[Sutripta]

Originally Posted by Jaggu

Isn't this what they try to rule out with the initial set up run? i saw that rpm of both the wheels were almost same when that reading was taken. They do this couple of time and was done for all cars and the machine calibrates itself and check all parameters like drive ratio etc, after this the actual runs start.

I would expect no less from Dynapack. Question is how. I don't think initial setup has anything much to do with it. Initial setup would be for finding the correlation factor between engine and hub rpm, and a validation that all systems are go. (I could be totally wrong.) BTW, what is the calibration cycle of a Dynapack? Is there a system of calibrating a pair simultaneously?

Dynapack built its reputation on its hydraulic pump system, the heart of its dynamometer. But there were rumours that they had shifted to an electrical brake (or maybe added one in addition). Does anyone know if its true or false? And if true, the details.

Regards
Sutripta

[Mpower]

Yes its a hydraulic system AFAIK and the key to have equal load on both sides.

Originally Posted by Sutripta

I would expect no less from Dynapack. Question is how.

Same way they make sure all 4 cylinders of an engine and putting out the same amount of power. Sound design, Hi-precision machining, fabrication & assembly.

[im_srini]

Originally Posted by Mpower

Same way they make sure all 4 cylinders of an engine and putting out the same amount of power. Sound design, Hi-precision machining, fabrication & assembly.

Hi, true, but in an engine, even if there's a discrepancy between the cylinders, all the pistons are connected to the same crankshaft - so the crank would "even out" the discrepancies. Here, the hubs on both sides aren't connected, except by the car's drivetrain itself.

I guess what Sutripta's asking is if the DynaPak compensates for differential action, & if it does, how ? As an example, say one of the car's brake is dragging heavily, on a regular roller-dyno it isn't much of a problem since the roller is common between both wheels & will eliminate any differential action. In the DynaPak however, differential action would come into play, no ?

[Sutripta]

^^^
Hi,
Right. You are better with words than I am.

Originally Posted by im_srini

As an example, say one of the car's brake is dragging heavily, on a regular roller-dyno it isn't much of a problem since the roller is common between both wheels & will eliminate any differential action. In the DynaPak however, differential action would come into play, no ?

Thanks for extending the thought. It would be interesting to see how the Dynapacks would behave if one purposely introduced drag on one side.

Regards
Sutripta

[Jaggu]

I dont know how it does the calibration but if you look at the video, you will see what it does.

YouTube - Dynapack

[Mpower]

Originally Posted by im_srini

Hi, true, but in an engine, even if there's a discrepancy between the cylinders, all the pistons are connected to the same crankshaft -

Thats not the point I was trying to make. I'm saying that its possible to ensure that the loading is equal.

Originally Posted by im_srini

H
I guess what Sutripta's asking is if the DynaPak compensates for differential action, & if it does, how ? As an example, say one of the car's brake is dragging heavily, on a regular roller-dyno it isn't much of a problem since the roller is common between both wheels & will eliminate any differential action. In the DynaPak however, differential action would come into play, no ?

I guess you would end up with a speed difference. But I dont see why it should hurt in any way. The operator should hopefully figure out that something is wrong.

You'll end up with lower power on one half of the dyno and overall you will see power loss. OR the dynapack might try to reduce loading on one side to keep rpms constant (reduced load => reduced power since power is torque x rpm). So the end result is the same. Depends on what mode they want to run it in.

Of course, I have not operated this dyno, so I cannot say for sure, but all I'm saying is that the logic is sound.

[Vid6639]

Originally Posted by Jaggu

I dont know how it does the calibration but if you look at the video, you will see what it does.

YouTube - Dynapack

The dynapack calibration at 2000rpm is done by holding the hub at 2000rpm for both left and right wheels. The dyno has a braking system that holds the hub rpm to calibrate both left and right at the same speed. After that the dyno run is performed.

[Sutripta]

Originally Posted by Mpower

....
Same way they make sure all 4 cylinders of an engine and putting out the same amount of power. Sound design, Hi-precision machining, fabrication & assembly.

I would rather say like making two engines which have absolutely identical characteristics. Difficult.

Originally Posted by Mpower

.....
I guess you would end up with a speed difference. But I dont see why it should hurt in any way. The operator should hopefully figure out that something is wrong.

You'll end up with lower power on one half of the dyno and overall you will see power loss. OR the dynapack might try to reduce loading on one side to keep rpms constant (reduced load => reduced power since power is torque x rpm). So the end result is the same. Depends on what mode they want to run it in.
.....

As I said before

Originally Posted by Sutripta

......
Total power output is the sum of the outputs of the two dynos, so hub speed should not matter. But the differential will come into play, and will absorb some power. Also, a machine constantly trying to correct its braking torque will not be stable. Neither will make for consistent (let alone accurate) readings.

Different hub speeds, or same hub speeds with different loadings are ok for spot readings, or live tuning. Will be (I think) problematic for a sweep.

Originally Posted by vid6639

The dyno has a braking system that holds the hub rpm to calibrate both left and right at the same speed. After that the dyno run is performed.

This dyno is a brake.

Regards
Sutripta

[Mpower]

Originally Posted by Sutripta

I would rather say like making two engines which have absolutely identical characteristics. Difficult.

Honda and Toyota are already doing a good job with it in mass production. These are instrumentation grade components (10x the price) and tight tolerances are the norm here.

But is not relevant anymore since Vid clarified that load can be varied (and thus the speed). I'm guessing its a hydraulic pump with a variable orfice for load control.

[Vid6639]

Originally Posted by Mpower

But is not relevant anymore since Vid clarified that load can be varied (and thus the speed). I'm guessing its a hydraulic pump with a variable orfice for load control.

I don't think it was hydraulic. I believe it is an electric brake unit. The entire unit is water cooled. Notice the large water pipes going in and out of the dyno.

[mayankjha1806]

Originally Posted by crazydiablo

Yeah I am selling if I get a good offer. Otherwise it stays.

This is way old post, so i am not sure what happened after that, Did you manage to sell the car. Now i am planning to do something similar to my Baleno wanted to know where did you get everything done, and if possible their phone number so as i can reach out to them. I see that Koni have stopped Baleno suspension manufacturing, which one would you recommend to be put on Baleno. Cheers.

[crazydiablo]

I have been off the forums for a long time. Car is sold to a good friend in Mangalore, still running the same setup and closing in on 58000kms now.

I have experience only with Konis, i believe the fronts are still available and you can retrofit them at the rear as well.

[theMAG]

So, the car went back to its place of genesis, eh?! What made you sell the car, if I may ask?

[james]

Picking up where Crazy left off-

I Picked up the car as CD was moving abroad. It was a spontaneous decision to buy it!

On Dec 26, 2010, i sent CD a sms at night saying ill be hitting blore to check out the car the next morning. He met me at the bus stop with this gleaming black car and we went for a spin! I was amazed at the crisp acceleration. At that point of time i was using a SX4 vvt and a Mivec lancer in its NA form bac home. I was clear in my mind that if the car performed better than the sx4 and the 0-60 felt similar to the mivec, i would pick it up for the asking price.
As luck would have it, the car impressed me and i had to buy it(bye bye to all my savings + hello to a personal loan). By 9am i was the proud owner of the car!
After a sumptuous breakfast prepared by CD's wife, idrove straight to Belgaum for a function and all i can say is i loved every minute of the drive! The car was so composed and had a good torque curve. I reached Belgaum in record time with a big smile on my face! Mileage returned was 12.8kpl with constant redlining.

Like every blore car, this one had its share of dents and dings. Took it in for repairs and ended up changing all the wheel bearings as well. CD, a true gentleman that he is immediately reimbursed the money i spent on the repair as promised earlier.

Over the last 17 months, the journey has been filled with a lotta ups and downs. I had 2 GB failures, one of which left me stranded in the middle of nowhere at night. The Mandovi mech said the car made a lot of power and thats the reason the bolts holding a flange in place sheared off and got stuck between the 5th gear cogs. I was like.. Lotsa power..my A$$. It was just poor workmanship by the guy who worked on the GB last. The Bolts were fastened too much. I took a day off from work and made sure everything was done by the book. I was happy to see the mech using a torque wrench- No kidding!!
I was given an option of picking up a Cultus GB but finances were a bit of a concern so just rebuilt the extisting one.
P.S Ive never done a hard launch. Just normal driving but with some hard acceleration and redlining in higher gears.

Apart from the GB issue, we had a rat infestation and the fat buggers pulled out some wires from the Wideband. We had to rely on the WWW and some some guesses from Karthik @ race dynamics(over the phone) to get the wiring right. Once fixed, i havent faced a problem with it.

Small yet expensive(!!) stuff like weather strips, some rubber stuff and the batt were also replaced over this period. There was an electrical leak(fixed) and ofcourse a dead tacho(electrical prob again). There are some more things that ill put them up as and when i recall.

If you'll want to know if my happy with this purchase even after the things ive been through, the answer is a definite YES! Shes a dream to drive, quite reliable, a Maruti(!!), Full service history, beautifully maintained interior and exterior and last but not least, a great enthusiastic and trustworthy (previous) owner.

The clock currently relfects 58.2k and mileage in city cycle is around 7 without ac. The reason for the mileage is that the car is used quite rarely as i prefer the bike, i warm up the car for a minute every time i take it out, the AD07's are sapping power as they have worn quite a bit and i have a very heavy right foot!

Ill leave you'll with some pics of the car.

The Gleaming ol' girl




Pic of the GB the first time it broke down


The second time around i was wiser! I made them dismantle the entire GB, check every part for wear right in front of me and replace the parts that were out of spec.



The sheared off bolts that caused all the trouble on both the occasions.


The damaged 5th gr cogs (costed around 3k each)



Some weekend TLC. Swapping the wheels and spraying antirust into the door cavities etc.



Cheers!

[james]

Update- Managed to clock another 1k in the last 6 months and im inching towards the 60k 'big' service. The car is running fab with no problems or surprises. *touchwood*