911 engine test stand
 

Does anyone have a proven or reliable diagram of a 911 engine test stand that I could fabricate? I would like to fabricate out of box tubing using my stock oil tank, 901 bell housing for the starter etc.

My goal is to run in my newly rebuilt 3.0 while refining jetting and tune on headers and muffler choices etc.

I have the Rich Johnson 911 engine mount for my 914-6 which includes all mounting hardware and engine yoke or bracket.

Also, Is there a specific relationship between the elevation of the engine sump and the oil tank as I no longer have a 911 to measure that for mounting bracket locations?

Thanks in advance for any help in this area.
Cheers

What are you going to use for the 'load' for the engine?

I would strongly advise against trying to break-in any engine at zero load.

I was thinking of doing the same thing. The test stand would be nothing more than a substitute for the engine stand, allowing me to fill the engine with oil and fire it up to check for leaks before installing in the car.

I too have an empty/junk transmission case that I can use to mount the starter and also use to support the flywheel side of the engine.

With carbs, the fuel setup is very easy with a low pressure pump sucking out of a small fuel tank, the basic PMO style regulator feeding the carbs, and a return line back to the tank. Tank of course vented.

Factory 911 oil tank is simple and ideal to supply the oil, being that it has simple oil in/out & venting connections. Oil tank should be oriented on your stand similar to how it sits in the car. The outlet of the tank should be level with the inlet tube beneath the oil cooler

Agree with Chris that the only break-in you can achieve with the stand is the 2000+ rpm running to adequately break-in the cams. But i've always thought that the cam break-in period has been misunderstood by a lot of people. I interpret it as keeping the rpms at no lower than 2000 rpm for the first 20 minutes of running to ensure the cams and rockers receive adequate lubrication as they're running-in their wear pattern. In other words, I don't like the idea of the engine just sitting there running for 20 minutes at a 2000 rpm idle speed. because doing that goes against the goal of breaking in the rings by varying load and rpm during the initial period of running the engine?

Kevin,

What do you think about cam break-in issues?

Are we being led by the 'Pushrod' engine crowd where cams were only lubricated by 'splash' systems and didn't get enough oil at lower engine speeds or do you believe it is generally true that cams need to be treated as a separate part of the engine when it comes to break in .

When we first started Rallying we used to use SOHC Coventry Climax based engines and Twin Cam Lotus engines, we revved the hell out of them and abused them very weekend and we never paid much notice to breaking in cams - we used to build them and run them and never had any cam problems.

In the early Eighties all of the UK 'Tuning' magazines suddenly started publishing articles about cam lube and the essential requirements of running in a cam and we all slavishly followed along.

I have to say that we now follow the procedure but we never had any issues prior to being 'correctly educated'.

Are we just being 'politically correct' ? :)

Chris,

I feel the same way as you do. The general rule of thumb that's been passed along from many years of building pushrod style engines with splash oiled cams seems to have become gospel.

Considering that our overhead cams are typically swabbed with assembly lube, the bearings are direct-oiled via the oil feed bar in the cam housing, and the lobes are spray oiled by the oil feed bar, I really don't see how the 20 minute break in at 2000 rpm is critically necessary. That said, it certainly doesn't hurt the cams to run them in like that.

But I just think the cams are getting PLENTY of oil right from the start when oil pressure is established. What I don't like is running the engine at a steady rpm with no load right from the initial startup. I don't think that helps at all with seating the rings.

I agree,

I think a steady speed and zero load for 20 minutes is a bad idea.

We used to run our BDA engines in in a dyno and varied the load and speed as soon as they ran reasonably well.

Engine test stand..........a convenient gizmo.
 

Kevin,

You must have read my 'problematic engine rebuild' that took me a long time to determine the root causes of the problems. If I remember correctly, I even asked for your opinion. I am not a professional engine rebuilder and that's a good reason I should have a test stand. An engine test stand like mine is simply a convenient set up to inspect, test, repair, and run the engine briefly before doing an engine break-in procedure. Whether you want to do the engine break-in with or without a load is a choice.

I am very happy and satisfied with my home made engine test stand and building a second one that is more versatile than the first unit. Since I only get the motor for the rebuild project, it gives me full satisfaction and confidence that the engine is running and ready for pick up. Rather than turning over the engine sitting on a pallet to the owner and hope that everything is good and working.

Now that the 13th. motor has been delivered to the owner from out of state, the 14th motor is scheduled for mid Dec. start-up and another one in January 2017. BTW, I assemble the engine in my basement and bring it up by myself. No further assistance from anyone (solo job). Preliminary hazard analysis was done for moving this heavy load and has safely transported four (4) engines from my basement to the garage. I am doing another one next week.

Tony

Thanks to all for the experiences and the sage advice. The load issue is an interesting question. My read is that there is no different load on startup on a stand verses one's engine mounted in the car- assuming fine tuning of the carbs and linkages may be necessary to give it a go on the street under varying loads. That said, my goal was to have a shop environment where i could fine tune the carbs after warmup and vary the rpm blips under 3K to confirm no leakage or electrical issues /and to refine my wiring harness to my new gauges needed to address a 914-6 conversion with oil level, pressure, fuel pressure, etc.

Thanks again for the input. Its off to the industrial metal store......


http://forums.pelicanparts.com/uploa...1480534748.jpg

Breaking-in an engine at zero load contradicts virtually every published work on this subject.

Shell published a guide to engine Break-In many years ago where they clearly state:


However, successful break-in not only means the use of a straight oil of the correct grade but also the use of high power settings. High power settings mean high combustion pressures which, due to the piston ring design, forces the piston ring out to rupture the oil film. This is the key to the break-in process.


The time taken to set up cabs and balance on an engine that hasn't had the rings bedded in has the potential to cause serious problems.

How can you set up carbs on an engine that hasn't reached its stable operating condition?

How long do you guys think you can run a fresh engine at zero load before you do damage?

I would argue that the best procedure is to run on a dyno and set it up once broken-in. This would be considered Best Practice.

If you don't have a dyno chuck it in the car get it running as quickly as possible don't let it idle for long, and if you can't make it run well enough to drive turn off and try again.

Once it runs well enough to run, drive it load it up, break it it in and then do the detailed set up.

If you don't think it has been built correctly just don't start it up.

Zero Load and new engines - very worrying.

Breaking-in an engine at zero load contradicts virtually every published work on this subject.

Shell published a guide to engine Break-In many years ago where they clearly state:


However, successful break-in not only means the use of a straight oil of the correct grade but also the use of high power settings. High power settings mean high combustion pressures which, due to piston ring design, forces the piston ring out to rupture the oil film. This is the key to the break-in process.


The time taken to set up carbs and balance on an engine that hasn't had the rings bedded in has the potential to cause serious problems.

How can you set up carbs on an engine that hasn't reached its stable operating condition?

How long do you guys think you can run a fresh engine at zero load before you do damage?

I would argue that the best procedure is to run on a dyno and set it up once broken-in. This would be considered Best Practice.

If you don't have a dyno chuck it in the car get it running as quickly as possible don't let it idle for long, and if you can't make it run well enough to drive turn off and try again.

Once it runs well enough to run, drive it load it up, break it it in and then do the detailed set up.

If you don't think it has been built correctly just don't start it up.

Zero Load and new engines - very worrying.

Engine break in with no load = oil burning engine with low compression forever. Don't baby it. Run in the cam and then LOAD it. short shift to keep R's down but full throttle to load the rings then close throttle decel and repeat.

How do you do that with a track only vehicle?

M

On the track or dyno..

I think you misunderstand boyt911sc point and good reason for an engine stand.

It makes good sense to test oil leaks and even set up idling on an easy accessed platform. Same process is going on if mounted to a car on a dyno. Professional engine builders do not avoid oil leaks on their own freshly build engines sometimes, just look in this forum. The best of them even inform about when it happens and correct it. Time consuming to pull in- and out of car.

You asked the question your self without answer - you asked "How long do you guys think you can run a fresh engine at zero load before you do damage?"

Well to answer that question from my experience, I have never experienced or heard of any freshly build engine being damaged by setting up idle on a dyno. Neither have I ever experienced or heard of any engine damage when testing for oil leaks as a start. The engine do not care whether you put it on a dyno or on an engine stand in this required process. The wheels are turning, so why put it on the dyno. Neither have I experienced or heard of any engine damage from running in cams @ 2000rpm for several minutes after testing for oil leaks.

When you put a freshly engine on a dyno, lets say EFI, you obvioulsy dont put heavy load on it at once. What you do is 1) You set parameters to get the engine started, then "walk-around" test for oil leaks 2) You then start adjusting parameters to get stable idle. 3) You now, after several minutes, start tuning up the rpm scale on NA configuration, 4) Then gradually, and carefully you start put load on it, listning for detonation and tuning towards LPPBT (Location of Peak Pressure for Best Tourge) 5) If forced induction, you now start put really load on it and get above 0 sea level pressure. I can tell you this process takes time, and please note an engine is always under load from any combustion cycle, even when idling, hence the piston moving - the piston rings dosnt care whether you have bolted the engine to a chassis or a welded frame.

An engine stand makes perfect sense to make a "walk-around" oil leak test + setting up the idling. This makes it much more easy to handover to 3rd party for tuning if not doing the tuning your self.

I haven't misunderstood, I just don't agree with running new engines at zero load.

The general advice on cams is not to let the engine idle for the first few minutes - now stretched to 20 minutes. No mention that this has to be zero load and loaded or not the cams will see the same forces.

I know how to run engines in on a dyno - I have been involved with building Race Engines for more than 35 years.

If you guys want to allow fresh engines to idle that's fine by me but I will always be sceptical and will always dislike the practice.

If you have build engines for 35 year, then you know that you can not put full load on an "empty-brained" ECU on a dyno on first start-up....it has to start first and idle at some point

when doing so the wheels are not turning....so why the argument that you need to setup an engine on a dyno?

...it would be misunderstood if you think of ZERO load in a running engine - a piston and rest of engine is always under load from any combustion cycle, even when idling, hence the piston moving.

Jakob, not picking sides, but that's why it's been said (in general) to use carbs or CIS and a dizzy to "break-in" the engine, then remove for EFI tuning.

1st I've heard of loading being important too on break-in.

Good to know.

I've always babied my motors and luckily had the rings seal.

Phew

I think you need to be very clear about what I am trying to say.

I do not like the concept of trying to break in engines at zero load.

To advise that it is an option to break-in engines in this way, is I believe, mistaken and not a good idea.

Running them in at zero load conditions will generally glaze bores in relatively short time periods, which I believe need to be considered in terms of minutes and most certainly much less that the time to fully set up and finely balance carbs.

I can't quantify the 'safe' time period, hence my question, and we have always tried to keep this time to an absolute minimum.

I have never said that you need to set an engine up on a dyno.

What I said is that 'Best Practice' is to break in engines on dynos and then final set up is normally the final stage of this process.

I have broken-in many engines in this way and the final set up was always the last part of the process.

There are, of course, many other ways to break-in engines and before we had the money to spend on dyno hours we used to fit them to a car and drive them.

Breaking in an engine without a map in an ECU also seems an unusual choice.

It would never occur to me to try to run a brand new engine on FULL LOAD without a map - what on earth makes you believe I would do something so patently stupid? :D

We have just completed our first EFI system and fitted it to an engine that we have been running for around 3 years on a set of Webers.

This has enabled us to develop a 'conservative' map that we would use for both initial installation of the complete EFI system and for breaking in new engines fitted with this system.

I would not have considered developing this start up map on a brand new engine - I guess its a matter of confidence.

As most of the engines we built in recent years have been used in Historic Motorsport our EFI experience is limited which is why we adopted this approach.

Most of the ECU manufacturers we spoke with prior to making our choice said that they had conservative rev and advance limited maps available for just this reason.

All I believe that I am saying is that accepted wisdom dictates that engines should be broken in with some reasonable load applied as soon as possible after initial start up.

"and please note an engine is always under load from any combustion cycle, even when idling, hence the piston moving - the piston rings dosnt care whether you have bolted the engine to a chassis or a welded frame."

That is simply not true. To get new rings to bed in to the wall you need to maximize the gas force behind the rings to force them into the wall. That can only be done if the combustion chamber pressures are maximized, that requires high throttle opening to get max air and fuel charge into the chamber, more air/fuel = higher chamber psi when it ignites. When a new engine is first started there is a lot of blow-by of combustion gases past the rings. If you do not force the rings into the wall that hot blow-by burns the oil on the wall and creates a coating that fills in the cross hatch on the wall. That's glazing. When that happens the rings never seat because they are riding up against a smooth surface instead of the relative rough surface created by the cross-hatch.

I disagree.

The piston ring does not adequately seal into the bore as the pressures in the combustion cycle at idle or zero load are insufficient to enable the ring to develop the correct forces to allow it to bed in to the cylinder.

I will repeat the comments made about break-in procedures made by Shell many years ago.

When a cylinder is manufactured, a cross-hatch hone is used to score a diamond pattern into the surface of the liner; this is necessary to allow an oil film to be held on the surface of the cylinder wall and lubricate the piston during operation.

If glazing of these honing grooves occurs before the break-in period is complete then the piston ring will not seal properly, and the cylinder wall will no longer have the surface groves necessary to carry lubricant, and the combination will result in a poor gas seal and high oil consumption. The only way to remove such a glaze is by re-honing the cylinder wall - meaning expensive and avoidable additional maintenance.

However, successful break-in not only means the use of a straight oil of the correct grade but also the use of high power settings. High power settings mean high combustion pressures which, due t piston ring design, forces the piston ring out to rupture the oil film. This is the key to the break-in process.

I can understand why you don't believe my comments but surely Shell have some idea?

Yes, or use a start-up map, but that is related to rpm (cams), not load (break in)

Starting an engine first on an engine stand and do the "walk-around" oil leak test and running some cam rpm's is in no way wrong

Hereafter you do the tuning and break with wheels turning some backpressure

Now we are saying the same thing :) Define please "initial startup"

... initial start-up, could be on an engine stand, right?

Bore glaizing is most likely to happen from cold engines running looong periods with low loads, and most incidents are found on new watercooled engines. And it is not burned oil from blow by (there is no oil in 4 stroked gas), it is condensation of burned combustion products that fills the cross hatch on the wall. Having air-cooled engines we dont run much cold for loong periods, not even on idling.

You still have load on the pistons when idling. The question is in which direction and how much, how do you think you get vertical downwards or directional horizontal load on the rings?

Why would you think that there is more blow-by on new rings vs. used rings?
Why would you think you can force the rings to the cylinder any differently using old rings?
Why would you think glazing only happens on new rings and fresh cross hatch?

For the record, I didn't load my engine and babied it for 500 miles. I had no blowby and the rings seated within minutes.

To Jakob

Sorry, you are wrong and appear to not understand the basics.

You get pressure on the back side of the ring from the chamber pressure that gets behind the ring and forces it into the wall. You want to maximize that pressure to get the rings to bed into the wall. Now tell me that the pressure behind the ring is going to be the same at idle as at WOT under load...

Glazing IS a hard coating created by oil burned on the cylinder wall that fills in the cross hatch. Doesn't matter if it is air cooled or water cooled.

" (there is no oil in 4 stroked gas)" Really ? Do you run a 4 stroke without any oil in the crankcase?? The oil gets on the bores from the lube oil in the case.

"Why would you think that there is more blow-by on new rings vs. used rings? Where did I say that? I said new rings will have a lot of blow-by because they have not bedded in to the bore.

"Why would you think you can force the rings to the cylinder any differently using old rings?"
Again, where did I say anything about old rings?? I said to get the new rings to seat you want max gas pressure on the back of the ring.

"Why would you think glazing only happens on new rings and fresh cross hatch? " Where did I say that?

It's your engine, let it idle for a couple hours to break it in..

Jakob,

Your three questions are not really sensible and bear no relationship to the situation regarding a 'fresh' engine.

No-one has made any comments about the other situations that create issues although there is much published work on the subject of diesel engine problems due to time spent idling.

The first question I responded to was about a test stand to setup carbs with respect to jetting and exhaust system comparison.

I believe that to carry out these procedures on a fresh engine at zero load is a mistake. You clearly don't agree.

The next statement was that Break-In with load or at zero load was an option. I still disagree.

You then suggested that I should know better than to run fresh engines with empty maps at full load - a ridiculous statement.

You are now trying to question my meaning of 'initial start up' which somehow seems quite obvious.

I think this entire debate has become futile and frankly life is too short.

I will stick to my opinion which is that 'zero load' running of a fresh engine should be avoided whenever possible and the time spent in these conditions kept to a minimum.

I am more than happy for you to disagree but please try not to alter the meaning on my comments, which I hope I try to make clear.

My last comment on this subject concerns piston ring forces and I would refer you to this work carried out by Federal Mogul.

http://www.federalmogul.com/en-US/Media/Documents/ICES200976080.pdf

If you drove it you did apply load, maybe not much but significantly more than when idling. :)

Tippy - how do you know you wouldn't have had better leak down and compression by loading it during break-in?

Interesting discussion but I've got better things to do.

kindly read again, it says gas. Do you have oil in your 4 stroked engine GAS? No. And it is the other way around when using the "blow-by" term which I am sure you know :) When engine oil lubricates the cylinder walls you dont get coating, if it goes back up in the combustion chamber (reversed blow-by), then you get blue smoke. Again the Glazing, as seen from my perspective and experience, is from burned combustion products on mostly cold running engines over long periods.

there is no reason really to put in ironic comments, no one breaks in an engine on an engine stand, only initial startup configuration, just like you would do in a car on a still sitting dyno.

I have build and tuned many water cooled race engines, I have used race cars on still sitting dynos as "engines stands" for initial start-up configurations before break in on the same dyno 5 minutes later. Initial start-up configuration using start-up maps and "walk-around" test for oil leaks is short time. Personally, I see no reason for not doing the same on a hotter idling aircooled engine.
.

Examples (no affiliation)

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<iframe width="560" height="315" src="https://www.youtube.com/embed/B0N0ayYOui8" frameborder="0" allowfullscreen></iframe>

I don't believe Al's engine videos there are freshly rebuilt engines. I think that is his test engine, one that's already got driven miles on it, and he uses it to develop his EFI systems.

Slightly off topic... but where do you guys buy your metal to build engine stands, etc?

If you buy from a metal supply house, its stupid expensive...

Tried to buy some material to finish off a roll bar and a 3 ft piece of tubing was close to $100 with shipping...

Do any of the local stores (home depot/menards/lowes) carry metal suitable for building engine stands?

For example: metal fence posts, 6 foot length, are $5. Need to get the galvanizing off, but plenty strong to build an engine stand with...

Menards has boxed metal tubing for building garages, its also dirt cheap...

Any other options? Would love to find a cheap source for 2inch square metal tubing... tons of uses for it, like engine stands/frames/etc...

Bo,

Try checking out metalsupermarkets.com. They have a store in Green Bay, Waukesha and Rockford. I bought a bunch of steel tubing & plate to modify my cage & reinforce the suspension in the racecar.

Good people to deal with. Can order it on line and go pick it up to save $ on shipping.

Thanks! will look into it...

"kindly read again, it says gas. Do you have oil in your 4 stroked engine GAS? No. And it is the other way around when using the "blow-by" term which I am sure you know When engine oil lubricates the cylinder walls you dont get coating, if it goes back up in the combustion chamber (reversed blow-by), then you get blue smoke. Again the Glazing, as seen from my perspective and experience, is from burned combustion products on mostly cold running engines over long periods.

I'm not going to argue with you anymore. Do you think Lycoming knows anything about air cooled engines? This is from them:

quote:

Hard Facts About Engine Break-In

Tips

Most people seem to operate on the philosophy that they can best get their money’s worth from any mechanical device by treating it with great care. This is probably true, but in many cases, it is necessary to interpret what great care really means. This is particularly applicable when considering the break-in of a modern, reciprocating aircraft engine. Aircraft owners frequently ask about the proper procedures for run-in of a new or rebuilt engine so they can carefully complete the required steps. Many of these recommended break-in procedures also apply to engines which have been overhauled or had a cylinder replaced.

The first careful consideration for engine run-in is the oil to be used. The latest revision of Lycoming Service Instruction 1014 should be consulted for this information. The basic rule which applies to most normally aspirated Lycoming piston engines is simple: use straight mineral oil of the proper viscosity for the first fifty hours or until oil consumption stabilizes. Then switch to ashless dispersant (AD) oil.

The exceptions to the basic rule above are the O-320-H and the O/LO-360-E series. These engines may be operated using either straight mineral oil or ashless dispersant oil; however, if the engine is delivered with ashless dispersant oil installed, it must remain on ashless dispersant oil. The Lycoming oil additive P/N LW-16702 must be added to the O-320-H and O/LO-360-E engines at airframe installation, and every 50 hours thereafter or at every oil change. An FAA-approved lubricating oil that contains, in the proper amount, an oil additive equivalent to LW-16702 will meet the requirements for the additive as stated in Lycoming Service Instruction No. 1014M.

All Lycoming turbocharged engines must be broken in with ashless dispersant oil only

When taking delivery of a new aircraft, there is another point which must be emphasized. Some aircraft manufacturers add approved preservative lubricating oil to protect new engines from rust and corrosion at the time the aircraft leaves the factory. This preservative oil must be removed by the end of the first 25 hours of operation.

Each new or rebuilt engine is given a production test run at the factory before the engine is delivered to an aircraft manufacturer or customer. After installation in the aircraft, the engine is run again during the test flights. These test runs will ensure that the engine is operating normally and will provide an opportunity to locate small oil leaks or other minor discrepancies. In addition, these test runs do the initial seating of the piston rings. The rest of the break-in is the responsibility of the pilot who flies the aircraft during the next 50 hours.

A new, rebuilt or overhauled engine should receive the same start, warm-up and preflight checks as any other engine. There are some aircraft owners and pilots who would prefer to use low power settings for cruise during the break-in period. This is not recommended. A good break-in requires that the piston rings expand sufficiently to seat with the cylinder walls. This seating of the ring with the cylinder wall will only occur when pressures inside the cylinder are great enough to cause expansion of the piston rings. Pressures in the cylinder only become great enough for a good break-in when power settings above 65% are used.

Full power for takeoff and climb during the break-in period is not harmful; it is beneficial, although engine temperatures should be monitored closely to ensure that overheating does not occur. Cruise power settings above 65%, and preferably in the 70% to 75% of rated power range, should be used to achieve a good engine break-in.

Remember that if the new or rebuilt engine is normally aspirated (non-turbocharged), it will be necessary to cruise at lower altitudes to obtain the required cruise power levels. Density altitudes in excess of 8000 feet (5000 feet is recommended) will not allow the engine to develop sufficient cruise power for a good break-in.

For those who still think that running the engine hard during break-in falls into the category of cruel and unusual punishment, there is one more argument for high power settings during engine break-in. The use of low power settings does not expand the piston rings enough, and a film of oil is left on the cylinder walls. The high temperatures in the combustion chamber will oxidize this oil film so that it creates a condition commonly known as glazing of the cylinder walls. When this happens, the ring break-in process stops, and excessive oil consumption frequently occurs. The bad news is that extensive glazing can only be corrected by removing the cylinders and rehoning the walls. This is expensive, and it is an expense that can be avoided by proper break-in procedures.

To summarize, there are just a few items to remember about engine break-in:

If a preservative oil has been added by the aircraft manufacturer, drain it no later than the first 25 hours of operation;
Follow the engine manufacturer’s recommendation regarding the oil to be used for break-in and the period between changes;
Run the engine at high cruise power levels for best piston ring/ cylinder wall mating;
Continue break-in operation for 50 hours or until oil consumption stabilizes. These simple procedures should eliminate the possibility of cylinder wall glazing and should prepare the engine for a long and satisfactory service life.


The oil that blows by the new rings IS what causes the glazing of the bores.

end of quote.

This is sorta like being in a strip club (i've heard...).

Everybody has an opinion of what works and what doesn't....


sorry for asking.....................

I'll take Shell and Lycoming's opinion on what works....

You will be a lot sorrier if you try breaking in a new engine on a test stand.

Alright. So bolt it in, start it up, and check for oil loss. Then drive (LOAD) it at reasonable rpm's under 3.5 maybe but do this for how many miles?

The 3.0 SC Weber 20/21 webcam regrind data from WC says do not allow the engine to idle below 2k for the first 15 minutes of use.... That would be easy if the carbs were tuned prior to break in... conundrum 101 ....???