1.5 pistons

libbybapa · Post by **libbybapa** » Wed May 20, 2009 10:59 am

I don't think that anyone has suggested that you need to spin the 1.5 higher but rather that it's an upside that you can.

Andrew

VW Jon · Post by **VW Jon** » Wed May 20, 2009 4:27 pm

I can't argue with the mileage. My 1.5 liter gets 52 mpg, and is a struggle to get it to dip below 50 with a lot of in-town driving. My gas Rabbit gets a max of 37 mpg (usually is around 35) but if you get extended in town use with the gasser, the mileage makes a more significant drop.

Swampy · Post by **Swampy** » Wed May 20, 2009 9:41 pm

You guys are making want to build a 1.5 instead of the 1.6! Doesnt piston speed and reciprocating mass somewhat dictate ability to rev?

82vdub · Post by **82vdub** » Wed May 20, 2009 11:14 pm

Swampy wrote:Doesnt piston speed and reciprocating mass somewhat dictate ability to rev?

Yes. A shorter stroke yields less reciprocating mass (not static mass) and it's ability to change rotation speeds quicker is a key benefit.

Josh · Post by **Josh** » Thu May 21, 2009 12:52 am

The only thing that may be true but not obvious is that apparently the stroke of the 1.5 vs 1.6 is a factor of the pistons and not the rods?

Fatmobile, I've thought the same basic thing about a 1.5, but didn't consider a VNT. But it's been done, so why not? As long as we're dreaming, might as well provide for on the fly fueling increases, no?

libbybapa · Post by **libbybapa** » Thu May 21, 2009 1:05 am

Stroke is always determined by the offset of the center line of the rod journals from the center line of the crank. The rods of the 1.5 are longer and the piston pin to crown distance is different from the 1.6 to compensate for the shorter stroke and still maintain the same main bearing and top of block locations.

Andrew

Post by **Fatmobile** » Fri May 22, 2009 12:39 am

You guys are making want to build a 1.5

Where are you at?
I have a spare 1.5 crank and rods,... don't make me scrap them.

Put it all in a 1.6, 12mm block.

Josh · Post by **Josh** » Fri May 22, 2009 9:07 pm

Ok, so a 12 mm 1.6TD block properly rebuilt using 1.6TD parts save for sporting 1.5 pistons, crank, and rods would give you a motor with shorter piston throw, smaller displacement, and lower rotating mass. This could provide the basis for the most efficient build combo for these engines; the advantages of the 1.5's displacement and rotating mass, with the benefits of a TD's oil squirters and the turbo itself.

This is right, right? Because I've got a 1.6TD jetta setup waiting for a rebuild, and may have a sweet shell to pop it in soon... I so want to announce it, but I'm being coy until it's certain.

Andrew, progressing on the Suzuki swap-in?

-Josh

libbybapa · Post by **libbybapa** » Fri May 22, 2009 9:39 pm

You'd need to notch the pistons to clear the piston coolers and balance them afterward.

I've fixed the Suzuki up a fair amount, but don't plan on starting on that conversion for some time to come. Plenty of other projects to do first.

Andrew