Impressed by Ruggerini MD151 performance

[albertaphil]

I have to say that my Honda/Ruggerini build is exceeding my performance expectations. The data plate says 16hp which would be at sea level. I am at 4000ft, which should drop hp by over 10%. With me on it, the bike weighs at least 278kg, but it will climb an 8% grade at 90kmh. The bike is not suited to speed limits over 100kmh, but on local roads here, I can comfortable go 105kmh with no wind and have enough power to climb a decent hill without dropping below 100kmh. Steep hills will bring me down to 95kmh. And I can push a 20kmh wind steadily without running below 100kmh. I guess what I'm trying to say is that I expected to build a bike that would barely be able to handle a 100kmh speed limit, but in it's current form, I have a bike that doesn't feel like it is struggling at all to run with traffic (either in acceleration or top speed) on such roads.

Moreover, all of my intake air gets sucked through a 3cm inside diameter hose that is corrugated (thus reducing airflow) and is 45cm long. Additionally, my exhaust is squeezing out through multiple sharp bends in a pipe with and ID of not more than 25mm. I think if I could free up the breathing in and out I could realize even more power.

Incidentally, running with maximum acceleration and at 100kmh+, my last 200km gave a fuel economy of 82mpg imperial. That figure is somewhat lower than others I have read on this forum. Is it my driving habits? Not to complain or anything.

[BertTrack]

Congratulations on the result.

Sounds like a dream come true.

Any movies in the making?

[albertaphil]

Thanks. I don't see a gopro camera in the near future so I will have to rope someone into being videographer for me...

[tappy]

Incidentally, running with maximum acceleration and at 100kmh+, my last 200km gave a fuel economy of 82mpg imperial. That figure is somewhat lower than others I have read on this forum. Is it my driving habits? Not to complain or anything.

Diesel engine are more economical when they're not revving too high - typically ~2250rpm for an MD151. So if it's geared to accelerate and climb hills but is revving at say 3000+rpm when cruising then yeah - it'll drink a bit more fuel.

[albertaphil]

Which begs my Next question... is there a danger in "lugging" these engines?

I recognize that this is a generations-old debate. I also recognize that on-highway diesels are designed to run wary down near max torque rpm all day long. But engines we are running are not on-highway diesels. They are mostly stationary engines that were expected to run at rated rpm.

Probably I could answer my own question by installing exhaust temperature, oil temperature, oil pressure and cylinder head temperature gauges. But I haven't yet and I wonder if anyone has any thoughts.

[BertTrack]

I wouldn't worry too much about it.

As-long as you're not running so slow and hard that the mechanical job of the flywheel becomes hard, you're ok. (Unless low engine speed also results in low injection pressure)

When it's warmed up you are free to do as you please.

If you keep an eye on the fuel specific diagram you won't lug them.

[alexanderfoti]

Which begs my Next question... is there a danger in "lugging" these engines?

I recognize that this is a generations-old debate. I also recognize that on-highway diesels are designed to run wary down near max torque rpm all day long. But engines we are running are not on-highway diesels. They are mostly stationary engines that were expected to run at rated rpm.

Probably I could answer my own question by installing exhaust temperature, oil temperature, oil pressure and cylinder head temperature gauges. But I haven't yet and I wonder if anyone has any thoughts.

I have a cylinder head temperature gauge in my bike, which controls the fans.

It measures the temperature right next to the injector tip, as close as possible. Around town 70-80 degrees is normal in our current weather, that is around 2000rpm most of the time.

If I get on an A road etc, and sit at redline (3600) for any period of time, then the engine temperature stays around 90, untill I slow down where it jumps to 110-115, the fans run constantly.

My theory is that the oil is heated up during the running on 3600 rpm, and then keeps the cylinder head temps high until it cools down.

If your fuelling is ok, then sitting at redline the whole time should be fine in my opinion.

[henneberg]

I am even more impressed by the Ruggerini MD151 performance after replacing the standard industrial air filter with a KN SU airfilter and after cutting off the flywheel fan part.

Top speed of 112 kmh is reached faster and the acceleration is quite improved ( flywheel lost 2 kg

So ideally the engine should run at lower rev., will go for a larger gearbox sprocket 21->22 at next rebuild