Questions for the dyno gurus

[kitabel]

Not familiar with this as a limit, and that DCR sounds high to me. What IVC point @ nominal duration?

BTW: the "correction factor" is a number the operator invents to make the output chart show numbers he likes. Vizard is famous for testing engines built by big-name shops that produce 100 hp less on his dyno...
Yes, it's completely subjective.

[Maxeffort]

Originally Posted by kitabel

Not familiar with this as a limit, and that DCR sounds low to me. What IVC point @ nominal duration?

BTW: the "correction factor" is a number the operator invents to make the output chart show numbers he likes. Vizard is famous for testing engines built by big-name shops that produce 100 hp less on his dyno...
Yes, it's completely subjective.

some unscrupulous dyno operators can deliberately skew or misuse correction factor.

To claim that correction factor is “completely subjective” or something “the operator invents” is simply NOT true.

Correction factor is to SAE standard conditions. The importance is so that an engine tested under any condition, will correct to standard conditions.

I have run thousands of dyno tests and that have been corrected to standard conditions. I have also done all the math many times to verify that the software is correcting properly. If testing and I see a bigger (or smaller) than expected correction factor, it’s a good reason to look and find out why.

Read a bit here:

http://www.mie.uth.gr/ekp_yliko/SAE_...917;Κ.pdf

[davesz1r]

Originally Posted by kitabel

Not familiar with this as a limit, and that DCR sounds low to me. What IVC point @ nominal duration?

BTW: the "correction factor" is a number the operator invents to make the output chart show numbers he likes. Vizard is famous for testing engines built by big-name shops that produce 100 hp less on his dyno...
Yes, it's completely subjective.

Ok, I'll bite. What corrected or dynamic cr doesn't seem too low? Aaron at hammer performance suggests max of 9.2:1 on pump gas. My 1275 is at 9.3:1 and will detonate on 91 octane. 28 degrees total timing and Lucas octane booster and all is good.

[kitabel]

Correction factor is to SAE standard conditions.

Yes, I'm familiar with GM Test 20, but the factored in adjustment relies on the operator not to... push the envelope.
How else would the results of 2 tests done within days of each other on the same brand dyno in the same town show an engine at 740 hp, and Vizard reports 665?

[kitabel]

I wrote an Excel program to calculate CCP and DCR from IVC, rod geo, and static CR. 10.1:1 needs closing at only 47 ABDC to drop to 9:1. Closing @ 70 (much more likely) gives 7.8:1.
Where is your IVC?

[Maxeffort]

Originally Posted by kitabel

Correction factor is to SAE standard conditions.

Yes, I'm familiar with GM Test 20, but the factored in adjustment relies on the operator not to... push the envelope.
How else would the results of 2 tests done within days of each other on the same brand dyno in the same town show an engine at 740 hp, and Vizard reports 665?

Either your equipment and sensors are in calibration or not.

If some one wants to cheat, they can in a variety of ways. That’s not pushing any envelope... its plain cheating.

As far as same engine on two dynos.... this is popular on forums. I’d have to see all the data and conditions for both runs on both days.

[davesz1r]

Originally Posted by kitabel

I wrote an Excel program to calculate CCP and DCR from IVC, rod geo, and static CR. 10.1:1 needs closing at only 47 ABDC to drop to 9:1. Closing @ 70 (much more likely) gives 7.8:1.
Where is your IVC?

Impact 560 cams. 48 degrees abdc. Your math would appear to be very accurate. I'm lazy and just use the calculator on hammers website. I don't know 60gunners cam specs. Suspect bottom end to midrange cams with early intake closing. Btw, my static cr is 10.53:1. 60gunner is shooting for 10:1.

[aswracing]

Originally Posted by kitabel

BTW: the "correction factor" is a number the operator invents to make the output chart show numbers he likes.

I can assure you that Dynojet Dynamometers don't allow you to "invent" the CF. A weather station is built into the electronics stack. The software reads the environmental conditions at the time each pull is made and calculates the number automatically and applies it when it graphs the result. You can select the type of correction (SAE, STD, etc), but you can't fiddle with the number.

[kitabel]

The only vague dimension is the "ratio of variable heats of compressible gasses" exponent, given ideal as 1.4. This generally gives an unrealistically high figure, mine is around 1.25-.29 depending on the cooling system.
Here's some more of my comments on my site here: http://victorylibrary.com/mopar/cam-tech.htm

[rocketmangb]

Project TQ Pig is 11.79:1 Static
Still deciding on cams