Technical What torque and power can you expect from a 540cc conversion?

[smart51]

I've been looking for a 500R or a 500 with a 650 engine. There's not much about for sensible money, so I'm considering getting a 499cc car and fitting 540cc barrels and pistons. I'm not looing for high RPM power figures or massive acceleration. I just want to cruise at 50 MPH without slowing down much on hills, so more torque at 3700 RPM.

What kind of power and torque can a 540 expect to make? I'd be willing to swap to a 30/70 cam if it will do the business.

 

[smart51]

Looking in to this further, I may not need a 540cc conversion to do what I need. The 110F engine has the same cam and swept capacity as the 500 Sport, which made 21.2 BHP. The sport will have gained 1 of its extra horsepower from the increased compression and the other 2.2 from the bigger carb (22mm venturi vs 21mm). A bigger still 28IMB carb from the 126 plus a head skim and some porting should give a torque curve similar to a 126 engine, but with less cost and less work.

 

[Goldnrust]

I can't really comment on what engine combo or what power you will need to achieve any specific performance... my first hand 500 experience is limited to a short passenger ride and to my own car in many pieces!

But what I can say is that if you're on the hunt for a 500 then engines are comparatively cheap, and tuning parts are commonly available. So the usual boring advice applies of buy a car with the best body condition you can, and then there are many roads you can follow to chase performance later

Maybe by driving the standard 499cc engine you'll better understand whether you want the all round extra grunt that a capacity gain offers, or just want to be able to make some power by revving the engine a bit harder, in which case some head work, a cam, carb and exhaust may be just what you need?

I'm interested to take on the challenge of navigating modern traffic with my stock 499cc engine, but I'm no purist and I'd be very surprised if it stays standard for long!

 

[the hobbler]

Looking in to this further, I may not need a 540cc conversion to do what I need. The 110F engine has the same cam and swept capacity as the 500 Sport, which made 21.2 BHP. The sport will have gained 1 of its extra horsepower from the increased compression and the other 2.2 from the bigger carb (22mm venturi vs 21mm). A bigger still 28IMB carb from the 126 plus a head skim and some porting should give a torque curve similar to a 126 engine, but with less cost and less work.

 

[the hobbler]

I can't really comment on what engine combo or what power you will need to achieve any specific performance... my first hand 500 experience is limited to a short passenger ride and to my own car in many pieces!

But what I can say is that if you're on the hunt for a 500 then engines are comparatively cheap, and tuning parts are commonly available. So the usual boring advice applies of buy a car with the best body condition you can, and then there are many roads you can follow to chase performance later

Maybe by driving the standard 499cc engine you'll better understand whether you want the all round extra grunt that a capacity gain offers, or just want to be able to make some power by revving the engine a bit harder, in which case some head work, a cam, carb and exhaust may be just what you need?

I'm interested to take on the challenge of navigating modern traffic with my stock 499cc engine, but I'm no purist and I'd be very surprised if it stays standard for long!

I agree, you WILL gain a little performance improvement by fitting the 28 carb, porting and skimming the head, but whether it will give enough extra to achieve what you are aiming for is debateable. If you have the head off, for the amount of extra work required, you might as well fit a '540' kit and, possibly, a 35/75/75/35 cam. The standard exhaust won't help, so maybe a good quality 'sports' exhaust as well. If you do decide to fit the 28IMB, make sure that it fits properly over the mounting studs. The '28' when fitted to a 126 utilises a 'fuel-return' system--some people say just blank it off, but I always advise that it is used, by fitting a 'return' pipe back to a METAL 'T' piece let into the fuel system just ahead of the fuel-pump. I have led my return-pipe round the back of the big "cooling-air intake", inside a section of suitably sized fuel-pipe (to protect it), held in place with rubber-lined 'P' clips. By allowing the fuel to continually flow, it will stay a bit cooler which will help with hot-weather, hot-engine starting

 

[Toshi 975]

I've been looking for a 500R or a 500 with a 650 engine. There's not much about for sensible money, so I'm considering getting a 499cc car and fitting 540cc barrels and pistons. I'm not looing for high RPM power figures or massive acceleration. I just want to cruise at 50 MPH without slowing down much on hills, so more torque at 3700 RPM.

What kind of power and torque can a 540 expect to make? I'd be willing to swap to a 30/70 cam if it will do the business.

Yes going up a long hill is the big test the inlet port on a 500 head is 26mm and 30mm on the 126 head and spacer so quite easy to open that up. I have a picture that shows the specs in Italian of the Giannini models and you can see how the power increases were made.

 

[smart51]

Yes going up a long hill is the big test the inlet port on a 500 head is 26mm and 30mm on the 126 head and spacer so quite easy to open that up. I have a picture that shows the specs in Italian of the Giannini models and you can see how the power increases were made.
View attachment 423927View attachment 423928

That's quite interesting. It shows that my intuition is fairly sound - a well sorted 500cc engine can make similar power to a basic 650. 29 SAE HP is about 24 or 24.5 BHP. The higher compression ratio gives about 1.2 of those BHP. The extra RPM gives another 1.5 maybe. The other 3.5 must be from better volumetric efficiency - actually filling the cylinders with air and fuel. The "modified carburettor" might be enough, or perhaps there was some light porting too.

 

[smart51]

I've arranged with a dealer to go and see a 500R next week, so I might not need to do much work to get my 23 BHP.