Dissapointing Dyno (rolling road) Result…

Last weekend I got a good offer from a garage owner friend who wants to dyno Dolly, I think he is a bit curious about dolly. Of course I agree,  it is always good to know the power curve of our car.

I am very confident that Dolly will get a good result as I already upgrade few things : Electronic ignition and Carburetor  and I have rebuild the engine.  so the expectation is : I will get higher power than stock, there is no way it will be lower. Finally the day came and we prepare Dolly on the rolling road, setting up big  fan in front of Dolly  to cool her engine.

Full of expectation, my eyes set on the computer while the operator revving the engine as high as he can…. A lot of gibberish number, I only want to see one thing… 70 or above… that is the HP (horse power) for stock engine… however that number never came… and when I see the operator is amused (not in a good way like scratching his head), my heart sunk… oh my God… whats wrong…?

And then he asked the owner to try to operate dolly.  He too also gives a “give-up” look and then he ask… what is the engine cc..? “2.250 cc” I said and hastily added “low RPM torque type of engine” to make sure he understand that peak torque is around  2200 RPM not like racing cars.

Do you know the peak BHP for this car… “at least 70..!”  Me answering his question…  “Yeah I thought so” he said… fiuh… I feel relieved…  so all the confused look is seems because they expect a gazillion torque or horse power  like many of their racing customer cars. ” So what’s the result look like…” I impatiently asked.

“Not even 50 BHP” … hearing him saying that, you will feel like you got stung by hornet in the forehead… he see me stunned he continue his sentence:  “yap… we have tried it three time and the result is the same… sorry…”  and then he gave me a print out showing the result.  To give you a perspective on the dyno result, here I charted dolly BHP and added “Standard” engine BHP from their brochure (I actually stole it from Darren one of the land rover forum friend).

BHP dolly

The standard engine BHP is measuring the engine on the flywheel (engine Power) while dolly is using on the wheel (wheel power), so the gap is acceptable, sometime the difference is as high as 30%

Comparing the above chart, you will see that Dolly’s peak power is at 2300 RPM at only 48 BHP, while standard engine peak power is at 3600 RPM at 74 BHP… now the question is why Dolly’s power seems to prematurely ended… certainly she is not a young girl anymore, but I am sure she should be able to out do anyone with stock engine.. :)

I hear you ask…: How come I do not know the problem in the first place… I should have known right..? I ride her every day how can I not notice it…  (I can see your smirk there Bas****d). The answer is because I never ride her hard… Dolly is at best when you ride her slowly, attentively, and she will reward you with satisfying side to side smooth and gentle rocking… (Are we still talking about car here…??? ).

I am glad now I found the problem that is half the answer… A lot of things can go wrong, The carburetor, the ignition, the engine, fuel pump, chain timing, vacuum leak etc… So I need to check it one by one… its time to play doctor with Dolly..  if you have any ideas what to check and have experience sorting out similar problem.. it will be great if you can share it down below

Cheers…

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5 thoughts on “Dissapointing Dyno (rolling road) Result…

  1. Pingback: Dissapointing dyno result – Solved..! | Vidinur.com
  2. Any news yet on the cause?

    I was thinking the other day that your power curve looks very like that of a 2.25 diesel ie: nothing below 2-3K rpm and nothing above! A very narrow power band – are you sure you haven’t got a 2.25d cam in that engine of yours ;-)

  3. Sadly I don’t know much about petrol engines so will be of no help. However 50hp at the wheels is probably about right for a 2.25p isn’t it? The transmission losses are huge in these trucks so the factory flywheel test data is not so good to measure against. Odd though that you get a sudden drop off. Did you test with the oil bath air cleaner in place or did you remove that? I think the factory tests are without air cleaner from memory so that would explain another few hp :-)

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