Shoptalkforums.com

I am currently building a "daily driver" Bug and I am trying to decide which engine to build. I am looking for something with as much power as I can get while still using the 69 stroke and standard Dual Port heads and still be reliable.

Some say go with the 94's and others say go with the 90.5's. I am not sure which way to go. ANY good technical suggestions would be GREATLY appreciated.

THANKS!!!

Thickwall 92s.

Has the case been machined previously?

Thick wall 92's. Best of both worlds.

No, the heads and case have not been machined. I have had a ton of people tell me to stay away from the 92's. Even the thick ones. I am worried that the 94's with stock heads will not be a good combination.

The usage of stock heads will depend on your rpm.
To use the stock heads, you will need a good porting job done.

BTW another vote for the thickwall 92

"Standard" dualport heads covers a bit of territory...I think to most folks it means stock 35.5x32 valves, perhaps some mild porting (similar to "mini-D"s) and single valve springs. If it means something else to you, please specify.

If you don't plan to invest in bigger heater boxes, don't go bigger than 1850 even for a mild motor. That leaves 90.5s and 92s, and thinwall "classic 92s are indeed something to avoid for most applications - especially for a reliable D.D. that's going to see some miles. There's also an old-school thinwall 90.5 that hasn't been produced for ages but occasionally you come across an N.O.S. set; shun those too.
Thickwall 92s are indeed the way to go these days - and if you don't want to whack the case out to the "94" O.D. they give you the option of having the lower spigots turned down instead (oddly, that operation seems to make the cylinder I.D. shrink slightly at the bottom, so I recommend hitting them with a Tru-Hone after cutting them down).

IMO eight-dowelling the crank/flywheel should be mandatory for anything more than a warmed-over 1641; you don't necessarily need a counterweighted crank if the heads/carburetion/exhaust/cam choice are going to limit you to <5000-5500 RPM anyway, and for a street engine which has those limitations I don't recommend going with too light of a flywheel either...the ubiquitous 12½ lb is fine with a CW crank, with a stock crank I prefer to stay up around 16-16½ lbs.

You know what, swing by aircooled.net and read through some of the tech articles, that would give you quite a bit of info.
John knows his sh1t

Big Z wrote:I am currently building a "daily driver" Bug and I am trying to decide which engine to build. I am looking for something with as much power as I can get while still using the 69 stroke and standard Dual Port heads and still be reliable.

Some say go with the 94's and others say go with the 90.5's. I am not sure which way to go. ANY good technical suggestions would be GREATLY appreciated.

THANKS!!!

You need to decide on what "reliable" means to you. I personally have never gotten the durability out of 94 mm Mahle cylinders that I have from their 90.5 kit (I used them in both Buses and Beetles). The 94 pistons are fine, but for whatever reason the 94 cylinders are kind of a "half-life" product, in my experience. If you plan to drive a lot of miles (e.g. 15,000 per year), then I would recommend the 90.5's.

Having said that, I'm trying a new set of Mahle 94's (4-5 years old) and they have the thicker cylinder wall, so Mahle certainly listened to feedback from their customers (they're so thick that you need to clearance the head stud grooves so that even the 8 mm studs will fit). I don't have enough mileage on the new 94 cylinders yet, to make a decision on their reliability in the long run.

I haven't had any experience with the newer AA thick-walled 92's but as noted above, they seem to be a reliable product.

I would advise along the lines that Marc gave.

A daily driver should be staid and reliable, it you get you down the road for many miles and get you back again. It should also get you to work everyday w/o worries.

If you are building a daily driver then stay conservative on the case (90.5s would be a good start and start with a later '70's DP case or equivalent) and build a nice reliable motor smooth running motor. I also think I would full-flow it and add an oil filter and maybe a alt to allow you to do your tunes but keep it reliable so as not to shorten it's life or break other components that additional power can do for you.

Conservative also sells better as a general rule. It is a known fact that a nice quiet and gracious car will attract more looks than a loud obnoxious ride as the observers are trying to see what all you have done; noise is quickly figured out.

Lee

My opinion is worth slightly less than you paid for it.

If I told you, you would not know; you simply would have been told. (Robert Helpmann)

92TW