PTUNING: Dyno day clarifications
09-18-2007, 04:21 PM
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PTUNING: Dyno day clarifications
In case I forget, thanks again everyone for showing up to the meet. From what I was told the turnout was great. Sorry I did not get a chance to talk to some of you, but I had to keep the dyno running.
I'm hoping this post will quell the heated debate over the dyno numbers seen on Sunday. PLEASE let us all refrain from turning this thread into a nasty debate. Lets stay on topic and just play nice.
It seems like there was a whole lot of debate over the dyno pulls and some questions about the dynocell. I think MrC covered the whole dynocell issue pretty well in one of the previous posts here, but I'll add a few of my own comments. I can tell you as the dyno operator and tuner it would be difficult for me to go from our current set-up to a non enclosed set-up. What we've created is a purpose built dynocell sound abatement chamber (not a glorified paint booth) that has special walls and glass that absorb sound and allows us to maintain day to day operations without having to wait for "special dyno hours".
Our fan extraction system allows us to remove heat from underneath the car and all throughout the dynocell to create a setting similiar to dynoing a car in a wide open field with fresh recirulating air. This would be no different than driving your car down the highway.
The main advantage from a tuner's standpoint is that you do not have to wait as long between load tuning or sweep tests after each change has been made to the ECU, etc. I can tell you from my personal experience tuning my own car that it only takes about 2-3 minutes with both extractor fans and the front cooling fan running to allow my oil, water, and intake temps to stabilize back to pre-dyno run conditions. This helps to speed up dyno tuning sessions in most cases.
Okay, now for the dyno numbers that were showing. I can probably shed some light on this since I was the one running the dyno.
DJ.Hits, you definitely should not have to defend yourself, since I was the one dynoing your car. Your car's three pulls were all within one HP of each other. To start off with for those who want to know the technical aspecs of the dyno settings. The dyno day runs for all cars were the same. Fourth gears pulls on the S2000 consistently gives the best reading on OUR dyno except the EVO which always makes best power numbers in third gear (same for the 6 spd MR or the non-MR tested on Sunday). The ramp rate for the pulls were set at 120 vs. 100 -> normally used on DYNO Shootout mode. This means that the car is allowed to accelerate at 12.0 km per sec. . I chose the 120 mode since it places a little less "strain" on the car given the shorter run time for each pull. 100 (shootout mode) would not have made a difference during any of these runs with any of the S2000s tested (already verified that many times over).
Temp correction was not used for any car since the correction factor on Sunday would have amounted to less than even a small fraction of 1HP. Using the temp probe in my opinion would have caused further debate, because face it, you don't drive your car with the hood open anyways and some were running CAI and others snorkels, etc.
Also, all cars were running 45 psi on the driven tires during the dyno runs. This would factor out any traction problems, especially since no one was busting out 400-500+HP runs. The extra pressure allows the tires to make proper contact with the rollers during the testing when the cars are strapped down on the rollers. To answer a commonly asked question, lower tires pressures do not make for better traction when dynoing a car on a roller dyno. This only works when you take your car to the drag strip.
In defense of everyone being skeptical about DJ.Hits dyno numbers. I can honestly say that I was too until the second and third pull. BTW, On another note, I don't think that anyone was really trying to talk smack, we all just want answers.
The dyno was reading properly for ALL cars, including the Turbo RSX, which I'll get to in a bit. What I can conclude is that we did not see any bone-stock AP1 vs. AP2 comparison. Here are some facts, a dyno measures a cars ability to spin the rollers (whether it be an inertia dyno or a loading dyno). Lighter wheels and narrower tires will result is a slight power improvement (contribute to lower rotational and frictional losses on the roller). Thinner engine, trans, and diff fluid will result in improved numbers. And something generally overlooked is the toe angle on the driven wheels (frictional losses too). All these factors other than the actual engine upgrades will affect power output. I recall DJ.Hits being one of the few cars tested that sported lightweight 16" work wheels - correct me if I'm wrong. To elaborate further on the toe-angle issue, cause I know I'll get a lot of feedback on this. Ever wonder why when you go to tirerack reviews the guys with the camaros and mustang (IRS Cobras excluded) will say they got 25K more miles on their S-02s or RE050s when we know that we'd be lucky to get 12K- 15K miles out of our rear tires. The answer is that their live axle runs zero toe wheres our S2000, especially the AP1 models runs lots of toe-in (like dragging your shoes sideways down the road, this causes excessive wear and friction). Also keep in mind that when your lower your car and don't align it, the toe-in becomes worse. Now strap your car down on the dyno and toe-in increases even more. What does this all mean. Maybe DJ.Hits lighter wheel/tire combo, rear end alignment, was more favorable. Couple this with this one-off exhaust set-up and possibly better than average motor and you have yourself a potentially higher dynoing car.
Now about the Turbo RSX-S. The car was tuned for, I believe, 16-19 psi and apparently made 392HP on a Dynojet. The customer told us that he had since lowered the boost. The first two runs were similar 263.2HP and 266.3HP - turns out the over axle exhaust section of his car was being restricted by the AFR probe. First time I've seen this, but hey you learn something new everyday. FYI, this car puts out that power through a 2.25" exhaust, hence my surprise over the AFR probe restriction (ASSumed the car was running a three inch exhaust). The third run appears to show that the probe did introduce some backpressure. Run three 317.9 HP at 14-15 psi. Customer then turns up the boost for the last run (the extra run was given to him, because of the AFR probe deal). Turns out he incorrectly turned up the manual boost controller (not enough clicks) so the car gains less than 1 psi on the last run, resulting in a final pull of 326.3 HP.
The fact is that the dyno pulls were ALL accurate, otherwise I would not have had any problems with giving a fourth, fifth, or even sixth run (had I known that there would be so much debate over the numbers. If you guys notice the most important thing though is that all dyno pulls for a given car were within a very small percentage of each other, which does show the consistency and accuracy of the dyno throughout the day.
DJ.Hits' dyno numbers are correct for HIS given set-up. All tests were equal. Temps, humidity, barometic pressure etc. were also very stable throughout the day.
***Just overlayed all the dyno numbers for all the NA S2Ks. A couple of interesting points to note. DJ.Hits may possibly be onto something with his custom exhaust set-up or whatever other engine mods he has in place. His power number are less than 3 HP more than the next guy until he hits VTEC. That's when the power is really unleashed. HP numbers increase dramatically in VTEC with power peak (8700 rpms) being the same as all the other AP1s. Also, his car's set-up places the car AFR during VTEC at around slightly leaner (but generally better for NA F20C, F22C)) 13.0 AFR v.s 12.0 AFR for all the other NA cars that were dynoed. This may also have contributed to a very slight increase in power too.
Other than the dyno numbers, I hope everyone had a great time. Hopefully we'll be able to make this a yearly event for you guys.....
- Toan
I'm hoping this post will quell the heated debate over the dyno numbers seen on Sunday. PLEASE let us all refrain from turning this thread into a nasty debate. Lets stay on topic and just play nice.
It seems like there was a whole lot of debate over the dyno pulls and some questions about the dynocell. I think MrC covered the whole dynocell issue pretty well in one of the previous posts here, but I'll add a few of my own comments. I can tell you as the dyno operator and tuner it would be difficult for me to go from our current set-up to a non enclosed set-up. What we've created is a purpose built dynocell sound abatement chamber (not a glorified paint booth) that has special walls and glass that absorb sound and allows us to maintain day to day operations without having to wait for "special dyno hours".
Our fan extraction system allows us to remove heat from underneath the car and all throughout the dynocell to create a setting similiar to dynoing a car in a wide open field with fresh recirulating air. This would be no different than driving your car down the highway.
The main advantage from a tuner's standpoint is that you do not have to wait as long between load tuning or sweep tests after each change has been made to the ECU, etc. I can tell you from my personal experience tuning my own car that it only takes about 2-3 minutes with both extractor fans and the front cooling fan running to allow my oil, water, and intake temps to stabilize back to pre-dyno run conditions. This helps to speed up dyno tuning sessions in most cases.
Okay, now for the dyno numbers that were showing. I can probably shed some light on this since I was the one running the dyno.
DJ.Hits, you definitely should not have to defend yourself, since I was the one dynoing your car. Your car's three pulls were all within one HP of each other. To start off with for those who want to know the technical aspecs of the dyno settings. The dyno day runs for all cars were the same. Fourth gears pulls on the S2000 consistently gives the best reading on OUR dyno except the EVO which always makes best power numbers in third gear (same for the 6 spd MR or the non-MR tested on Sunday). The ramp rate for the pulls were set at 120 vs. 100 -> normally used on DYNO Shootout mode. This means that the car is allowed to accelerate at 12.0 km per sec. . I chose the 120 mode since it places a little less "strain" on the car given the shorter run time for each pull. 100 (shootout mode) would not have made a difference during any of these runs with any of the S2000s tested (already verified that many times over).
Temp correction was not used for any car since the correction factor on Sunday would have amounted to less than even a small fraction of 1HP. Using the temp probe in my opinion would have caused further debate, because face it, you don't drive your car with the hood open anyways and some were running CAI and others snorkels, etc.
Also, all cars were running 45 psi on the driven tires during the dyno runs. This would factor out any traction problems, especially since no one was busting out 400-500+HP runs. The extra pressure allows the tires to make proper contact with the rollers during the testing when the cars are strapped down on the rollers. To answer a commonly asked question, lower tires pressures do not make for better traction when dynoing a car on a roller dyno. This only works when you take your car to the drag strip.
In defense of everyone being skeptical about DJ.Hits dyno numbers. I can honestly say that I was too until the second and third pull. BTW, On another note, I don't think that anyone was really trying to talk smack, we all just want answers.
The dyno was reading properly for ALL cars, including the Turbo RSX, which I'll get to in a bit. What I can conclude is that we did not see any bone-stock AP1 vs. AP2 comparison. Here are some facts, a dyno measures a cars ability to spin the rollers (whether it be an inertia dyno or a loading dyno). Lighter wheels and narrower tires will result is a slight power improvement (contribute to lower rotational and frictional losses on the roller). Thinner engine, trans, and diff fluid will result in improved numbers. And something generally overlooked is the toe angle on the driven wheels (frictional losses too). All these factors other than the actual engine upgrades will affect power output. I recall DJ.Hits being one of the few cars tested that sported lightweight 16" work wheels - correct me if I'm wrong. To elaborate further on the toe-angle issue, cause I know I'll get a lot of feedback on this. Ever wonder why when you go to tirerack reviews the guys with the camaros and mustang (IRS Cobras excluded) will say they got 25K more miles on their S-02s or RE050s when we know that we'd be lucky to get 12K- 15K miles out of our rear tires. The answer is that their live axle runs zero toe wheres our S2000, especially the AP1 models runs lots of toe-in (like dragging your shoes sideways down the road, this causes excessive wear and friction). Also keep in mind that when your lower your car and don't align it, the toe-in becomes worse. Now strap your car down on the dyno and toe-in increases even more. What does this all mean. Maybe DJ.Hits lighter wheel/tire combo, rear end alignment, was more favorable. Couple this with this one-off exhaust set-up and possibly better than average motor and you have yourself a potentially higher dynoing car.
Now about the Turbo RSX-S. The car was tuned for, I believe, 16-19 psi and apparently made 392HP on a Dynojet. The customer told us that he had since lowered the boost. The first two runs were similar 263.2HP and 266.3HP - turns out the over axle exhaust section of his car was being restricted by the AFR probe. First time I've seen this, but hey you learn something new everyday. FYI, this car puts out that power through a 2.25" exhaust, hence my surprise over the AFR probe restriction (ASSumed the car was running a three inch exhaust). The third run appears to show that the probe did introduce some backpressure. Run three 317.9 HP at 14-15 psi. Customer then turns up the boost for the last run (the extra run was given to him, because of the AFR probe deal). Turns out he incorrectly turned up the manual boost controller (not enough clicks) so the car gains less than 1 psi on the last run, resulting in a final pull of 326.3 HP.
The fact is that the dyno pulls were ALL accurate, otherwise I would not have had any problems with giving a fourth, fifth, or even sixth run (had I known that there would be so much debate over the numbers. If you guys notice the most important thing though is that all dyno pulls for a given car were within a very small percentage of each other, which does show the consistency and accuracy of the dyno throughout the day.
DJ.Hits' dyno numbers are correct for HIS given set-up. All tests were equal. Temps, humidity, barometic pressure etc. were also very stable throughout the day.
***Just overlayed all the dyno numbers for all the NA S2Ks. A couple of interesting points to note. DJ.Hits may possibly be onto something with his custom exhaust set-up or whatever other engine mods he has in place. His power number are less than 3 HP more than the next guy until he hits VTEC. That's when the power is really unleashed. HP numbers increase dramatically in VTEC with power peak (8700 rpms) being the same as all the other AP1s. Also, his car's set-up places the car AFR during VTEC at around slightly leaner (but generally better for NA F20C, F22C)) 13.0 AFR v.s 12.0 AFR for all the other NA cars that were dynoed. This may also have contributed to a very slight increase in power too.
Other than the dyno numbers, I hope everyone had a great time. Hopefully we'll be able to make this a yearly event for you guys.....
- Toan
09-18-2007, 04:46 PM
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Toan - Thank you for the very elaborate and thorough explanation. 
I hope it settles some of the questions that have been raised.
-Aaron
I hope it settles some of the questions that have been raised.-Aaron
09-18-2007, 06:21 PM
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Thanks for the explanation! I appreciate all the effort that you guys have put into explaining things to us! Sorry if I started a bit of a war by asking about the dyno numbers. I'm always a curious person 
Never intended to start any arguements, just some discussion as to possibilities of two AP1s with similar bolt-on mods running at a 30whp difference. Glad to hear some explanations!
BTW- Thanks again for hosting us. I really hope you guys can make this a yearly event!
Never intended to start any arguements, just some discussion as to possibilities of two AP1s with similar bolt-on mods running at a 30whp difference. Glad to hear some explanations! BTW- Thanks again for hosting us. I really hope you guys can make this a yearly event!
