Hi

I was wondering how easy / hard it would be to set up an engine test bed? Presumably it would have supports to minic the chassis rails and provision for mounting a radiator close to the fan? Also, it would need some sort of pipework to carry the exhaust gases from the manifold to outside, via a silencer.

Does anyone have such a setup?

Regards

Colin

Colin,

Yes, got one made out of half a ruby chassis (i didnt one in half for the purpose). It has a radiator (BMC mini) and exhaust pipe leading into a massive range rover tail silencer to keep the neighbours happy.

Dad also made a water brake out of a fluid flywheel so that you can run the engine under load. The load can be controlled so it can measure torque and power curves, makes for very effective tuning.

Regards

Rob

Hi Rob

Yes, I wondered about loading the engine - was considering some sort of friction device or an electric motor!

Also thinking about guards to keep it safe.

Regards

Colin

Colin

The engine should be alright, but the guards MAY help your own safety!

Algie

Colin,

Friction brakes would have to be enormous to cope with the heat generated from loading the engine for any period of time. If you can get a fluid flywheel it is not terribly complicated to make a water brake. The load is varied by controlling the flow of water through the flywheel, the water draining out is warm.

Another possibility would be to make a centrifugal fan but the noise would be horrendous.

You could of course buy a froude water brake, there is a company in worcester dealing in second hand units but probably not cheap.

Regards

Rob

Rob,

Showing my ignorance here, but what exactly is a froude water brake and where is it used?
Re your Dad's fluid flywheel, presumably this is similar to those fitted to Daimler cars, buses and Lanchester cars among others?

Jeff.

I think the fluid flywheel came off a mercedes. It was bought from a scrapyard in the mid sixties.

A froude water brake is a proper purpose made engine test dynamometer - we have rows of them at uni in various sizes attached to all sorts of engines.

Regards

Rob

You need Arthur Mallocks "Comparator".
A big paddle wheel attached to a wheel of a 750 clubmans car (U2) and see what it revs too?

Read Paul Lawrence's book "The Lone Furrow" for this and some more incredible stories about a great character and it seems forgotten engineer and genius.

Steve.

http:I have enjoyed this site for ages and felt that it is time to offer a picture from my 'Brooklands' Flickr pictures. My newly rebuilt engine three-point mounted on a Froude. We use the two front mountings and a 'steady' under the gearbox union.
Mike Telford's engine was on there before mine!
//farm3.static.flickr.com/2280/2078450881_b83ad70000.jpg

Heres mine. Engine on front chassis section mounted on old barbecue frame. Petrol tank on wall. rad steadied by cow horns and stiff wire. Exhaust out the window. Wish I could make the picture bigger

Hi

Thanks. The picture shows that I have also to think about where to put a fuel tank - a significant omission - I knew there was something else!

Regards

Colin

Norman, I'm intrigued. How do you gauge apparent output? We run the Froude to measure the galloping horses at a range of engine speeds. I have been looking at improving the figures in the low to mid range, rather than just the screaming limits that seem to be important elsewhere.
A testing by ear can be fine in a static or unloaded engine, but we are looking for an ability to pull two possibly weighty adults up steep hills. I might also be looking for reasons for misfires under loads as if travelling at 55mph in top, say. I can immitate such conditions at the bench. (In fact I can immitate howling gales, today, or wind speeds over the carb intake akin to such conditions, too. Some b***er left the door open every time I cranked it up today!)

I think some people are looking for a way to start up and test an engine before running it in the car, whilst others actually want to load up and properly test an engines performance out of the car.

May be of interest... I have recently seen an "inertia" rolling road as opposed to a conventional alternator loaded type. This would seem to be a neat way of measuring power without much in the way of calibration or compensating factors that an alternator type needs and therefore less likely to have a bulls***t factor.
Only trouble is it cant hold at given revs so not much good for fault finding?
Perhaps a giant flywheel is whats needed for these engine test beds ?

Steve

Steve,

If you are considering making an inertia test setup - very good indeed for fiddling with carb setup for throttle responce - make sure that the flywheel is not connected hard to the engine, it needs a rubber joint otherwise the torque pulses and gear noise etc will create massive loads in the transmission. On the car this job is done by the tyres.

Regards

Rob

Jim, I am running only to establish unsophisticated things such as noises, leaks, fine tuning, and tweaking etc. It makes life so much easier when the engine is out of the car. It runs sweet enough but I cant tell much about the performance until I fit the motor in the car. The petrol tank which I have bolted to the wall is higher than would be in the car so the 'head' of petrol is higher but no ill effects have been noted

Thanks for tip ref the drive system Rob, Would like to have an engine test bed someday, but pick up project, lathe, etc etc and of course the little one are using all the time at the moment!!

As a point of interest when I built the special 1st time around the bulkhead and front heel board were all removable , so I fitted the engine in the chassis and rigged it up to a life support system and was able to run it in the chassis with easy access to all parts. I also ran without the gearbox and was suprised at the run out of the flywheel.

Steve

Norman, its me again. The idea of raising the engine to walking height is a back-saver of great merit. I used a workbench in a greenhouse to run my mag engine last spring. It was so much easier to sort it at a good height in good light, as well as being able to simply lift out panes of glass for fuel and exhaust! Looking back, I wish I had a photo record of the fun. At full chat, a pane of glass dropped out, one evening. It is way too noisy to be of future use. I really like the natural light for working, though.

Hi

Has anyone with the facility to test engines produced any power/torque data for different engine set-ups e.g. standard engine with low and high compression heads, different carbs, breathing etc.?

Any information of this type would be very interesting.

Regards

Colin

Colin,

When i get that far i will gladly post up the data, unfortuneatly the engine is still someway off!

Regards

Rob

To gather this information and present it in a spreadsheet, will depend on some essential needs for honesty and/or the real identity of the source.
My engine as currently testing has a range of features that are clearly not standard.
The fine details often make quite a difference once you go outside the standard.
As a sample:
Pistons used?
Rods used - weights?
Cyl head - Std or high comp head - but what actual compression? Gasket or glue?
Porting - simply smooth? polished? flowed? enlarged?
Inlet valves - fairly standard? larger?
Seats - flush? recessed?
Manifold - cast iron? alloy straight? alloy sloper?
Carb - Std Zenith? SU? choke sizes? needle?
Exhaust - Standard? Bananas? 3 or 4 into collector?
Oil pump -
Oil pressure -
Crank - Std or steel/Phoenix
Bearings
Gearbox fitted? 3 or 4 (I saw pictures of a roller-bearing gearbox in current use this week).
Axle/Diff ratio?
Engine oil weight/thickness? Synth, mineral or veggie
Gearbox oil? Some use diesel lubricants .....
Clearances (built when? tight or worn)
Are you running thermo-syphon or pumped water?

You will think I'm getting too silly, but I left out the brand of fuel and the octane (goes with compression) but we see a difference. Try a splash of diesel fuel in a low comp engine to a tank of petrol!
Are you measuring at the gearbox or at the driven wheel?
I lost count of the variables.
If you want an idea of how it is done well, ask Paul Rogers Engineering about flow-bench running.

Within a narrower band of standard to fairly ordinary home-brewed 'tune', you can predict a fairly narrow range of output.
We try to avoid silly mods that produce silly responses. By which, for example, I would avoid oil pressures over 65lbs because lip-seals don't last. A well made oil pump can easily exceed this on a cold morning in a pressure-fed engine. Spit & hopers don't have this issue. Oil pressure is essential at 6500rpm, but oil takes power to move it.
Don't expect standard cars to 'rev' much beyond 3500. Horse-power will be best seen in useful torque rather than noise to scare the other horses.

Sorry - I talk too much!

Hi Jim

With respect to your comment:

"Within a narrower band of standard to fairly ordinary home-brewed 'tune', you can predict a fairly narrow range of output."

and accepting that there will be a fair amount of 'natural' variation on the performance of these engines given the number of variables involved, have you seen power/torque date for these?

Regards

Colin

Colin, I'm very interested in trying to compile some sort of data spreadsheet. I suppose it all starts with the first figures we log.
For instance, this afternoon in running a slightly higher comp head with an SU 1.125" and a bunch of bananas, I recall a reading of 17hp at 2900/3000rpm after fiddling around with the dizzy for optimum settings. The plugs were NGK's: 8's I think.
A similar engine last week ran about 15 at 3500, but on standard carb and exhaust manifold. We start off on torque readings [as in foot/lbs] and these are fed into a little computation that spits out horses.
The engines both had virtually standard valve sizes and a gentle polish. The engine running today had a high comp, slightly special head but last week, we ran with standard shape combustion chamber and about 7 to 1.
Colin, is this what you want?
I'm told that in period, the 3000 output may have been about 12hp on a good day.

Hi Jim

Thank you for your reply.

The figure usually quoted for a late Ruby engine, with a compression ratio of 6:1, is 17bhp at 3800rpm (747cc) - so this is all I have had in the past to go on! All the figures you quote are therefore of interest.

So, given your 15bhp at 3500rpm with a 7:1 compression ratio, perhaps the standard engine 17bhp figure would appear to be a little optimistic?

Do you know what effect the modern type of petrol has on engine power? Is this a factor?

Regards

Colin

Modern petrol?
I can only dimly recall those strange historic brews.
We use unleaded pump fuel.
I'm told it varies slightly winter to summer.
Comparing 1930's fuel is really not useful.
We don't have to filter through a chamois, anymore.
We all expect agreed standards, today.

If we get into ethanol and methanol with all the recipes from my Dad's past ..... well, lets not! It's highly carcinogenic.

Hi Jim

Do you measure or control the engine running temperatures? My interest in the fuel types was whether the unleaded fuel we use now runs hotter than in the past, and is more prone to vapourisation, affecting power from the standard engine.

Regards

Colin

The current radiator needs a fan to really stabilise temperatures. As a rule of thumb, we reckon to run just under boiling temp for optimum.
As for hotter burn. Is this a measure of octane rating? The quality of burn is supposed to be better than 20th century stuff.
Fuel vaporising has always presented problems, but more or less - dunno!
I have burnt and melted valves or pistons in the 1970's and still do it occasionally - I'm not learning, obviously!
Everyone will tell you that the apparent shelf-life of unleaded fuel is not good in comparing the old and the new. I recall starting an aero engine on 100 octane in about 1970 that had a tank filled from five year old fuel. We switched it on and after due checks flew from Baginton to Halfpenny Green. I'd bet it wouldn't do it on todays stuff. We got a bit of an ear-bashing about it at the time! Told it was pool petrol for cleaning.