Interesting Dyno results 2530 / setting up the tiing with a dial gauge

[iruvyouskyrine]

I'm selling my car because I am at a point in my life where I need to prioritise money for other things that aren't cars. Your douchbage levels astound me.

Menthol were those the timing numbers when aligned with the marks on the RB25 backing plate?

[menthol369]

I dont recall exactly where the marks lined up on the covers as i used a dial gauge an degree wheel to set the timing this time round.

[Scott Black]

On 15/01/2017 at 10:43 AM, KiwiRS4T said:

That explanation doesn't make sense to me. Saying that  the printed mph/kph figure is too  unreliable to convert to rpm means you have given up on getting accurate data. . Given that for many purposes the ecu requires an accurate rpm signal it would seem that the tuner hasn't gone to enough trouble to make the necessary connections to get a proper rpm reading. 

Seeing videos of people sitting in the boot of cars trying to stop tyre slip on dynos is another reason why i think hub dynos are by far preferable.

Ok, Basically dyno doesn't actually read rpm for any of its primary calcs except derived torque, the power and motive force are calculated directly off road speed based on pressure applied to the load cell, then you have have a few other calculations going on to get derived torque based off either an input on the dyno to measure rpm or off a user set rpm based off road speed. so the primary scale for all dynos is actually road speed on a roller, or hub rpm on a hub, (hub rpm is very different to engine rpm) to get rpm readings on some cars can be a real prick, even with you have inductive and primary based pickups, as some cars especially ones with msd units will fire more than once giving really stupid readings on inductive pickups if you cant access the tach output on the msd box (very common occurrence when idiots have mounted the box right up under the dash behind alot of crap)
also the rpm pickups are sensitive to interference that can make them unreliable at times, my own person car that works well on my dyno 95% of the time still has the occasional run where the pickup gets some interference off something else on the car and gives me readings of like 30krpm, where as because the road speed pickup is always dead accurate to the result. (not saying the dynos road speed is the same as actual road speed as tyre slip and crap puts that out a fair bit,if you have a decent tach input and graph rpm vs kph you can see this very easily )
in terms of tuning, the only time it really matters is it makes it a bit quicker to do the ramp testing high load stuff yet even then there's still delays in fueling from wide-band placement and how quick the engine accelerates means your rarely adjusting the 5krpm cells for a issue with 5krpm on the plot and as far at steady state lower load situations all the ecu side of tuning, the tuning software and logging software on the laptop your tuning with gets a perfect rpm signal direct from the ecu your adjusting (sometimes this signal can be fed direct to the dyno to depending on dyno and ecu brand and what level of options you have on the dyno) so in terms of tuning the dyno having the rpm reading isn't a huge advantage all the time.