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Home > Performance Mods > Engine Mods > Beginners Introduction to Turbo Part II

Beginners Introduction to Turbo Part II

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Orin


Reg'd: Dec 08, 2005


do not post questions asking which kit will give you the most hp, it will be deleted. Open a new thread and keep post on topic

any discussion of which brand to buy will be deleted, open a new thread

This post is not an end all guide, but should help people who are starting to learn about turbo.




Twin Turbo? Sequential? What? Series?


In our previous post we talked about a single turbo set up which receives it's power from exhaust which spins the turbines and provides power to all cylinders, but there is a lot more than just single turbo out there. There are turbochargers that provide power to other turbochargers (sequential---used in diesel setups)

TWIN TURBO

image showing a monstrous Corvette Twin Turbo

In a twin turbo setup, one turbo compressor provides power to half of the engine's cylinders. Both compressors will provide air to the intake manifold simultaneously.


SEQUENTIAL TWIN TURBO

A sequential turbo runs a smaller turbo at low engine speeds and eventually moves to two parallel turbos at a certain engine speed or load. This setup allows the use of much larger turbochargers at high engine speeds without the lag due to the smaller turbo at low speed.


SERIES TURBO


Series turbos feed one off the other so higher levels of boost can be achieved, normally used in diesel setups.


TERMS TO KNOW



BOOST THRESHOLD
Boost threshold is the level at which there is enough engine speed to provide the exhaust needed to spin the turbines enough to create boost.



BOOST SPIKE
Boost spike is a period of uncontrolled boost usually in lower gears during the onset of boost. It happens when the boost controller can't keep up with the quickly changing engine conditions.



BOOST LEAK
A boost leak is exactly that, boost is escaping somewhere in either the turbo or the intake. Usually caused by a bad crack or seal or maybe a crack in the turbo housing.


BOOST CREEP
Boost creep happens when the opened wastegate can't allow enough exhaust fumes to bypass the turbo itself, so the boost keeps rising. Say you have your boost controller set to 8 psi, if you get boost creep, there might be a quick rise to 9-10 psi. This usually happens at higher rpm. You can avoid boost creep by adding an external wastegate.


BOOST CONTROLLER
A boost controller can be mechanical or electronic, but to make a long story short, it controls your boost by manipulating your wastegate actuator. During higher boost, the wastegate stays closed and to lower boost it bleeds the wastegate. The controller also makes sure the wastegate stays closed or opens depending on desired boost levels and conditions.

The type of boost controller you buy will depend mostly on your set-up and desired function.


TURBO TIMER
The need for a turbo timer will depend on how hard you use your boost. What the turbo timer does is allow the engine to run at idle for a specific amount of time after ignition is turned off. What this does is reduce something called "coking" coking is the burned oil deposits on surfaces which can lead to blocked passages.

Some turbos can cool off much more efficiently than others because they are water cooled, therefore the need for a turbo timer is practically eliminated.


INTERCOOLER HEAT SOAK
Intercooler heat soak is when the intercooler can't get rid of the heat it absorbs from the turbocharger fast enough, so it's not as effective. This is also why turbo cars tend to run slower in hot weather.



other helpful links

Beginners Introduction: Turbo

Wikipedia: Twin Turbo

last up dated on 02/11/08 --- 10:06 central by Orin

updated --- information about intercooler heat soak 02/12/08 --- 10:08 central
[#] Feb 11, 2008 10:56am
lee_tc


Reg'd: Jan 12, 2007

Vehicle Designer

ur the best orin


[#] Feb 11, 2008 12:49pm
Orin


Reg'd: Dec 08, 2005


^nah, I'm just sharing stuff I'm researching.

updated

added information about Intercooler Heat Soak

[#] Feb 12, 2008 11:12am
Racr350


Reg'd: May 18, 2007

Chief Mechanic

Thank you for posting about heat soak. People really need to know what that is and how much power you can lose due to it...


-BearZ Rules!
[#] Feb 12, 2008 11:15am
java09


Reg'd: Aug 05, 2007

Scion Guru

^^very true, i get much better boost response in cooler weather.. especially at night.. it also depends a lot on the quality of the Core and the tanks.

good stuff!


BOOSTED BY: TURBOTOYOTAS!

Need Something Installed in Hawaii? Click Me!
[#] Feb 12, 2008 11:28am
dsm3383


Reg'd: Mar 14, 2007

Scion Guru

Yes, intercoolers are air to air heat exchangers. So, it all depends on the ambient temperature of the outside air to determine the cooling of the charged air.

It's not really effective to cool hot air with hot air ya know!

Great addition Orin!

P.S.
Forced Convection heat transfer plays alot also if your intercooler is exposed to free flowing air while driving but that is another subject that I may explain at a later time.


Beer is proof that God loves us and wants us to be happy.

-Ben Franklin
[#] Feb 12, 2008 01:06pm
Racr350


Reg'd: May 18, 2007

Chief Mechanic

Another way to go for intercoolers are water-air. Sometimes you dont even need an intercooler if you know some tricks. My Uncle's Duntov Turbo Corvette uses winshield washer fluid that is injected straight into the turbo when its up on boost. Pretty clever for a 1980 Corvette. Then again Arkus Duntov is a GENIUS!


-BearZ Rules!
[#] Feb 12, 2008 01:12pm
dsm3383


Reg'd: Mar 14, 2007

Scion Guru

Racr350 wrote:
Another way to go for intercoolers are water-air. Sometimes you dont even need an intercooler if you know some tricks. My Uncle's Duntov Turbo Corvette uses winshield washer fluid that is injected straight into the turbo when its up on boost. Pretty clever for a 1980 Corvette. Then again Arkus Duntov is a GENIUS!


That is what is known as a "water cooled" turbo. All ball bearing turbos must be oil and water cooled.

A ball bearing turbo is faster to spool since it uses a ball bearing. But to add to being faster it also creates much more heat at the bearing. Thus, you need to water cool it so the turbo won't seize up on you. Journal bearings only need to be oil cooled due to how they work.

Usually you just tap into your radiator tubing / water pump and cool it that way but using windshield washer fluid is a good way too.

You must remember having any water get sucked up into your intake from the throttle body is VERY BAD.

The windshield washer fluid in the application your stating is not sprayed in the charge pipe to cool the charged air itself. It is only used to cool the turbo alone.

There is such a thing known as "water injection". This method is used for very high horsepower engines. To prevent detonation at extreme combustions, water is actually injected into the combustion chamber along with the fuel.

The only way to really have a consistent cooled charged air option is a water to air intercooler. This will involve a seperate water pump, resevoir, and much more to set-up. You do not want to use your radiator fluid cause it is too hot! It is very costly and space consuming in the engine compartment thus not really ever used.

If you want super cold air though you can go down the route of methanol injection. This includes shooting methanol directly into your charge pipe to go into your intake through your throttle body. Just like nitrous you can only carry around so much so it is best used for the track.

Beer is proof that God loves us and wants us to be happy.

-Ben Franklin
[#] Feb 12, 2008 01:40pm

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