ShopTalk Forums | Aircooled VW Tech & Restoration Help

I think the head will be slightly wider and deeper than stock which gives a big increase in surface area and the bottom fin will be thicker towards the barrel but not enough to interfere with the top barrel fin and I can add some risers between the plug and top fin. I'm reluctant to put solid areas in between fins as it would stop air flow but would make it easy just to tig weld the area for extra strength and extra stud if needed

Sounds all good to me

Wally
Don't suppose you have any specs on the popular 103 and 105 pistons
out there -pin height, pin offset,overall height etc?

You really gonna like the next pic I post up on here!

Cheers

Paul

Paul H wrote:Wally
Don't suppose you have any specs on the popular 103 and 105 pistons
out there -pin height, pin offset,overall height etc?

You really gonna like the next pic I post up on here!

Cheers

Paul

Yeah, I have a broken JE 103mm one. Will measure tomorrow
Really curieus....

The reason why I ask is the piston skirt length and shape is critical in the area shown in the image. Dummy 103 piston with full round skirt 60mm long is yellow,barrel std 94mm bored to 96 red, bellhousing purple, cylinder stud hole is pink.

The piston is on a 5.7 rod and 90mm crank at bdc and would require a 17mm spacer to give 50 thou deck height with a 1.1 ch piston.

I need to fill in the area and leave enough for cylinder bore and piston skirt clearance and I haven't got much room to play with. Bellhousing plate will need clearancing and the fins skimming a little.

The flywheel is a regular 200mm 8dowel but with a flange crank which is the most likely thing to get put in there I get another 3mm to play with !

Ultimately I'd like to be able to fit a nice thickwall 103 ally barrel and I don't have any dimensions of said barrels

I posted this awhile back for a fellow fitting some Duetz jugs.

103 jug dimensions for fitting...
Measured with a handy pair of Starret calipers off QSC alloys, which may or may not be a great "reference"

Head OD: 4.5205. (Nickies feel a few thou smaller )
Case OD: 4.270"
depth in case: 1.355"
flange-to-flange: 3.425
Depth in head: .260"

Thanks Pile
Those dims went in nice assuming the 103 JE's are slipper skirt with no material down the sides to clatter the case and and back of the adjacent rod
then I think there is room for at least 105's and a 4 inch bore on a 88mm stroke would be childs play

Purdy drawing! This narrow margin from cylinder to case bellhousing flange is only with the 3rd cylinder, so you depicted the 3rd cylinder here right?

Paul H wrote:
The piston is on a 5.7 rod and 90mm crank at bdc and would require a 17mm spacer to give 50 thou deck height with a 1.1 ch piston.

90mm crank?? can you simulate rod to cam lobe clearence as well? cause I think you will have a problem there unless you start with 46mm Rabbit journals which gives all other sorts of problems...
Is this a real project-motor or just a try to find the limits dimentionally with the type 4 case?

The flywheel is a regular 200mm 8dowel but with a flange crank which is the most likely thing to get put in there

8 dowel? The type 4 is blessed with the much stronger 5-bolt connection. With the right bolts and machining, this set-up will hold anything you can throw at them. Just don't lesson the crank-flywheel area by adding 5 more dowels to them...

Ultimately I'd like to be able to fit a nice thickwall 103 ally barrel and I don't have any dimensions of said barrels

I have those in my engine now, so I can't really measure it up, but you have the case dimensions and you know your bore size, so the rest should be possible to fill-in from your wish/vision to make things thick and strong

The 'regular' JE psiton is actually a piston derived from a V8 piston or so I believe. I've seen many and all have the valve pocket excess material in the wrong spot for a type 4 valve spacing/orientation
I'll make a pic tonite. Mine is the 'stroker' version, so it should fill in your 90 stroke plans

Yes that is the number 3 cyl and it's the only one with any real contraints.

The engine is actually a real concept and is similar to a Autocraft 4 piece case and not a type 4. With some tweeking a set of type 4 cylinders will fit in there retaining the original stud pattern along with 2 extra studs top and bottom on the same PCD as the original. It will use a type 1 flange crank with all type 4 mains which are readily available now and VW T1 rods.
Only issue I can see so far and I don't think it's really an issue is that the rods will run 6mm off centre-what's 6mm in a 103mm bore?
Cam is dropped 4mm and the rod just touches it in the usual place. 90mm with a VW journal and a Pauter rod with 3/8 bolts is definately the worst case scenario I guess a 88mm stroke with a chevy journal will just fall in without any cam clearancing.
The main thing is It will accept the new heads and make it more viable to produce them as a alternative to 910's and other 4 inch bore heads which are a bit small and lacking in finnage to make them a serious contender for 3 litre street motors.

Paul H wrote:
The engine is actually a real concept and is similar to a Autocraft 4 piece case and not a type 4. With some tweeking a set of type 4 cylinders will fit in there retaining the original stud pattern along with 2 extra studs top and bottom on the same PCD as the original. It will use a type 1 flange crank with all type 4 mains which are readily available now and VW T1 rods.

Cam is dropped 4mm and the rod just touches it in the usual place. 90mm with a VW journal and a Pauter rod with 3/8 bolts is definately the worst case scenario I guess a 88mm stroke with a chevy journal will just fall in without any cam clearancing.
The main thing is It will accept the new heads and make it more viable to produce them as a alternative to 910's and other 4 inch bore heads which are a bit small and lacking in finnage to make them a serious contender for 3 litre street motors.

Cool, though I am very fond of the original type 4 case, I also like the above features a lot!

Only issue I can see so far and I don't think it's really an issue is that the rods will run 6mm off centre-what's 6mm in a 103mm bore?

Not sure 'bout that one though..but I have no experience or knowledge to think anything about it. Center-center would seem best for strength as the whole case seems to be about that also. getting the 'right' crank in there would not be that cost-prohibitive. I would consider it to have a type 4 crank fit the case They also have 'type 4 mains' as stock

Just measured my single JE:
CH=1.150 inch or 29,20 mm
Total height = 59,75mm or 2.352"

And some pics:




Lemme know if you need more dimensions,
Walter

That's great

What's the distance between the pin bosses for this 6mm offset


Cheers

Paul

31,4mm These are the 22mm pin version.

It'd need 3mm machining off the inside of the boss -I could live with that

Bump.

Paul, any new info on the heads?

Piston pin heights, can come quite short. The pics are of an older design 104.8mm bore, 23.6mm pin, Ross piston with a pin height of .930". These I have been
saving for a big stroker.

You will more than likely have to have a piston that uses around a 2.950" length pin in order to have enough material in the pin boss to off set it as much as you
want. You can get some of the clearance from the small end of the rod, I just picked up a set of rods with a small end width of .800" for .787" - 20mm pins, which
are used as piston guided rods . But most rods that most of us deal with have a small end width of just over 1.0".

I mix and match as needed and even slightly modify from what I acquire, to get things to work for me. But I think it will be a little harder for you.

As for a 5.7" rod with a 90 stroke, thats a 1.61 rod to stroke ratio, I think is way to short, you need at least a 6.0" rod (1.7 to 1) but better yet a 6.2" rod (1.75 to 1)