Is there any particular reason why all the diesels have turbo chargers rather than Superchargers???

Wouldn't a supercharger liven up the bottom end and help to eliminate the turbo lag???

Gerry

 

reliability mostlikely.

 

superchargers take power to make power...turbos use wasted energy and turn is in to power . aroots type blower will move a lot of air at idle but it would be hard to mount one on. and most modern paxton or vortec type blowers are basicly a belt driven turbo(no exaust turban) ...so why not just use a turbo its free power.

 

Old diesel used to have superchargers. the 8-71 blowers got their name by being on 8 cylinder diesels with a cylinder displacemint of 71 cub. inches. They switched to turbos for performance. super chargers take too much power to drive compared to a turbo and ca't flow the same air.

 

Your talking about a 2-stroke that needed the super-charger to move air into the chamber for start. They also had turbos to build real boost.

Randy

 

2-cycle diesels such as the -53, -71 and -92 series GM used scavenging air blowers. These are not superchargers (although they are used as superchargers in other applications) - they are required to move air through the cylinders in order for the engine to run.

Rusty

 

A Roots blower is still a supercharger whether it is for the purpose of maintaining air flow for an engine to run or pressurising an engine for power. Detroit 2 stroke diesels need the roots to run and in the end they were fitted with turbos above the blower for more power. This in it self created problems as turbo boost pressures rise to the point of over running the blowers speed. Detroit then installed blower air operated clutches to release the blower drive so the turbo could push the blower paddles fast than the mechanical drive. The Silver 92 series had this system and it definitely made more power than previous models along with other refinements in the gasket and leak prevention areas. Cat now builds the new series engines with 2 turbos for the afore mentioned reasons to reduce emissions and boost the bottom end. 2 turbos flow together while a blower would become a flow hinderance at higher air flow rates. In the end Detroit dropped the 2 cycle engines in favor of the 40,50,60 Series 4 stroke engines for reliability and economy producing less emissions through direct electronic fuel distribution DDEC1. Thats right Detroit was the pioneer in the total electronic fuel management systems surpassing the automotive industry by having zero mechanical connections to the engine other than the fuel peddle rheostat (TPS). Detroit Diesel still manufactures 2 stroke engines for industrial applications only and even they are being updated to DDEC 4 stroke engines. Street blowers also run at considerably less pressure than diesel turbo chargers on gas engines for anti-detonation reasons increasing mechanical reliability. PK

 

Supercharging, by definition, means the air pressure is higher than atmospheric pressure at the beginning of the compression stroke - that's why they call it super (meaning "above") charging - the engine is charged above atmospheric pressure. Scavenging blowers used on 2 cycle engines do not meet this criteria since on most 2 cycles the intake ports close before the exhaust ports/valves. This means that the trapped air in a non-turbocharged 2 cycle is basically at atmospheric pressure (minus exhaust passage flow losses) at the beginning of the compression stroke, and the engine, by definition, is NOT supercharged.

This is an industry definition - I'm quite aware of the implications of the use of the term "supercharging" since I've been an employee of an engine manufacturer for over 31 years with 27 of those having been in technical management.

Rusty

 

Both would be much better. Well I thought I had seen someone playing with supercharger on a Cummins.

http://www.turbodieselregister.com/f...d.php?t=126750

 

Yeah, Piers Harry and his guys were toying with a supercharger on a B-series Cummins.

Rusty

 

I think that should remove any lag from his twin setup .