Building an engine dyno.
 

Over the last couple of months I have come top the conclusion that we basicly have no solid number on what each mod will do to our engines as regards power. We make a number of changes and have no idea if they all worked or only some.
I have redesigned the roller throttle port size lots of times and clearly have no clear idea which is best. Having read that recent artical I have change my mind again so i want to be able to run tests to be able to give clear direction.

Okay enough reason, now to "HOW I THINK I WILL DO It",
I am talking to a guy to buy a "Eddy Retarders from a truck" this is then anchoured with a strain guage to measure the torque and a prox reading revs.
From that you get to calc HP and torque at the different revs.

Was going to use a water pump but they have issue and are a bit difficult for me to find.
Tony

Re: Thinking of building a engine dyno.
 

You guy are pretty quite,

I paid for the Telma eddy Retarder today (PDF of the unit is attached). It provides the load for the engine. A shaft is connected to the front and back for support with the front attached to a pulley and chain driven to a shaft driven from the engine. Eddy current units are limited to around 4,000 rpm so thats why the cahin drive. I am using 2.5 reduction to enable the unit to read up to 10,000 rpm on the motor & 1,600nm.
The centre section of the retarder is floating and will be fitted with a 1 ft lever at the end of which is a strain guage (set of scales). At any point in time its just a simple matter to read the pound weight and you have the ft pound the engine is producing. At the same time measure revs and you can calc the HP being produced.
I am ahead of myself a bit we control the load on the engine by feeding between 0 to 24vDC to the coils (using a old electric forklift charger) on the retarder as required to keep the engine at full load.
I recently purchased a half cut and I will pull the ECU and wiring harness from it to enable me set up the test bed.
My plan is to start with a stock standard low k engine (100,000 kilometer is low to me). Attach it as if it was in a car, full exhaust, standard intake then do a couple of base line numbers.
Then with out touching the internals of the engine I want to see what can be done to get more power from the out side, extrators, different ECU (have got the Wolf going), different injectors & roller throttle. All of it one step at a time to put solid number at each stage.

Okay thats it for me for the moment will keep you posted as I go, given that it is the slow part of the year (only working 60hour now) for me I want it all built and running in the next 6 weeks or sooner.
Have a great day all.
Tony

Re: Thinking of building a engine dyno.
 

Good luck Tony :)

Re: Thinking of building a engine dyno.
 

I'll be reading that ! Very interresting to know real numbers. :)

Re: Thinking of building a engine dyno.
 

was also thinking about build/purchasing one a while back... Quickly realized it would be cheaper albeit inefficient on time to just dyno the car on a chassis dyno

Tom

Re: Thinking of building a engine dyno.
 

I had the same thought Tom and agree that is cheaper.
Clearly thought you never get the research done that is need to develop the SVX engine. Take for example cams. On a engine dyno you don't run timing belt covers, and when you want to change the cam its a simple matter. If the engine is in the car you have to pull it, put it back everytime.
I don't know of any serious race engine that has been developed that hasn't spent time on a engine dyno.

Besides a guy needs a hobby to keep him off the streets.
Have a great day.
Tony

Re: Thinking of building a engine dyno.
 

That would have bee the sole reason to build one for me... I can change a manifold in the car... Change a header in the car... But cams... it can be done w/o pulling the engine but what a PITA!! Good luck!

Tom

Re: Thinking of building a engine dyno.
 

Thanks Tom, I may need all the luck I can get.
We need to get a discussion going about what we all would like to acheive in the end and how best to step through to that point.
Tony

Re: Thinking of building a engine dyno.
 

Lolz, I just like ours :tongue:. Except it's a water brake dyno, good for ~1000BHP

http://www.huntsmachine.com/images/TEST&TUNE.jpg

Re: Thinking of building a engine dyno.
 

Adam do you find engine dyno's handy, I read one guy say "The engine dyno always comes before the car dyno" what do you think?
Tony

Re: Thinking of building a engine dyno.
 

Another fascinating thread from Tony, what fun to measure the changes! :)

Re: Thinking of building a engine dyno.
 

Tony the hardest part of building the eddy current dyno, is getting rid of the heat that is produced. If the engine puts out 180 kW, you have to get rid of 180 kWs of heat.
The water or "Froude brake" uses the water to dissipate the heat. The Eddy current has to be air cooled, so it can only be used for short runs.

Harvey.

Re: Thinking of building a engine dyno.
 

Hi Harvey,.
Thats true so the way I get round it is to use a unit capable of handling 1,600nm which is way over kill. It is also open to the air so the unit provides self cooling. As I understand it the cooling of the unit can handle lower heat levels for long periods.
Should be interesting.
Tony

Re: Thinking of building a engine dyno.
 

The retarder was delivered, as they say its a big mother. I put an injector so you can get a idea of the size.
Tony

Re: Thinking of building a engine dyno.
 

It does look like it could dissipate the heat OK, if it is feed plenty of air.
Ozzie ingenuity at its Best.:D

Harvey.

Re: Thinking of building a engine dyno.
 

It's personal preference for tuning really, as both can provide proper load for engine tuning. The benefit I find with an engine dyno is the ability to make changes and adjustments to the engine hardware far easier than if it were in a car strapped to a chassis dyno. For example, camshaft choice on a purpose built v8 can be finiky and requires multiple cams to test and find the right choice. On an engine dyno it's clearly easier to make those cam swaps without much down time.

The way we have ours setup is in a modular fashion. the engines are mounted in a mobile cart that has adjustable supports and fixtures to fit multiple motor makes/models. We then have an array of adapters that bolt directly to the flywheel/flexplate on the motor and connect to the water brake via a short(adjustable ~12-14") "driveshaft". The cart rolls up to the dyno and is pinned/locked in place to the actual dyno frame.

This all avoids the multiple, and complicated array of bellhousing style adapters. Starter motor engages a ring gear affixed to the brake itself, so there's never a worry about having to find a way to get the engines actual starter motor to work with the dyno.

Re: Thinking of building a engine dyno.
 

The starter motor idea is a great one, I will do it the same way, thanks for the suggestion.
Tony

Re: Thinking of building a engine dyno.
 

If you would like more pictures of our setup just let me know. I'll be at the shop putting a subaru motor together and will take photographs of the entire setup if needed.

Re: Thinking of building a engine dyno.
 

Adam would love a couple of photos to help me.
Also I need to get my head around how the dyno load works as regards load managment.
As I understand it I adjust the load generated by the retarder as the engine revs up, what I don't get is do I increase the load on the retarder or decrease it? Or to add confusion is it both ways?
Tony

Re: Thinking of building a engine dyno.
 

In an ideal world, you would want the dyno to allow controlled power runs and also tuning at static revs.

A lot of dynos do power runs...this is a controlled run from low revs to max revs. You'd want the dyno to lag behind the engine torque so that the engine can still accelerate in a timely and controlled fashion. If you could build a timer so that the retarder would let the engine increment revs in 10 rpm per second...that might make a nice power run. Ie, from Idle (700rpm) to max revs (7000rpm) would take 63 seconds...as I read that, maybe you want it to increment 20rpm per second. The retarder could then vary its load in such a way that if it exceeded 10rpm per second, it would apply more load, and release load if it was taking longer than 10rpm per second.

probably am not making any sense.

For tuning, you want to be able to dial in load to let you hold various throttle positions at various revs. Again, you could build a circuit that allowed the retarder to vary load to keep it at a certain RPM.

Full load on the retarder will stall the engine. Finding the balance will take time.

I would think

Re: Thinking of building a engine dyno.
 

I think you are right Matt, its going to be a bit of suck it and see. As I see it the graph will be over rev's not time so it less critial to increase the revs at a constant rate.

The frame is built and shafts for the retarder are being made, belt drive is ordered. PLC is here so its all coming together.

A question for all you old hands out there. What will exhaust gase temp on each cyclinder tell you & how can you tell which cyclinder is developing the most power,,,, is it the hottest exhaust?
Tony

Re: Thinking of building a engine dyno.
 

EGT's don't necc tell you which cylinder is making the most power... EGT's can change based on ignition timing, cam timing, and fuel quantity.

Tom

Re: Thinking of building a engine dyno.
 

Tony,

I will be accused of boasting but what the hell. I can advise you on the basis of having knowledge of the subject. Many years ago my Company, Relays NZ Pty Ltd was commissioned by Repco Ltd, to design and supply the control gear for a wheel dynamometer they were intending to produce locally.

From your comments I can see that you know exactly what you are about due to your reference to a strain gauge , torque and RPM. You are not building a dyno on a commercial basis and do not requite any form of direct read out, as is required to impress paying customers, and as was required by Repco.

You only have to register engine speed in RPM, and torque in Kilograms Meter, or Pounds Foot as is held/resisted by the retarder/brake. You can draw up a simple graph from which you can then directly read off horse power. This is in point of fact the correct way to achieve properly reliable results.

Absolute simplicity will provide maximum accuracy, and in this regard a lever operating a simple mechanical spring balance is preferable to a strain gauge. You can directly measure the lever and easily check the accuracy of the spring balance, only the calibration of the tachometer will be beyond your control. Therefore you will be able to be very confident with your results.

Direct manual control of the load applied by the retarder (brake), will enable you to record engine performance at any throttle opening. In respect of acceleration, if required this can be established against set values of torque, using a stop watch.

Re: Thinking of building a engine dyno.
 

Hi Trevor,
The strain guage and data feed costs me all of $200 so its worth geting the data feed to a PL to PC. I have also figuring out how to read each exhast gase temp, just trying to work out how to read 6 Narrow band O2 sensors back to the PLC (Convert output to 0to 5 or 0 to 10v).

You are correct in saying I only want a base line number to work from that is why the base will be from a 100,000k engine with standard everything (No AC).

On you project did the load have to be increased as the engine increased rev right up to red line?

Tom I kind of agree that all the things you suggest change exhaust gase temp but feel that equally is a reflection of change in power. To some degree increased air & increased fuel means higher temp & a sort of increased power.

keep the info coming so the interest on the job stays.
Tony

Re: Thinking of building a engine dyno.
 

Kinda of confused... The heat lost through the exhaust is energy not transferred to the flywheel. In all theory, the higher the EGT's the less power you *could* be making. I un derstand what you are getting at but you can run low on power with insanely high EGT's...

Its a line you have to walk... retarded timing can be a caused for higher EGT's because combustion comes too late and the charge is leaving without a full burn.

Tom

Re: Thinking of building a engine dyno.
 

Tom,
Don't quite agree, heat is a byproduct of creating energy that goes to the flywheel, no heat no energy.

Re: Thinking of building a engine dyno.
 

I understand completely... If you were measuring the heat produced by engine in a whole, taking into account the cooling system and radiance through the block along with exhaust gas temps the power measured could theoretically be seen through temp readings...

Exhaust gas temps change with the three variables afformentioned... I have adjusted timing on my engine with the Hydra based soley on EGT's in the past. When I drag raced on the ECUTune chip I would see EGT's top out above 1500*F w/ only 8* ignition advance. We all know that no engine is making good power at 8* advance at WOT but it sure as hell made a lot of heat. W/ the new ECU and a decent timing map my temps dropped around 1200-1300 and made twice the power.

Highway cruising I was seeing around 900*F EGT's with my basic maps... Advanced timing a little more and watched them drop to 700*F. A late spark will not allow a complete burn and thus a good deal of unburned fuel and unfinished combustion is released into the exhaust creating a high EGT but will not make any more power. You will need to rely on another source of measurement for how you want to gauge the power output of the engine

Tom

Re: Thinking of building a engine dyno.
 

it's always a good idea have a good wide band AF gauge installed....the EG33 tends to like to run a little leaner AF than you would expect to produce max power, yet you tempt the engine melt down gods as you start leaning things out...

-Bill

Re: Thinking of building a engine dyno.
 

I accept your point Tom.
Tony

Re: Thinking of building a engine dyno.
 

The EGT will only tell you how much energy is wasted out the exhaust. To tell how much torque each cylinder delivers to the crank, you would need to read the pulsations that the crank has on a scope triggered off No 1, cylinder, but I don't think it is worth the trouble.

I would use the load cell with a digital readout, and a rev counter. Connect a data logger to record the load over the rpm. You can then load this to an Excel sheet.

To run the engine for a torque reading, you run the engine at about 3000 rpm to get it to operating temp, apply a small amount of load to get the retarder to temp. Then raise the rpm to 4000, start applying load as you open the throttle to keep it at 4000. Just like letting the clutch out.:). When the engine is on full throttle at 4000 wind on more load till the rpm drops to 2000.
You can then start the torque readings by reducing the load, to allow the rpm to rise up through the rev range to say 7000, to complete the readings. Then start closing the throttle and reducing the load till it is back to 2000, with the load removed and engine running for a cool down time.

To do spark timing or fuel adjustments, you just run the engine to the rpm that you want to do, hold it there with the load, on full throttle, while moving the timing, watch the load reading for the highest reading.

Harvey.

Re: Thinking of building a engine dyno.
 

It is impossible to measure the torque delivered individually by each cylinder. Reciprocating weight is specifically built into the engine, as a means of eliminating the very factor involved.

A very simple principle is being applied and the application in practice is surely self explanatory. Once the engine is braked, i.e. held back from accelerating, at any given RPM, the force delivered by the brake via a lever, exactly constitutes torque. The length of the lever and the force delivered provides an exact means of calibration. All else is secondary.

It should be noted that variations in the performance of the brake from time to time, as a result of temperature or whatever, have no affect on measurements. All that is necessary is to hold a steady state sufficient for each measurement to be recorded. The brake has only to resist the available torque for that given short time, it does not matter how this is achieved or how the accrued power is dissipated.

In respect of engine tuning, comparative measurement is the key requirement and repetitive accuracy over an extended period is absolutely essential. Complication is a disadvantage.

Re: Thinking of building a engine dyno.
 

Thanks guys for the input it is a real help, I think the project is a bit at the limits of my skill so I need all the input everyone can offer. Harvey that sounds like a great way to do the run.

My reason for testing EGT was more to find the differences in power in each cyclinder is producing. I think it will be a case of read them and see if there is a major difference between each one if so go loooking why.

Okay are you guys siting down I am wondering if its possiable to run one cyclinder for the big first stages of development. Have the other 5 turned off and maybe plug out valves removed. The logic is that I don't have to spend 6 times the money, for example 6 different ram pipes for each trial.
So what do you think is it possiable or just a dumb idea?
Tony

Re: Thinking of building a engine dyno.
 

Current design. The PDF maybe black just click on it and the image will show. Remember its 3d so you can spin etc.
Tony

Re: Thinking of building a engine dyno.
 

Kia ora Tony,

Not a dumb idea, particularly in view of the paper you introduced in the throttle body thread. However as pointed out there, at the engine speeds and valve timing you are working with, not altogether practical.

You are involved with a situation where several induction and exhaust tracts are of necessity, arranged to take advantage of gas movement occurring in adjacent cylinders, and therefore all six must be treated as part of a single system. A single detached cylinder would involve quite different parameters. You are stuck with the cost of a six pack.;)

Trevor.

Re: Thinking of building a engine dyno.
 

Hi Trevor,
I think it would give resonable data as the intake will be ITB and the exhaust will be extrator but should have some simlar bases.
Tony

Re: Thinking of building a engine dyno.
 

Tony, I took a handfull of pictures of our dyno for you. I've just got to DL them from the camera and UL them to photobucket or picasa later tonight. Wife and I are going out for a bit right now.

I'll post them here later on for all to see since they are on-topic afterall :)

Re: Thinking of building a engine dyno.
 

CAD diagram looks good.

Have you got a bearing supporting the shaft from the motor? Looks long, and a bit flexible under load maybe?

Re: Thinking of building a engine dyno.
 

Motor drive shaft is still in development phase, I am thinking of using a tail shaft but even that has some issues. I will post photos tonight of were construction is up to. I want to find a flywheel for the motor so I can use the clutch plate, do you know were I can find a cheap fly wheel?
Tony

Re: Thinking of building a engine dyno.
 

Project underway here is were its up to. Need to sort out drive from engine.
Tony

Re: Thinking of building a engine dyno.
 

Looks good Tony,

Very interesting project and you are well on the way with it.:) Will you please explain the purpose of what appears to be a belt drive as shown in your photo.

Thanks, Trevor.