Hi D,
Thanks for your advice, but after a long think and based on my relative inexperiance (i have only rebuilt one engine before) i have decided on the following plan.

I have an A14 running nicely, but hanker after more power and torque.
I have an A15 stripped down in box's and a H89 head.
I have a Camtech 621 cam ready to be used and a set of A12T carbs.

Car is for the road, not drag racing or motorsports.

I would like to keep the same A14 block as it reduces the aggravation of changing documents.

Option 1. Strip down A14 and insert A15 crank/conrods/pistons together with new rings and bearings. Use new camshaft and twin carbs and gasket match to the H89 head.
This is the cheapest option and will give me some good power gains . However only possible if the A15 pistons are the same diameter as the ones in my A14 now (the A14 ones may be oversized from the last rebore.)

Option 2, If the A14 pistons currently in use are bigger than the A15 ones, then go for the 79mm option as i would have to buy new pistons anyway.


Filing the block with cement is a bit advanced for me at the moment and keeping it cool is also a worry ...

On further research I remember there were some audi/volkswagen 140kw and over engines using an 81mm flat top of CP 30.17 mm, which can be taken down to 28.5, 29, 29.5 depending on your deck height.

http://www.ebay.co.uk/itm/AUDI-VW-SKO ... AQD-ATX-BBG-/301445227459

http://www.ebay.com/itm/Audi-A4-TT-Qu ... :wUgAAOSwgQ9VnCJt&vxp=mtr

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  audi vw slugs.GIF (19.91 KB)

That is actually the piston I had in mind
HG could use reworked jp performance 80mm but Id rather
use custom hg with your needs with O-ring.
Lemonhead went to 82mm with liners just have
to make sure you grout the bottom end to have
better rigidity to suit rpm.

mmm interesting... whats involved in going to 81mm ?
The machine shop in my town is good at general rebores etc and spend most of their time sorting out truck and tractor engines..
They put liners in quite regularly and have a large stock.
There is also a guy in Bangkok that makes custom headgaskets....

could use this piston ? from a mitsubishi...

81mm pistons with 82mm A15 crank makes it 1690cc
i have a spare block if it goes wrong.....

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  81mm piston.png (35.32 KB)

no need usually for offset boring but walls could be porous from rust as is usually the case with some older A series donks. Im not sure what the prices are in Thailand Thai frog but I would say not so high that I would sleeve for 81mm and grout the bottom end up to the welsch plugs.

If going to 79mm diameter pistons does the block need to be offset bored ?