Pfc H/c V's Tacho

[Kaido_RR]

Hi,

Im just wondering which is more accurate PFC H/C or my Tacho.

Below 50km/hr the difference doesnt seem much but when i get up in speed the difference seem to get pretty big (the pfc h/c reads about 10km/hr less than the tacho)

Cheers Michael

[Guilt-Toy]

This is how it goes.. When you say tacho you mean engine revs yes? then you mention speed.

Engine Revs is correct on the power FC compared to the stock tacho meter

SPEEDO can be correct on the indash display and not on the PFC or vice versa OR they could be both wrong.

Get someone in a late model car do some tests with you on speed one check at 40 then 60 then 80 then 100 etc etc

Then you will know which one is correct.

My PFC speedo used to be correct then i got a different ratio diff and now the indash speedo is correct.

[Kaido_RR]

cheers for the reply

my rpm are alittle out too oh well

[GeeTR]

Yah, I agree with Troy, engine revs would comes from same source, and feed both FC and dash gauge.

The dash speedo though would be from a cable connected to gear box. As evident when heavy breaking and accelerating, there can be huge hysteresis in the needle.

PFC would however take the speed from the hall effect sensors on each wheel for your ABS system. Me think the requirement for the ABS to have a good idea of vehicle speed, would automatically mean its more accurate then the dash speedo.

2c

- Michael

[cameron]

Tacho will most likly read higher than FC... Same with speed.

[Busky2k]

I think speedos are all calibrated to overread by a small amount eg 2%. All cars do it.

I would trust the PowerFC especially with the RPM - after all, its the PowerFC that should know it better than a dumb analogue needle because it controls the darn motor!