Anyone ever strap their cars down to both a dynojet....

[blykins]

....and a mustang brand dyno? I see some shops stating 10-12% difference between the two, with the dynojet showing higher.

Any experiences here?

[fordracing65]

I have seen this also, I believe a dynojet uses large steel roller to contain mass, the mass is fixed and can never change, so they are the same fromdyno to dyno day to day, where as a mustang dyno is an electric load dyno, so its not a true inertia dyno, taking into many consideration which may lead to less hp numbers on average, but im really just guessing here, I always see mustang dyno's around me..

[PaulProe]

On some of the higher horsepower - lighter weight vehicles (does that sound like a cobra?) there are issues of wheel slip which lowers the readings.

Try adding weight to the trunk to increase rear wheel traction and see if the readings change

Also, the older the dyno, and smoother the roller surface, the more this becomes an issue.

Paul

[twobjshelbys]

The dyno wars are never going to be resolved. The best you get out of a dyno is the same car on the same dyno on the same day (but if a thunderstorm rolls in in the afternoon, you don't even get credit on the same day). I consider them a "delta" measurement (change something see if it is better or worse) but not an absolute measurement.

The guy that did my Cobra fuel injection on the dyno said that Colorado was going to do a "weights and measures" official calibration that would insure that it was repeatable. I don't know if they ever did it. My question was "what would you use for the golden standard?"

[blykins]

Tony, I agree with your thinking.

Dynos are delta devices only, but it seems like a lot of builders get roped into the dyno wars debacle.

There was a post on my other thread about adding engine dyno results to my webpage, and a reply was made that it needs to be coupled with a chassis dyno report. However, there is no direct correlation, and with different chassis dynos even showing 10-12% differences between brands, I can't see how someone can put that constraint out there.

And....

There is no golden standard. Even on engine dynos. The only way you could even make an A to B connection would be to have both an engine dyno and chassis dyno in a facility, pop the engine off the engine dyno, stick it in the car, then put the car on the chassis dyno. And even then, the only thing you would be able to say, would be: "Here's a correlation between *my* dynos."

[Cashburn]

If you don't know that some Mustang dynos are actually inertia dynos just like Dynojets it's going to be even tougher to draw those comparisons...

But I suppose you are correct, if you are selling just the engine and ignoring its final use/application then just demonstrating its peak numbers without any of the actual final bolt ons is a better marketing tool?

Or if the numbers are strong then why not? A big part of each story is what it went in and where. There's a builder online that sells a sh!t ton of "engines" but I strongly feel that most of them never even get into the cars or the cars never get finished so all the "satisfied customers" really have nothing to go on.

[blykins]

If all numbers are not relative to each other, then how is it a marketing tool?

If I build an engine and it makes x horsepower here, y on a Dynojet in the car, and z on a Mustang in the car, then what is the standard, and who's to say that the engine dyno is just a marketing tool?

Turning the accessories actually takes a negligible amount of horsepower. Between the water pump and alternator, we have measured about 8 hp loss.

Of course we can't mount sidepipes on the dyno, and I send out a lot of engines where the customer doesn't have an idea on how much hood clearance he will have, so it's really pointless to mount an air cleaner. Do you lose hp to an air cleaner? Sometimes. Sometimes you don't. We actually have an air cleaner here that straightens the airflow out and will net a hp/torque increase.

The best I can do is get the A/F ratio as close as I can, get the water temp and oil temp as close as I can and make a pull on it.

[Cashburn]

It's not the 8hp loss we want to see, it's the proper operation of the bolt on parts when the engine is supplied. If you want to get the water temp right, hope you have the water pump and more importantly the pulleys (ratios) the engine is going to ship with. The radiator is the next big problem but obviously that's not for the engine builder to get setup.

Another big builder had their pulley ratios off and cooked a bunch of engines ... this was because one of their suppliers changed the part and the engines were dyno setup with the electric pump and then before going out the door the other parts were added (also resulted in leaks in the car due to bolts not torqued properly and never tested while running). It's great to ensure no leaks on the engine dyno before getting in the car right?

Other items like oil pumps should be tested on the dyno beforehand as well right? That's why I like to see the final setup as much as possible if the engine builder is supplying those components.

[blykins]

I'm not talking about pulley ratios, cooking engines, and dry sump pumps. I like to see functional carb linkages that don't cost 42 rear wheel horsepower, but I'm not going to whine about it.

I am, however, talking about horsepower loss from engine dyno to chassis dyno. When one chassis dyno reads 10-12% lower than another, and one engine dyno reads 5% lower than another, it's hard to have a standard.

[fordracing65]

Originally Posted by blykins

I'm not talking about pulley ratios, cooking engines, and dry sump pumps. I like to see functional carb linkages that don't cost 42 rear wheel horsepower, but I'm not going to whine about it.

I am, however, talking about horsepower loss from engine dyno to chassis dyno. When one chassis dyno reads 10-12% lower than another, and one engine dyno reads 5% lower than another, it's hard to have a standard.

Probably no standard, just keep building your bad ass engines, it almost becomes pointless how much hp a dyno puts out, quarter miles times are better, the dyno as you know just becomes a tool for the engine builder and for some of us TOOLS WHO NEED TO SE INFLATED NUMBERS BY SUCKER SHOPS...

[Cashburn]

I've got a stronger desire for no leaks and functional oil systems, but yeah let's leave it there.

That's the beauty of running the same cars on the same dyno with simply different engines from different builders, we're getting closer to parity than others can.

[joyridin']

Originally Posted by Cashburn

If you don't know that some Mustang dynos are actually inertia dynos just like Dynojets it's going to be even tougher to draw those comparisons...

But I suppose you are correct, if you are selling just the engine and ignoring its final use/application then just demonstrating its peak numbers without any of the actual final bolt ons is a better marketing tool?

Or if the numbers are strong then why not? A big part of each story is what it went in and where. There's a builder online that sells a sh!t ton of "engines" but I strongly feel that most of them never even get into the cars or the cars never get finished so all the "satisfied customers" really have nothing to go on.

I do not believe it is a marketing tool. It is the best way to measure the numbers between engines, and possibly builders.

So what if it puts out 550 RWHP? In a 10k pound truck, this may not mean squat. In a 1800 pound stripped out Opel GT, it could mean 10 second quarters.

The questions most people should be asking are; Is he reputable? Yes. Are the engines durable? Yes. Does it meet YOUR HP requirements? Yes. Does it have decent torque across YOUR operating range? Yes. Does it have a reasonable price? Yes. Then buy it.

[blykins]

Originally Posted by Cashburn

I've got a stronger desire for no leaks and functional oil systems, but yeah let's leave it there.

That's the beauty of running the same cars on the same dyno with simply different engines from different builders, we're getting closer to parity than others can.

I agree. But when you cross-test different cars, different engines, and different dynos, there's not much room to point fingers and be critical.

[blykins]

Originally Posted by joyridin'

I do not believe it is a marketing tool. It is the best way to measure the numbers between engines, and possibly builders.

So what if it puts out 550 RWHP? In a 10k pound truck, this may not mean squat. In a 1800 pound stripped out Opel GT, it could mean 10 second quarters.

The questions most people should be asking are; Is he reputable? Yes. Are the engines durable? Yes. Does it meet YOUR HP requirements? Yes. Does it have decent torque across YOUR operating range? Yes. Does it have a reasonable price? Yes. Then buy it.

That's kind of the underlying point here...

If it does put out 550 rwhp on one dyno, and you run down the road and put it on another brand and it only makes 500, which one is right?

That leads to discussions that involve, "That particular engine builder is apparently fluffing his numbers because it only made x horsepower on our dyno."

[itstock]

Originally Posted by blykins

That's kind of the underlying point here...

If it does put out 550 rwhp on one dyno, and you run down the road and put it on another brand and it only makes 500, which one is right?

That leads to discussions that involve, "That particular engine builder is apparently fluffing his numbers because it only made x horsepower on our dyno."

Given a certain DA and corrected dyno numbers, it would be the rwhp figure that most closely resembles a trap speed. Of course then you have to figure in driver error and what not, but it is at least more of a direct comparison.

[Ace23]

Originally Posted by blykins

....and a mustang brand dyno? I see some shops stating 10-12% difference between the two, with the dynojet showing higher.

Any experiences here?

Brent,
I don't understand the technical aspect of the difference in the dyno's but I do know that a Mustang dyno will result in lower numbers than a dyno jet. To me that motor is making the exact same power regardless of what dyno it is on.....you may just get different results based on how that particular dyno reads rwhp.

[Cobra #3170]

Originally Posted by blykins

Tony, I agree with your thinking.

Dynos are delta devices only, but it seems like a lot of builders get roped into the dyno wars debacle.

There was a post on my other thread about adding engine dyno results to my webpage, and a reply was made that it needs to be coupled with a chassis dyno report. However, there is no direct correlation, and with different chassis dynos even showing 10-12% differences between brands, I can't see how someone can put that constraint out there.

And....

There is no golden standard. Even on engine dynos. The only way you could even make an A to B connection would be to have both an engine dyno and chassis dyno in a facility, pop the engine off the engine dyno, stick it in the car, then put the car on the chassis dyno. And even then, the only thing you would be able to say, would be: "Here's a correlation between *my* dynos."

Agree on the delta factor, when my son was racing gokarts I built a dyno to evaluate different engines. My design used a power absorption unit with a calibrated load cell. That thing led us down the wrong path many times even though I was using accepted correction factors for density altitude. We finally built a standard engine that we only used for back to back comparisons when dynoing a new engine. That actually worked because it gave us a delta from the standard engine to the compared engine. We tested the standard engine from time to time under the same conditions of humidity, barometric pressure and temperature to make sure it remained a good standard and wasn't wearing out or getting better. The main thing I learned was that if you wanted to get a new track record (they charged $10 per attempt) you did it on a cool day with a very high barometric pressure. I tried making my own correction equations but the actuals were so non linear that it was never as accurate as back to back with our standard engine.

[Cashburn]

Originally Posted by joyridin'

I do not believe it is a marketing tool. It is the best way to measure the numbers between engines, and possibly builders.

So what if it puts out 550 RWHP? In a 10k pound truck, this may not mean squat. In a 1800 pound stripped out Opel GT, it could mean 10 second quarters.

The questions most people should be asking are; Is he reputable? Yes. Are the engines durable? Yes. Does it meet YOUR HP requirements? Yes. Does it have decent torque across YOUR operating range? Yes. Does it have a reasonable price? Yes. Then buy it.

Do you mean that without the curve/graph and some detail on the vehicle it went into (and you are adding the price they paid) the info is meaningless? Probably not. Your not going to get a fair durability listing, but the other details could be shared. That's where marketing comes in and answers those questions without asking them individually.

Ultimately if it is a drag engine then I'd want to know what it did and inside of what. If it's a street engine I'd like to see the curve and how it will act in the lower rpms, but at the same time what it does up top. The more you can tell me about the ultimate performance of the engine the better... a lot of shops just don't do that in a clear manner. I mean .750 is great on the heads, does the cam even go there? I don't know, I just want to drive the bastid, how will it drive?

[eschaider]

If everything is so ambiguous dyno to dyno and pull to pull did anyone ever ponder the question about how Detroit seems to maintain their equipment so as to produce repeatable results for regulatory purposes??

Of course there is always the explanation that real life is always a special situation that can not be relied upon.


Ed

[Ace23]

Not to argue but I'm sure if a car manufacturer had or does have any in house dyno then all their production of a certain model would generate like conditions wouldn't they? For example if you take multiple factory coyote motors or factory LS3 motors and stick them on the same dyno they are going to make very similar if not almost identical power levels......these levels may fluctuate from dyno to dyno but that is not a component of the motors but more so the actual dynos. I'm a fan of chassis dyno as I feel like your are tuning the motor "IN" the car with load as opposed to just the motor on a stand.......not a deal breaker but a chassis dyno would make me feel better......then again I'm no tuner or builder

Originally Posted by eschaider

If everything is so ambiguous dyno to dyno and pull to pull did anyone ever ponder the question about how Detroit seems to maintain their equipment so as to produce repeatable results for regulatory purposes??

Of course there is always the explanation that real life is always a special situation that can not be relied upon.


Ed