RPM issue and APEXI VAFC - Honda Prelude Forum

asimdada · 10-31-2009, 01:13 PM

Hello,
My newly acquired prelude has the following

60mph@3k rpm and 70mph@6800 rpm.

Do these numbers sound alarming?

The previous owner had an Apexi VAFC hooked up to the car but told me that the vtec engagement point is to stock level( little over 5k rpm) . What may the problem be?

Also, the check engine light came on today. How can i tackle that?

Thanks a million.

lude4lifeh22 · 10-31-2009, 01:19 PM

huh?

at what gear?

asimdada · 10-31-2009, 02:03 PM

crapp...i got it all wrong...

60mph@3000 rpm and 70mph@3900 rpm (in 5th gear)

Sorry

Twiggz · 10-31-2009, 02:53 PM

I don't understand your RPM issue. A VAFC can't change your gearing if thats what you're thinking.

asimdada · 10-31-2009, 04:56 PM

I see....so what may be causing my RPM to be so high. I remember on my auto prelude the rpm used to be around 33-34k at 70 mph in 5th gear.
Thanks.

rhangman · 10-31-2009, 05:14 PM

5th gear on an auto?
Auto should only be 4 gears.

RPM's come down to the gear ratio, final drive and rolling circumference of your wheels. Possible that the owner changed the final drive or wheels, but the fact is that you wouldn't expect the RPM's to be the same between an auto and a manual since they gearboxes and therefore ratios are different.

edit: I guess unless you have your speedo recalibrated, then the wheels won't effect RPM, at least not compared to the (now wrong) speedo. Only be +/- 3% max difference anyway.

spin_r_g · 10-31-2009, 05:19 PM

Quote:

Originally Posted by asimdada

I see....so what may be causing my RPM to be so high. I remember on my auto prelude the rpm used to be around 33-34k at 70 mph in 5th gear.
Thanks.

Wait what? Your auto prelude used to be around 33,000-34,000 rpm?

asimdada · 10-31-2009, 06:17 PM

sorry about the confusion...I realize my auto had 4 gears, but what i meant was that on 4th gear in my auto prelude, i used to be doing 3300-3400 rpm@70mph. Im pretty sure of that.
The original owner did not change the wheels or the final drive. Just checked with him over the phone.
I also realize 4gear-auto and 5-speed gearbox have different ratios but what i was wondering was if on my 5-speed, its normal to have the rpm at 60mph@3000 rpm and 70mph@3900 rpm

Thanks.

lude4lifeh22 · 10-31-2009, 06:20 PM

^yes

asimdada · 10-31-2009, 06:24 PM

kool...Thanks.

indylude18 · 10-31-2009, 06:42 PM

Check out Kronn's transmission speed chart. It outlines what rpm you should see at a given speed in a given gear:

asimdada · 11-01-2009, 01:20 PM

Thanks alot Indy....this char is really helpful. Will compare it to my lude.

Artifex · 11-01-2009, 09:46 PM

Dude that's completely normal. Auto cars have different gearing, so yes the RPMs will be different. There's nothing wrong with your car, it's totally normal.

asimdada · 11-03-2009, 08:10 PM

Thanks artifex. I was getting paranoid with this issue

.
Thanks all.