My pretend Ulster engine is the same as Malcolm's except for Speedex head. I go up to 5000rev/min now and again but as Malcolm has remarked it becomes very noisy at higher revs so I try not to go above 4500. It has a light flywheel and is dynamically balanced. Ian Bennett who posts on here has a supercharged Pigsty engine I think with a splash fed crank and his car is very fast by my standards.
Dave.

Location: Sheffield

My Ulster has an engine identical in spec to Malcolm's except that his SU is down draught, mine semi down draught. I do go to 5000 rpm or even slightly above on the odd occasion but that's only when competing and I can't hear the noise with my helmet on On the road, 4500 is as far as I go. I run a 5.25:1 CWP whereas Malcolm's is 4.9 (I think)

The engine in my Trials car is also to the same specification except that it has Phoenix rods. I sometimes think that that would rev to 'bang' but 6000 is as much as we normally do but 6500 has been noted on the odd occasion when the red mist's come down (5.67:1 CWP).

Steve

Location: North Yorkshire

Thank you all for the suggestions. It looks like 5000 is my "end" point with the caveat that things will be sounding pretty frantic by that point. I had a Series IIA LR with a low comp engine and it was obvious when it was unhappy(about 65mph downhill with a tail wind).

Location: Sunny Seattle

An 1.5in crank with Phoenix rods and slipper Pistons will do 7000 revs provided it's been balanced and put together properly. A counterbalanced crank even more.
The problem with the 1 5/16in crank set up isn't the crank, it's that standard rods aren't good for more than just over 6000 revs. However, unless you have double valve springs, it's unlikely you'll get to those speeds.
Certainly, you'd need a really good engine to pull more than 5000 revs in top on a 4.9 diff and 3.50x19s.