I agree with this 100%

 

Dyno's are really only a tuning tool. They should be used for modifying and correcting A/F ratios and tuning. You can check them for performance gains after mods are done but it should be done the same day or on a day with similar temps and humidity otherwise you won't really have correct numbers. Numbers are numbers track times are what really matters, because they tell you what you really have.

 

I talked to RENNtech about the results and they said for that machine they were pretty good #'s (266rwhp). They said the stock C32 AMG on that dyno jet was 289rwhp.They also said on a dyno jet I would have probably been in the mid 300's.
[above edited, looked at notes and had posted wrong machine & #'s forC32 AMG- posted from home, notes at work]

A/F ratio's were the main reason for doing the dyno + I did want to know what it was putting to the ground. I was just so shocked because the rwhp was 80 or so less than what I thought I'd see.

 

Motors are the same, SRT6=SLK32=C32. Ours put out the same power as the MBs.

 

Jody, keep in mind the math only works if you're careful. This example may help:

Let's just say our example car has a true crank hp of 300. Assuming a drive train loss of 20%, that car would have an actual wheel hp of 240. (That's 300 * .80 = 240)

Now put that example car on a Mustang Dyno, which reads numbers 12% less. So a 240 whp car should read as 211.2 on a Mustang dyno. (240 * .88 = 211.2)

Now, I know that you're thinking that I worked that backwards, and you're right. But I did that deliberately. When you talk about losses, you need to work down from the big number (100%).

To work up from the Mustang number, the math works a bit different. In our example car it read 211.2 on the Mustang. To figure out what the actual whp would be we have to divide the 211.2 by 88, then multiply the result by 100. See how that "upsizes" the number proportionally? 211.2 / 88 = 2.4, 2.4 * 100 = 240.

Then to get the crank hp from the whp, divide the whp by 80 then multiply the result by 100. So: 240 / 80 = 3, 3 * 100 = 300. Notice how the numbers work exactly back up to the original crank hp number, showing that the math works, just the method is different dependent on which direction your calculating.

I hope that helps.

In Steve's case:
Mustang hp: 266
Adjusted WHP = 266 / 88 * 100 = 302.3
Adjusted Crank HP = 302.3 / 80 * 100 = 377.9

That's assuming 12% loss for the Mustang dyno, and 20% loss for drivetrain.

Steve: also note your dyno run only went to 5548 RPM. If you take that up to 6200 RPM your numbers should go up another 15-20 hp.

 

tom2112,

Wow... base on your math (which I can find no fault with)...

That means that my car was making the following... STOCK!!!

NOTE: I DID get to redline... Didn't matter that I had both fuses 17 & 18 pulled or not, both runs came out almost identical. This one was without. I can only guess that it was because of the front and back rollers being linked.

Mustang HP: 249
Adjusted WHP = 249 / 88 * 100 = 282.95
Adjusted Crank HP = 282.95 / 80 * 100 = 353.69

Mustang torque: 252
Adjusted Wheel torque = 252 / 88 * 100 = 286.36
Adjusted Crank torque = 286.36 / 80 * 100 = 357.5

Holy horsies Batman! I guess we are about the same stock as the SLK 32 AMG/C32 AMG!!!

... AND I have a slight factory freak!

 

Take a look at the A/F chart.

Assuming that it was a tailpipe reading, the 11:1 (approx) average is actually reading about a half-point leaner than it actually is.

This means that you were closer to 10.5:1 in acutality. There is a bit more power to be had in your combo, IMO.

 

I made a correction in post 43, it was posted from home and I was just going by memory. After I got to work this morning I seen the note I had made and relized I had made a false statement, so I corrected it.

 

Steve,

I'm sorry to see/hear that you are dissapointed with your visit to our facility. I am happy to read on here that other owners are not particularly suprised with the dyno numbers that you are seeing based on your particular combination. As mentioned while you were here, it is IMPOSSIBLE to calculate and exact parasitic drivetrain loss or a specific dyno percentage loss as compared to other brands/facilities. Also, it would be wise to take into account that a companies advertised power increases are never exact and each and every car reacts differently to modifications, weather conditions, altitiude, baro pressure, ect ect ect. Just because someone elses car makes X whp and Xwtq in Washington State obviously doesnt mean that your car, or even that car will make that same power in Florida (or Kentucky for that matter). I'm sure you are aware of that aspect however.

As far as the "100 mph" thing that you mentioned. I had/have no problem taking that dyno to 160mph (which is what it is rated at) and have done so multiple times before. I saw no reason based on your cars output graph (refer to the one you posted originally) to take your car beyond where we did. As you can see the HP levels were leveled off and there were no significant gains to be had over where we were. (Possibly 1-3 whp). I would have had no problem taking it higher for you had you mentioned it while you were here. There is simply no need to beat on it any more then nessasary if you are not going to see any gain from it in my opinion.

Also, with the fuel curve I was seeing on the dyno and my experience with tuning cars, I have to come to the conclusion one of three things. Either A: your tune is off and your car needs to be leaned out in the upper RPMS, B: your tune is off and your car is adding fuel based off of excessive knock voltage to protect itself, or C: your tune is spot on and the IAT's on your car are excessively high do to the added boost through the stock heat exchanger and the computer is adding fuel based off these values to cool the combustion and protect itself from knock. In either event, this is also another reason not to take your car any higher in the RPM's then we did while we had it here. The computers will also learn based on the conditions and driving styles of the owner and it could have been seeing these higher IAT's for some time and just trimmed the fuel curve richer based on this condition.

In either event, I am sorry you were not happy with your experience here or that you did not find our facility to be as nice (or as "state of the art" I believe you put it) as you expected and if there is anyway that I might be able to help correct this I am open to suggestion. Please feel free to email or call me anytime you like.

Charles Gordon
Auto Motion Inc.
502 589 1155

 

OUCH!!! He sounds like a genuine person. From the pics I seen (atleast from the inside) it looks modern enough to me. You knew what you were getting into with a mustang dyno as far as low numbers. Sometimes that cold hard reality sucks. Go to a dynojet and track and make yourself feel better steve.

 

Sounds like a nice guy to me!

 

They were great people to work with and very nice people. I did not knock them or their facility, when I said not a "state of the art facility", that term would have a different meaning to differtent people. The term to me would mean several new machines in a spotless new large facility, not that their place was dirty by no means and it was a pretty nice small facility. As far as knowing what I was getting into with a Mustang Dyno, I did not know that they put out such low #'s compared to a dynojet. That was the first time I have ever been to a dyno shop or even seen one run in person. I guess I was in "DYNO SHOCK" since the #'s were at least 80rwhp than I expected. I feel really bad if they thought I was knocking them or their facility, because they were such great people. I even started this thread (post #2) saying "The people were nice and seemed to know what they were doing"

 

The shop looks nice and clean to me, Charles seems nice also.And to have not one but two dynos is a huge investment. Most shops can't even afford one.

 

I wouldn't get too excited yet. I'm not really comfortable saying the a Mustang dyno reads out 12% lower than actual whp. I think it's safe to say that it reads out 12% lower than a dynojet. But who is to say which one is reading out the correct number? I'd put money on it that neither one is actually correct, and that both are off by some margin. I'd also bet that we could get experts from both dynojet and mustang to tell you why theirs is correct. I wish there was a way to tell.

I've tried running the numbers with ET's weights and speeds when compared to dyno numbers, but I can't get the math right to figure it out. I'll keep crunching numbers until I get somewhere. I _know_ there is a mathematical formula for determining the amount of power required to displace a vehicle 1/4 of a mile in a specified period of time. That would give us a good imperical whp number to work with. Maybe I'll stop by my old physics professor's and ask him!

 

I know everybody is saying it's just numbers and they don't mean a thing, but waldig must have one mean machine. His car on the Mustang
Dyno pulled 56 more rwhp the my car did, his mod's are listed in his signature.
.

 

Please look at my chart on my signature, I did a mustang dyno after a CAI and head porting (home done )with the gaskets on the inlet, for comparison. Enjoy, Woody

 

You sir, could not be more correct. These machines are tuning tools only. Dynojet put out a press release several years back stating that their machines read higher because thats what customers want. Its a marketing tactic that works for them. We purchased mustang dyno's because they are load bearing and provide the resolution that we feel we need to accurately tune a car to its potential, within the limits of safety. No two machines read the same and everyone thinks theirs is correct. I don't pay hardly any attention to the horsepower when I am tuning other then to see where it has changed and how much. The numbers are just numbers to me, although I know people get hung-up on them.

We try and keep these machines as accurate as possible. Things are constantly changing. Things as simple as a bearing getting wear and adding more drag can effect the results slightly, and that is the reason why we spend as much money on maintenence on these two dyno's as possible.

What are ALL the mods on your car Waldig? If it is just the CAI and gasket matching, with no other modifications and you are making the same or more power according to your dyno runs as guys with CAI, Pulley, full exhaust, Computer reflash, ect. then I would have to question your numbers being high, just as Steve questions his being low. Just curious.

I along with ANY OTHER dyno owner/operator can make these machines read higher or lower if they want. What benifit would I have to making them read LOW and having people dissatisfied? Much more to gain by turning them up and showing people what they want to see, whether its right or not.

Charles

 

Thanks for your insight and expertise Charles. We really appreciate you taking the time to come here and fill us in.

 

Charles,
Like tom said, thanks for coming here to explain things a little better and I agree with you! Its "just a number" and people get hung up on the numbers. Use the dyno to fine tune the car under acceleration. After that, head to the 1/4 mile to do some testing. That is the true test IMO.

Steve,
do you plan on taking it to the track?

 

Yes I do. I've been signed up for two events this spring, one at Indy that got cancelled because it was to cold and one at US 41 Drag Way April 12th that was being sponsored by www.letmotorsports.com & CTP that was cancelled because of rain. The US 41 is rescheduled for May 17th and I sure hope the weather cooperates this time. I hope that someone there will be able to run a data log on my car to see how my IAT's are running. Charles, who I can't apologize enough to for sounding like I was knocking his facility, didn't have the equipment to do so on our SRT 6's. I sent the dyno charts & #'s that Charles ran for me to RENNtech, they looked them over and agreed that I was running a little on the rich side toward the top end. They offered to re-tune my ECU for free, but they would like to see how high the IAT's are toward the top end first. I'm getting quite the education here because I'm new to the forced induction world and really didn't know there was that much differences in dyno machines.