roots blown 710

hi,i was wondering if emd dropped the roots blower with the introduction of the 710 powered 60 series in 1984?or has it something to do with tier/tier2 emmisions,or is being used in other applications ie:marine ,industrial? thanks, dash7

dash7---
As far as I know, EMD has never produced a roots-blown version of the 710. Since it wouldn't offer much advantage over the still widely available 645 (about 10% more cylinder volume, so probably about 10% more power...), my guess is that there has been no perceived demand for it.

Some time ago (I think it may be down on the second or third page of the index) this FORUM had a string on the fictitious "SD58" locomotive: the fiction is boring, but some interesting posts were made about what would be involved in a roots-blown 710, giving hints as to why we haven't seen any.

thanks allen, do they still mass produce the 645e?, because i know that emd export loco's still used the 645 well after 710 production was introduced. thanks allen ,cheers dash7

I get Railway Age. There is an as by EMD about the 710. I have seen something about re-powering older locos with it. I think it is targeted at 645 powered units, such as the SD40.

One of the last things I did at EMD was put together an EUI version of the V-8 710 engine using some Marine Engine parts, since there was no EUI version of the eight cylinder on the locomotive or industrial power side, then test it to see if it met Tier 2 emissions. It did easily without any tweaking. They were going to have it available for rebuilding those old low horsepower locomotives. All 710's had turbos since to go to the effort to develope a new casting to hold the blower (the 710 engine is slightly taller than the 645 due to the longer stroke of the pistons) was just not economically feasible - i.e. no market. The turbo is just so much more efficient and the 645 had such a following (still does) that there is just no reason to make a 710 blower.

I was under the impression that turbocharged versions of EMD two-stroke cycle diesels still have a scavenging blower.

Without one how do you scavenge the engine at idle and low load, when the turbo is not pushing much air?

With EMD at lowspeed the turbo is gear driven via a clutch.
At higher speed the clutch releses and turbo runs of exhaust gas.