BNSF GP38-2

[BNSFdude]

May not be screen shot ready, but nothing wrong with a little audio preview?
***quality vastly reduced for obvious reasons***
https://www.dropbox.com/s/ryh87adsac0qoe6/Start.mp3

[BigBoyMoon]

Krellnut, I think you recorded from a GP39-2 instead of a GP38-2. It still sounds great though

[Rich_S]

Now that we have that all settled my question which I still don't know is the 645 in the GP38-2 just plain normally aspirated (no boost of any kind) or does it have some sort of pressure boost on the intake?

I know wikipedia is not always accurate but it says:"The GP38-2 differs externally from the earlier GP38 only in minor details. Its most distinctive identifying feature is the cooling water level sight glass on the right side of the long hood. The battery box covers of the Dash 2s are bolted down instead of hinged. It can be distinguished from the contemporary GP39-2 and GP40-2 in that its Roots blown engine had two exhaust stacks, one on each side of the dynamic brake fan,"

All EMD locomotives are 2 stroke diesels, which means they don't have a intake valve and rely on either the roots blower or the turbocharger to blow fresh air into the cylinders through the cylinder ports and force the exhaust gas out of the cylinder through the exhaust valve. All of the normally aspirated EMD locomotives have roots blowers. (All switchers, All F Units, GP7, SD7, GP9, SD9, SD18, GP38, SD38, GP38-2, SD38-2) The 16 cylinder 645 diesel engine with a roots blower will produce 2,000 HP. The GP40, GP40-2, SD40 and SD40-2 have EMD turbochargers meaning they are shaft driven below notch 5, above notch 5 the clutch pack disengages and they are true turbochargers running off the exhaust. The turbocharged 645 produces 3,000 HP in the 40 series locomotive. By turning up the fuel, EMD was able to produce 3,500 HP from the 645 turbocharged diesel for the SD50, but this was a little too much for the 645, hence the 710 was introduced for use in the GP60, SD60 and now in the SD70's. On a side note, the meaning behind 567, 645 and 710. The numbers indicate the cubic inch displacement of each cylinder in the diesel engine.

Onto the second part, externally the above is true, EMD locomotive with roots blowers have at lest one exhaust stack in front of and behind the dynamic brake fan or fans on the 38 model. Turbocharged EMD's have one square exhaust in front of the dynamic brake fan or fans on 39 and 40 models. On the 50's, 60's and early 70's, EMD moved the pie shaped grids and grid blower (dynamic brake fan) next to the cab, so the turbo stack is located just behind the grids on those models. Lastly the difference between the GP38, SD38, SD40 and the GP38-2, SD38-2 and SD40-2 is a main alternator has replaced the main generator along with digital modules replacing relays on the older units. The control stands were upgraded with a dynamic brake handle and the removal of the selector handle and a upgraded wheel slip system just to name a few items.

Rich S.

[glenn68]

I have yet to see any GM diesel engines that were not supercharged, Two stroke diesel needs the supercharger. Oh, Rich answered the question above.
So where is the preview of the GP38-2?

[buzz456]

I have yet to see any GM diesel engines that were not supercharged, Two stroke diesel needs the supercharger. Oh, Rich answered the question above.
So where is the preview of the GP38-2?

It got lost in all of the thread swiping.