Engine Output comparisons(splinter thread)

[Hog]

In order to not muddle up what is promising to be an excellent thread about stock cube LT5s, I am starting this splinter thread.


Here is Todds Stock 350 cube thread
http://www.zr1.net/forum/showthread.php?t=28786&page=2


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Originally Posted by tpepmeie

You guys know what I think about converting rwhp on a dynojet to brake horsepower on an Engine dyno...

Originally Posted by efnfast

Sure Todd, but that's all most of us can do. -Steve

Originally Posted by tpepmeie

427 LT5 build 1 observations

• 1/19/2011: SF901 Engine Dyno, 300 rpm/sec, SAE1349 correction - 669 bhp [703 using STP correction]
• 8/9/2012: Dynojet shop "A", SAE1349 correction - 637.2 rwhp
• 5/10/2013: Dynojet shop "A", SAE1349 correction - 638.2 rwhp
• 5/10/2013: Dynojet shop "B", SAE1349 correction - 634.1 rwhp

I realize this is but one like-for-like comparison, but three different chassis dyno tests, across two days and two shops, and nearly 1 year apart. the variance is 4 hp.

The same engine, on the superflow engine dyno, at the same atmospheric correction, was only 30-35 hp higher. Maybe that engine dyno is a bit stingy? However, using the internet accepted 15% driveline loss, that engine should have made close to 750 brake horsepower on the engine dyno. Unlikely.

I've tested a couple others on that engine dyno, but unfortunately haven't done a chassis dyno on those. Not my engines, so not so easy to do the comparison testing.

Sorry, didn't mean to get off topic. I'm expecting a solid 550-560 brake hp out of this cammed 350 cid project.

Originally Posted by Top Toy

Engine dyno numbers don't make good comparison points, either, because you're no longer using using the in car accessories (IAF housing, exhaust, cooling, drivetrain et al). The only valid comparison is SAE on the same day and same chassis dyno. Should also be based on area under the curve to account for the full range of operation, not just a one point spike or engine tuned for peak HP only. Anyone up for a shoot out? [emoji6]

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An engine dynoing 600hp@6000rpm/650 torque@2500 will still outaccelerate an engine that dynos at 550hp@6000rpm/600lb/ft torque @ 2500 rpm once you get both cars into the car, the same car that is.


The great equalizer came for Model Year (2006) when Chev voluntarily made the GEN IV SBC 7.0/427 the very 1st engine to officially use the SAE CERTIFIED Power rating SAE J1349.
Many Japanese engines lost engine power while many North American cars increased. No more rounding up toth nearest 10 horsepower, no more using an oil sump with 2 literrs of oilmissing, no more stone cold engine temps for testing.


Before J1349 the LS7 was 500 hp at 6,300 RPM with 475 lb.-ft. of torque.







After SAE Certified Power it was 505HP @ rpm and 470 lb/ft torque







The application that has the biggest diffrence for GM has to be the Cadillac Northstar LC3 supercharged VVT engine. in the XLR its rated at 443hp@6400rpms and 414lb/ft@3900rpms and the SAME engine in the Cadillac STS is rated at 469hp@6400rpm 439@3900rpm.
These differences come from different intakes and exhausts forced upon the engines due to the different vehicle packages.


I still cant believe the SAE Certified power numbers for the 2019+ LT5, which is pretty much a warmed over LT4, with a slowed down blower that makes 13.9psi of boost being fueled by 8 Direct Injection squirters for conventional cruising idling duties and using a separate fueling controller, the 8 conventional port fuel injectors come online 2hen the boost starts a flowing.
Hey at least the "new" LT5 got 16 injectors.

[tpepmeie]

The J1349 standard as an atmospheric correction factor was not new. I believe it dates to the mid-80s. The certified testing procedure, including much more than the correction factor, was the new standard about the time of the Z06. I believe there is another J* standard number for it, but don't remember the number.

[Hog]

Originally Posted by tpepmeie

The J1349 standard as an atmospheric correction factor was not new. I believe it dates to the mid-80s. The certified testing procedure, including much more than the correction factor, was the new standard about the time of the Z06. I believe there is another J* standard number for it, but don't remember the number.

The newer code you are referring to is SAE J2723, which in itself is NOT a specific testing procedure but it does state that for manufacturers who advertise "CERTIFIED POWER" must rate their engines using the testing procedures of either:
J1349 (revision 08/04)(CERTIFIED NET POWER)
or
J1995 (revised 01/04)(CERTIFIED GROSS POWER).


SAE J2723 was enacted in 2005, revised in 2007 and again in 2015.



J1349 does have roots all the way back to 1980, but was revised in 2004 and again 2011.
This SAE Standard has been adopted by SAE to specify
) A basis for net engine power rating
b) Reference inlet air and fuel supply test conditions
c) A method for correcting observed power to reference conditions
d) A method for determining net full load engine power with a dyno


J-1995
This SAE Standard has been adopted by SAE to specify:
a) A basis for gross engine power rating
b) Reference inlet air and fuel supply test conditions,
c) A method for correcting observed power to reference conditions
d) A method for determining gross full load engine power with a dyno.








The new standard is SAE J2723 which allows manufacturers to advertise "SAE Certified Power" was adopted in 2005 and requires manufacturers to test using procedures under the actual "J1349" testing standards or SAE J1995 testing standards. It seems as though the J2723 is merely the certification of the J1349 or J1995 test procedures.





These all seem to be interrelated, but my head hurts now.

[efnfast]

Glad you admitted your head hurt, 'cause so does mine.

[Paul Workman]

Originally Posted by efnfast

Glad you admitted your head hurt, 'cause so does mine.

Yeah, I feel your pain, Steve!

IMO, the only cure is the "Keep it simple, stupid" law.

For me, that comes down to the power/torque (at the wheels) under the curve. Everything else just further confuses the issue (and the conversation goes down 'the rabbit hole', but QUICK!).

The ONLY people engine dyno numbers are important to are (automotive) engineers and salesmen (bragging rights).

Case in point: When the Japanese got into the outboard motor competition, the domestic motors couldn't keep up with the Japanese outboards. The reason came down to the fact the Japanese rated their motors at the prop shaft, whereas domestic companies went for the crankshaft value.

Same with our cars: measurements at the wheels is what is really important. It doesn't matter how (power) got there, 'it is what it is and that's all that matters (or should matter).

[tpepmeie]

Originally Posted by Paul Workman

Yeah, I feel your pain, Steve!

IMO, the only cure is the "Keep it simple, stupid" law.

For me, that comes down to the power/torque (at the wheels) under the curve. Everything else just further confuses the issue (and the conversation goes down 'the rabbit hole', but QUICK!).

The ONLY people engine dyno numbers are important to are (automotive) engineers and salesmen (bragging rights).

Case in point: When the Japanese got into the outboard motor competition, the domestic motors couldn't keep up with the Japanese outboards. The reason came down to the fact the Japanese rated their motors at the prop shaft, whereas domestic companies went for the crankshaft value.

Same with our cars: measurements at the wheels is what is really important. It doesn't matter how (power) got there, 'it is what it is and that's all that matters (or should matter).

Paul,
ya know I love ya, man. But I have to respond to this one.

-- I can't recall ever seeing a comparison, or a even a calculation of, the area under the curve for any engine, ever. Requires integration of tq over time. And then, over what speed range? Peak Tq to Peak HP? I dunno, this isn't defined anywhere by SAE. If you have an example of such integration, please share Also, optimal gear selection can/and should be used to maximize the torque available for acceleration at the rear wheels. Dynojets pull in a constant gear, usually 1:1 (4th in our case). That's not how most people drive....

-- measuring power at the rear wheels is a valid form of comparison. But it requires so many variables to be held constant. Day-to-day, and car-to-car. Very hard to control. For instance, higher tire pressure can "cheat" the chassis dyno results by reducing friction between the tire and roller. Lower viscosity gear lube, transmission & diff. temp., even roller lubrication You get the picture. Not to mention that chassis dyno cells are often nothing more than an open bay in a workshop. They are not always (rarely?) designed to exchange the room air adequately to make sure the intake air is not contaminated.

-- 99% of chassis dynos, such as most dynojets, are inertia only. You can't expect to hold a constant speed/load point and optimize the tuning. the engine is always accelerating the roller mass (and at varying rates, at that). If that happens to match the acceleration rate for your car down the drag strip then great. Otherwise not sure it is a sound correlation to performance.

-- Most reputable race engine shops, from professional race teams to high end consumer shops, have an engine dyno to break in and calibrate their engine. And especially to do detailed development work on cams, manifolds, etc. Not to mention that OEM's also certify their engines' performance on a controlled engine dynamometer program.

Look, I like chassis dyno's as well for convenience, availability and ease of use. You can tune WOT fueling pretty well, as many do. My own testing confirmed that if configured and calibrated correctly, Dynojets can be very consistent between locations, in my case within 5 hp. But you can't deny the wisdom of using a controlled engine dyno to accurately measure the performance of a race or high performance engine.

To each his own, my friend Buy you a beer in BG if I attend.

[jss06c6]

Originally Posted by tpepmeie

Paul,
ya know I love ya, man. But I have to respond to this one.

-- I can't recall ever seeing a comparison, or a even a calculation of, the area under the curve for any engine, ever. Requires integration of tq over time. And then, over what speed range? Peak Tq to Peak HP? I dunno, this isn't defined anywhere by SAE. If you have an example of such integration, please share Also, optimal gear selection can/and should be used to maximize the torque available for acceleration at the rear wheels. Dynojets pull in a constant gear, usually 1:1 (4th in our case). That's not how most people drive....

-- measuring power at the rear wheels is a valid form of comparison. But it requires so many variables to be held constant. Day-to-day, and car-to-car. Very hard to control. For instance, higher tire pressure can "cheat" the chassis dyno results by reducing friction between the tire and roller. Lower viscosity gear lube, transmission & diff. temp., even roller lubrication You get the picture. Not to mention that chassis dyno cells are often nothing more than an open bay in a workshop. They are not always (rarely?) designed to exchange the room air adequately to make sure the intake air is not contaminated.

-- 99% of chassis dynos, such as most dynojets, are inertia only. You can't expect to hold a constant speed/load point and optimize the tuning. the engine is always accelerating the roller mass (and at varying rates, at that). If that happens to match the acceleration rate for your car down the drag strip then great. Otherwise not sure it is a sound correlation to performance.

-- Most reputable race engine shops, from professional race teams to high end consumer shops, have an engine dyno to break in and calibrate their engine. And especially to do detailed development work on cams, manifolds, etc. Not to mention that OEM's also certify their engines' performance on a controlled engine dynamometer program.

Look, I like chassis dyno's as well for convenience, availability and ease of use. You can tune WOT fueling pretty well, as many do. My own testing confirmed that if configured and calibrated correctly, Dynojets can be very consistent between locations, in my case within 5 hp. But you can't deny the wisdom of using a controlled engine dyno to accurately measure the performance of a race or high performance engine.

To each his own, my friend Buy you a beer in BG if I attend.

Todd,

Just to add a slight twist on your notes... there are indeed chassis dyno's that, when properly equipped, are capable of holding virtually any load at any RPM for tuning. We labored hard between three platforms for tuning our engines and powertrains at my new shop; Engine Dyno, Hub Dyno and Chassis Dyno. For a performance shop, after a lot of discussion, we opted for a properly equipped Chassis Dyno. The Engine Dyno is great for engine development work but requires a dedicated dyno cell with controlled air supply, exhaust and engine cooling. Obviously, it requires the engine to be pulled from the vehicle. When trying to optimize the engine performance itself, it provides the most repeatable environment for engine builds, hands down.

Hub dyno's have the ability to hold a load at very high HP/TQ ranges (in the thousands), making them great for powertrain tuning for race day. BUT, and this is a big BUT, they can be damned hard on limited slip differentials as each hub is independent, making it very hard to keep the load presented to each axle consistent, which is very risky at high HP/TQ numbers. This can lead to severe loads presented to the clutches in your diff, unless you're running spools versus differentials (NHRA class).

Properly equipped chassis dynos (large eddy brake setups) allow ease of tuning across the entire RPM/MAP table just like an engine dyno or hub dyno. This setup will hold virtually any load at any rpm for enough time to grenade the engine (not your objective!). We opted to go this route. The setup we came up with will hold up to 3,500 hp and uses drums large enough to limit slipping of the tires. We have the option of adding a second large eddy brake should we need this.

Our desire for our Dyno is for TUNING, not simply putting out a WOT number (useless in my mind).

Great dialog in this thread.. Admire your work Todd!!

Steve

[tpepmeie]

You made a good choice. Eddy current chassis dynos are a pretty rare item. Which one did you get?

Superflow 833 and beyond are fine examples. Mustang has a 1750 (?) which I’m told is rather good too.





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[jss06c6]

Dynocom 2WD 15,000 with Frenelsa F-16 GR CM Eddy Brake (largest made anywhere). Extended frame to allow addition of second Frenelsa F-16 GR CM Eddy Brake..

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[jss06c6]

What we learned with Chassis Dynos is how critical the drum diameter and configuration is. High HP/TQ builds cause the tire to "Climb" up on the front roller in a typical two roller setup. This causes tire slip since you are trying to rotate a small diameter drum at high RPM. Same logic as 10 speed bicycle! At 10th gear on a bicycle, you're exerting the force across a short moment arm. With small diameter dual drum dyno's as you pour more HP to it, the tire looses traction and slips. You need 24" or larger drums to work with combinations putting down anything over about 1,100 hp..

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