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Discussion Starter · #1 ·
Just for my own curiousity what is the average difference between what a mustang dyno will read compared to a dynojet?

I realize that you can setup either show higher or lower numbers but my perspective is that most mustang dyno's that I have been to are setup to read very conservatively, and seem to be found more in hard core fundamental race shops (just a observation based on what I've seen personally, not saying theres anything wrong with dynojet).

This question was brought up when I raced a friend at the track recently with a gsr IX who dyno'd around 320whp 300 tq (stage I parts) on a local dynojet, my VIII MR dynoed 280 whp 270tq.
We both cut 1.8 60 fts however I pulled just under a car length on him at the 1/4 and I ran a [email protected] to his [email protected]

We both thought he was going to murder me, and we were both kinda shocked at my marginal victory, however both of us had decent launchs and no shifting glitches.
From what I gathered I would assume that we more than likely have about the same amount of power, but there is a 40whp difference between dynos.

So I'm curious if anyone has put there car on both dynos and has any feedback.
 

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Avg. difference is around 14-15% I believe. With the mustang dyno reading the lower of the two. If your numbers came from a mustang dyno then 280x1.14= 319.2, which would make since why it was such a close race.
 

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There is no average difference, because of many factors:

1) Almost all Dynojets read the same or within a close percentage, however

2) The same car on two separate Dynojets at the same time and same conditions can have much different numbers if they don't use the same Correction Factor. The most common are SAE and STD, but I prefer to use uncorrected, because that is actual power, whereas the correction factors try to normalize the numbers by accounting for temperature, humidity, and altitude.

3) Mustang Dynos almost NEVER read the same as each other, because they have many parameters that can be changed in the computer between runs AND because if the rollers are set up differently, then they can read exactly like a Dynojet. So, you cannot simply take numbers from a random Mustang Dyno and convert them to Dynojet numbers. You have to take the same car from that specific Mustang Dyno and then go put it on a local Dynojet to get a direct comparison. Or, if you have many samples of trap speeds to compare between that Mustang Dyno and those from a Dynojet, then you can make a basic comparison calculation.

If you put down 280 on a Mustang Dyno like the one at Buschur Racing, then you would definitely be on par with any Evo that puts down 320 on a Dynojet. If that's the case here, then it makes sense. Your trap speed is 109 while his is 108, which unfortunately means that neither of you are trapping what a 320whp Evo should trap, but the driving looks good on both, so I don't think there is any major discrepancy between what you ran and what the car is fully capable of...

I have done a lot of research and work on making sure I knew what my car could do at each stage of modding by hitting the track and dyno'ing as many times as I could. This is what I found:

Stock/93oct ------- 248whp - [email protected] (sucky 1.92 60' due to 5k limiter)
SAFC only/93oct ---270whp - [email protected] (removed 5k limiter and got 1.76 60')
SAFC/cat-back/MBC/93oct --- 282whp - [email protected] (1.75 60')
SAFC/cat-back/MBC/104oct --- (never dyno'd on race gas) - [email protected] (1.72 60')
SAFC/TBE/MBC/BOV/93oct --- 294whp - [email protected] (1.75 60')
TBE/MBC/BOV/Dynoflash/93oct --- 305whp - [email protected] (1.66 60')
TBE/MBC/BOV/Dynoflash/104oct --- (never dyno'd on race gas) - [email protected] (1.66 60')

So, as you can see, you both ran about what I did when I had 294whp, and all my dyno'ing was done on a Dynojet. The 12.52 was in 80+ degree weather, but the 12.26 was done in 60-degree weather.
 

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Regardless of how many points and paragraphs WT posts if you're looking for a ROUGH idea then what I typed above will give you a general idea. If you're trying to get down the the exact horsepower conversion then yeah, you need a couple dozen parameters and ?'s answered. If I had no experience with this I wouldn't respond, but this is my personal experience with my car and numerous car friends who have had their cars on multiple dynojet and mustang dyno's in our area. IMO, the only thing that matters is what your time slip says, assuming you can drive and your a/f is o.k. If you start dyno racing you're simply chasing your tail. No disrespect to anyone in this thread, I guess I'll just agree to disagree and go with what I have witnessed with my own two eyes.
 

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Discussion Starter · #5 ·
I was more looking at a general figure, so my theory falls in line with mdog. Not to say you are not correct warrtalon, but I think you are looking at it more as a definitive yes or no type of answer and a exact conversion figure, such as the "coefficent of dyno conversion" ROFL

It has been my experiance so far that most of the serious race shops in my area seem to prefer the mustang dyno, where the fly by night and "jdm" shops seem to prefer dynojet, as dynojets appear to show higher power numbers compared with the local mustang dyno's this makes sense from a advertising perspective. This may be local to my area, but for example, there are several stockish LS1 powered fbody's making 300+ on the dynojet , yet are trapping around 105 mph with 13.xx et's.
Another of my friends with a 2003 SS Camaro with bolt ons made 320ish on the same mustang dyno I use but traps 115 on street tires with mid 12 et's (would be better if he could hook, car is on half bald nitto 555's).

Just for clarification, I am not saying anyone is right or wrong on the dynojet-mustang, just wondering if it was common to any other guys.

Thanks for the input.
 

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What do you mean, mdog? I don't see where anyone disagreed, and I don't see where what you have seen with your own eyes has been refuted. NOthing I said refuted what you said. All I did was give a more detailed response that you cannot simply throw a percentage out there and expect it to be right. Many people have made big mistakes and been very disappointed when doing that - I've seen THAT with my own two eyes many, many times.

You also have to remember that you can't do a straight up % conversion, because it does not hold true at the high and low extremes. It's more of a linear difference between the dynos, not a percentage difference in many cases, so as the power increases on a car, the percentage difference tends to be lower (vice versa for lower power levels).

So, it's very possibly and in many cases likely that the difference between the two dynos is 15%, but I just didn't want him (or anyone who reads this) to take that percentage as gospel. In the DC area, there is a Mustang Dyno that puts out the same numbers as local Dynojets, and there is another Mustang Dyno that is about 10% off in the 200-300whp range. However, that 2nd one doesn't read as low as the Buschur MD, so you never really know...
 

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Well, Dynojets are considered the STANDARD for power measurement and power comparisons, but Mustang Dynos are far better as tuning devices, because they are load bearing. That would be why the hardcore shops around you have the MD probably, because they are more interested in steady-state maximum brake torque tuning, which is the most sophisticated and best way to tune, but it takes a lot of time and effort. Dynojets are not load-bearing, so they are best used as a checkpoint for power gains...not the best for tuning.
 

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superflyjmysnk said:
Just for my own curiousity what is the average difference between what a mustang dyno will read compared to a dynojet?

I realize that you can setup either show higher or lower numbers but my perspective is that most mustang dyno's that I have been to are setup to read very conservatively, and seem to be found more in hard core fundamental race shops (just a observation based on what I've seen personally, not saying theres anything wrong with dynojet).

This question was brought up when I raced a friend at the track recently with a gsr IX who dyno'd around 320whp 300 tq (stage I parts) on a local dynojet, my VIII MR dynoed 280 whp 270tq.
We both cut 1.8 60 fts however I pulled just under a car length on him at the 1/4 and I ran a [email protected] to his [email protected]

We both thought he was going to murder me, and we were both kinda shocked at my marginal victory, however both of us had decent launchs and no shifting glitches.
From what I gathered I would assume that we more than likely have about the same amount of power, but there is a 40whp difference between dynos.

So I'm curious if anyone has put there car on both dynos and has any feedback.
When people look for a way of measuring something that involves tons of different parameters they realize there isn't an easy way to create an equation. You can't oversimplify something in hopes of having a handy equation that works for every situation. It just doesn't work that way.

Trying to use a simple rule of thumb for comparing dynojet dynos to mustang dynos is a perfect example of that. You just can't come up with a simple "average" that holds true in all situations. Comparing the "average" from one situation to the next would produce numbers that could be way off.

I guess the average number you're looking for could work in a 2 dyno comparison where it can be tested, but trying to apply the comparison to all dynos everywhere wouldn't work without test data.
 

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It looks like Warrtalon and I have much the same opinion/experience with dyno's so maybe I should have prefaced in my first post as being a really really generalized number just to give folks an idea. See, I didn't reallly want to bother with my whole thoughts on dyno #'s and their usefullness/lack of usefullness, how MD load the rollers, are better for tuning, but cost more $ etc...... IMO, the only one I'd use for tuning is a properly set up MD. And that would be all the use to me a dyno would have. I guess the number is nice for a reference when chronicaling the addition/subtraction of mods, but an even better number(s) to look at is your TIMESLIP. I have just been so fed up with folks bench racing this # to that # and then you ask them what they run and they give you the, "Well, I've not been to the track blah, blah, blah...." For example, with the Mustang I have now. People always start talking #'s with me and I just get blank stares when I tell them this car has never even touched the rollers. I look at my timeslips and plugs to see if what I'm doing is working, and it is fuel injected, so it has the ability to be tuned electronically. It's hilarious to tell someone you run 7.3's in the 1/8th and then when they ask how much hp it makes you tell them I don't know, ..........blank stare............. Of course I have calculations I use to get a rought estimate, but I really don't know for sure and don't care for that matter. Regardless, this thread is fun and makes for good conversation so cheers all around.
 

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100% in agreement. I hate bench racing, and I generally do not like talking about dyno numbers. I do use them as a tool but only in combination with my track times. I have over 250 drag runs in my Evo and have been on the dyno probably 10 times, so you can see which one I prefer. Whenever someone asks me how much power I make, I just say "around 300." I don't go into a long diatribe about 300WHP vs 300HP vs SAE corrected vs Uncorrected, blah blah. I also don't ask people how much power they make - I only ask their trap speed (to see the car's power) and ET (to see their driving ability).

As for tuning, I agree that an MD is one of the best, but my local shop happens to have a Dyno Dynamics that also provides load along with MAP-sensor boost logs and AFRs, which is very helpful when combined with my own logging using EvoScan.
 

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The interesting part to me is that the two people in my area I would actually trust to tune a Ford/Mustang don't own or use a dyno. It's all road test with them. They'll log on hills at part throttle, WOT pulls on flat stretches, idling around town, etc, etc...... And then tweak everything and load that tune up. 99% of the time they get it almost spot on pretty quick. The only time I ever used a dyno for my own personal car was after having a procharged gt tuned and then wanting to verify my a/f were pretty safe. I even used a switch chip that had multiple tunes loaded into it and with the turn of a knob I could go from mild to wild in 2 seconds, now that was nice. :)
 

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Yah, all of my Evo tunes have been on the road except the one time it was raining, so I had to get it done on the dyno. One other time, I tuned myself on the dyno with my SAFC just because I don't have a wideband and needed to do a pretty drastic change where I turned off my alky injection and used 100 octane instead. This was because alky injection is not legal in SCCA Solo II, so I had to adapt quickly. Now, with EcuFlash, I have multiple tunes for all situations: street, drag, circuit, auto-x using different combinations of alky and octane.
 

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Sounds like my plans to grab EvoScan and ECUflash will be well worth it then. I'll pick your brain about that after I've actually picked up an Evo. :) All I'm really interested in though is having a good pump gas tune and then something for 107 octane for when I hit the track. Other than that, the software will just be something fun and interesting for me to learn and become familiar with.
 

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It will be perfect for that scenario: a good pump gas daily driving tune, then a balls-to-the-wall race gas tune for the track. You won't be able to change tunes with the flip of a switch, since you'll have to stop and reflash the car, but that's not really a downer, because you have to stop and put in race gas anyway.
 
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