Dyno Info

MotherNatureVer2 · 01-08-2006, 07:35 PM

OK guys .... the Sprint is no longer a virgin ... a Dyno Virgin that is ;)

Before I announce the details I would love a bit of info on Dynos & the techniques used to do these .........

I have seen a couple done before but that was a few years ago in Victoria ....... Am actually wondering if the Mexicans do it different orrrrrr did the guy I use have NFI !!!!!!!!!!!!!!

Questions I have are:

At what speed does a Dyno operator pull out so to speak ?????

What gear (Auto) is a dyno done in ?????

Is it usual for a car to be tied down ?????

How many cords/ leads go under the bonnet ?????

brenx · 01-08-2006, 07:46 PM

Quote:

Originally Posted by MotherNature

OK guys .... the Sprint is no longer a virgin ... a Dyno Virgin that is ;)

Before I announce the details I would love a bit of info on Dynos & the techniques used to do these .........

I have seen a couple done before but that was a few years ago in Victoria ....... Am actually wondering if the Mexicans do it different orrrrrr did the guy I use have NFI !!!!!!!!!!!!!!

Questions I have are:

At what speed does a Dyno operator pull out so to speak ?????

When the car stops making power. Some that I've seen choose to over rev them which just hurts the engine.

Quote:

What gear (Auto) is a dyno done in ?????

Generally top gear 1:1 ratio.

Quote:

Is it usual for a car to be tied down ?????

No a point of contention is how hard the car should be tied down. It's a variable.

Quote:

How many cords/ leads go under the bonnet ?????

From what I've seen it depends on what exactly you having done. Tune or power run.

You have;

- knock sensor which has head phones attached. So the dyno op can hear everything.
- Tacho sensor attached to no 1 lead
- Air temp sensor
- Vac line

Most dyno ops will have a timing light also attached at varying stages.

XRchic · 01-08-2006, 07:52 PM

Quote:

Originally Posted by MotherNature

OK guys .... the Sprint is no longer a virgin ... a Dyno Virgin that is ;)

Before I announce the details I would love a bit of info on Dynos & the techniques used to do these .........

I have seen a couple done before but that was a few years ago in Victoria ....... Am actually wondering if the Mexicans do it different orrrrrr did the guy I use have NFI !!!!!!!!!!!!!!

Questions I have are:

At what speed does a Dyno operator pull out so to speak ?????

What gear (Auto) is a dyno done in ?????

Is it usual for a car to be tied down ?????

How many cords/ leads go under the bonnet ?????

Hey Lisa! How's things?

Firstly, dont worry too much about what a dyno says. Each dyno is different, and the atmospheric conditions are usually quite influential on the final figures, particularly air temp and humidity. This can also be influenced by the size of the fan in the dyno, if any. Cool and dry temps are best. Means denser air.

If you get a lower figure, it doesnt mean much as many cars with lower dyno figures are actually faster than ones with higher rwkw - mine is a classic example of one with a reasonable dyno result but relatively poor track times compared to other cars with lower dyno figures.

So that means that you car MAY pull a lower power figure on the dyno but flog a lot of more powerful cars anyway. Being auto can give a lower dyno reading too.

Question 1: Dyno operators usually stop when peak power has been reached and the graph begins to decline again (from what I have seen) - there is no point in continuing to a certain speed if the peak power has been reached and the graph is heading back down. However, I THINK most DDD have a speed limit of 200kmh, apparently for safety reasons etc.

Question 2: Dynos are usually done in higher gears to give a more accurate reading at the wheels. In manuals, 4th is ideal as it is 1:1 but often the speed limit is reached before maximum power, so often its done in 3rd. Sometimes they are done in 2nd but that usually gives a higher and less accurate power figure. Im sure someone else on here will be able to give you a much more accurate and technical explanation - perhaps see the sponsor sections say, Autotech, G&D, Bluepower etc - those guys do this stuff all the time.

Question 3: Cars are not often tied down, but very powerful ones are, from what I have seen, to ensure cars do not fly off the rollers. Im not sure if it is an advantage or not with a reasonably powered car.

Question 4: No clue, sorry. I have mainly just seen leads which run to laptops and devices in the exhaust, I guess to measure air and fuel.

A low dyno figure may just indicate that your car is in need of a good custom tune. Did the graph give you air/fuel ratios? If you have a low air/fuel ratio, it is an indicator it is running too rich and needs a tune - which means there is more potential in it - which is good!

Hope this helps a bit.

Jac

TURBOTAXI · 01-08-2006, 07:55 PM

C'mon Lisa...... I logged on just to see what you got..... dont keep me waiting.

Casper · 01-08-2006, 07:59 PM

ok Lisa, here it is in simple terms.
1. Dyno should be run to redline unless the engine is still making power.. in which case they will take it as far as is safe

2. All BTR auto's (like yours) SHOULD be run in 3rd gear. As yours is a Sprint there is no reason to run it in any other gear as the 200kph issue wont apply and neither will the speed limiter.

3. If the car isnt tied down the reading is high.. period. If the car is tied to ONLY the the front roller the reading is still hight.. period.
In general, the car must be tied down (hard) or it will crawl up the front roller, lose resistance and make a false reading.

4. This is open to debate however at least one should go into the intake to measure temps (and not into or on the radiator as this will "trick" the dyno to think ambient temps are high and to over compensate power loss based on temps... and give a false reading)

MotherNatureVer2 · 01-08-2006, 08:16 PM

OK ....... I needed to know the first one mainly ..........

There is NO way in hell she was red lining ...... she was in 3rd and sounded sweet as ..... wanting more ........ I know that sounds silly but I do know what my car sounds like when shes working & she wasnt ...... Even my wonderful OH thought it was a bit off that she wasnt taken 'all the way' & that was before we saw the reading ......

She wasnt tied down at all ......... He took her to 160 & stopped ...... kept on saying for these things that was a normal reading ....... then we started talking & Im sure he was thinking a normal XR8 ....... He looked funny as we spoke of what she was & what she had as opposed to the standard .......

Must need a few more things done to her as she only pulled a 150hp ........

Casper · 01-08-2006, 08:20 PM

Quote:

Originally Posted by MotherNature

OK ....... I needed to know the first one mainly ..........

There is NO way in hell she was red lining ...... she was in 3rd and sounded sweet as ..... wanting more ........ I know that sounds silly but I do know what my car sounds like when shes working & she wasnt ...... Even my wonderful OH thought it was a bit off that she wasnt taken 'all the way' & that was before we saw the reading ......

She wasnt tied down at all ......... He took her to 160 & stopped ...... kept on saying for these things that was a normal reading ....... then we started talking & Im sure he was thinking a normal XR8 ....... He looked funny as we spoke of what she was & what she had as opposed to the standard .......

Must need a few more things done to her as she only pulled a 150hp ........

Wasnt tied down.

Take dyno reading
Throw in bin
Ignore.

Take it somewhere else, that reading is totally and utterly pointless. May as well be another cars reading.

MotherNatureVer2 · 01-08-2006, 08:23 PM

Quote:

Originally Posted by Casper

In general, the car must be tied down (hard) or it will crawl up the front roller, lose resistance and make a false reading.

Also .... OH just said .... crawl up ???? ..... LOL She was near climbing off ..... He had great view of the rears where he was standing ;)

Casper · 01-08-2006, 08:25 PM

Quote:

Originally Posted by MotherNature

Also .... OH just said .... crawl up ???? ..... LOL She was near climbing off ..... He had great view of the rears where he was standing ;)

even worse.. see above post.

XRchic · 01-08-2006, 08:26 PM

Quote:

Originally Posted by MotherNature

OK ....... I needed to know the first one mainly ..........

There is NO way in hell she was red lining ...... she was in 3rd and sounded sweet as ..... wanting more ........ I know that sounds silly but I do know what my car sounds like when shes working & she wasnt ...... Even my wonderful OH thought it was a bit off that she wasnt taken 'all the way' & that was before we saw the reading ......

She wasnt tied down at all ......... He took her to 160 & stopped ...... kept on saying for these things that was a normal reading ....... then we started talking & Im sure he was thinking a normal XR8 ....... He looked funny as we spoke of what she was & what she had as opposed to the standard .......

Must need a few more things done to her as she only pulled a 150hp ........

Lisa, it doesnt need to be at redline to be at peak power. Most peak power is reached before redline, I would think. But in fairness, it should be close enough to be making some noise! The graph should tell the story!

I take it that is 150 RW hp? Converted to rwkw, that is about 112rwkw? That seems quite low - would have thought 140rwkw ish? Perhaps it is in need of a good tune! Perhaps the dyno could be done elsewhere to see if its consistent...

Did you get an air fuel ratio reading or a tractive effort reading? Can you post the graph?

MotherNatureVer2 · 01-08-2006, 08:27 PM

Will be doing that for sure Capser.....

Knew it wasnt right ..... just needed to know that this thing wasnt done as I thought it should be ......

I didnt want anyone to think I was just whinging cause I didnt get what I expected.

MotherNatureVer2 · 01-08-2006, 08:29 PM

There was no air/fuel done ... hence the question on how many leads are normally used ..... there was one in the air intake & that was it ......

I havent got a scanner here but can post tomorrow at work ..... not that theres much to see on this one ........ it is a very bare reading to say the least.

XRchic · 01-08-2006, 08:31 PM

Quote:

Originally Posted by MotherNature

Will be doing that for sure Capser.....

Knew it wasnt right ..... just needed to know that this thing wasnt done as I thought it should be ......

I didnt want anyone to think I was just whinging cause I didnt get what I expected.

Wouldnt the car not being tied down give a higher result rather than a lower one??? Im not sure, just asking.

TURBOTAXI · 01-08-2006, 08:34 PM

Lisa, I wouldnt worry about what the Dyno has said - it seems there are lots of reasons the Dyno could be off.

As long as you are happy with the performance of the car (and we all know it looks great) I would ignore the Dyno figure and try something else (another Dyno, a G-Tech etc.... )

The actual horsepower figure is probably not as important as the torque and the power delivey.

Casper · 01-08-2006, 08:34 PM

Quote:

Originally Posted by XRchic

Wouldnt the car not being tied down give a higher result rather than a lower one??? Im not sure, just asking.

nope, by tieing it down the rear wheels are forced onto the rollers and are effected by them. By not tying it down the rears ride up the front roller and therefore are only affected by 1 roller. Effectivly resistance is reduced and the car "appears" to have a higher rwkw reading accordingly.

XRchic · 01-08-2006, 08:35 PM

Quote:

Originally Posted by MotherNature

There was no air/fuel done ... hence the question on how many leads are normally used ..... there was one in the air intake & that was it ......

I havent got a scanner here but can post tomorrow at work ..... not that theres much to see on this one ........ it is a very bare reading to say the least.

Be interesting to see, because it sounds like its very dodgy - hard to say without seeing the graph though. Was it a DDD or some other kind of dyno like a nameless one we have seen before? LOL

Is there any kind of scale on either of the axes, with the graph? Roughly, what does the curve look like? Does it reach a peak and come back down towards the end or does it keep climbing as it ends? Is there data at the bottom about air temp, humidity etc?

XRchic · 01-08-2006, 08:38 PM

Quote:

Originally Posted by Casper

nope, by tieing it down the rear wheels are forced onto the rollers and are effected by them. By not tying it down the rears ride up the front roller and therefore are only affected by 1 roller. Effectivly resistance is reduced and the car "appears" to have a higher rwkw reading accordingly.

Thats actually what I meant :P I should have said a "false high reading".... which is why I asked, if Lisa got a low reading, then Im obviously lost. LOL

MotherNatureVer2 · 01-08-2006, 08:41 PM

Proberly easier if I post the piccy tomorrow ....... theres no other info on it apart from the HP reading ..... have a KW one too ...... that looks worse figure wise :P

Is a decent incline upto 135k's then flattens out as did the guys foot .......

Im really not whinging ...... just need to know if I have a dud engine .... which after driving her home I doubt .... she copped a bit .... just to make sure it was there :P

XRchic · 01-08-2006, 10:33 PM

Quote:

Originally Posted by MotherNature

Proberly easier if I post the piccy tomorrow ....... theres no other info on it apart from the HP reading ..... have a KW one too ...... that looks worse figure wise :P

Is a decent incline upto 135k's then flattens out as did the guys foot .......

Im really not whinging ...... just need to know if I have a dud engine .... which after driving her home I doubt .... she copped a bit .... just to make sure it was there :P

Hey Lisa. I hope that your car is good too, it will be interesting to see the graph. The curve sounds ok in that it peaks and then drops back as it stops - that just means that peak power is reached before redline, which is a good thing! You dont want to hit peak power on redline! Kinda useless then.

Do you mean it flattens out at about 135kmh or 135rwkw or 135rwhp? The graph flattening out is about the power output at that time, which would not related to when the bloke took his foot off.

If the curve declines before it ends, then it means that he didnt take his foot off too early as the peak poiwer had been reached and was declining, even though speed was increasing. Once you reach peak power and then it declines, there isnt a lot of sense in keeping the foot to the floor and damaging the engine, just to get to the fuel cutout point.

It sounds like in that respect the bloke was ok. It is just a matter of determining what the peak power was and where it was at, in relation to revs or kmh (which is why I asked about the axes). It is a shame there was no air/fuel ratio given as that may give an indication of why power may have been lacking.

Im also wondering about the tying down issue. I cant say that I have ever noticed cars being tied down, but then, I never really look at the front of the car on the dyno so I dont think I would know. I have assumed my car has never been tied down because I never saw it, but Eamon assures me that it was tied down at all the dyno days we have been to. I was thinking of the big straps used for the 300+rwkw XR6T that we saw but it appears I was thinking of something different.

I would be checking with the bloke to see what he actually DID.

I also think that if the numbers are unexplainably dodgy, then defintely get it done somewhere else and get more info on the prinout - Im sure the people doing it would be able to offer an opinion as to why a car would be so underpowered, even if it was a defensive answer... LOL.

If it was not a Dyno Dynamics Dyno, I wouldnt have gone near it, personally, but you should be able to tell that by the graph you have. It sounds suspiciously like its not.

Having said that, just bear in mind mate, that dyno figures dont mean much. Its the driveability of the car, the power you can feel in your bum when you floor it and the ETs/mph that give you a better picture of what you car is capable of - as you said, you know how it feels! You know your car and you are probably correct.

At the end of the day I guess a car the same as yours should be getting closer to 130-140rwkw (in my opinion) conservatively so a figure of 112 rwkw is low for some reason.

Anyways, look forward to seeing the graph and also to hearing some more technical opinions on the subject from people who know a ****load more than I do!!!

Jac

PS I think everyone will agree with me when I say it is unlikely you have a dud engine. It seems that a dud dyno is a possibility and at worst, the engine is good, but just in need of a good tune! And the real purpose of a dyno is to do just that - its a tuning tool!

philstoj · 01-08-2006, 10:56 PM

Quote:

Originally Posted by Casper

nope, by tieing it down the rear wheels are forced onto the rollers and are effected by them. By not tying it down the rears ride up the front roller and therefore are only affected by 1 roller. Effectivly resistance is reduced and the car "appears" to have a higher rwkw reading accordingly.

The front roller is the one that measures power, its the one that the retarder is hooked onto, not the back one, that just spins on bearings.

You have to let the car ride up the front roller otherwise you wont get a reading from the back one!

A mate has a sprint,auto, i remember it had about 190-200 rwhp.

The air/fuel lead is the one that goes in the tail pipe.

MotherNatureVer2 · 02-08-2006, 01:13 PM

OK heres the piccy of the dyno ......

Am going to try get her booked into the only other place that does it up here ...... that or wait till I get to sydney next & get one of the site sponsers to do it for me with a complete explanation

_

Walkinshaw · 02-08-2006, 03:07 PM

Definatly not done correctly Lisa. Wasnt performed in SHOOT_8 and definatly looks as if someone backed off the rollers. DDD's have no issue going over 200kmh, well aparently they don't. My run went to 204kmh iirc.

I wouldn't worry too much about a sheet of paper lisa. As long as you are happy ;)

MotherNatureVer2 · 02-08-2006, 03:20 PM

I am rapt with the car ..... Its just a bit annoying to realise that you have paid for something and not got what you paid for ........

I was hoping for real detail so I can make plans for what we want to do with her in the near future ;)

notty1978 · 02-08-2006, 05:27 PM

Every dyno you go to you will get a different reading

mcflux · 02-08-2006, 06:12 PM

I'm assuming the diff in the Sprint is a 3.45...

135kph in 3rd (auto) would mean only around 3800rpm?

ratter · 02-08-2006, 06:22 PM

Quote:

Originally Posted by philstoj

The front roller is the one that measures power, its the one that the retarder is hooked onto, not the back one, that just spins on bearings.

You have to let the car ride up the front roller otherwise you wont get a reading from the back one!

.

Your statement is not quite true, yes the front roller is the roller that measures your power, but if the car rides up on the fornt roller so it comes off the rear roller, it will give a higher reading, It still takes power to turn the rear roller if the car is strapped to it, so that will show as less power the car is making, but it will show the correct figure, well as correct as the dyno allows.

This dyno operator sounds a little lazy as was just after a quick buck.

XRchic · 02-08-2006, 11:27 PM

Not good Lisa. There seems to be a lot of data missing as well, like all the atmospheric stuff at the bottom of the sheet such as air temp, humidity, etc, etc.... sort of indicates, yes, lazy bloke as it probably wasnt measured.

I see what you mean about that curve, and yeah it does look like he backed off, doesnt it? I would have been questioning that a bit, can you contact him again??? Thats pretty bad service.

As Dan said, dont worry about it too much and if you want to know more, get it taken somewhere reputable, as you have said.

Good luck mate!

Jac