Got my car Dyno'd

[P11GT]

Finally got my Unichip remapped with the custom Piper Cams installed. It now running at 146BHP. The previous best was 141BHP but due to the amount of time between tests i cant be certain of what it was. The car is meant to be 150BHP standard but them figures can be a bit optimistic. As you can see from the graph, the gain happens around 4,000rpm, and increases right the way up, 4,000rpm being where the car normally pulls hard. Its good, the car runs well, but still could do with a few more ponnies. Now im just waiting delivery of the HS header and CAI.

Comments Please......

[P11GT]

note: theres a maximum gain of around 8BHP right at the top but 146BHP was at 6,375rpm

One thing the technician did say was that the car showed as running at 60 MPH at 3,700 revs in forth gear when his dyno actually read 60 MPH at 3,200 revs??????? Dont know why that is, maybe my speedo/odometer is off

[P10DET]

Questions......

1) It appears to be using a chassis dyno, is that correct?

2) If so, are the hp figures for at the wheels or calculated at the crank?

3) If they are calculated crankshaft hp, what conversion equation are they using?

4) Are they correcting for atmospheric, or weather conditions?

[P11GT]

phew!!.........straight over my head. All i know is the car sits on the rollers in a booth and he trashes it in forth gear. The figures i get are at the flywheel, so i dont know any equations to calculate it at the wheels.

[P10DET]

Originally posted by P11GT
phew!!.........straight over my head. All i know is the car sits on the rollers in a booth and he trashes it in forth gear. The figures i get are at the flywheel, so i dont know any equations to calculate it at the wheels.

You should ask the dyno operator. Those things are very important.

I suspect that they are not adjusting for weather conditions. It would also help to know their conversion from wheel hp to flywheel hp. I'd be very surprised if you are not making a lot more power that the dyno test indicates.

Actually hp doesn't necessarily matter as long as you can be sure what the effect of your modifications are. But, to be sure about that, the operator must adjust for weather conditions.

See if you can find that information out.

[G-Forces]

Heh, George is right. I was talking to the dyno operator when some of my friends were getting their cars done. He showed me some of the different standards for measuring power at the wheels. SAE is what's usually used but there were some standards that caused the power numbers to be larger. He told me some guys ask him to change the standard to the 'highest looking' one for print out. Wankers.

Also it's hard to compare dyno charts from different dyno's too. Even different shops running the same dyno. That's why I alwasy go to the same place to dyno my car. When I move to Vancouver in a couple years I'll find a good dyno operator there and stick with them too.

On another note your powerband looks nice and linear. I would also be interested to know what those final numbers are supposed to represent.

[P11GT]

The cars been re-dyno'd with the Hotshot CAI and Header

Heres the results................

I have mixed feeling

Even though it shows little gain, all in all, the car feels and drives faster. I suppose its hard to tell that on the rollers.

note: it looks a little ruff from 0-4,000 rpm, but thats just this particular printout of the map, the others looked more like the original run, meaning more linear.

[T4 Primera]

Are you getting the Dastek Unichip remapped to compliment the latest mods? or did they do that on this dyno run?

[P11GT]

The technician said the fueling etc was fine and didnt require any further mapping. So, thats it!!! after all the mods, i mow have a maximum BHP of 149, and the book figure is standard 150 BHP!!!! go figure

[b-b00gie]

Are you sure thats crank HP?


Something seems a little strange to me. With all the mods the car is only 149HP @ crank? Are you sure thats not @ wheels? That seems a little more feasible. A stock SR20DE is around 120-124 HP @ wheels, which with all your mods would result in a 25HP jump @ the wheels.

A stock 2000 G20 which is "145HP" will put down 125 HP @ wheels on the dyno. Theres no way that a "chipped" SR20DE w/ header, CAI, etc will only give 1 or 2 whp over stock.


My conclusion is:

1) That is wheel HP, so you're car is a LOT faster than they are telling you.

2) If somehow those figures are crank HP, than something is seriously wrong w/ your engine


BTW, do you have dyno charts from your stock engine so you can compare??

[ragt20]

all of those changes and still only getting upto book HP...... something must be wrong......hopefully not your engine !!!!

[P10DET]

Originally posted by ragt20
all of those changes and still only getting upto book HP...... something must be wrong......hopefully not your engine !!!!

Unless the cams were installed with the timing off (don't think so looking at the plots), I think it's the mokey operating the dyno.

We don't know the conversion from wheel hp to crank hp (it must be a calcuation input into the dyno software).

We don't know if the figures are being corrected for atmospheric conditions.

There are a variety of other factors that could influence the numbers. There is no bloody way a set of JWT cams and a CAI will only net you 4 hp. Most people can gain that much of more just by doing a ignition timing sweep on the dyno. Something is wrong with the plots. I have little doubt of that.

[P11GT]

[/b]BTW, do you have dyno charts from your stock engine so you can compare?? [/b][/quote]


The first dyno graph at the top of this thread showing 140 BHP is the standard figure of the car, this one is then compared to the run with the cams installed. Then the second graph is the figures for the cams compared to the HS header and CAI.

He tell me that the figures are from the flywheel/crank. Its not the first time ive used his dyno, and on previous cars, all the figures have always been at the flywheel/crank.

[Anthony]

Maybe you should try another dyno if there is another one locally.

That dyno *must* be at the wheels judging by the figures, unless there is something seriously wrong with the dyno or your car.

149 wheel bhp + 15% drivetrain loss = 171 crank bhp, which sounds more like what I'd expect

Just out of interest Kevin, how much does a dyno run set you back?

[P11GT]

so far........ none of the dyno runs have cost me a penny. Thats probably cos ive done so much business with him in the past. I only paid for the unichip, and i think one other mapping session, but the last few times, he hasnt charged me at all