Gen1 vs gen2 cylinder barrel

[jumjum01]

The gen2 cylinder has the skirt cut to aid pumping losses. Has anyone done a test to see how much that equates to horsepower wise compared to gen1??

 

[Berlin Germany]

i just did the repair of a gen1 by a gen2 block

only the gen2 block
but
with gen1 pistons & rings
and gen1 head/foot gaskets

NO change in the power because the bore is 100% equal in the block gen1 = gen2

the 40 ccm more they produced by other rods and diff. crankshaft (a lil bit mo stroke) and different pistons

so a repair of a gen1 with a gen2 block works perfect.

but
but the spare part prices at piston ´n rings are astronomically high
at least here in Germany

 

[Dnyce]

Yea just bcuz the skirts are scalloped, no real power gain. Maybe more efficient, better mpg? Idk. Negligible.

 

[Dennis]

Supposedly it's an old racers trick to pick up a little more power. It may take a really controlled test to see the difference. Unless you are running nitrous at +3mm bore size the Gen2 block seems to work fine. The Gen1 blocks are a popular upgrade for nitrous applications and is what I'm currently using in my 1507 Gen2.

 

[RacingJake]

More info from APE if you want to go big.

Hayabusazone - Tech

 

[jumjum01]

Since no gen2 cylinder barrel "hp inprovement proof" was available, I used gen1 barrel for this build, which I had in stock.
Gen1 stock bore, modified OEM pistons, 12.4:1 compression, stock gen1 intake cam, gen3 exhaust cam, diy ported head, pump gas

Torque is metric NM and correction is SAE -not STD