HPBCANADA.COM

Behind the scenes there have been and still in progress some interesting projects to build different combinations of cylinder sleeves using different engine blocks. There are two sleeves, the Bridgeport and the Oval port. There are 3 different blocks, the early production or sand cast, the first foam cast and the second version foam cast. You can install either sleeve in any of the 3 blocks.
The sleeve and porting are only two parts of the equation that results in a super performance 56 OMC., but it is interesting that some of these mixed combinations are working well on T boats.
The original prototype SST 60 was using a production or sand cast block. The block was replaced with the foam cast when the class specs were submitted to APBA . So this combo is not special.
But installing oval port sleeves in a production sand cast block is different.
The two foam cast blocks in stock form indicated that the second version oval port had the possibility to be the better block. With a carburetor upgrade the performance greatly improved.
Question was....is it the oval port sleeve or the powerhead flows better or the combination of both?
Well it seems that if you install bridge port sleeves in that block....the motor is even better performance wise.

It will be interesting to try these combos to see if they really do perform better. Has anyone out there tried this? Any report on how it worked out?

I don’t think any of the do it yourself T boat people have even thought of doing a sleeve replacement. Most don’t have the knowledge, skill or the equipment to do it. Having a machine shop do it is very costly and without really knowing it will work out....it’s not worth the cost. In T850 racing we know it’s not just the motor that makes a very competitive boat. I think what happens is the person tries something different in the motor build and that motor ends up being better than their previous motor or motors. Until multiple people do the same build with the same results and those motors dominate every other motor they run against. It’s just hearsay. Mod race classes in OPC other than F1 all died because there was to much difference in the performance within the class and non competitive racers dropped out. That’s why you hear “he that cheats best wins”...”he with the most money wins”.
All this being said my gut feeling is there is some advantage to switching sleeves. I just don’t think the advantage makes that much of a difference.....but I would like to learn more about it.

I think the big draw back with running a bridgeport sleeve in an oval port will be the longevity of the bridge in that motor, it will may run better but for how long, without the casting behind the bridge you are going to losing a significant amount of cooling to the bridge, this maybe fine for a drag motor but not sure it would last as a lake ripper. Paul has one built but has not run it yet, will be interesting to see how it performs and that it can last. In our foam cast bridgeport we have to jet the middle cylinder in terms of helping heat control versus performance. At least the oval ports do cool better so who knows maybe survival is not an issue only testing will tell. Perhaps we will get Paul's out in the fall