Dyno do’s and Dyno don’ts

[Bennyt]

The old dyno's were rough. We used to have to hold a load for extended periods, turning valves, reading gauges, etc and I've seen lots of motors come apart on them. Was it harder then what the customer will put it through, probably not, just a little wear and tear early on. If you like analogies; go bench press your max 1x, and then do it and hold it for 30 minutes. Same load, one makes you sore though.

The new dyno's that are computer controlled can do what took us 30 minutes in probably 2 minutes or less. Way less wear and tear.

 

[Bennyt]

My opinion has to do with what I perceive to be widespread use of too much valvespring seat pressure so builders can blame their wiped cam lobes on new motor oil.

I urge substantial consideration given to valvetrain component selection and proper installation.

How many of the last 4 motors were vortex headed?

Slightly off topic...When I was teenager, I worked at PAW, and I used to have to Rockwell test "bad cams" that were returned due to being too soft and wiping lobes. Out of the hundred's I tested from every major manufacturer, I never found one that wasn't the proper hardness. What we did find was wrong spring pressure, and lifters that had stopped rotating and/ or pumping up D/T rust in lifter bores, and break in material, dirt, etc in the lifter. If I recall, lifters have the tightest clearance of any part on the engine at 0.003.

 

[Matt69olds]

The transmission plant I work in has a test garage with one of each engine/transmission family’s on a dyno. The run a continuous cycle to duplicate everyday use. Lots of idling, full throttle acceleration, full throttle upshifts/downshifts, high speeds, it’s about as brutal an environment as it can be. Other than routine maintenance, they are never shut off. Some of them have the equivalent of half a million miles of use. None of the test garage people can recall a engine failing during testing. Not really a apples to apples comparison of what your wanting to do, but somewhat relevant.

Is the dyno operator the same guy or shop that was involved in the engine build? It would be nice if they were, it would eliminate a lot of the blame game if something did happen, the finger point would lead to the same place.

I would think a engine dyno would be best for tuning just the engine. For example, you wonder what effect this size header tube has on the power curve verses this size? Or maybe different intake manifolds, carbs, cam timing, valve lash, etc. Those kinds of tests would be pretty time consuming on a chassis dyno.

However, if you have already installed the engine, or just want to optimize what you have, it’s hard to beat a chassis dyno.

 

[Salty Crusty]

I was fortunate enough to be able to watch dozens of big-inch engines being broken in and tuned on a dyno in a top shelf engine builder's shop.
They NEVER had one blow up on the dyno.
A dyno gives you a chance to seat the rings correctly and double check everything before you hammer on it.
Load can vary and is at the control of the operator. Most use 600rpm/sec for the sweep.

During the first 565 I watched him carry to about 7500 and I cringed most of the way, expecting it to "come from together". When I asked the shop owner if he did that with his own or client's engines, he said that "if you cringe when you pass 6000rpm, you used the wrong parts".
Build it right and with the best parts and have confidence in your engine.

I did get to watch a Comp Eliminator on this dyno once. Huge bores with shorter strokes than a GM 350, they wound it to 12K on about a half dozen pulls. From about 8K through the end of the run the engine pretty much sounded the same...MAD!!! Engine's owner said they average breaking 1-2 valve springs per 1/4 mile run. .900+ lift on the cam. Lobes looked like the journals on mine, effin' huge.

This shop got the first half dozen aluminum big blocks that Brodix cast. Main caps weren't seating correctly and they helped Brodix get 'em set right.

Build it with good parts and machine work....and send it!!!

Good luck, you'll be fine.

But I have a crisp $100 bill that says you pinch a hole in your shorts when the engine is screaming near your rev limit.

Anybody who has built a few engines knows that they're basically trying to tear themselves apart at the hit of the starter. That they stay together and make power for years is nothing short of a miracle in my book.

And while you're worried about it, think of this: At 7200rpm, the spark plug is firing at the same rate as the fluorescent lights in your office. 60 times every second, that engine gulps, compresses, burns and spits out an air/fuel mixture and the other 7 are doing the same thing.
I've seen it many, many times but still can't wrap my head around what's actually happening in an engine at that speed.

 

[82sbshortbed]

I always wanted to put my SS on a dyno but, have seen some disasters on them. Like rear end fails, transmission or engine fails.

When I had it tuned, he did a road tune no dyno. Although he couldn't give me an exact hp number, he's done enough to give you a close enough number. He said he'd put it at around 400hp.

I'd just put 4.5k in New clutch and transmission and tune. I didn't want to chance something going wrong on the dyno and kiss that money goodbye.

With that being said, I'd never go to a shop that blew the last 4 engines they ran on it. Sounds like they're doing something wrong. Then tell you tuff **** your build was ****.

We have a pretty reputable dyno shop down here. They charge $500 to dyno and tune. I payed $400 to have mine done with road tune. Even they've had a couple engines blow on the dyno.

For me it was not a roll of the dice I was willing to take.

 

[SquareRoot]

How many of the last 4 motors were vortex headed?

LOL. Vortecs continue to live in Rustys head.

 

[BigDaddy72]

Wow excellent excellent comments!!!

If those of you who would please list the dyno shops you used and location. Both chassis dyno and engine dyno.

I am really enjoying all the information and experiences.

Please don’t worry about going off topic it’s all great info for those of us that know to reflect on and refresh our memory’s and for those of us who are hearing it for the first time.

Thanks again y’all great thread!!

 

[Green79Scottsdale]

I m not really talking about how an engine is set up.

Any engine that has problems (too much timing, lean, too much spring pressure, not enough spring pressure, ect ect.) will have problems regardless if it’s in the vehicle or on a dyno either engine dyno or chassis dyno.

What I’m referring to is the stress the dyno itself puts on the engine.

I’ve been told it puts tremendous stress on the engine. In effect a load that is not real world ie: what a vehicle would experience in any other condition.

I think of it this way:

The engine starts to rev to say 3000 rpm then such a tremendous load is put on it at wide open throttle that it stops the engine from accelerating and holds it there while the engine labors to start building rpm again.

In my mind similar to putting an extremely heavy load on your truck, then hitting the nitrous button and holding it there as it struggles to reach maximum rpm.

Like purging no2 at idle through the motor, I know of a lot of guys say it’s not going to hurt anything but it’s not something I would do to my engine.

I have only been told this I have no experience as to weather a dyno puts a dangerous amount of stress on an engine.

But it’s stories like that true or not is why I’m asking.

In my mind...

I don’t lack knowledge of how to build an engine or have a lack of confidence in what I’ve built.

I have a lack of knowledge as to how an engine dyno works and a lack of Experience with one and that is enough to scare me away.

But if you don’t ask you don’t know

I want to make an educated decision before I throw a $10,000 engine on one turn someone I don’t know loose on it and hope for the best.

I certainly don’t mean to sound disrespectful to anyone and am not saying any of my statements are true.

So please don’t take offense, I’m not the best at getting my point across in writing.

Hopefully I explained my questions better.

I understand the logic behind your thinking... but I personally do not believe that logic to hold water. Until someone comes along with numbers showing the stress put on your engine in a vehicle versus on the dyno, I simply can not believe it. What your logic is basically saying, IMO, is that every engine builder out there with an in-house dyno is doing their job wrong and not using the proper equipment. Is Steve Morris doing his job wrong by putting every engine he builds ($50K+) on the dyno? If the dyno, which is a purpose built measuring instrument remember, is horrible for your engine, why would anyone use it? It makes no logical sense.

I think the better thought line is this... The dyno (engine or chassis) is not going to ruin your engine. The dyno is simply going to find the problems in your setup, and your engine will ruin itself. And you would have found these problems regardless in you had a dyno session or not. By rights, if you are scared to put your engine on a dyno in fears of it being ruined, you should be scared to put it in a vehicle and run it with any seriousness. Don't you ever romp on it in the vehicle if you were too scared to put it on a dyno.

Same as the OP, I am not trying to hurt anybodies feelings or pick on people. Just thinking that seems logical in my head.

 

[82sbshortbed]

The worries of something failing are real and it's not always the engine that fails. I think sometimes they hold it too long and it fails. Them having no responsibility at all bothers me too.

xc_hide_links_from_guests_guests_error_hide_media

 

[BigDaddy72]

I understand the logic behind your thinking... but I personally do not believe that logic to hold water. Until someone comes along with numbers showing the stress put on your engine in a vehicle versus on the dyno, I simply can not believe it. What your logic is basically saying, IMO, is that every engine builder out there with an in-house dyno is doing their job wrong and not using the proper equipment. Is Steve Morris doing his job wrong by putting every engine he builds ($50K+) on the dyno? If the dyno, which is a purpose built measuring instrument remember, is horrible for your engine, why would anyone use it? It makes no logical sense.

I think the better thought line is this... The dyno (engine or chassis) is not going to ruin your engine. The dyno is simply going to find the problems in your setup, and your engine will ruin itself. And you would have found these problems regardless in you had a dyno session or not. By rights, if you are scared to put your engine on a dyno in fears of it being ruined, you should be scared to put it in a vehicle and run it with any seriousness. Don't you ever romp on it in the vehicle if you were too scared to put it on a dyno.

Same as the OP, I am not trying to hurt anybodies feelings or pick on people. Just thinking that seems logical in my head.

Thanks for the input.

That’s what we are trying to drill down to.

There are many “scary” stories out there floating around that dyno’s and dyno operators can cause damage to an engine that would otherwise have been fine.

Do those stories hold water???

Are they completely unfounded or are they true or partially true?

I (like most) don’t really know what to believe not having any personal experience or knowledge of how a dyno loads an engine, or having an engine dynoed myself.

Additionally I am not interested in being right or wrong I just want to get “the facts”

So please voice your experience or opinion on either side.

What I mean to say is...

If my “understanding” of how or what an engine goes through on a dyno is wrong or incorrect then by all means please correct it.

Thank you all sincerely for the input!

 

[QBuff02]

I think part of it is taking your engine/vehicle to a REPUTABLE dyno shop is what makes a ton of difference. I firmly believe some "fly by night" place is going to run your equipment a little more haphazardly than a reputable shop will. If a dyno shop has a history of grenading engines and breaking parts, I will certainly be less inclined to take my stuff there as opposed to a place where everyone raves about the work performed and services completed. I also feel like you need to be realistic with your goals. For example, I built my 454 to handle around 7,000 rpm but the cam dictates it should be running out of power by about 6,200ish rpm. So am I going to let them wing it to 7,200 just to see what she'll do or if it will take it? absolutely not! but will I have them make a few baseline pulls to set timing, check operation, and get a feel for it? Yes. If I want them to first spin it to 6,000 and go from there once some baselines are set, and the first pull they take it to 6,800, i'm probably going to be a little put off. But if we pull it to say 6,200rpm and there's some meat left on the bone, i'm probably going to have them bump the rpm up in successive pulls so I can find out where it runs out of steam and tune it accordingly. I built my engine with some good parts for a little added safety factor, so it should live at 5,500-6,000rpm for a long time. If you pull your engine repeatedly to the edge of parts breakage, it's only a matter of time until something breaks. And that's where I believe a reputable place is going to ask the questions and keep the answers in mind when twisting the tail on your powerplant. I actually plan to dyno my engine at some point, and based off of what I've heard from people that have done it, going in with realistic goals is a good place to start.

 

[WesN]

One of the cheapest and most fun ways to tune and find out how much horsepower your motor is making is to head to a quarter mile drag strip with your buddies, some jets, a timing light and a Moroso Power Speed Calculator. Buddies are there because they have all the right answers lol. Spend a day or two at the track, have fun and if by chance something does break you know you did it and you might even know why. You will also need to weigh your vehicle with you in it for the Moroso calculations.
I don’t disagree with dynos they do have there purpose and in some situations it is the only way to pretest a motor before it goes to work.

 

[shiftpro]

xc_hide_links_from_guests_guests_error_hide_media

 

[BigDaddy72]

I will say this most all the dyno fail videos are imports/diesels running mega boost.

The others seem to be equipment or tire fails.

That’s a bit encouraging.

Could be to as has been touched on, engines built on the ragged edge making huge power.

 

[BigDaddy72]

Can anyone find a bbc or sbc naturally aspirated engine failure?