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Sun Feb 01, 2015 7:58 pm

I have a 1835cc 92mm cut case. I want to leave the case 92mm for a later stroker engine. I have a set of 94mm pistons and cylinders sitting around. So heres the deal. I need to get an engine back in the car but want to keep the case 92mm.

I hear people are cutting skirts down on 94mm cylinders down to fit 92,90.5. This true? I figure any well to do can set these cylinders on a lathe and cut them. I dont have my 92mm engine apart yet so I dont know the outside size of the skirt. Any ideas? Thanks guys..

Sun Feb 01, 2015 8:17 pm

It can be done, the 94" are 97mm while the 90.5/92 are 96mm OD at the case.
Will have to clearance the case's lower bore large enough to let the piston fit below the cylinder also, so it's a PITA.

I think it is easier to cut the case. mag cuts easier than iron you know!
And the case should be decked .060 anyway when using 94 cylinders, or you'll have too much deck, which you could fix with a stroker crank.....or just do it right jeez :wink:

Sun Feb 01, 2015 8:20 pm

Modok, you saying the piston will come below the skirt, hitting the case?

Sun Feb 01, 2015 8:22 pm

correct. Most cases are bored with two sizes, one to clear the cylinder and another smaller size below that to clear the piston, this leaves more metal(strength) in the case rather than boring just one size!

Of course, there is a small chance you case IS just bored to one size. I've seen that a few times.

Sun Feb 01, 2015 8:32 pm

Modok, thanks for the heads up. I know I'm cutting corners I just don't want to open it to 94mm unless I have too. Maybe I should break er down and see how er jug holes look. Thanks, man

Sun Feb 01, 2015 8:40 pm

-Rusted_Radio- wrote: Modok, you saying the piston will come below the skirt, hitting the case?

If you do the longer stroke in the future be sure to check the piston skirt to case clearance. Mahle have a much bigger skirt than the slipper skirt style pistons. I have had to add extra clearance sometimes so that the skirt did not hit the case or the crank counter weights and opposing rods at BDC. Have Fun :)

Sun Feb 01, 2015 8:58 pm

my new 94 case would not clear the pistons,si i trimed it.no problem, if you can cut the cylinders and want it that way do it.my newer case is 92 so i will be cutting the cylinders down a bit also.and triming for pistons if needed.
as far as needing to cut the case just mesure it and cut the cylinder shorter to get what you want.so there is no real issue there either,

Sun Feb 01, 2015 9:43 pm

Hp gain really worth it? Going from 1835 to 1915 maybe not.

Sun Feb 01, 2015 11:14 pm

I have progressed from 1776 cc to 2017 cc to 2332 cc while keeping the same 90.5/92 case holes...now using the trimmed 94 mm Mahle slip-in cylinders.

As noted above, check your clearances, depending on how the previous shop machined your 92 mm case holes.

Good luck!

Mon Feb 02, 2015 8:33 pm

1874to 2028 to 2332 to 2393.....and possiaby bigger.if I had got a non drilled case the 2393 would be a lot biger.drop cam tfcase even biger.

Mon Feb 02, 2015 8:40 pm

I can use 10mm studs with 94mm right? I hear some trimming made need to be done.

Tue Feb 03, 2015 7:27 am

I did this on my 2276, had to clearance the case just a bit for the pistons to clear. No big deal to me. I like doing this because it gives more of a seal area for the cyl to case surface and I didn't have to re balance the pistons.

Tue Feb 03, 2015 11:08 am

-Rusted_Radio- wrote: I can use 10mm studs with 94mm right? I hear some trimming made need to be done. yup sme cylinders will need some triming for stud clearance .also if the scase incerts are sticken up they too will contact the cylinders so that also needs to be addressed.

Sat Feb 07, 2015 1:03 pm

-Rusted_Radio- wrote: I can use 10mm studs with 94mm right? I hear some trimming made need to be done.
You should always use 8mm head studs. The 10mm studs do not expand at the correct rate like the 8mm studs do. So your head torque changes based on engine temperature. That is why the VW factory changed to 8mm studs with case savers in later motors.

Sat Feb 07, 2015 2:30 pm

On another post thread modok says:

Quote: cylinder length stock/90.5/92 kit: 112.5mm
cylinder length 94 kit: 114mm

I did not know that. When I joined SAMBA in 2007 after decades out of the VW hobby I learned so much new stuff. Still learning.

Thanks modok and all other gurus.

Mike T

Sat Feb 07, 2015 4:46 pm

and many diferent pin hights too,
stock85.5,:1.550
90.5,92&94 A piston 1.560
90.5 stroker"B"1.338
92 stroker "B" 1.359
94 stroker "B" 1.377
havent checked the AA stuff to see what they are.Im pretty sure there also another set of numbers to add to the list.
and the "C" pin hight pistons and all the other pistons with the same pin size you can get a lot of different combos.

Sat Feb 07, 2015 5:52 pm

Thanks guys I will let you know what I find

Sat Feb 07, 2015 7:18 pm

jestes wrote: -Rusted_Radio- wrote: I can use 10mm studs with 94mm right? I hear some trimming made need to be done.
You should always use 8mm head studs. The 10mm studs do not expand at the correct rate like the 8mm studs do. So your head torque changes based on engine temperature. That is why the VW factory changed to 8mm studs with case savers in later motors.

That old saw? 10mm studs are made of the same material as 8mm studs, so obviously they will expand at the same rate. Of course they will pull a little harder, hence the different torque requirements, but also why they were popular with the turbo crowd. I suspect VW made the change in order to allow more strength in the case, reducing the chance of them pulling. Case savers work well, but you may find the cylinder bore encroaching on them, especially if they are the larger type. This gives you an idea of the reduced strength of the material around the case saver, which is why many don't like to enlarge the spigot for 94mm cylinders with 10mm studs. If they are already fitted with case savers you don't have much choice, so the cut down cylinders are an option.

Sun Feb 08, 2015 10:08 am

are you guys kidding?? what a farce.the reason vw changed the stud size was 2 things, 1 the 8mm studs were cheeper,( they were learingg vw guys were the cheepest asses in the world, next to a blow boater)and 2, the 8mm studs were lighter so the mpg was uped so you could cut more grass before running out of gas in your vw powered lawnmowder :shock: :wink: now how do i lower that darn blade on this thing :181_yellow: .

Sun Feb 08, 2015 10:49 am

mark tucker wrote: are you guys kidding?? what a farce.the reason vw changed the stud size was 2 things, 1 the 8mm studs were cheeper,( they were learingg vw guys were the cheepest asses in the world, next to a blow boater)and 2, the 8mm studs were lighter so the mpg was uped so you could cut more grass before running out of gas in your vw powered lawnmowder :shock: :wink: now how do i lower that darn blade on this thing :181_yellow: .

John Connolly wrote an article, "Building a ‘Big’ Aircooled VW Engine (Type 1)". In it he says, "Use factory VW 8mm head studs (used are fine), since they expand and contract at the correct rate, and keep head torque constant. 10mm studs don’t do this, and that’s why 10mm stud engines have a problem with pulled studs. The VW factory changed to case savers and 8mm head studs in 1972 to solve this problem."