etzilon

Leaking (well, more like dripping) front shock kept me out of our 2nd NASA TX event for 2015 :-(

I could have/should have caught it earlier... my job keeps getting in between me and my hobby ;-P

Arca_ex

iTrader: (10)

So I got raped by the mobile dyno last weekend. No idea why he dragged that piece of **** to AZ from California. Took away a first place time and $350 worth of free tires and $150 worth of free brakes. Couldn't compete on Sunday and I was pretty much for sure gonna get another first place and another $350 worth of tires. Pretty pissed.

I did 125WHP on the local dyno, my cap was 128WHP and I pulled 133WHP on the mobile dyno.


Oh and on Saturday, first session of the day I was 6 hundredths off the track record on 40 heat cycle Maxxis RC1. The record for that track was set on Hoosiers and has stood for over three years in TTE. I had probably another 20lbs I could take out of the car and I think I could have broke it on Sunday but I got worked over on Saturday.

MagnusRacing

iTrader: (2)

I did test my RX8 again last Friday at a local Dyno and put down 220hp to the rear wheels. The MCE dyno had 224hp. However, it was hot and dry at the local dyno and cool and wet at the track when MCE tested the car so that could be the 4hp difference there.

I any case, dyno variance can be very frustrating. I'm considering moving away from a dyno reclass. I don't think the MCE dyno is all that inaccurate but every machine is going to read different so unless you've tested on the MCE machine before you'll never really know what you're gonna be making.

RockLobster

That dyno is giving EVERYONE trouble. Lots of discussion on various boards about a mass protest of that Dyno and it's Operator.

Perhaps we need to get a petition going and start spreading it around to get NASA to quit using that guy. His Dyno is GARBAGE.

What are you guys running for a rear gear?

MagnusRacing

iTrader: (2)

A run in 6th gear would certainly produce higher numbers as the faster you turn the dyno the higher it will read...


... however it is HIGHLY unlikely that you will ever be tested in 6th gear. The reason Greg made the rule change it that some clever folks with fancy ECUs were tuning their cars to make less power in only the 1:1 ratio gear.


>


I regards to rear gear ratios I run the 5.12 gears. It would seem to be an advantage to run a higher gear ratio to reduce the speed at which you are turning the dyno drum.

RIWWP

iTrader: (2)

Question: Is there any reason this is acceptable when it's provable that at a given load cell on the fuel map you are using the same amount of fuel regardless of what gear you are in ?
(obviously ignoring the cheaters here)

Same fuel + same AFR + same hardware = same power. I understand a dyno can read different, but it clearly isn't actually making any different power output.

MagnusRacing

iTrader: (2)

Even though I have been disqualified by the MCE dyno I don't really know that it's garbage. It seems fairly consistent for most vehicles. However, I think it does reads a bit higher than most other dynos in general. It does lack a few things it should have - like a weather station.


The unfortunately thing is that wheel dynos are just not that consistent for many technical reasons. Therefore you really need to put in a lot more room for the "dyno variance" than even Greg recommends.


Also, I'm not sure what other options are really out there for a mobile dynojet dyno. There can't be that many.


The whole dyno classed NASA racing class system is of course far from perfect. But how to class cars in a competitive manner is sort of a universal problem that has always plagued racing in general. Given the huge variety of cars that race in PT/TT classes I'm actually surprised that the level of competition is as good as it is and tends to stay fairly close. It's an imperfect system but I'm not sure what the better alternative is.

MagnusRacing

iTrader: (2)

I think the actual horsepower the motor is making is not changing (I could be mistaken, does the load on a motor effect its power output? The nuances of power measurement can get surprisingly complex). It's just that the speed at which the dyno drum is being turned tends to result in different readings at the wheels. I'm not sure why this is as I'm not an expert on wheel dynos... I wish it wasn't the case. Wheel dynos are not precise instruments and as far as I'm concerned only good for comparisons on the same dyno machine under the same conditions.


The testing is normally done in a 1:1 gear and most people never end up racing in their overdrive gear anyway. In theory if you were tested in a low gear it would be to your advantage. I don't think Greg intends to test anyone in overdrive gears. But if he suspects you of making less power via tuning specific to your 1:1 gear he might want to test you in 3rd gear or something to verify you don't go higher.


I don't think Greg has yet exercised the "NASA can test you in any gear" provision yet. He'll probably only use it if you are suspected of cheating and most likely would not test an overdrive gear.

RIWWP

iTrader: (2)

Yeah, I completely understand and get the testing to make sure that there isn't any cheating involved. Hopefully they will recognize that changing the gear used by itself can change the power reading without any actual power difference from the engine.

Thanks

RockLobster

I've been on at least a dozen dynos with my car. Even non dynojets when adjusted to read as if a DynoJet have been vastly more consistent with the DynoJet numbers than that specific Dyno. I've never had the WHP of my car at it's current tune vary by more than 2hp on any dyno regardless of temperature or what dyno i was on. On his dyno my car just kept going up and up...which tells me something is wrong with the equipment.

I think his temp sensor is always a problem and I also think the electronics in that thing are messed up. It needs to go back to DynoJet for an overhaul.

The proof is in the pudding. It's not just one anecdote it's literally hundreds of competitors having the same experience.

I'm certainly not implicating Dyno as a BoP tool in general. Just this specific machine. No, it's not perfect but that setup is a wildcard that literally is pushing people away from NASA.

RockLobster

It may not have any power difference from the engine but it does change the power to the ground. Factors like changes in driveline loss and torque multiplication can and do have real world impacts on how much motive force is transferred to move the car. The rub is that what they are trying to measure is motive power not power produced at the flywheel. This can and does change the readings and is a change in the overall acceleration. Then you throw in the dyno drum speed variance that is inherent to DynoJets and operator and equipment error it's just silly...

RockLobster

They really need to work with one of the data logger companies in earnest to develop the acceleration circle equation to give a maximum HP number based on measured competition weight after each session. They've been dabbling in it for a number of years now and it's rife with it's own set of problems and unknowns but i think overall it could produce more consistent real world results in the BoP effort.

MagnusRacing

iTrader: (2)

Yeah... they've been trying to get a good data logging system that would insure horsepower compliance... but as you said it's still pretty problematic. The technology keeps improving and I hope there will be something good available soon.

In the meantime I think I'll move away from a dyno reclass and just go back to base classing.

MagnusRacing

iTrader: (2)

Attached are my MCE dyno results and the results from a local dyno shop the next week. MCE reads about 4hp higher and lots more torque. Anyone else have dyno graphs to compare with MCE?

TeamRX8

iTrader: (25)

looks like a full flow exhaust collector would help up high

RockLobster

I also think his dyno's error increases inversely to the RPM. I saw the same +4HP vs local dyno at peak power (7k). But the miatas and other cars which make peak power between 5 and 6k rpm saw much higher increases. Where we are seeing like 2-3% higher at 7-8k rpm they are seeing upwards of 7-8% higher numbers. This would make sense with your observation of the considerably higher peak torque.

etzilon

I finally decided to go back to stock sway bars. I'm surprised how much I had to bump up spring rate, specially in the rear of the car... after a few frustrating track weekends, I think I'm back on a car that's a delight to drive.

kbrewmr2

told you so

and another preemptive I told you so on going to purple crack

One of these days you guys will listen.

etzilon

Yes, honey...

MagnusRacing

iTrader: (2)

Off to the NASA West Coast Nationals and Mazda Raceway Laguna Seca later this week. Should be a mostly RX-8 and Miata field in my class. Some super competitive Miatas at nationals lately and again this year. It'll be really hard to win but a podium finish may be possible. Everything seems well sorted out with the car. Just gotta hope that darn MCE dyno doesn't disqualify me.

etzilon

Good luck out there!

speed7

Awww.. wish I was back in town.. would have gone with you to help out. Love Seca.. can't wait to race it finally. I have all of these tires I need to use up. =)

etzilon

MagnusRacing: 1:49.283... Keep pushing!

MagnusRacing

iTrader: (2)

Yeah, that first qualifying time was pretty sad. I did much better in the qualifying races and managed to be gridded 3rd for Sundays championship race. I got into the 1:45s but the fast Miatas were a couple seconds faster. I knew I would have my work cut out for me to retain 3rd as several Miatas were much faster but had issues in qualifying. I ended up finishing 4th but could have been 3rd if not for an error on my part (I failed to realize the third place finishing Miata was in my same class and did not defend against his pass). The race was a mess mostly due to a selfishly aggressive charge from the rear of the grid by last years champ Erik Powell from Florida in a unbelievably fast Miata. He needlessly hit many slower cars including me. After crashing several people out he managed to take himself out just after the corkscrew. His carnage caused our race to finish early. Overall it was a good weekend as my car ran flawlessly and I suppose I was the fastest non Miata!

etzilon

I noticed Eric ran a 1:40 on TTD. I know he's a great driver but that's an incredible gap among good drivers.