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(erielack) Re:ALCOS
EMD did not use turbo chargers until the GP20 so all their early units do not use them. Remember EMD's are 2-cycle engines with a scavenging stroke which requires the roots blowers (not really a supercharger). Alco, Baldwin, GE's are 4-cycle. The exhaust gas pressure between the two designs is very different. 4 cycle engines have exhaust pressure which can drive a turbo while the two cycle would need to be at much higher RPM's.
The clutch drive mechanism for driving the turbo on an EMD (GP20 thru GP35) is complicated and very expensive and technical to replace. On the other hand a turbo on an Alco is a simple device capable of being changed out by any shortline shop. Look at how many original configuration GP35's are in service today versus the Alco C424/425 which was the equivalent machine.
The new type of fuel-limiting governor is being applied to Alco's also. The D-L has several of their Alco's equipped with them. You do not see heavy black smoke from these locomotives. New acquisitions such as LV 414 and some other are amoung those not with this type of governor.
Rich Jahn
On Oct 11, 2012, at 9:05 PM, Richard Onorevole wrote:
>
> Being out railfanning on the Delaware Lackawanna today I saw some first
> hand examples of Alco's and smoke. One of the better relations I've heard
> on this matter was this off of Trainorders some time ago:
>
> " Most transient diesel smoke is caused by turbo-lag. There is too much
> fuel being injected into the turbo-charger until to comes up to speed to
> provide sufficient boost. EMD engines had a big advantage in that the non
> turbo-charged engines had an engine driven super-charger (Roots blower)
> and had a gear drive with an over-running clutch. At low power, the
> turbo-charger was engine driven while at high power it was driven by the
> exhaust turbine. Newer GE engines avoid this problem by controlling the
> amount of fuel injected while the turbine comes up to speed."
>
> FWIW
>
> Rich Onorevole
>
> On Thu, Oct 11, 2012 at 12:28 PM, Ed Montgomery <etmontgomery46_@_gmail.com>wrote:
>
>>
>> Here's a question that has been in my mind for the last few days:
>>
>> Alco engines always seemed to accelerate with a blast of dark exhaust
>> coming out the stack. I remember hearing this was caused by the
>> turbocharger lagging. Could this have been corrected or was it part of the
>> engine design? Was it common to all ALCO engines? I heard stories of
>> fires breaking out around the exhaust stack of the PA's. Was this common
>> to the RS and S units as well?
>>
>> Ed Montgomery
>>
>>
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>
>
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