|
| |
|
| |
Buy with confidence!
If for any reason
you're not
completely satisfied
with an item, simply
return it within 7
days and the
purchase price will
be refunded.
|
|
|
|
| |
|
| |
We ship world wide.
All international
orders must be paid
online. Checks or
money orders drawn
on non-US banks will
not be accepted.
|
|
|
|
|
|
Turbocharging
|
|
|
Since a turbocharger is essentially an exhaust-driven supercharger, and because we’ve spent so
much of this book explaining how superchargers work, the best way to transition into talking about
turbos is to compare and contrast them with centrifugal superchargers. In an ultimate power
shootout, turbochargers always win. There is a reason F1 cars were turbocharged. Perhaps the
best example is the most powerful F1 engine ever created – the 1,500-cc BMW turbocharged
engine powering the Brabham car in the mid 1980s. It developed over 1,500 horsepower in
qualifying tune. That’s over one-horsepower per cubic centimeter of displacement!
|
|
|
 |
|
|
|
The twin-turbocharged Toyota iForce
V-8 that powers the Turbonetics Celica
is a masterwork of modern
turbocharger technology. The roller
bearing turbos spool quickly and feed
into a huge air-to-water intercooler.
This car was the first import racer to
run an NHRA sanctioned 200-mph
quarter-mile speed.
|
|
|
|
|
|
Getting back to turbo theory, the compressor section of a turbo is exactly the same as a centrifugal
supercharger; the difference is that the turbo uses another impeller and scroll housing, through
which hot exhaust gas travels to drive the unit. Thus the turbo takes no crankshaft horsepower from
the engine to run. Instead, it recovers some of the heat and mass-flow energy normally wasted by
the engine in the exhaust to do the work of compressing the intake charge. Combustion heats the
exhaust, causing it to expand; so the exhaust is already pressurized. The drive portion of the turbo
works in the reverse of the compressor side – it “absorbs” the pressure of the exhaust gas to spin
an impeller. The exhaust enters the impeller radially at the blade tips and leaves axially from the
center. The impeller of the turbo driven by the exhaust is connected directly, by a common shaft, to
the impeller that compresses the intake charge.
If the above is slightly confusing, let’s unpack the process by focusing on a few fundamentals.
Remember that the internal combustion engine is an air-consuming machine (burns air and fuel). A
turbocharger is an air pump that operates on the normally wasted energy in the exhaust gas.
These gases drive the turbine wheel, which is coupled to the compressor wheel. The turbine spins
the compressor wheel at very high RPM, and in doing so, increases the pressure and density of the
air in the intake tract. As a result of the increased mass of compressed air, more fuel can be
burned to produce more heat and pressure – and thus horsepower – from a given engine size.
|
|
|
To better understand turbocharging, you need to understand engine operation. Basically, it’s all
about pressure differentials and mass flow through the engine’s four-cycle process. To get any
useful force transferred to the crankshaft, you need to get very high pressure developed in the
cylinders. Near the end of the power stroke, even though most of the useful pressure has been
captured as work, cylinder pressures can still be quite high. At this point, the exhaust valve opens
and the high pressure releases its energy into the exhaust manifold.
The amount of energy released as waste into the exhaust is directly proportional to the power level
the engine is producing. For example, little energy is left over to exit into the exhaust manifold at
part throttle or at idle. On the other hand, at full throttle, full load, significant amounts of energy in
the form of high-temperature, high-pressure air is wasted in the exhaust system. The turbocharger
captures some of this energy and uses it to provide denser air back into the engine. The force-fed
cylinder develops more pressure and power at the crank, and so produces more energy to drive
the turbocharger – and the cycle begins anew.
|
|
|
However, the process isn’t infinite, and at some point the capacities of the turbocharger, the intake
and exhaust ports and manifolds, and of course ever-increasing friction, prevents further power
increase. Intuitively, it’s the physical limits of the engine, i.e., how much pressure it can contain,
which comes first. The engine is also limited by the ability of the fuel to resist detonation. There is
also a limit in turbocharged engine combinations that tuners call “crossover.”
In a properly designed and operating turbo engine, the backpressure should be lower than the
boost pressure until it reaches crossover. Crossover is the point at which the backpressure equals
the boost pressure. For example, with 10-psi boost in the intake, it’ll have 10 psi of backpressure. In
this condition, the intake pressure pushing on the piston when the intake valve is open equals the
exhaust backpressure pushing on the piston when the exhaust valve is open, so the forces cancel.
As the engine makes more RPM, the backpressure increases above the pressure on the intake, so
the force acting on the piston when the exhaust valve is open is greater than the force acting
through the intake. This resists the piston moving up the bore on the exhaust stroke, causing a loss
of power at the crankshaft.
|
|
|
In a race motor, an engine builder can optimize the RPM or power level at which this occurs by
choosing different combinations of turbine housing, tuned exhaust, head porting, and cam choice,
as well as compressor housing and impeller choices. For example, as a general rule, if you want to
build a low-RPM power combo, use a smaller A/R turbo, as it’ll reach crossover at a lower RPM than
a high-RPM power combo with a larger A/R.
We’ve already discussed the differences between turbos and crank-driven blowers in general.
However, some contrasts between turbos and belt-driven, centrifugal blowers – which seem, at first,
to operate in identical fashion – are very interesting.
Let’s first look at some of the less desirable features of turbochargers.
|
|
|
Previous | Next
|
|
|
|
|
|
|
|
|
|
|
This has been a sample page from
|
|
|
|
|
 |
|
Sport Compact Turbos & Blowers
by Joe Pettitt
|
|
|
|
|
|
Lightweight and high-revving, sport compacts are today’s most
popular cars. They have developed a cult following among today’s
youth and are fueling a multi-million dollar industry in modification
parts and equipment.
While most owners of sport compacts can afford the simple bolt-
ons available, some owners want to take their modifications a step
further. There is intense competition to be the fastest, and quite
often the only way to win is to go to the next level – by installing a
supercharger/blower or turbocharger on your engine.
This book is an enthusiast’s guide to understanding and using
turbochargers and superchargers on sport compact cars. It
covers the basics of each system and compares their pros and
cons. Building and tuning small-displacement 4- and 6-cylinder
engines to maximize performance and reliability with forced
induction is also covered.
|
|
|
Click below to view sample
pages from each chapter!
|
|
|
|
Chap. 1 - Exotic or Practical
Chap. 2 - Supercharging
Chap. 3 - Roots Blowers
Chap. 4 - Centrifugal Blowers
Chap. 5 - Turbocharging
Chap. 6 - Turbos & Compacts
Chap. 7 - Tuning for Boost
Chap. 8 - Building Engines
Chap. 9 - History
|
|
|
|
|
|
Softbound
8-1/2 x 11
128 pages
300 black & white photos
Item: SA89
Price: $18.95
|
|
Click here to buy now!
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
Other items you might be interested in
|
|
|
|
|
|
Turbochargers
How to select and install the correct turbo for big or small
horsepower gains. Discusses turbocharger design, sizing,
matching, controls, carburetion, exhaust, ignition,
intercooling, marine and high altitude applications. The most
comprehensive book available. Turbo suppliers and kit
maker addresses are included. “Everything you could possibly
need to know about turbochargers for automotive applications
is in this book.
|
|
|
 |
|
|
Price:
$18.95
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Engine Management: Advanced Tuning
Engine Management: Advanced Tuning explains how the EFI system
determines engine operation and how to change the controlling
parameters to optimize actual engine performance. This book takes
engine-tuning techniques to the next level. It is a must-have for tuners
and a valuable resource for anyone who wants to make horsepower
with a fuel-injected, electronically controlled engine.
|
|
|
 |
|
|
Price:
$22.95
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Shipping is combined and discounted for multiple item purchases!
Buy more and save on shipping!
We ship Worldwide! See International Shipping for more information!
|
|
|
Search Our Store for More Great Ford, Lincoln & Mercury Items!
|
|
|
FAST AND EFFICIENT SERVICE
We believe customer service and online retail can coexist. Our policy is to treat customers the way
we would like to be to treated. We strive to describe all items correctly. You have many options
online, but we believe our service is the best. We work around the clock to fill orders and ship items
within one business day. It is our goal to serve the customer before, during and after the checkout
process. Why gamble with your money and purchase from other sellers? We look forward to doing
business with you now and in the future.
|
|
|
FAST SHIPPING
Items usually ship within one business day of receipt of payment! We keep large quantities on hand
and have a state of the art inventory management system to ensure your items are in stock and
ready to ship.
|
|
|
YES, WE HAVE A RETURN POLICY
Satisfaction is guaranteed. Our store has a NO HASSLE RETURN POLICY within 7 days of
purchase. Your exchange will be processed upon receipt. If you are not satisfied with your
purchase, our knowledgeable team will do their best to make sure you get what you are looking for.
|
|
|
QUALITY AND AFFORDABILITY
Why pay retail when you can save money and benefit from our purchasing power? We stock large
quantities to get you the best prices and assure the item you order will be in stock and ready to
ship. We have a COMBINED SHIPPING incentive whereby each additional item adds $1.95 to the
s/h. The more you buy, the more you can save!
|
|
|
SHIPPING
Standard shipping is a flat rate of $4.95 to anywhere in the United States with USPS Media Mail.
Priority Mail shipping is available for an additional $3.00, or $7.95 shipping. Shipping is combined
and discounted for multiple items purchases as follows: first item regular price shipping, add $1.95
for each additional item.
INTERNATIONAL SHIPPING
We ship to Canada and Mexico with Priority Mail International for $10.95, and to most locations in
Europe, Australia, Asia, Japan and South America for $14.95. Shipping is combined and discounted
for multiple items purchases as follows: first item regular price shipping, add $1.95 for each
additional item. All international orders must be ordered and paid online, as we can no longer
accept checks or money orders drawn on non-US banks.
|
|
|
PAYMENT & SALES TAX
We accept Paypal, Visa, Mastercard, Checks and Money orders. Paypal is the preferred form of
payment. Our online shopping cart system is powered by PayPal, the most secure way to send
payment online. Iowa residents must add 7% sales tax.
|
|
|
If you have any questions or comments please feel free to contact us. We look forward to serving
you and fulfilling your needs.
|
|
|
Thanks for your business!
|
|
|
MRE
PO Box 47
Grinnell, IA 50112
|
|
|
|
|
|
|
|
