Hi, I would like to get an advice if there is possibility to use 96 mm Volvo B23 flat deck pistons to rebored 94 mm cylinders? I have heard an opinion that it is better solution to rebore old original cylinders than buy new chinese after market kit. Has anybody used such a solution?Greeting, Waldemar
I guess you mean a type4 engine? 94/96 is moohasive on a type1 engine. At what point to the walls become to thin, that's why there's the odd size of 90.5mm on a type1 engine. guess the same must apply on a type4?
When you say Chinese aftermarket, do you mean AA Performance products 96mm kits? We have AA 96mm pistons and barrels in our type 4, the pistons are very well made, machined accurately and for us, have done well with no issues to date
Cylinder walls are thin enough. I would worry more about additionally thinned wall bored out pistons amd cylinders than AA brand. A lot of the moaning about AA comes from high performance builders in the States who get worried about things not being exactly how they like it, and how they learned it, sometimes they are stuck in a sort of mind set that says the world has ended because AA decide to use something other than cast iron piston rings for instance . After all a loose valve head can destroy a Mahle forged piston just as effectively as any other brand.
I have no experinces in this matter.Thanks for your comment. I am glad too hear a good opinion about AA Performance. In a case of useing 96 mm kit should be a block rebored for new barrels?
Our case was an AP (1800) and the pistons & barrels fit straight away with no boring. What case do you have?
I have a CU (2000) it means std. 94x71 mm. So I wonder why a barrel wall can be too thin if the use of 96 mm barrels does not require reboring a case? After all, barrels for the 94 mm and 96 mm pistons must have the same outer diameter.Am I wrong?
Standard 94mm cylinders can be machine out to 96mm without any problems and new 96mm cylinders don’t require the case to be machined - the cylinder OD remains the same as standard but the wall thickness is less. I don’t know the spec of Volvo B23 pistons but you need to check pin diameter and compression height. Unless you particularly want to use Volvo pistons it’s easier to simply buy 96mm KB hypereutectic pistons from a Type 4 parts supplier. Forged pistons are not necessary unless the engine is highly tuned but if you decide that’s what you want avoid 4000 alloys due to the very high expansion rate.
Sorry for not replying until now, busy with our westy's roof and other bits n bats. Geoff (77Westy) answered a good one. Have you got the Tom Wilson book, that's a very informative read. https://www.amazon.co.uk/Rebuild-Aircooled-VW-Engines-HP255/dp/0895862255
I don't have to use Volvo pistons. Simply I could get them from Sweden in easy way. So I decided to buy KB 96 mm pistons and use rebored cylinders. Do you have any idea where can I buy KB pistons in Europe?
http://www.statesidetuning.co.uk/t4barrels.html Yep - try James at Stateside Tuning - he provided mine. Have a look at me resto thread for a photo of new and old. http://thelatebay.com/index.php?threads/two-seater-targa-topped-bus-restoration-914.75583/page-8
@DESIO This^ and I suggest you use Hastings rings – Jim can supply them. Take care with the top ring gap, it will need to be increased from ‘out of the box’ because the top ring in KB pistons is close to the top and gets hot. The specs will be with the pistons. The Tom Wilson book is good for the basics of building an engine but it’s not much use once you start deviating from standard. What is the engine for, a bus presumably but what use will it have? The engine spec would be interesting.
It’s quite difficult to find somebody that will bore out barrels , most places aren’t interested and it works out cheaper to buy new . If you go too thin wall thickness you get sealing issues and they can go out of round .. the 1700 has the best sealing head , especially if a higher compression is used .
