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By
now, you've probably read of Malvin Quinones' turbo magic (story),
transforming a mild-mannered Honda Trx400EX into a rocket. |
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Malvin's
company, Turbo Tech, of Aguada, Puerto Rico,
specializes in turbochargers for heavy industrial equipment, cars
and trucks. A devoted ATVer; Malvin successfully multiplied the Honda's
dyno-measured rear wheel horsepower by a factor of two (to 51.8 horsepower)
by implanting a turbocharger. |
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Why
not try this act on a Yamaha Raptor 660R? Ah, does the night follow
the day?
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At
right is the complete kit Broken down into each part needed to create
this (Intercooled Turbo-charged) Raptor 660R |
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Malvin
started his Raptor enhancement by selecting the proper turbocharger
for the conversion from gravity-fed, naturally aspirated carburetion
to fuel-pumped, turbocharger-boosted induction. A critical factor
in this decision is the Air Ratio, or AR; this figure must be selected
carefully, insuring appropriate response, minimizing "turbo lag"
when intake boost is called for. The turbo chosen for the Raptor is
the T25, manufactured by the turbocharger industry's world leader,
Garrett. Sized right, the T25's design encompasses the correct AR
of 0.35 to 0.49. |
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The
next step involved customizing the Raptor's exhaust manifold to
accept the turbocharger plumbing.
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The
Raptor's OEM manifold header was modified, permitting turbocharger
installation under the quad's seat. |
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While
the 400EX's manifold had to be custom-made (accommodating the turbocharger
forward of the engine), |
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After
mounting the turbocharger and connecting it to the exhaust
manifold, the fuel system required upgrading (carburetor jetting,
electric fuel pump integration; fabrication of intake plenum chamber,
etc.). |
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Next
came installation of specialized components necessary to finish
the job-such as a super power flow air filter, mounted on the left
front fender plastic; the "super sequential blow-off valve"
to relieve compressor surge pressurized air normally forced backward
through the turbo upon deceleration; |
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Fabricating
all-aluminum pipes from the turbo to the intercooler; then, from
the intercooler to the intake manifold and carburetors (modified
twin Mikuni 33 mm's).
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Operating
at the cutting edge of performance, as Malvin's turboed machines
do, knowing what's going on is a good idea. Measuring and control
system installation available provides important information and
controls critical processes:
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- A
boost gauge measures pressure above atmospheric (operating up
to 14 psi, nearly doubling atmospheric pressure).
- An
Exhaust Gas Temperature (EGT) gauge measures the intensity of
the air-fuel combustion (the Raptor operates up to 850 degrees
Celsius).
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fuel pressure gauge registers idle pressure from 2 psi to boost
mode, varying from 10 to 16 psi, depending upon demand.
- An
HKS Electronic Valve Control (EVC) unit operates as the turbo's
"brain," managing the wastegate position, controlling
turbo rotation at speeds up to 80,000 rpm.
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A
Turbo-Timer insures turbine bearings are lubricated during spin-down;
80 grand of rpm on dry bearings sounds, well, EXPENSIVE! Since
the turbine bearings are ordinarily lubricated by crankcase oil
under engine oil pump pressure, the Turbo-Timer insures a flow
of oil to the bearings during the interval between the time the
engine is shut off and the turbine coasts to a stop.
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Finally,
the 2-1/4" diameter exhaust piping (replacing nominal 1-1/2"
diameter stock plumbing) must be fitted to the White Brothers E Series,
or other custom muffler at the customer's order. Insuring adequate
exhaust system capacity is key to turbo performance on any engine. |
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The
really classy machine seen in Hector E. Vega's lyrical photos
accompanying this article, producing around 72 rear wheel horsepower
on Jose A. Velez' Moto Tech Service Dyno Jet dynamometer. |
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Malvin's
team effort was made possible with the help of Bernardo Cortes
of Junior Racing Watercraft and ATV, Domingo Aviles, Turbo Tech master
technician, and Gave Armijo of HKS, USA; manufacturer of essential
components used in the installation. Serafin Lorenzo applied his artistic
talents to the Turbo Tech signs, logos, and posters. |
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The
basic turbo kit, consisting of Turbocharger, White Brothers
E-Series exhaust with custom turbo exhaust pipe, custom aluminum plenum
chamber, electric fuel pump and regulator, modified carburetors, high-flow
petcock, and basic instrumentation and fasteners. Kits are available
now for either the Honda Trx400EX or the Yamaha Raptor 660R, priced
at $ 3.900; with intercooler, the price is $ 4,400. |
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Options
available include
White Brothers R4 exhaust, HKS Electronic Valve Control (EVC), chrome
filter cage, Super Sequential Blow-off Valve, Turbo-Timer, JE forged
piston kit, exhaust temperature gauge, and fuel pressure gauge. |
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What
Is A Turbocharger? Why Turbocharge?
A
turbocharger consists of a turbine (think of a fan blade) driven
by exhaust gasses; the turbine in turn drives a compressor, forcing
air into an internal combustion engine.
Since
more air is forced into the engine, more fuel is available also
for combustion and production of additional power, over a "naturally-aspirated"
engine.
How
much more power? Atmospheric pressure is about 14.7 psi; Turbo Tech's
ATV turbochargers boost intake pressure to around 14 psi above atmospheric
pressure; adding pressure equal to nearly another atmosphere. The
result: rear-wheel horsepower's of the Honda TRX400EX (51.8 hp)
and the Yamaha Raptor 600R (72 hp) doubling over stock ATV output.
Turbochargers
may be enhanced by "intercoolers," heat exchangers cooling
the compressed air entering the engine. When air or any gas is compressed,
the gas is heated. An intercooler, connected between the turbocharger
compressor and the carburetor intake, cools the compressed air.
Cooler air allows a higher boost pressure and contains more oxygen
molecules, permitting greater mixture combustion per unit time and
consequently, production of more horsepower.
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Read
about it in ATV
Sport ( May) issue. In stores now. |
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