Dyno rules

[PSH]

Now here's a question.. dyno runs.. bonnet open or closed[8|].. I've been told today that the bonnet should always be open while on a dyno as you can not get enough airflow with it closed. I've also read today that to put the temp probe under a closed bonnet is bad practice as the heat generated under the bonnet while not moving will be far higher and thus power sapping.
What do you guy's think/know?.. interesting to note that the last two reasonably poor runs that i've had the bonnet has been closed, in the case of yesterdays run it was actually shut whereas in bournemouth it was at least partially ajar?

The bonnet was certainly open for Waynes mapping and also at the silverstone dyno day in 2007 so do I have a big problem or is it down to dyno practice, I can't remember if all bonnet's were closed saturday although I suspect this would have a far more detrimental effect on a turbo car than a N/A.

Would be interested to hear your views as the car does not seem slower on the road and also on the dyno it made less than 1.2 bar which was .2 bar lower than the boost was set at. I checked this on the way home and the boost gauge( very accurate one) and the apexi digital display showed the car achieving the 1.4 that it is set for?

Pete

 

[Alexw]

Hi, nice to finally meet you yesterday!
Wouldn't it be more "natural" to have the bonnet closed? I know you can't mimic the air flow over the car at the speeds it would be doing exactly, but with the bonnet up wouldn't you create an unnaturally cool engine and therefore higher results then you would get in the real world?

 

[PSH]

Hi.. good to meet you too..[]

well that's why I asked. 3 things i question though... first the IT was very high ( higher than any dyno i've ever done and seeing Pauls graph from a day that I didn't attend it looks out of place type of high) and I'd like to ascertain why so I can then fix the problem if indeed there is one, second I guess all cars are different and some need the car moving to get the correct airflow or to have a powerful enough fan or bonnet open to allow for this , thirdly and most importantly Steve said to me during the debrief that the car would probably produce a lot more power on the road due to the airflow......???

[8|]

Pete

 

[Mike_Pollock]

Hi Pete

Guessing Steve meant that on the road the airflow thru the intercooler will cool the charge quite considerably. That begs the question though, how did the it work on previous occasions?

Mike

 

[944Turbo]

How long have you had the extra angle in the turbo outlet? the route to the IC looked a little more convoluted than ideal, and it is over the top of the hot engine,
Tony

 

[PSH]

How long have you had the extra angle in the turbo outlet?

HI Tony... when I say the angle may have changed I only mean due to the MAF being taken off and put back on during routine servicing. So nothing that I would expect to make any real difference to the car, I only mentioned it as it may be different now. I'm also wondering about the boost lvl, the piggyback system can not read boost and thus it can not retard the ignition. When with wayne it was set at 17psi, at silverstone I had increased it to 19psi, both runs gave the same BHP... The last two dyno days which have given far less power the boost has been higher, in bournemouth this was due to a broken boost controller as even after changing all the hoses( suspected problem) we still could not get the boost below 21psi and yesterday with the new APEXI it was around 23psi which seems a lot quicker on the road but then most driving is mid range and so you wouldn't neccessarily notice a drop in power at the top until on the dyno.
As you can see I'm analysing everything learnt from both past results and yesterdays in an attempt to sort the car out, I suspect that until I can get the V-FLEX installed and remapped I will not get the power above the 368bhp, in the interim I have now reduced the boost level to monitor any difference in performance.

I'll get it sorted in the end mate...[]


Pete

 

[944Turbo]

Was talking about the metal right angle pipe on the turbo outlet it makes the route to the IC longer, and puts it right on top of the hot engine. Not sure where they were measuring intake temps, whether it was on the intake pipe after the IC or at the air filter - after the IC makes more sense on a turbo car.

If they didn't have a probe at weltmeister previous dyno temp figures might have been ambient in the cell.


The KLR still has the boost input, so the ECU can still retard the ignition with high boost, the piggyback only takes the signal from the ecu and retards or advances it by an amount fixed by the pre programmed level. so if the ecu retards the piggy back will add the same to the new retarded figure.

The ecu can only retard the ignition 6 or 8 degrees, once this limit is reached it can retard no further, so running more boost is likely to end in detonation and headgasket or piston failure.

Running too much boost on a small turbo results in excess heat being generated. hot air is less dense so will give less bang. Have you got a standard IC?

Tony

 

[PSH]

Was talking about the metal right angle pipe on the turbo outlet it makes the route to the IC longer, and puts it right on top of the hot engine. Not sure where they were measuring intake temps, whether it was on the intake pipe after the IC or at the air filter - after the IC makes more sense on a turbo car.

Ah.. ok now I understand what your asking?

I can't remember if I had that at Bournemouth or not but yes that was not there for either of the 368 runs?