I think we are on to something with RPMs, seeing as we can't get longer pump stroke or bigger elements very easily or cheaply...

I read somewhere (I think VW Vortex?... maybe the link was posted on this board?) about people revving VW 1.6L IDI motors to somewhere north of 6000rpm. This was possible due to the fact that its IDI (bingo! so is the 617) and it has a very square bore to stroke ratio (so does the 617). More RPMs = more horsepower. Seemingly, the old wives tale about the flame front not propogating fast enough to warrant high rpm operation was not true.. I wish I had the link to the discussion, because it was very informative.

We know the 617 has a VERY strong bottom end. What we don't know is whether we need better valve springs to prevent float, and whether the engine is balanced well enough to spin 7000rpm. Also possibly need to set valve lash differently and set timing differently. I'm sure there are other design parameters I am completely overlooking as well, someone please chime in... Oh, btw. the bosch MW pump is only rated for 2500rpm, so this could be a stretch for it....

I don't intend to hijack here, just seemed like maybe a good place to insert this idea fragment because the topic of conversation is relevant to RPMs.

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99 E300 Turbodiesel 100k