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VW Enthusiast
Posts: 1
Reply with quote  #1 

I am doing a paper design on upgrading a stock 1600 engine to 120bhp range.  In terms of increasing displacement there seems to be two choices bigger bores and stroker cranks.  From what I have read, it seems that if cylinder bore is increased to more than 90.5mm, blowby becomes an issue and there are concerns with thin cylinder walls.  This is my first post and my first VW engine.  I have worked on '70 muscle cars.  I would appreciate any inputs.  Thanks


VW Know-it-all
Posts: 507
Reply with quote  #2 
When I built my 1835(69x92) I was worried about about blowby because I had heard that cylinder walls were thinner than stock on the larger sizes. That engine ran in my Ghia for 2 years and then in my old VW Thing for another five before I sold the Thing with that engine in it. When it was in the Thing I used it as a summer and winter car and would drive it in the summer down to Kenai, Ak from Anchorage,AK (about 170 miles one way) every weekend for fishing. Sometimes in good weather it had a 14' cartop boat on the rollbar and the boat motor in the back along with fishing gear. I will say that she was a little slow on the hills but everything else was 70mph all the way. When I sold the Thing the engine was showing signs of being tired, lower fuel mileage, using more oil between changes and such but there was very little if any smoke(blowby) when running only at start up(valve guides)
Now in my Ghia I am running a 1904(74x90.5) but would not be afraid of going to 92's on my next engine. But I will add that now that I am driving a stroker(and a small one at that) I would never go back to the stock stroke in an engine that I build because it is not that hard to do the work to get it to run and the benefits compared to just bumping up the bore are tremendous.

66 Ghia, "Dexter" 76 flat window Beetle
It's not a Car it's a VolksWagon!
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