Turbo theory

Alright, looks like I finally found a website where people know what they are talking about. Here is my question, err, questions... Is there a device on the market that will measure pre-turbo exhaust pressure? also, is there one that will measure turbine rpms. finally, when exhaust gas causes the exhaust turbine to spin, what kind of reduction gear (if any) connects the exhaust side to the intake side? Let me know if your a turbo expert, cause i have a few much more technical questions for you.

1. I don't know of any name brands of products that can measure that and stand up to the heat.

2.turbine RPMs, same as above.

3. No gear reduction exists between the exhaust side and intake side. The turbines are pitched and angled differently.

So, its basically (very basically) like the difference between a fan with more surface area to act (say 5 blades) on spinning a fan with less ( 3 blades)?

Sport Compact Car had a great ongoing series on turbocharging.

Check out the "Suck, Squish, Bang, Blow" article in the October 2001 back-issue at your local library for a great technical primer. Should answer most of your questions ...and probably a bunch that you haven't come up with yet :-)

Originally posted by DBainer
So, its basically (very basically) like the difference between a fan with more surface area to act (say 5 blades) on spinning a fan with less ( 3 blades)?

The compressor sections are also always large than the turbine section (in a modern unit), and although both look similar there are differences in how they operate. I recommend you first purchase Corky Bell's "Maximum Boost", the definitive book on turbocharging IMO. It's on Amazon.

You can use the exhaust pressure to control a wastegate so you can probably measure it to. But why? Check the temperature instead, higher temperature = higher pressure.

Yes you can measure turbo rpm. Turbos used in rally (wrc), cart and lemans races uses a turbo speed sensor. The ECU uses this infomation to improve engine control.

A turbo can spin over 200,000 rpm, the turbine wheel is directly connected to the compressor wheel. How big the housing seems to be doesn't matter. It's the A/R ratio, and airflow capacity which are most important.
Higher A/R, more high end hp. Lower A/R will have the opposite effect. With higer airflow capacity (m^3/s - CFM) the turbo can give more hp to the engine. When the turbo flow more than the engine can use this will make a boost which force in more air to the cylinders.

Let's take a Holset HX50 as an example. It is a modern turbo, and the compressor have 7 fins and the turbine 12. Its weight is around 15 kg, yes it's heavy - I know, but it's built to hold. It is recommended to diesel engines up to around 450 hp, but if we put it on a modfied gas engine it will probably handle to deliver air up to 750 hp, or maybe even higher.

Here's a few manufacturers (all?)
Garrett - www.egarrett.com
Holset - www.holset.co.uk
Mitsubishi - no known hp
KKK (Kuhle Kopf Kausch) - no known hp
IHI - no known hp
Schwitzer - no known hp
Rajay - no known hp
Turbonetics - www.turboneticsinc.com

Yes, maximum boost is a very good book about turbos, advanced engine technology is also a good book even if it is about all piston engines.