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Engine Masters rod ratio test results

General engine tech -- Drag Racing to Circle Track

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GARY C
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Re: Engine Masters rod ratio test results

Post by GARY C » Thu Mar 05, 2020 5:16 pm

gmrocket wrote:
Thu Mar 05, 2020 2:46 pm
GARY C wrote:
Mon Mar 02, 2020 10:53 pm
Lizardracing wrote:
Mon Mar 02, 2020 9:07 pm
Every time I see/hear/read one of these shows/articles that go about testing stuff I get the critical feeling that ratings and controversy are more important and cleverly hidden inside illegitimate ABA type testing. It’s really hard to take any of them serious when something kinda important is glossed over because it doesn’t fit a narrative.
After watching all of their shows and listening to their reasoning I get the idea that they are still doing mostly 1990's magazine articles, for example in this one Frieburger has wanted to do this test since 1997 and he seems oblivious to the fact that this has been hammered to death, both in discussion and testing and that just changing rod length is an invalid test. So I sent him a link to googlesearch/speedtalk/rod length/rod ratio. :)

They do have some cool stuff on dyno testing basic stuff that the pubic would encounter but they don't seem to take into account what has bee learned over the past decade. I also understand that they probably have a lot of money tied up in one 20 minute dyno video publication.
At the beginning of the video did you notice he mixed up the long rod and short rod every time he pointed too each? Didn’t get it right once 😁

If a total beginner was watching they would be saying,, what the heck?? 🤪
Yeah I kept wondering if it was the camera angle because it looked like he was pointing to the wrong one.
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GARY C
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Re: Engine Masters rod ratio test results

Post by GARY C » Fri Mar 06, 2020 12:27 am

You guys should love tomorrows useless EMC test.

"Picking a fight between Edelbrock, Summit, and Demon carburetors! Stream an all-new episode of Engine Masters TOMORROW on the MotorTrend OnDemand App!"
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gmrocket
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Re: Engine Masters rod ratio test results

Post by gmrocket » Fri Mar 06, 2020 12:45 am

take a look at the data between the two engines during steady state peak TQ test.

The conditions were kinda different..air inlet temp about 10 deg diff as well as other stuff

The steady state peak TQ test also showed the short rod had a much higher bsfc making the same TQ

digger
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Re: Engine Masters rod ratio test results

Post by digger » Fri Mar 06, 2020 5:51 am

gmrocket wrote:
Fri Mar 06, 2020 12:45 am
take a look at the data between the two engines during steady state peak TQ test.

The conditions were kinda different..air inlet temp about 10 deg diff as well as other stuff

The steady state peak TQ test also showed the short rod had a much higher bsfc making the same TQ
you sure about that ?

BSFC
rpm/long/short
3000/0.535/0.560
5700/0.455/0.436

the short rod was 8-10F hotter IAT

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Re: Engine Masters rod ratio test results

Post by gmrocket » Fri Mar 06, 2020 9:22 am

digger wrote:
Fri Mar 06, 2020 5:51 am
gmrocket wrote:
Fri Mar 06, 2020 12:45 am
take a look at the data between the two engines during steady state peak TQ test.

The conditions were kinda different..air inlet temp about 10 deg diff as well as other stuff

The steady state peak TQ test also showed the short rod had a much higher bsfc making the same TQ
you sure about that ?

BSFC
rpm/long/short
3000/0.535/0.560
5700/0.455/0.436

the short rod was 8-10F hotter IAT
Ya I’m sure about it at peak TQ which is where you should get your best #’s

Video in slo mo , and don’t include the jump in the numbers as he backs off the throttle :wink: that’s where you got the .455 from

Long rod first @5700 low .419 hi .429 avg .424 622.9

Short rod @5800 low .433 hi .445 avg .439 621.2

Long rod slightly better on both counts at 100 lower

The 3000 steady state was meaningless to me..it’s so far under the power band you can have funky stuff going on in the intake....even though at steady state both made indentical TQ

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Re: Engine Masters rod ratio test results

Post by digger » Fri Mar 06, 2020 4:21 pm

like i said much higher? or just a bit higher....

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Re: Engine Masters rod ratio test results

Post by gmrocket » Fri Mar 06, 2020 5:42 pm

digger wrote:
Fri Mar 06, 2020 4:21 pm
like i said much higher? or just a bit higher....
You said it was the opposite..

That the long rod had a higher bsfc

Daryl S.
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Re: Engine Masters rod ratio test results

Post by Daryl S. » Fri Mar 06, 2020 7:59 pm

Is there a difference in NVH with longer/shorter rods?

Daryl

digger
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Re: Engine Masters rod ratio test results

Post by digger » Fri Mar 06, 2020 9:08 pm

gmrocket wrote:
Fri Mar 06, 2020 5:42 pm
digger wrote:
Fri Mar 06, 2020 4:21 pm
like i said much higher? or just a bit higher....
You said it was the opposite..

That the long rod had a higher bsfc
at the 5,700 the number i gave was not a good number for the short rod as it was at the extreme end not an average
at 3,000 i said the long rod was was better

in both cases it was still a small difference not a huge difference like you said

its probably better to try and understand why

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Re: Engine Masters rod ratio test results

Post by David Redszus » Sat Mar 07, 2020 3:01 pm

its probably better to try and understand why
Digger, you are asking for trouble. :)

While it seems easy to understand measured values, even without an appreciation of measurement error,
it becomes a real son of a biitch to understand WHY.

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Re: Engine Masters rod ratio test results

Post by gmrocket » Sat Mar 07, 2020 4:54 pm

Here’s my takeaway from this particular test.

The long rod was clearly better on the bottom end from 4K thru about 5.2k, the difference is clear on the overlay graph. I wonder why they didn’t point that out and tell us the difference? It’s more noticeable than the tiny difference at the top end.

The below peak TQ was more noticeable to me.

The short rod had a small gain above 7k to 7.5k

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Re: Engine Masters rod ratio test results

Post by digger » Sat Mar 07, 2020 5:47 pm

David Redszus wrote:
Sat Mar 07, 2020 3:01 pm
its probably better to try and understand why
Digger, you are asking for trouble. :)

While it seems easy to understand measured values, even without an appreciation of measurement error,
it becomes a real son of a biitch to understand WHY.
friction hurts BSFC, negative work hurts BSFC.

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Re: Engine Masters rod ratio test results

Post by Tuner » Sat Mar 07, 2020 8:22 pm

Were any of these comparison tests done with the spark advance curve optimized from the lowest to highest RPM, perhaps in 500 RPM steps or ? In any case, was the difference in best advance for peak output at all engine speeds accounted for? It seems to me that engines of the 'short rod' variety want more advance from torque peak to power peak.

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Re: Engine Masters rod ratio test results

Post by digger » Sun Mar 08, 2020 10:33 pm

it would have been good to see the differences in airflow using a hat flow meter.

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Stan Weiss
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Re: Engine Masters rod ratio test results

Post by Stan Weiss » Mon Mar 09, 2020 12:35 am

Where are these dyno sheets at?

If you have accurate dyno room weather data (BP, VP, TEMP), fuel lbs/hr and A/F ratio. SCFM can be calculated.

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Offering Performance Software Since 1987
Do you use engine simulation software that uses cylinder head flow files?
We have a package of more than 3025 DFW or FLW Files

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