS SHOWN ON 8 1/2 x 11
WHITE 16 POUND BOND PAPER. PRINT ON BOTH SIDES, EXCLUDING TEMPLATES.
TO BE UNITIZED IN ACCORDANCE WITH GM SPECIFICATIONS.
19417614
IR 13SE18
PART NO.
DATE
13SE18
Initial Release - Alin Dragoiu
10
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REVISION
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