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Fri Jul 27, 2012 7:59 pm

Is there a basic formula or maybe someone with knowledge that can help me. I'd like to build a larger bug motor (I was a chevy guy in the past) Which engines can be bored to what sizes? Excuse the new guy lack of knowledge.... be easy on me.

Thanks.

Fri Jul 27, 2012 8:11 pm

Go to the Air Cooled.Net website and go to the tech articles and read about building different engine combos, carburation, etc. There are waaay to many combos to discuss here. You need to get a bit of a background and an idea of what would suit you, then we can help you with thousands of confusing suggestions - most of which are good! :lol:

http://www.aircooled.net/vw-technical-articles/

Fri Jul 27, 2012 8:12 pm

Just remember to have everything else capable to handle the larger jugs. 94's and I tink even 101's

Fri Jul 27, 2012 8:13 pm

Do a search for vw engine calculator. Engine size is dependant on crankshaft stroke and piston ad cylinder size. 88mm 90.5 mm 92mm and 94mm

Fri Jul 27, 2012 9:11 pm

The first question any competent engine builder is going to ask is what can you realistically afford to spend? You can build a $2500 1776cc or you can spend $8K on a 2332cc engine.

Sat Jul 28, 2012 7:41 am

VW motors aren't "bored out" like Chev's and Fords are. The cylinders are removable and you just put on bigger ones (a little simplistic- usually the case and heads will have to be cut bigger as well). A 1600 uses 85.5mm pistons and as said before, there are 87's (1641 cc's- kind of a waste of time), 88's (1679), 90.5's (1775), 92's (1835) and 94's (1915). A longer stroke crankshaft in any motor does wonders for the powerband as well as adding cc's, and we all know what happens when motors get bigger! :twisted: . A 1600 crank is 69mm, and 74, 76, 78, 82, 84, 86, 88 and 90mm cranks are available.

A fairly simple build for one new to VW's would be a stock stroke (any of the engine sizes I mentioned in the previous paragraph) with a mild cam, stock or ported dual port heads, dual carbs and a 1 3/8" header/muffler. Power will range from 70-75hp (1641) to 95-100hp (1915) depending on parts used. You can get 130 hp out of a 1775 (it will have to rev to 6500 with power) or a 2276 (82x94), and as always the bigger motor won't have to rev as high (5500?). And of course, the higher it revs, the more often you have to mess with it....

The secret to any VW aircooled motor's output is the heads- stock dual port heads are capable of about 85hp, properly ported stock valve (35mm intake, 32mm exhaust) heads will support about 120-125hp, ported 40x35 heads about 170-180hp and 44x37 will go to 230? 240? hp. This of course assumes that the carburetion, intake manifolds, cam/rockers, compression and exhaust are all suited to the combo. An matching components is essential (especially in smaller motors); a cam/head mismatch can make an otherwise great combo seem to procuce no more power than a tired 1600. And no matter what the advertisements say, 400 or $500 big valve heads WILL NOT make 200hp- for that kind of power output expect to pay twice that (or more).

Which brings me to another point; VW's are no longer cheap, but they can be very fun! :twisted: :lol:

As usual, just my 2 1/2 cents (I'm Canadian, eh). Al

Sat Jul 28, 2012 1:43 pm

why did you leave the comfartzone of chevy land?there much cheeper and make much more power and parts are everywhere,crap even I have a pile of chevy parts.(well in reality, just 1 real chevy part a steel main caped bowtie tall deck bigblock,like this vw shit 99% of the chevy parts are thrown away and replaced) remember 1 thing, the motor dosent know what name is on the valve cover.it's just an engine.

Sat Jul 28, 2012 2:18 pm

Any 1300,1500, 1600 engine case can be bored to accept the 90.5 or 92mm cylinders or smaller

Engine cases from the mid 70's and newer use 8mm head studs and have 12mm OD steel inserts in the case that hold the studs, these cases can be bored to accept the 94mm cylinders no problem. There are some tricks to putting the big cylinders on earlier engine cases, but it unlikely to find usable old OE cases so we won't go into that