Race engine. What would movitate someone to do this? What's the bang for the buck? Ignore any motivation being to increase displacement. Thanks. Mike

 

Maybe it's been bored out from honing multiple times and needs sleeves to get back to spec? Or they really like spending extra money

 

some people are just intimidated by the aluminum block.

 

In many applications a sleeve provides for a more true or straight bore, 4 bores perfectly aligned together will be a better motor. Also could be done if one of the cylinders was damaged. A few other reasons as well but those are usually the 2 main reasons why someone does it.

 

Different choice of piston?

 

I had one block sleeved due to damaged bores. Ended up being about the same cost as getting them redone.

Of the last 4 motors I have pulled from random parts cars, every single one has had bores that could not be repaired by a hone alone. Of six blocks I have here, two are good and 4 are bad.

 

Darton MID sleeves, basically replaces the cylinder with a steel one. Lots of advantages such as large selection of pistons that have various degrees of skirting. If you lose a piston and damage the cylinder it can be machined out by most machine shops, or just replace the cylinder. Improved cooling. Contact Chris White he can tell you even more advantages.

 

Thanks everyone. Yes, a call to Chris White might be prudent.

Anyone care to offer their opinion if a (Darton) sleeved 2.5NA race motor is an advantage? I can see liability if not done right (bore runout to crank, desired/proper press with sleeve). Given your choice, for a race motor, would you rather have an the OEM block or sleeved block assuming properly done?

Thanks,

Mike

 

I don't know on a 944 specifically, but there are some motors that the first thing you do is sleeve them. I'd say it's an advantage.

 

The only advantage in a spec 944 engine is to save a block or buy cheaper pistons. You can argue that a ductile iron sleeve is a stronger surface and retains oil better, but with years of racing these sub 200hp engines, the stock alusil bores have proven very durable. The spec 944 engines aren't making enough power/heat to warrant any other arguments in my opinion.

 

Thanks for sharing your experience 944cs. Most helpful.

Mike

 

These cars also also 20+ years old and good rebuildable used engines are getting harder to come by. For spec type classes it is currently illegal to resleeve but that might change in the coming years.

 

Good point on age and thus increased need to consider sleeving. FYI, ok to resleeve in 944 Cup series I believe.

Mike

 

Yes...
So far we are still seeing enough supply of useable blocks to not require this. If that supply gets hard to come by we will have to consider sleeving or repair/oversize.

The concern right now is people taking good blocks and putting alot of money just to gain some small edge further increasing the gap between the big money types and those that don't have big money to spend.

 

Yep, ok to resleeve for 944 Cup. My turbo engine is sleeved, although with repair sleeves. All the new engines we are building are sleeved with either repair sleeves (cheap) or Darton sleeves (more expensive). I actually prefer the Darton sleeves. Worth it.

We use either 88 pistons with appropriate rings or custom Woosner pistons. For all the above-mentionned reasons.

c.