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Greg G.

2016 Proposed ST Rules Revisions

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J_Roberts

Winpep (freeware from DynoJet) will give you a 50 RPM increment as it is right now. No need for special software. The data set you need is exactly the same data set as the currently proposed rule, which is 50 RPM increments in the data table.

 

The only difference is that you are using more data points from the SAME table. The procedure is the SAME. It is not much harder to grab seven data points instead of four (I'm including the peak HP), add seven numbers instead of four, and divide by seven instead of four. More resolution improves the intended performance of the proposed rule, and the difference is so slight it is trivial IMO. With all due respect, it seems like a no-brainer to me.

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Greg G.
Winpep (freeware from DynoJet) will give you a 50 RPM increment as it is right now. No need for special software. The data set you need is exactly the same data set as the currently proposed rule, which is 50 RPM increments in the data table.

 

The only difference is that you are using more data points from the SAME table. The procedure is the SAME. It is not much harder to grab seven data points instead of four (I'm including the peak HP), add seven numbers instead of four, and divide by seven instead of four. More resolution improves the intended performance of the proposed rule, and the difference is so slight it is trivial IMO. With all due respect, it seems like a no-brainer to me.

John, you are thinking like someone who doesn't mind a little math, and doesn't mind picking the top 6 data points out of a table that doesn't have the HP numbers organized by highest to lowest. Our drivers like simplicity. If someone is tuning, picking out those numbers by hand every time they do a Dyno run would be pretty time consuming, and get old quickly. The same goes for when we are doing compliance inspections, and trying to run a bunch of folks through the Dyno. Sure, for you to sit at home, with your table, use only the highest Max HP graph, and pick out 6 data points, use your calculator and divide by 7 after adding in the Max HP number, it's no problem. But, when we are testing and need to know the Avg HP of every run quickly, and to know if we want to test more runs as there is a line up of 6 cars to get Dyno'd, or if a guy is using an hour of tuning time on the Dyno, it needs to be simple and quick. If the dyno curve is not "normal", and is one of the tuned/flat curves, then the data points can be all over that table--manually picking the top six can be a pain. Also, if for whatever reason, someone doesn't have a calculator handy (sure, unlikely due to phones, but possible), the divide by 4 calculation is simple in one's head--just divide by two twice. So, you are just going to have to have faith that we know our drivers better than you.

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J_Roberts

I still don't agree the difference is that significant, especially given the benefit. But, respectfully, we'll agree to disagree, and leave it at that.

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StreetSpeed

Been following this whole conversation even though I'm in ST2. Sounds to me like that might be the way ST2 is headed in 2017 so I guess I should pay attention.

 

Here's my dyno plot for my C5Z. I peak at 400whp at 6000rpm. Being that this is a "traditional" power curve, using the 4 data points per the ST3 rules it looks like my average is 362whp. So I can shift this whole dyno plot up another 38whp and still punch in at my ST2 fighting weight? Awesome!!

 

383%20power.jpg

 

I did my first 2 races in October, so I haven't been doing this very long, but I would have figured an engine that peaks at almost 440whp and averages 400whp would be faster than a dead-flat motor that peaks and averages at 400whp. Perhaps I'm wrong, but irregardless who are these rules really going to help and really going to hurt? Seems to me it's really gonna help the Vette's and N/A V8 guys and hurt the 4 and 6 cylinder turbo guys. Am I misconstruing something here?

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sperkins

We are still working on discussions with Dynojet. Unless they can do some special software tweaks for us, we will leave the rules as they are currently drafted.

What about those who don't have access to a Dynojet and use a Mustang Dyno with the adjustment factor?

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davidfarmer

I would assume Mustang is as before, add 10%. My local mustang is about 6% off in my limited experience, so it would be to your advantage to find a Dynojet.

 

Yes Streetspeed, cars with normal curves will have higher peaks than those with flat curves. But remember ST1 and ST2 will likely go to this model soon also,

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Drew W.
I would assume Mustang is as before, add 10%. My local mustang is about 6% off in my limited experience, so it would be to your advantage to find a Dynojet.

 

Yes Streetspeed, cars with normal curves will have higher peaks than those with flat curves. But remember ST1 and ST2 will likely go to this model soon also,

 

Looks like I'm getting longtubes and a fresh tune for 2017!

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Greg G.

What about those who don't have access to a Dynojet and use a Mustang Dyno with the adjustment factor?

If they cannot provide the necessary data, then they will end up using Peak HP (still with 10% adjustment), or

a very conservative choice of data points off the graph by the Series Director (that cannot be mistaken as being

an underestimate). If they can provide the same data as on a Dynojet, then we would just use that, and put the

10% on the final number.

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Murphdog

I'd like to see the gap in ST2 grow and lessen the gap in ST1, that would help make ST2 a bit faster and a more competitive ST1 group.

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AWH

Question for Greg on the AVG HP calculation, now that the new rules are official...

 

If the Max HP point from the graph is not on an exact 50 rpm break (as listed on the data chart), which set of surrounding points do we use? Closest? Round-up? Round-down? Ouija board?

 

Example: Max hp is at 5026 rpm. Which 10 data points get used?

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Greg G.
Question for Greg on the AVG HP calculation, now that the new rules are official...

 

If the Max HP point from the graph is not on an exact 50 rpm break (as listed on the data chart), which set of surrounding points do we use? Closest? Round-up? Round-down? Ouija board?

 

Example: Max hp is at 5026 rpm. Which 10 data points get used?

Unless something changes with the process, one uses the Max HP on the graph, and then uses the highest HP listed on the 50 rpm increment data export table to find the 500 rpm increment data points. We are still working with Dynojet and on our own with the data files to see what the best way to obtain this data is. But, for now, if you take a Dynojet file, export the data in 50 rpm increments, you will easily see which data point to start with.

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davidfarmer

just some feedback, did some tuning on my car yesterday and this new procedure is going to be time consuming. It's hard to predict exactly where your measurement points will turn out, so even when you think you have your max dialed in, the average may be quite a bit lower or higher than you might expect. And with 10lbs for every HP, we might all be moving more weight around than before.

 

no complaints, just sharing. I hit my number in about 13 pulls, more or less got the curve I wanted (better than flat now that we don't need flat)

 

My Dynojet is up and running now in Concord NC if anyone needs annual techs or dyno time

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AWH
just some feedback, did some tuning on my car yesterday and this new procedure is going to be time consuming. It's hard to predict exactly where your measurement points will turn out, so even when you think you have your max dialed in, the average may be quite a bit lower or higher than you might expect. And with 10lbs for every HP, we might all be moving more weight around than before.

 

It's also going to be a possible compliance issue, since the peak power rpm is now susceptible to the vagueries of dyno inconsistency, in addition to the actual value. So if you have a relatively flat "curve" around the peak, a bump anywhere in that flat section defines the centering rpm for the additional data points used in the averaging calc. Cars that are induction limited typically produce this type of graph.

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davidfarmer

I agree, I see as much as a 2.5 variance between side-by-side measurements (usually less) but I guess that is upon the competitor to take that into account. Do you average, then throw in a few of the similar (but higher) points, and get a worse case measurement.

 

again, I think it will be on the competitor to plan for potential compliance issues when tested.

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Greg G.

Or, just use Peak HP and forget about the average (and hope that is enough for variance when we test you at the track and use the Avg HP calculation).

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