FBP EM1

When I'm driving on the freeway at about 80mph my RPM is running about 4500, is this normal? My car is bone stock with no mods whatsoever.

Thanks

hayabusa160

thats about right the stock tac is off a bit sometimes too mines off by 500 sometimes

Bense

i can completely relate to your thinking. Because a few months ago i was thinking exactly what you're thinking. I even thought about getting a integra LS 5th gear because the RPMs were so high.

Here's a quick lesson that will help you understand it.....

each RPM your pistons are moved all the way up and all the way down. the b16 has a very short stroke of 77mm so each rpm the pistons go down 77mm and back up 77mm. So that means that they move a total of 154mm each rpm. The b18b/b18a has a stroke of 89mm so each rpm the pistons are moved 178mm

so let's say that when your crusing at 4500rpms that's 4500 x 154 = 693,000
now lets take that number that we get when we multiply RPM x STROKE x 2

so 693,000 divided by 178mm (from the 2 times the b18b/a stroke of 89)

693,000 / 178 = 3893.2584 RPMs


so your b16a's 4500rpms is equivalent to an integra LS crusing at 3893.2584 RPMs


So there you go. Yes your cranking out the high rpms, but your motors pistons move significantly less each RPM than your average motor.

hope this helps.


Modified by thebense at 1:27 PM 8/24/2004

Gerbilo

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by thebense &raquo;</TD></TR><TR><TD CLASS="quote">hope this helps. </TD></TR></TABLE>

you're insane... mad scientist!

but yeah, at 80mph i'm at 4k in my GS-R... I thought that was insane after coming from my old civic or being in any of my friends cars that don't rev to 8k lol...
then my friend was sayin about his B16/tranny... just like yours... it's normal

handa

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by thebense &raquo;</TD></TR><TR><TD CLASS="quote">i can completely relate to your thinking. Because a few months ago i was thinking exactly what you're thinking. I even thought about getting a integra LS 5th gear because the RPMs were so high.

Here's a quick lesson that will help you understand it.....

each RPM your pistons are moved all the way up and all the way down. the b16 has a very short stroke of 77mm so each rpm the pistons go down 77mm and back up 77mm. So that means that they move a total of 154mm each rpm. The b18b/b18a has a stroke of 89mm so each rpm the pistons are moved 178mm

so let's say that when your crusing at 4500rpms that's 4500 x 154 = 693,000
now lets take that number that we get when we multiply RPM x STROKE x 2

so 693,000 divided by 178mm (from the 2 times the b18b/a stroke of 89)

693,000 / 178 = 3893.2584

So there you go. Yes your cranking out the high rpms, but your motors pistons move significantly less each RPM than your average motor.

hope this helps. </TD></TR></TABLE>

something new learned today

yeah i had the same question about a week ago: https://honda-tech.com/zerothread?id=961792

after going 80mph @ 4.5k rpm i just get used to it.

eL

I too wish my 5th gear wasnt so short.

00Red_SiR

Your engine revs that high because the transmission was designed to keep the engine near it's optimal power range. B16's make no torque and are designed to rev (short stroke) so they have to rev to really move. Put an LS transmission in a GSR, you'll rev less, get better gas mileage but the car will accelerate slower because the gears aren't optimized for that engines power curve. Everytime you shift, the car will drop out of VTEC and unless you keep it in VTEC it wil be SLOW.

Gerbilo

exactly! if you want good mileage go buy an HX!!

-Trinitron-

I hit VTEC in 5th at 100...an LS 5th would be such a drop in rpm though. Si's should be 6 speed!