90.5's or 94's?

[Big Z]

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!!!

[fivelugshortaxle]

Go in between. Get the thick walled 92's. Meatier than stock 85.5's. A nice 1835.
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[VWCOOL]

Go straight for 94s as - as you realise - you get the biggest capacity and best breathing over the standard-stroke crank. A well-built torquey 1916 is a joy to drive as a 'daily' car. A modest-spec 1916 will idle at 800rpm, put 65-70hp to the treads, run high-16s in the 1/4-mile (in a standard 1302/03) and do better than 10km/litre on a trip.

The whole '94s are bad..mmmkay' discussion is little more than marketing myth. 94s will cope with lots of boost so will present no issues N/A on the street.

I have several 1916 engines, track/drags and street, with the oldest street motor having components (rods, crank, cam, P&Cs etc) that date from 1985. It has travelled so that I have forgotten. At least 150,000 miles. These pots still throw 75HP to the chassis dyno

Your next challenge is to find a competent machinist!

Hope this helps

[vwracerdave]

It's a 1915 dude.

With stock heads, stock heater boxes, single carb, dual Kads or ICT's go with 90.5 pistons.

40x35.5 heads and dual IDF's go with the 94's

No matter what anybody tells you the 90.5 pistons run cooler and last longer then the 94's.

You could run the thick wall 92's with any of the above.
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[theDrew]

94's!

if you're worried about heat, knock the CR back a bit
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[mcmscott]

I just measured an old 94mm cima wall at .140"ish, then measured an AA 90.5,,,,,,,,, right at 140ish. Go with 94's
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[VWCOOL]

[sambabus]

It may be true that the 90.5's may last a LITTLE longer, but life is short, go for the 94's. And if you can, get some porting work done to the heads.
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[bugguy1967]

[vwracerdave]

[ach60]

[Quokka42]

The outside diameter of the fins must remain the same, while the portion of it which forms the cylinder gets larger - if you look at the side where the two cylinders meet and compare it you can really see the difference. Having said that, a lot of people have put a lot of miles on 94s - I say go for it, how likely are you to be running the engine without a rebuild in 100,000km? Unless you are forced to run 10mm studs with the larger inserts, cases tend to be hard to come by and expensive here.

Remember also that you need to feed that beastie - stock heads don't really cut it if you want to rev past 4,000rpm. There are other issues, such as stock heads won't take much of a flycut at the 94mm register, but for a streeter you'll probably be fine.
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[VWCOOL]

Footpath; sidewalk... Aluminium, aluminum... Down Under we round-up and call them 1916s.

Yeah I remember talking to Berg about his 94s 'testing' - how, what, etc - when I interviewed him in the 1990s. He wanted to change the subject real quick.

As I said, there is no data - engineering or metallurgical or otherwise - anywhere as to why 94s have somehow, weirdly, picked up the reputation for 'running hot' or any other 'claims' or 'beliefs'.

They work just fine. For hundreds of thousands of kays.

Quokka, my 'baby' 1916 puts 69.9hp (nearly 70!!) to the rollers at 5-5200rpm with stock untouched heads (except for bore machining) and Kaddies so they can work OK above 4000rpm. But it does go better with the 044s on it... but they owe me a stack more $

So to the OP, get some 94s and go nuts!

[vwracerdave]

For all you Americans that are metric challenged 100,000 KM = 62,137 miles.

Dude there is no metallurgy problems with 94's. They run hotter because they have less cooling fins. That is a fact that can not be debated.
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2017 Street Comp Champion - Thunder Valley Raceway Park - Noble, OK
2010 Sportsman ET Champion - Mid-America Dragway - Arkansas City, KS
1997 Sportsman ET Champion - Thunder Valley Raceway Park - Noble ,OK
Featured in Dec. 2001 HOT VW's Magazine page 63

Watch my racing video's http://www.youtube.com/user/okvwracer/videos

[mcmscott]

And if Berg said it, well then it has to be true
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[GTV]

[raul arrese]

[mark tucker]

Ive seen many different fin counts&dezines on cylinders. as for berg......whatever that was long ago.and just a few years earlyer the earth was rounded out from a flat,I gess somebody rolled it up,but whatever. I do have on my 2028 with a lot of miles the old berg slip in 90.5's, and there thin,dam thin.but berg claimed they were different aloy(iron mix)than reg cylinders. I have no issues at 10.4 cr daily driven. I think if your cooling system is up to the task your fine. I built a 1641 for an old friend,after a year he's saying it running awefull hot& oil pressure light flickers at idle,so i do some checken....no seal in engine compartment,rong fan in duh shroud....... well after some convincing he changed the fan.... wow this thing sounds like a weed blower back there!!(he had a old vw performance shop owner helping him assemble the engine into the car,the exspert knew ...well not much.and thus rong parts)funny thing it runs cooler now. now to get him to put a real set carbs on it instead of that junk picofshit.

[Dan Ruddock]

Are you guys calling berg a liar? Are you saying he never did the testing? My experience with mahle 94's was disappointing. It ran good and did not run hot but after a couple of years oil consumption and blow by got not what I would call ideal.

Where the cooling difference shows up is in sustained high output, high speed driving which most of us street folks don't do. I think this is why 94's are not popular with bus folk.

My current build will be mahle 90.5b because I need max longevity and I like the fact that the 90.5 pistons are lighter than 94's and with a 84mm crank light pistons are a benefit.

Another thing no one has said here is the bigger the bore the more surface exposed combustion heat. With water cooling and it's high capacity that is not a problem.

Dan

[Dan Ruddock]