pa951

Is it possible to just bore and sleeve to 104mm. That would make a 2.8l but can i work with the stock head and crank? Or does it require much more?

theedge

You can go big bore using the 2.5 crank and cylinder head yes. You would need 104mm pistons obviously. There are engines here that are bored out and sleeved to 104mm. I went the Darton MID sleeves route but others have gone the route you seem to be looking at.

blown 944

I'd only sleeve out that far with a deck plate or darton sleeves. The cylinders will be quite thin.

refresh951

Sid - David Floyd had good success with RollsRoyce Chromoly sleeves. He went to 106 mm with them on a 2.5L block. Have you any experience with them or know anything about them?

http://208.64.137.131/*andersonmotor...l_highperf.htm

blade7

That would be a 2.7, you may as well buy a 2.7 engine.

blown 944

I hadn't researched them, but I went with ductile iron flanged sleeves and a 105.5 bore and there is not much original material left. If it has been done successfully then great. I just don't see it myself.

David Floyd

Agreed cylinders a very thin

Mine has held up for 10 years and 100 k miles, But........ there were a hand full of 106mm bores built around the same time as mine and to my knowledge I have the only motor still running, so I would not recommend going that large and I won't when I have to build another.

Chromolly sleeves work very well, I would just stay in the 104mm range and do a hybrid stroker like you two are having success with

pa951

So the 104 would make it a 2.7 will that make the cilinders thick enough? Or would it indeed be better to use a 2.7 block as start?

blade7

Kind of depends what you want and how much you plan to spend. a 2.5 engine has plenty of potential, but if you had a complete 2.7 engine...

Dave W.

How thick should the sleeves be? What's better, thick cylinders with thin sleeves, or use thick sleeves at the expense of thinning the cylinder?

refresh951

I talked to a PHd Structural Engineer about this very question. He said is is more complicated in that simply you would want the thickest sleeve possible as iron is stiffer than aluminum but the thicker you go on the sleeve the more you compromise the foundation/fixed point for the cylinder. In general if you have a 3L block or a filled block you should be able to go thicker on the sleeve. Another consideration is the location of the HG seal ring. Really we need someone to do an FEA analysis.

Chris White

You would have to very good at FEA to handle this one!
You start with the ratio of parent material (Alusil) to Sleeve material (Steel) but then you get into the root of the alusil cylinders (floor of the block) and its ability to stabilize the cylinder...follow that up with issues regarding differential expansion rates, sleeve to parent material boundaries (for both heat transfer and long term stability) and then you can try and start to model the alusil casting irregularities (porosity and thickness variations - keep in mind that the stock cylinders actually taper and get wider towards the bottom due to casting release issues)....ummm, yeah, its a little complex....

refresh951

Yes, I agree it is a bit complex but maybe Harry or one of his friends could have a look.

Chris White

I have noticed that really good people rarely have 'spare time'....they seem to be busy!!!

blade7

So do 2mm thick iron dry liners in an Alusil block transfer heat to the water jacket as efficiently as Alusil cylinders ?.