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s1nst3r

Tuning Formula Sticky

Hey Hemi or Speedy can we put a sticcky up in this forum for some of those nifty formula's I keep reading becasue now I can't find em.

 

There was the one on actual spark and how to calculate the actual spark vs what the diablo shows. The other one was in the tire thread on how to calculate tire height. Both are extremely helpful and yes even tire height makes a difference in tuning and running at the track and would be of great benefit to us guys trying to calculate roll out and determine how to get more gear with out changing the gears. Also an FAQ on some of the common diablo questions would be awesome as well. Just some thoughts I was having as I was waiting for my brain to catch up to my mouth. lol

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Like to know opinions as to how three different dyno makes corralate to each others rwhp readings. Say Dyno Dynamics (Load dyno) to a Mustang (load dyno) to a Dyno Jet (inertia dyno) generally speaking. I understand how they work but there has to be some reletivaty between them? and what effect tire height say 28" versus 29"? I know I know, jusa number, but so is our IQ's and we like numbers, especially high ones not withstanding in the case of ET Sorry if this is off thread but from what I see every tuner has a definete opinion here, but for the consumer a drastic difference in output can be explained calculated and understood it's good  It can

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One way to calibrate your results is to get some data on the output of completely stock cars on the same dyno. At least you'll get a conversion ratio of wheel-to-crank assuming that the ratio stays the same for the range of horsepower between the stocker and your power levels.

 

Mustang dynos can be manipulated so that they read as high as Dynojets. Not sure about Dyno Dynamics but I would surmise that you can also play with parameters to make them read more friendly. I've heard of Mustang dyno-to-crank ratios ranging from 12% all the way to 30%. Also, the ratio is not necessarily fixed through the range of hp.

 

On your 28 vs. 29 inch question: here is what I assume - if they don't adjust for wheel size, then for a given torque at the axle, the torque measured at the point of contact with the roller drum will be lower. So let's say your engine is putting out torque of X at the driveshaft, then the resistance needed to compensate that torque as measured at the roller drum will be lower by a factor of 28/29 times some overall factors that will be fixed. Hence the whp should read lower by the factor of 28/29. Hopefully someone with actual knowledge of how these dynos are set up will correct me if I am wrong.

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there's a definite correlation between each type of dyno machine and within a reasonable accuracy a percentage of difference will give the rwhp as it relates to another dynotype regardles of load type or inertia measurement. Just had to find the data and the info is out there, I found it, it helped see it apples to apples.  Not a common problem when hitting the same type dyno everytime, not the way it went for me this time, better now, it's all on the internet 

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well I was let down at first on my final pull on the dynodynamics at 480rwhp.  But after getting myself some education on the three dyno manufacturers and two types of dyno's, that rwph number on a dynojet would be about 560rwhp on the same day both systems with reasonable cals etc.  Now I can relate to this number and how it corresponds to my iron block 426/cam and now new Alum 433/cam setup, There is margin of error either way but this makes sense and I really like sense. Now it can be just a number

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480rwhp on SHRs dyno isnt bad at all. To give you something else to compare off of, I know a guy with a KB 6.1 that made 470 on Eddys dyno. And as we all know, most KB 6.1s will put down 525+rwhp on a dyno jet.

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I'm just trying to keep up with my shit and what I know about it lol  the good thing about measureing devices is they can be formulated against other types of like measuring devices.  All about keeping tabs on our rides and no matter what dyno is now at the shop you go to you can calculate a comparable number from a previous pull when something else might have been there

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