Errrm Defector - what happened to the TOPIC mentioned in the thread title?

 

Those air fuel ratios look very aggressive, with your higher octane fuel I guess that is not a problem? Do you know how much boost your running?
How many miles on the car and do you road race it much? I am just trying to determine how tuff this little engine actually is.
Who actually sells this XT 330 package? Is it authorised/warranted from Mitsu or an after market upgrade?

Oh, I have added an under drive pulley (5-10WHP/TQ), removed a bunch of tools and equipment from my trunk (150-200LBS) that I forgot to take out in my first test. It was also a much cooler night 65-70 degrees F. My 40-100MPH times are now showing around 8.6 sec, testing as you described accelerating through 40MPH, 2nd, 3rd, 4th gear.

Thanks for the info

 

Thanks for posting up the dyno results. Nice to see a Dyno Dynamics dyno graph Quick question: Within what range of wheel hp do stock EVO 7s put down over there in the UK?

No question that your EVOs are stroner. The one EVO 7 grey market import we tested made substantially more power than any of the EVO 8s we tested-- even on 91 octane.

To make 250 wheel hp (on 91 octane on a DD dyno, that is) we need to add a 3" turbo-back exhaust, adjust cam timing a few degrees and remap fuel, spark and boost curves. Not exactly a simple upgrade.

What kind of engine control changes are included with the 330HP kit? Or are they relying on the HKS intake to induce MAF signal tweaking? If they are, that could be the cause of the dip at 5500rpm. On our cars, we have to specifically try to tune out that dip through fuel/spark adjustments.

Cheers,
shiv

 

You not wrong Sean, I should have shifted to a new thread. It's easily done isn't it? Not sure how to shift it now, though.....ooops this has posted under my sons name as he was still logged on on my system...my bad

 

temp was 80, i have new FMIC,AFCII, Boost Controller, Cat back, K$N filter, Exedy Clutch and B&M Short Shift Kit, Started In second and made too runs after shooting water on the FMIC. posted 9 flat, I am getting 272 cams next week.. ill tell you the difference! ohh yea this is with 200lb of audio equipment, so the numbers are going to be inconsistant with others

 

The octane in the UK for Optimax is 98.6 RON, but I understand its rating drops while sitting in the tank, so say 98. That equates to your 93/94 I believe. (I think I got that wrong in another thread).

Boost is running at 1.45 bar (21.3lbs/in2), 2,500 miles only, not driven that hard and then only for short bursts (no trackdays yet).

The XT330 is what the previously named Ralliart produce. They now go under the name Xtreme after a split with Mitsubishi. Mods include 3" Hayward & Scott TB exhaust, which is straight thru' catless, single back muffler, no resonators; HKS induction kit and they have tweeked the boost to around 1.4 bar nominal. Warranted by Xtreme for 1 year who imported the RSII and sold it to me new with the mods.

 

Chris Davies of G-Force answered this very question. He said very specifically that a stock EVO VII in the UK puts down 220-222 whp.

It is advertised as 320bhp/330 ft. lb torque, although mine makes 330bhp, probably due to the slightly higher boost setting.
No one wants to say exactly what they do, they just smile, but for sure there is no brass restrictor pill in the forward pipe to the boost solenoid now. They say they only make mechanical changes, not ECU changes.

Interestingly the plugs to the ECU look identical to those shown on your website, despite it having been reported on another thread that the US EVO had totally different connectors.

I am interested that you suggest that the intake mod may give rise to the 5500 dip, but how would that work?

When we asked Chris for an explanation of the 5500 rpm dip, he suggested that it may be the lean mixture before 5500rpm causing knock anticipation and the timing to be pulled.

I was very impressed by the demo Chris gave us (3 hours) of the effectiveness and accuracy of the Dyno Dynamics 4WD rolling road. I notice that the load cell pressure transducers reset to zero automatically when the road is powered up each day. They needed only a feather touch on them to register on the display. So it seems this answers someone elses query on how calibration takes place.

Another point of considerable interest was how the road will refuse to do a power run in shoot out mode when it detects that the front/aft power split exceeds a 30/70 split.

 

Do you recall what gear the run was conducted in?

I believe they share the same connectors based upon information I've received from Autronic regarding their plug-in ECU board.

The 5500rpm dip, from what i've seen with USDM cars at least, is caused by knock sensor activity/learning. If one were to monitor ignition advance through a OBD-II scanner, he'll likely see timing values go 4,4,5,5,6,7,5,5,6,7,8,9,12,15, etc,. The dip coincides with the dip in ignition timing. To eliminate that dip, I actually have to modify the timing curve in that area in order to keep it knock resistant. Or run race gas, of course. Then things start to fill out awfully nicely.

The intake doesn't directly cause this dip since I've seen stock cars behaving similarly. But if one were to apply a straight MAF trim (as one often does passively with the use of aftermarket intakes) to enlean the a/f mixtures, the 5500rpm dip can get more pronounced.

You're preachin' to the choir I'm sure some people are still dismayed by the lowish numbers they generate

Regards,
shiv

PS. We went to a dyno day at local AWD Dynojet dyno yesterday and our two WRX entries put down 300 and 320 wheel hp respectively. The locals were impressed. The same very people are indifferent when those same very cars put down 255 and 275 whp on our DD dyno

 

Yes, 3rd for my 5sp. box. He said he usually uses 4th for a 6 sp.

Quote:

I believe they share the same connectors based upon information I've received from Autronic regarding their plug-in ECU board.

Does that imply a European ECU could be used in a US EVO? I've heard (may be wrong) that the MAFs are different amongst other things, though.

Quote:

The 5500rpm dip, from what i've seen with USDM cars at least, is caused by knock sensor activity/learning. If one were to monitor ignition advance through a OBD-II scanner, he'll likely see timing values go 4,4,5,5,6,7,5,5,6,7,8,9,12,15, etc,. The dip coincides with the dip in ignition timing. To eliminate that dip, I actually have to modify the timing curve in that area in order to keep it knock resistant. Or run race gas, of course. Then things start to fill out awfully nicely.

That figures. So would the addition of Octane booster cause an improvement in this area without an ECU reset or any other changes?

Quote:

The intake doesn't directly cause this dip since I've seen stock cars behaving similarly. But if one were to apply a straight MAF trim (as one often does passively with the use of aftermarket intakes) to enlean the a/f mixtures, the 5500rpm dip can get more pronounced.

Are you saying that the increase in airflow caused by the inlet mod. takes the MAF signal output right up to its 5v(?) output limit and clipping, making the ECU think there is less air than there actually is, so taking it nearer to the det. point?

Quote:

You're preachin' to the choir I'm sure some people are still dismayed by the lowish numbers they generate

Regards,
shiv

PS. We went to a dyno day at local AWD Dynojet dyno yesterday and our two WRX entries put down 300 and 320 wheel hp respectively. The locals were impressed. The same very people are indifferent when those same very cars put down 255 and 275 whp on our DD dyno

That attitude's turned right round over here. Chris said he has found that people now challenge the high figures produced elsewhere with "yeah, but what will it make on G-Force's dyno?". That's because the very high repeatability he gets is recognised.

He specializes in top end race work and avoids boy racer jobs for this reason, because the professionals need real figures not just high sounding ones.

He said he picks up for them some real final horse power just 2 bhp at a time here and there, but it all mounts up. For that he needs to be able to reliably SEE changes as low as 2 bhp.

 

Good to hear. Same thing here. We used to dyno the 5sp EVOs in 4 gear at first. But 3rd keeps wheel speed (and thus, frictional losses) down and raises output by approx 10whp. People are more willing to believe that their EVO puts down 200whp instead of 190whp

I don't know. I wouldn't be surprised if they changed a few sensors and/or shuffled a few pins around. But the ECU connectors are the same from what I've seen and been told. If you have a pin out diagram you could send me, I could verify it.

It should. Might take a few runs but i've seen extra octane fill in those dips nicely time after time. Might want to try real race gas though since most of the octane boosters i've tried here in the States aren't what they are cracked up to be.

Not quite. Instead, what I've seen at times is the change in air filter shape/material/etc,. affects the flow patterns (not necessarily the volume) of the air, causing some of the air to go unmetered by the MAF wire is which located in the center of its inlet housing. I think this is much more of an issue in WRX applications which actually involve removing the MAFs hotwire assembly and reinstalling in the aftermarket inlet tube. Often, this tube is of different diamater or bent in a certain way which causes odd airflow characteristics which cause absolutely massive changes to MAF readings and therefore fueling. I haven't done enough controlled testing of different intakes in the EVO to say whether this is a big issue or not.

Cheers,
shiv

 

Sorry for the long off topic ramble but this is a subject near and dear to me, and I still have a lot of unanswered questions.

Did this actually occur with your car? What sort of torque splits did you see?

Yes, but this is only one factor regarding the accuracy of this type of dyno. I mean any good electronic bathroom scale will do the exact same thing. I am more interested in the "retarder" load simulator accuracy, how do you know if that is accurate at various RPM's and load levels?

Simulated load dynos have many advantages for tuning. For measuring maximum acceleration power they attempt to simulate a constant rotational load. Why use a simulation when you can use an actual constant unchanging load? Under ideal conditions a simulation can come close, but how can you possibly beat the real thing?

I have raised some very legitimate questions regarding the results from these dynos and as of yet have not gotten a single answer that addresses my specific questions. Unfortunately my questions have been construed as purely personal attacks, so most of the answers were more emotional than logical.
I really would like to know if this type of dyno is in fact more accurate for max acceleration (power to the road) measurements. Based on what I have learned so far I cannot understand why it would be.

For example: if you accelerate (on the road) in third gear from say 2000 RPM. At what RPM point do you feel the torque peak? On my EVO and all other stock/near stock cars, the torque peaks at around 3500 RPM in third gear. True inertia load dynos show the torque peaking around 3500 RPM, confirming our seat of the pants measurements. Yet all of the DD third and fourth gear pulls I have seen (like yours) show the torque peak at over 4000RPM. Is this a true representation of acceleration power on the road?



While there are some interested in just seeing big numbers, I believe that most simply want to know what is truly accurate and reliable.
I actually believe that most people in this world are very pessimistic. This makes it much easier to believe that the lower numbers are more accurate, even though there is no actual test data or theoretical logic to indicate this is true.

Besides the inconsistent data, when comparing these dyno results to real world performance I have a hard time with the idea that almost 90 HP is eaten up in the drive train. It just does not seem rational based on my observations.
I have been trying to better understand drive train losses so that this would make more sense. Unfortunately I have not been able to find a lot of test data or theoretical maps directly relating to automobile drive train losses.
From what I can tell so far drive train losses are caused by two main factors, rotational inertia and friction. Based on my extremely ruff calculations I believe that the actual majority of drive train losses (especially accelerating in the lower gears) may be due to rotational inertia of the drive train components. Especially the wheel/tire/rotor/hub assembly, with an average (estimated) weight of 75-100lbs and a diameter of 25.4" accelerating (3rd gear) from 300 to 1100 RPM's (tire speed), you could loose 2-5HP (depending on the rate of acceleration) per wheel right there. This is mostly why big/heavy wheel and tire packages can have such a noticeable affect on acceleration for low HP vehicles. Due to the smaller diameters and weights, the rest of the drive train components barely add up to the inertial losses of one wheel/tire assembly.
I am not a physicist or even a mechanical engineer so these estimations could be way off, feel free to correct me. Based on my half baked calculations total drive train inertia losses are some where between 10 to 30 HP for most cars. Some really fast cars with very heavy components could be even higher. For an average EVO I figure around 15-20HP, the rest of the losses would then be friction.
The inertia dyno's typically used in the US show the EVO drive train losses to be around 40-45HP in 3rd gear. That would mean 20-30HP or 15-20KW is used up as friction heat. This already seems like an awful lot to me, but spread out through all of the gears, bearings, and tires, etc, it seems almost possible. If the DD load dyno were to be believed we would have to more than double these heat values. This just seems like an unbelievable amount of heat that is being dissipated through a drive train that has no active cooling system.

I would love if someone could explain why my conclusions are incorrect and explain the discrepancies in the data provided by this dyno.

One test that would be interesting: compare acceleration HP at various RPM with constant load measurements in the same gear. The constant load values should be higher and the difference should indicate rotational inertia losses (mostly).

I really just want to know which system is correct, unlike the people who own/operate and sell these systems, I have nothing to gain or loose either way.


Kind regards,

Eric

 

Back to dyno losses again. SCC tech editor Dave Coleman came to our shop a few weeks ago to do some AWD/2WD testing. He is in the process of doing a dyno comparison test along the same vien as the one conducted by Turbo magazine a few months back. This test, however, will be a bit more comprehensive.

The test car he chose was some nondescript truck. I think it was a Ford. IIRC, it was rated at 160hp. Big V6 motor that revved to only 6k rpm. Needless to say, it is very repeatable and didn't have any intercoolers to heatsoak or turbo boost to monitor. This truck was also chosen because it had a 5 speed manual transmission with the ability to run in both 2WD and 4WD modes.

Running in 4WD mode, the car put approx 100 hp to the wheels (on our DD dyno, of course). 60hp loss running all four wheels. Running in 2WD mode, it put down roughly 130 wheel hp. This means that the spinning the extra set of wheels as well as the necessary extra driveline components accounted for ~30whp of loss. Seems to add up and support the notion that drivelines a lot less efficient that most people think.

The next test was engaging the 4WD Low mode. This 4WD mode is like the first one but with extra low gearing. Instead of running up to ~100mph, it would only run up to ~50mph. The ramp-up rate was adjusted so that the run duration remained constant. Running in this mode, the truck put down ~130 wheel hp, or approx 30whp more that it made in 4WD High mode. These results suggests that reducing wheelspeed by ~50mph reduced enough friction losses (between the rollers and tires) to gain a healthy ~30whp. Goes to show what a big component wheel speed is when it comes to driveline/tire losses.

Dave conducted the same testing on a number of other AWD dynos (Dynojet, DTS, etc,.) and the results will be in an upcoming issue of SCC. Should be pretty interesting.

Cheers,
shiv

 

This is true for me too.

Quote:

Did this actually occur with your car? What sort of torque splits did you see?

First of all I am not an expert, so what I will write here may not be correct, but may help.

As I understand it, the DD road has an inbuilt safety mechanism which can detect torque splits outside those specified for the vehicle being tested. If it detects this problem it will report it and not do the run in order to protect the centre diff. Chris at G-Force said this had happened only once when the owner didn't tell him beforehand that he had an extremely expensive trick diff. on the rear. As mine is standard the test ran as normal. We didn't record the split in these runs.

Quote:

Yes, but this is only one factor regarding the accuracy of this type of dyno. I mean any good electronic bathroom scale will do the exact same thing. I am more interested in the "retarder" load simulator accuracy, how do you know if that is accurate at various RPM's and load levels?

Simulated load dynos have many advantages for tuning. For measuring maximum acceleration power they attempt to simulate a constant rotational load. Why use a simulation when you can use an actual constant unchanging load? Under ideal conditions a simulation can come close, but how can you possibly beat the real thing?

I have raised some very legitimate questions regarding the results from these dynos and as of yet have not gotten a single answer that addresses my specific questions. Unfortunately my questions have been construed as purely personal attacks, so most of the answers were more emotional than logical.
I really would like to know if this type of dyno is in fact more accurate for max acceleration (power to the road) measurements. Based on what I have learned so far I cannot understand why it would be.

The phrase 'retarder load accuracy' you use doesn't really have a meaning here. This is the way I understand dyno operation.

There are two main things needed in a dyno.

1 A load against which the power source (car + engine) can do work over a period of time and which can dissipate that power.

2 An accurate means of measuring a parameter from which torque, power and other required parameters can be calculated.

In the inertia dynamometer both are cleverly achieved in just one element, a heavy rotating drum. This will absorb energy from the vehicle in the form of rotational inertia as it speeds up. At the same time, because its weight and diameter are accurately known, as well as its rotational speed as it accelerates and the time taken, the internal computer can determine what torque would have been necessary at each point in time to achieve that. From that, power and other parameters can be accurately calculated. Only after the run is the power actually dissipated into a cooled brake.

In a load dyno these two requirements are kept completely separate, to give greater flexibility. Light weight rollers transmit the vehicle power to what is effectively an electric generator with its output shorted out in discs (1) which are either air cooled or water cooled. This provides the load. As above, the progressive speed of rotation is measured accurately. This/these are NOT the measuring device. They are there to provide a controllable, very steady load. That is their sole job. They dissipate the power as they receive it. Hence it can be held in a steady state.

The measurement device (2) is placed between the frame of the retarder/s and the dyno deck. This device is a very accurate pressure transducer/load cell (good bathroom scales can record 1 lb. changes, whereas on this dyno, the device is many hundreds of times better than that). Because the radius at which this transducer is placed is very accurately known the torque may once again be calculated, and hence the other parameters.

Quote:

For example: if you accelerate (on the road) in third gear from say 2000 RPM. At what RPM point do you feel the torque peak? On my EVO and all other stock/near stock cars, the torque peaks at around 3500 RPM in third gear. True inertia load dynos show the torque peaking around 3500 RPM, confirming our seat of the pants measurements. Yet all of the DD third and fourth gear pulls I have seen (like yours) show the torque peak at over 4000RPM. Is this a true representation of acceleration power on the road?

The trouble with the 'seat of the pants' is that it isn't the cleverest part of the body to use. What you are experiencing is surely not torque but a FORCE on your back and 'seat of the pants'. This force you are experiencing is proportional to the mass of your body x the acceleration of the car at that speed (from Force = Mass x Acceleration). Also Power = Force x velocity, so a plot of this force would be in proportion to the power divided by the velocity. So if you take the power curve and divide the power at each point by the rpm you will get a curve very similar to tractive effort. Therefore what you are feeling in the seat of your pants is really tractive effort, not torque or power. If you look at the tractive effort curve for my car you will see that tractive effort peak is 500 to 1000 rpm lower than the torque peak. Which explains why the seat of your pants is lower than the torque curve. Hmmm

If you want to understand why this is from a 'feel' point of view, then it is because the Kinetic energy being stored is proportional to the SQUARE of the velocity (0.5 mv^2). That is, more power is required to raise the speed from 60-70mph in a given time than to raise it from 50-60mph in the same time.

Perhaps I'll stop there before I go into a spin.

Quote:

While there are some interested in just seeing big numbers, I believe that most simply want to know what is truly accurate and reliable.
I actually believe that most people in this world are very pessimistic. This makes it much easier to believe that the lower numbers are more accurate, even though there is no actual test data or theoretical logic to indicate this is true.

Besides the inconsistent data, when comparing these dyno results to real world performance I have a hard time with the idea that almost 90 HP is eaten up in the drive train. It just does not seem rational based on my observations.
I have been trying to better understand drive train losses so that this would make more sense. Unfortunately I have not been able to find a lot of test data or theoretical maps directly relating to automobile drive train losses.
From what I can tell so far drive train losses are caused by two main factors, rotational inertia and friction. Based on my extremely ruff calculations I believe that the actual majority of drive train losses (especially accelerating in the lower gears) may be due to rotational inertia of the drive train components. Especially the wheel/tire/rotor/hub assembly, with an average (estimated) weight of 75-100lbs and a diameter of 25.4" accelerating (3rd gear) from 300 to 1100 RPM's (tire speed), you could loose 2-5HP (depending on the rate of acceleration) per wheel right there. This is mostly why big/heavy wheel and tire packages can have such a noticeable affect on acceleration for low HP vehicles. Due to the smaller diameters and weights, the rest of the drive train components barely add up to the inertial losses of one wheel/tire assembly.
I am not a physicist or even a mechanical engineer so these estimations could be way off, feel free to correct me. Based on my half baked calculations total drive train inertia losses are some where between 10 to 30 HP for most cars. Some really fast cars with very heavy components could be even higher. For an average EVO I figure around 15-20HP, the rest of the losses would then be friction.
The inertia dyno's typically used in the US show the EVO drive train losses to be around 40-45HP in 3rd gear. That would mean 20-30HP or 15-20KW is used up as friction heat. This already seems like an awful lot to me, but spread out through all of the gears, bearings, and tires, etc, it seems almost possible. If the DD load dyno were to be believed we would have to more than double these heat values. This just seems like an unbelievable amount of heat that is being dissipated through a drive train that has no active cooling system.

I would love if someone could explain why my conclusions are incorrect and explain the discrepancies in the data provided by this dyno.

One test that would be interesting: compare acceleration HP at various RPM with constant load measurements in the same gear. The constant load values should be higher and the difference should indicate rotational inertia losses (mostly).

I really just want to know which system is correct, unlike the people who own/operate and sell these systems, I have nothing to gain or loose either way.


Kind regards,

Eric

Here you are combining inertial stored energy and frictional losses and referring to them jointly as drive train losses. Here, part of the power of the engine has gone into producing inertial energy stored in the rotating components of the drivetrain rather than into the body weight of the car, so I don't see you can call this element a loss unless you also call the energy stored in the body mass a loss. We all know that a lighter car will accelerate faster with the same powered engine. So the drive train loss to me is really only the frictional element.

That is another advantage of the Dyno Dynamics dyno. It can be run at constant speed to measure the power at a point, or at a very low ramp rate and effectively eliminate the inertial energy gains in the transmission. (Erm, I think)

I think someone from DD themselves may comment in this thread quite soon. Maybe they'll tear what I have said to shreds, but like you I'd like to learn more.

Cheers, Defector

 

Great explanation. Here's a little drawing i scribbled illustrating the relationship between the retarder units and the load cell.

As Defector said, the retarders are only used to add a load to the rollers. By load, I mean either a controlled load for steady state roller RPM or, if desired, a controlled load for a user-adjustable ramp-up rate. The actual measuring of wheel torque is done by the self-calibrating (and incredibly sensitive) load cell. In CA, we can even pick up regular daily earth tremors from the raw load cell readings

The roller spins the big round rotors. Big eddy current retarders apply braking forces to both sides of the rotors. From the big eddy current retarder housings sprouts an rigid arm. The end of this arm applies force upon a load cell when the retarders go about their work. With the pressure, and the length of the arm known, wheel torque (tractive effort) is calculated quite easily. With tractive effort and RPM, torque and hp can be calculated.

Cheers,
shiv

 

Quick question about the Dyno Dynamics runs above. All the printouts say: "Results plotted using Shootout Mode". What does this mean exactly?