Has anyone built a 1745cc engine (76mm stroke with 85.5mm stock 1600 size pistons) for their bus before? If so what was it like to drive? It sounds like a good and reasonably cheap combination to make. Very little clearancing for the crank, no machining of case or heads for bigger barrels.
A mate of mine is building this at the moment and its going well and hasnt come across any issues yet , still got a bit more too do yet but will be interesting to see how it goes
on paper it should be a really good engine for a bus... and probably in reality too I've never come across one, always someone asking about what they've like tho
From looking at the posts on thesamba and shop talk forums the piston skirts may need a little shaving off them for the rods to clear them. Not sure if it would be the same with the forged mahle 85.5mm b&ps. You'd need 3.5mm barrel spacers to keep the pistons in the barrels wouldn't you? Stock heads and valves and a engle100 cam should make a nice torquey motor for a bus. Not sure if you could also use 1:1.25 ratio rockers with an engle 100 for even more lift.
I would go with stainless valves, and a good port n polish on the heads Barrel spacers sound about right... as for going to 1.25 rockers, you might need to relieve the tops of the pistons so the valves don't hit them on cross over
Stainless valves are so cheap now its daft not to use them really and Ultra VW did a nice article on easy porting and polishing too. Hot VW mag ran a built article called Project mileage motor where they built a 1745cc engine. It ran over 16 issues: http://www.cbperformance.com/articles.asp Makes for some interesting reading as on the dyno it made 92.5bhp at 5000rpm and 120.8 ft.-lbs. at 2500 rpm. From the sound of it the forged 85.5mm pistons have a slightly shorter skirt (mini skirt ) than the cast pistons so require less trimming to avoid the rod touching. It looks like theres 2 options for rods/b&ps. Stock length (5.4") I beam rods and stock barrels and pistons with base shims. or 5.5" H beam rods and stroker B pistons with no barrel shims. Not sure which is the best way really but the B pistons have shorter skirts but are more expensive and more difficult to find too. H beam rods are more expensive too compared to I beam.
Dubdubz on EB has one, I have a 1699 (74mm crank), used forged pistons & I beam rods, engle 100, 1.25 ratio rockers & Brazilian FI heads with small valves that I ported & polished(33/32mm valves IIRC) 36drlas with 30 vents all blueprinted, goes pretty well.... Ended up Like this cos I got the parts cheap & just wanted to do something a bit different.
I thought about this too - it seems such an obvious cheap thing to do, but you know how one thing leads to another...
Loxy, do you run that engine in a late bay? 30mm venturies sound a little large for an engine that size in a bus. I take it you don't run into trouble with valve to piston clearance with the engle 100 and ratio rockers then? I like the idea of fitting fuel injection using the mexican manifolds and run it with a megasquirt or similar ECU so there goes the cheap engine.
No it's an EB (crossover! Lol) Got 28s too, fitted a zeitronix zt-2 wide band air fuel gauge/ datalogger for tuning too (with a view to going megasquirt FI and turbo in the future ) Had no problems with the cam and rockers, goes well gonna try a 6 rib box soon to see if it's man enough. My benchmark is a 3 mile hill on the way to work, before was 3rd gear now its 4th gear all the way and speedo indicated at 70mph (got smaller tyres f&r etc).
Sounds like its got a fair bit of torque then. Theres a hill in the lakes thats a good 2 mile climb and at the moment in my westy its a 2nd gear thrash at 30mph. My 1.9 T25 caravelle with 78bhp will do it in 4th at 50ish so i'm looking for that sort of power/torque.
I put one in for me mate, it made 80 ish on the dyno, one problem he had, but nothing tho do with the bore, he had high lift cams, the no 4 exhaust valve came out of the cup, broke the clip on the end of the rocker assembly. The rocker fell off closing the valve. The backfire through the carb was amazing Replaced the feet with articulated ones.
