RPM difference

MMamdouh · Post by **MMamdouh** » Thu Nov 01, 2007 1:54 pm

just noticed that on my dad's car that @ 90km/h the RPM is at 2600 RPM with 5th gear engaged but on my car it is at 2500 RPM yet both cars got the same 1.5 SOHC engine... any idea why their is a 100 RPM difference between two identical cars??

MMamdouh

jorge · Post by **jorge** » Thu Nov 01, 2007 4:06 pm

This test are in the same road??? And the same wind speed???

Audacity Racing · Post by **Audacity Racing** » Thu Nov 01, 2007 5:03 pm

It's a small enough difference to be signal difference through the system or even tire inflation

daewoomofo · Post by **daewoomofo** » Thu Nov 01, 2007 9:11 pm

whats the difference in the amount of miles on the 2 cars, your dads might be a bit more "tired" than yours if it has alot more miles on it.

mezomaster · Post by **mezomaster** » Thu Nov 01, 2007 11:08 pm

MM, ur rims are 14" nubira rims, i dunno whats ur dads car rims are, if they are the same, maybe its just a bit missing speed meter?

Damic · Post by **Damic** » Fri Nov 02, 2007 6:32 am

mezomaster wrote:MM, ur rims are 14" nubira rims, i dunno whats ur dads car rims are...

IMO it does not matter, as the ratio engine/gear/axle are the same.

Are the rev-meters the same on both cars? Even if they are, you still have two instruments on each car, tacho and speedo meter and every of them has own plus or minus tollerance.

MMamdouh · Post by **MMamdouh** » Sun Nov 04, 2007 8:24 am

jorge wrote:This test are in the same road??? And the same wind speed???

test done on various roads and conditions... same results every time.

MMamdouh

MMamdouh · Post by **MMamdouh** » Sun Nov 04, 2007 8:28 am

Audacity Racing wrote:It's a small enough difference to be signal difference through the system or even tire inflation

RPM connection circuit is the same on both cars... i have swapped it myself plus tires can't affect engine/tranny ratio... right?

MMamdouh

MMamdouh · Post by **MMamdouh** » Sun Nov 04, 2007 8:29 am

daewoomofo wrote:whats the difference in the amount of miles on the 2 cars, your dads might be a bit more "tired" than yours if it has alot more miles on it.

i got half as much miles as my dad's car... i am at 64k kms and his car is at 121k kms, can this be due a slipping clutch or so??

MMamdouh

MMamdouh · Post by **MMamdouh** » Sun Nov 04, 2007 8:44 am

mezomaster wrote:MM, ur rims are 14" nubira rims, i dunno whats ur dads car rims are, if they are the same, maybe its just a bit missing speed meter?

test was done with the 14" rims on both cars.

MMamdouh

MMamdouh · Post by **MMamdouh** » Sun Nov 04, 2007 8:52 am

Damic wrote:
mezomaster wrote:MM, ur rims are 14" nubira rims, i dunno whats ur dads car rims are...
IMO it does not matter, as the ratio engine/gear/axle are the same.

Are the rev-meters the same on both cars? Even if they are, you still have two instruments on each car, tacho and speedo meter and every of them has own plus or minus tollerance.

both cars doesn't have an OEM tach so i got myself an OEM cluster with tach and made the sigbal circuit that Tim introduced and installed the whole setup on dad's car... after i got mysef a woo i swapped the cluster with the tach circuit so it is the very same RPM measurmint hardware on both car.

one note though... the speedo on my dad's car is the old one with max speed of 200 kms only whereas on my car it is the new one with max speed of 220kms... can this mean that both speedometers are not that accurate compared to each other??

MMamdouh

Audacity Racing · Post by **Audacity Racing** » Sun Nov 04, 2007 9:00 am

We all know that the clusters aren't accurate... if you were to do a colored face swap, you have to be careful to mark the position of the needle after the stop-post is pulled out. Even a slight difference in that could mean 3-5 mph without thinking about it. It's easily understandable that no two Daewoos will have the same speed readings...

MMamdouh · Post by **MMamdouh** » Sun Nov 04, 2007 9:06 am

so this could be a tach calibration issue rather than a car/clutch issue... i can take that off my mind now.

thank you guys

MMamdouh