Hi All,

I'm having a recently acquired Ulster rep shipped to the US in a month or so. The engine was built by Pigsty. I have some specs but don't know some details and wonder how much I can rev the engine. I know they tend to spin well. The specs I know are that it has a 1 5/16" Phoenix crank, splash lubrication, a cam that is good for road use with good low torque(not sure of grind) Austin rods and pistons, standard block, Ruby head, sand cast crankcase. I have no idea what valves are in it. It has a 30 MOV carb rebuilt by Robert Foreman. The CWP is 4.9 and it runs a C/R 3 speed. My question is, how many revs are safe? Having not driven it, I don't know if, with these specs, it will run out of breath before dangerous revs are reached, or if it will rev happily until the Big Bang. I would guess the power drops off at some point.

Location: Sunny Seattle

Speak to Pigsty

My Pigsty engine, probably with a little bit more power than yours, suggests 4500 is probably a good stopping point, with little or no power increase at higher revs. Max power was at 5400, but not a lot more than at 4500, hence my suggested limit. It was run up go about 5750 rpm on their dynomometer whilst under test- it was a bit loud and scary too!

The engine in my Ulster is very similar specification apart from having an SU rather than the Solex.
I do not take my engine over 4500rpm. It is getting quite raucous at that speed and as it represents about 65mph in top I think it is sufficient.
If your engine has Phoenix rods it should be good for another 1000rpm but mine has 80 plus year old Austin rods.

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.