Before and After Dyno Charts

[bjmsam]

Absolute horsepower numbers are ultimately meaningless. What's important is the relative difference between a car's performance before modification vs. after modification. Superimpose the before and after dyno charts and the impact is clear, regardless of dyno type or method of operation (as long as they are reasonable and consistent).

Note that the same argument holds for performance meters such as the GTech-Pro. While its computed 1/4 mile ETs have been repeatedly proven consistent with strip ETs, the terminal speed it reports cannot be compared with the trap speed averaged over a specific distance at the track. But comparing GTech terminal speeds before and after a modification is just as useful as comparing trap speeds before and after a modification. It's all about evaluation in context!

[GTO NEMESIS]

I agree, I have several graphs of my car done at the same place though out the staged mods I have done.

I will get PE to do a multi chart graph for you tomorrow.
As for my previous post, I want to know the differnce form BHP and AWHP so if a set DR-650's add 100 BHP in the UK and they add 100 AWHP in the UK how can this be possible? It can't!
Someone is qouting something wrong somewhere? Either out figures are at the wheels or the US figures are at the crank.

Mark

[mjannusch]

Originally Posted by GTO NEMESIS

As for my previous post, I want to know the differnce form BHP and AWHP so if a set DR-650's add 100 BHP in the UK and they add 100 AWHP in the UK how can this be possible? It can't!
Someone is qouting something wrong somewhere? Either out figures are at the wheels or the US figures are at the crank.

...or simply your car(s) are making less power than the one(s) you are comparing to. You have to at least consider that as a possibility.

Can you post the dyno plots of your car and the plot of the car(s) that you are comparing it to?

[VR4neophyte]

Originally Posted by bjmsam

What clear, objective message is the marketplace presenting that quantifies relative performance? To use your example, what would it be like to upgrade from 9Bs to 13Gs vs. GT-347s / DR-500s vs. 15Gs vs. GT-357s / DR-650s? Clipped vs. unclipped? Pump vs. race gas? Are the "huge gains" being compared to 9Bs at stock boost or to 9Bs at maximum safe boost? We see some reporting low to mid 12s with 9Bs and fuel, while many, many others have made considerable investments in turbos, FMICs, intake, exhaust, etc. only to realize frustratingly similar results. The knowledge base is overly subjective.

Well, "clear, objective message" is probably anything but that, depending upon your goal. If I were considering a turbo upgrade right now, without question I'd head to Jeff Lucius' website to read his primer on turbos (http://www.stealth316.com/2-turboguide.htm). I'd absorb everything in there about turbocharging and how it relates to our cars. I'd read the specifications on each turbo (compressor, turbine, flow maps, etc.) Because Jeff is not compensated in any way, he enjoys a degree of credibility with prospective turbo buyers. He's an independent information source, gathering up specs and data and experience and presenting it without profit motive.

You ask, "what would it be like to upgrade from 9bs to" a variety of other turbos. At the end of Jeff's article there are a couple of graphs that provide the answer to that specific question. The data presented was collected from a variety of users of those turbos, in many configurations, as verified by real world track performance and timeslips. The likelihood of exaggeration is substantially decreased (although not completely eliminated, no doubt) because of this timeslip verification. The table information represents ALL of the variations out there in terms of modifications rather than some carefully crafted control group representing stock or BPU or highly modified.

If my goal is to be one of these fastest cars, and I have 9bs right now, what will happen if I upgrade to DR650s? As the chart says, the fastest 9bs support ETs in the range of 12.4 to 13 seconds, depending upon other modifications and driver capabilities. If I'm one of the best, I can expect that performance. On the other hand, holding the degree/diversity of modifications and drive capabilities constant, I can expect substantially better performance if I use DR650s. As the chart says, the fastest DR650s support ETs in the range of 11.0 to 12.3 seconds depending again on other modificationd and driver capabilities. 9bs' best traps are 105-115 mph, and DR650 best traps are 113-128 mph.

The variation, subjectivity, and bandwagon jumping is included equally in all of those. The prospective buyer is simply left to determine which performance characteristics they want given the information presented. Of course, after leaving Jeff's site, you can head over to 3si to read users somewhat biased but not profit motivated experiences. If you're active with other 3/S users locally, you can ride along, test drive, or go to the track with those who use one turbo or another.

Those on the lower end of the lists are using fewer mods (pump gas, SMICs, stock boost, granny-shifting, etc.) vs. those on the high end using more mods and aggressive driving (race gas, FMICs, max boost, no-lift shift, etc.)

In this example, the combination of Jeff's information, 3si posts, and personal experience with other members provides me with clear, objective perspective to support my choice and purchase, even though a dyno was never involved before or after. In fact, a dyno claim would have provided me with virtually no credible information in addition to what I found through Jeff, 3si, and my own experience. It is likely that any dynos and configurations used by product sellers would be so incredibly different from shop to shop that the comparisons would be close to meaningless anyway.

Erik

[bjmsam]

Originally Posted by VR4neophyte

At the end of Jeff's article there are a couple of graphs that provide the answer to that specific question.

Jeff's turbo page offers a wealth of information that is particularly valuable to those with the aptitude to digest flow maps and predict performance from published specifications. The graphs to which you refer do dilute biases through sample variation and are useful for estimating average peak power gains, but they do not characterize overall engine flexibility, which is the root of my interest as distinguished in previous posts. For example, drag strip data for the EVO FQ-400 is mighty impressive, but the car is an absolute pig on the road; such lack of street manners may be acceptable to some, but others would like to increase power without making their GTs perform like S2000s, RX-8s or other over-cammed vehicles that have to be run at stratospheric engine speeds just to get out of their own way.

Originally Posted by VR4neophyte

It is likely that any dynos and configurations used by product sellers would be so incredibly different from shop to shop that the comparisons would be close to meaningless anyway.

Again, I am not advocating for comparison of charts produced on different dynos. But if vendor A's product flattens, stretches and raises its baseline stock torque curve while vendor B's product turns its baseline stock torque curve into a mountain that peaks at redline, consumers would be in a better position to determine which option is best for their specific goals.

Originally Posted by VR4neophyte

a dyno claim would have provided me with virtually no credible information in addition to what I found through Jeff, 3si, and my own experience.

We agree that vendors may not see the need to invest in dyno runs due to adequate demand, but we disagree on the utility of dyno charts (which is fine; I understand and appreciate your argument).

[bjmsam]

A step in the right direction: 3SX Performance Customer Dyno Runs-Upgrades VS Power Increases