My apologies, Mitch (and Jan); I start on a topic and quite often it kind of writes itself!
Someone will get something out of it, I'm sure.
The extra power in your 2026 is (in part) from the lower rod ratio; it creates more torque down lower in the rpm range, and is one of the reasons stroker engines are just so much more fun!
But you already know that. VW first experimented with this in the type 4 engines so they could use smaller engines in the much heavier bus, and continued with what they'd learned in their watercooled engines. I was told (or maybe I read it? who the h*ll knows...) that Honda uses rod ratios as low as in the 1.5's (very short rods) in some production engines, and (I guess due to piston design and pin placement?) has no longevity issues.
For those of you that do not know- When using a longer stroke crankshaft the rod ratio goes down (especially if you stay with stock length rods) and, as I said above, this creates more low end power. VW was very conservative with the 1600 (they were looking for longevity) and the rod/cankshaft ratio (divide the rod length by the crankshaft length, so 137 divided by 69 =1.99) is quite high by today's standards. With a 78mm crank and stock (137mm) rods the ratio drops down to about 1.76. Porsche used shorter rods (136 or 135mm) with 74mm cranks in their 15 and 1600's and these engines moved their cars along surprisingly well for such small engines.
The pumps with the out/in covers aren't the best solution, but for an engine that peaks below 6,000 rpm they do work. As noted earlier, some of the passages in the cover are smaller than ideal, which restricts oil pressure down the line and the pumps have bigger gears than necessary (usually 30 or 32mm) to compensate.
Jan- Those smaller passages can only flow so much oil, and above about 6,000 rpm the pump is pumping more oil than can go through the cover, and as you rev it higher it gets worse. This is what breaks the pump drive tang (so I've read; I've never seen one or know anyone who's experienced it). If the engine peaks below 6,000rpm then this isn't an issue.
And yeah, while what we normally think of as "full flow" (out the cover and back to the case just before the oil pressure sender) is better- bigger openings for no restrictions, better pressure numbers and the ability to use a slightly smaller pump for achieve this with less friction/pumping losses, a pump with either the attached filter or out/in cover work for milder engines will work. It's not optimal, but it can be installed without drilling the case for the return line, and this is the attraction. And guys- again, I apologize if you already know this stuff; I'm sure someone will benefit from it. Al
And Jan- I have no idea what Mitch said!
