Hi,

This is my power graph from john nobles RR day.... My car is an MY95 WRX with straight through centre section, blitz nur spec back box, blitz SUS induction kit and dawes set to 11psi...





What could be the explanation for the dip in the curve for power and torque around 4000rpm...??? and is there a reason that my torque builds up then starts to drop off and peaks at 5300rpm which seems a bit high in the rev range..?

Any thoughts appreciated..

Dan



[Edited by dhorwich - 10/6/2002 9:02:55 PM]

 

What boost does your car run without the dawes then?

 

I think it would of been around 11psi... i say 11 psi because when it was on the rollers my gauge was only showing 11, however when i had it on the road before the RR day i was seeing 13-14 psi.....?????

Dan

 

A good rolling road plot would also show fuelling and boost, which helps in answering questions about dips or peaks. From what I have seen of rolling roads, the plots don't bear much resemblance to what happens on the road - boost tends to be less, fuelling is richer, charge temps are higher, drivetrain losses are higher, load is higher, and they can detonate. What makes a good drive on the road can look poor on the dyno and vice versa. Certainly this is the case for boost control - good boost control on the dyno will tend to overboost wildly on the road, and a car hitting boost targets on the road tends not to achieve them on the rollers as readily, hence funny shaped boost curves and low torque figures - particularly for ECU rather than Dawes boost control from what I have seen. Had the opportunity to map a car on the rollers recently, and was disappointed with the results compared to my usual of mapping on t the road. You are making adjustments based on false data, and the rolling road it seems is not a good simulator. Some would say this is terrible and place great stock by the phrase "dyno tuned" but it seems a bit odd to me since we drive them on the road. A few advantages are that you can see under the bonnet when the car is under load, you can hook up gas analysers, you can hold load at one point, but it all seems a bit artificial. Just my 2p.

 

cheers john,

The bloke who did the run said the fueling was good and it didnt run rich at the top end like some of the uk cars there...??

Thanks

dan

 

Jap cars tend to run leaner from what I have seen but that is later models.

 

Nearly every Scoob dyno plot I've seen has had this 'dip'.
seems that if it's in nearly standard trim this is what they produce on the rollers!

Steve

 

Agree with scoobyduck, overall I am very impressed with the power figure, given the low boost (acurate measurement required).

I have seen cars running closer to 14psi at the top end make this sort of power.

Paul

 

The guy reconed if i upped the boost i would probably get a bit more torque but not to much more bhp, probably due to my crappy standard intercooler getting to warm..!!!???

Dan