osix

Hi i recently tuned and resolve part of the problem of poor idling as well as unstable timing .

Here a Question . What kinda Speed should i expect to run at 2500RPM .

i notice i am going at about 90KM at 2500RPM rev

what should i be expecting .

i still have 1-2 more tuning session i can use what should i be asking for .
the ECu is a P70
Engine D16y8 top
D15B block .


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what i can do to improve it to 100 KM at 2500rpm .

pardon me for the noobish question .

94eg!

iTrader: (2)

To determine actual speed at a given rpm (not indicated speed since your speedometer is inaccurate), you need to know the following values....

- Tire size (example: 195/55r15)
- 5th Gear Ratio
- Final Drive Ratio

As you can see, it strictly depends on which transmission and tire you are using.

Custard

Lol what? Your speed in any given gear/RPM is determined by your tyre size and your transmission gearing. It cannot be changed by tuning, it is the simple result of the ratios of physical things that rotate in your car.

osix

assuming my Tire is 195/55r15

what tire can i change to improve the RPM / speed - so i can more speed at 2500 rpm ?

Gear ratio and Final Drive Ratio at do not know at the moment .

today i came home with an est of about 14km / liter

what advice would you give to improve the Mileage -

94eg!

iTrader: (2)

Switching to a larger diameter (taller) tire than the one you have now will increase your "ACTUAL" speed at any given rpm. The problem is your speedometer/odometer, which are driven by the spinning differential, cannot tell the difference. They will continue indicating exactly the same. To you it may even seem like you are accelerating a little slower because of it. Additionally your miles-per-gallon calculations will drop because you are actually traveling further than your odometer was indicating prior to the change. A 4% taller tire will have a 4% higher speed (at any rpm) than your previous tire. Your speedometer & Odometer will read 4% lower than actual. It will also cause a 4% drop in your mpg as you will be traveling 4% further.

A 195/55r15 is a very tall tire (23.44 inches). To contrast, the more common 205/50r15 is only 23.07 inches tall. A 205/45r16 is 23.26 inches tall.

jdblock

My advice for fuel mileage, install a 8 valve head.

Taller tires for increased fuel mileage is backwards. The extra rotating mass will use more gas when accelerating than you will save while cruising.

osix

Can you share more info on 8 Value Head ?

94eg!

iTrader: (2)

It is the head from the CX trim level. It would make your car extremely slow. That head was good for 70hp.

osix

at the moment the Vtec is Tune to open at 4500 rpm ,
the Idle is at about 850-900 rpm .
i am thinking if i can lower the RPM . to maybe 700 rpm at idle .

is all guesisng and i am leanring more .
I do not know the HP of the car now . but i am Running E20 Gasohol .

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i hope to get about 17Km / L about 40MPG Currently is at about 32MPG 75% highway 25 % city
wondering what i can do .

94eg!

iTrader: (2)

E20 + 32mpg is good. E20 has less energy than E5 or E10 we run in the USA.

The best way to lower rpm & improve your mpg's would be to swap in a transmission with long gears. This option makes the car no fun to drive any time.

Harder & skinnier tires (with high tire pressures) are another option, but then they sacrifice traction in all aspects. Though this can still be fun to drive, it may look awkward and handle poorly relative to other vehicles.

The best option is to remove stuff to make it lighter. This will increase mpgs AND make the car quicker. Though you do sacrifice road comfort.

Everything is a compromise.

osix

The tire is at 33 psi .
i am wondering if switching to E10 which is 10% more expensive worth it to improve the mpg .
currently when i move off i notice the Rpm can move up to about 2100rpm - making the 1st and and 2nd gear usually float at about 1700rpm - 2200 rpm . if i hit it too hard it go up to 2500-2800 rpm .
was wondering if it got to do with the Tuning .

i was not there at the workshop when there tune it and replace the Timing Belt to a 106 teeth .
i wonder if there did a TDC with a electrical device or using the classic screw driver dipper .

Swaping the Transmission seem like an Expensive job and also like you said i hope to have some fun . now is more like understanding the car and fine tune a little more .
maybe in the process pushing the Mpg to about 36-37 mpg would be fun .

the car is now about 4.5 inches from the ground . i am worry if i lower the car more i would have problem hitting the exhust . on some day when i drive i can hear a slight sound of my exhust hitting the slope when i move up at one of the place i go regularly

94eg!

iTrader: (2)

You shouldn't have any trouble hitting those mpgs with a 1.5L motor. My 1.8L B18C (super short gears) makes those numbers on E10 with wide sticky tires & 33psi.... Though my chassis is an EH2 which is the bare bones basic stripped down econo' hatchback (no power anything).

I'm guessing additional tuning will really help. Especially if you are running rich.