Redline/fuel shut-off

[S800Racer]

I've noticed that most everyone says their cars redline at 6800rpm. Of course, that is where the red starts on the tach. I've also noticed that just about all of the dyno charts stop at about 6800 rpm. My car revs well past 6800 and the fuel shut-off seems to be about 7100-7200rpm. While I have full confidence in Honda engineering and the K-series motor, I try not to test that limit very often.

Does anyone else have an EP that revs past 6800 or did I just get lucky?

If you want to talk about real high revving Hondas:
My 1967 Honda S800 tach has a red zone that starts at 8500 and the tach reads all the way to 11,000rpm. They put the 11,000 on the tach for a reason. I vintage race the car and I shift at 10,000rpm. I have dynoed that motor and peak torque is at 8500 and peak HP at 9500. Hell, I've missed shifts on that car, zinged the motor to something around 12,000rpm with no damage & I've done it several times. I'm not proud of missing the shifts, but I did build those motors pretty well!

[civicracer.com]

i shift around 7100

i bounce the limiter almost daily
specially in first gear

my EK limier is at 9200 sometimes i go overboard with the ep

lol

i agree its not 6800 or so its so much past 7k on mines!

[modern-perf]

Mine loves to bounce off fuel cut...right around 7200-7300 rpm. I usually shift at 7100 also.

[Glix2]

Just because you see your tach going over 6800 doesn't mean the actual fuel cut off isn't 6800. Tach's are not very accurate.

[S800Racer]

Originally posted by Glix2
Just because you see your tach going over 6800 doesn't mean the actual fuel cut off isn't 6800. Tach's are not very accurate.

The evidence based on the responses so far says the fuel shut off is around 7200. Mine and the two others that responded all say the same. So either all of our tachs read 400rpm too high. (not likely) OR... maybe they are all pretty accurate.

[Glix2]

Originally posted by S800Racer


The evidence based on the responses so far says the fuel shut off is around 7200. Mine and the two others that responded all say the same. So either all of our tachs read 400rpm too high. (not likely) OR... maybe they are all pretty accurate.

Think what you want fuel cut off is at 6800 regardless. Hondata would have no reason to bump our redline to 7200 if it was already there.

If you study our cars dyno you should be shifting at 6500 rpm anyway so why in the hell you're all bumping the rev limiter is beyond me.

[Nosjunke]

My experience with the fuel cut is this;

Your driving your car in 1st gear away from a stop light, you want to bump it off the fuel cut, so you go for it. The motor starts pulling and revs up getting near 6500 rpm, tons of fuel is being crammed into your motor and it's using it almost just as fast as it's getting it. So when you hit 6800 the fuel cut comes in but the motor is already at 7100 or 7200 rpm and runs out of fuel. The split second it takes to cut the fuel off lets your motor go up a few more rpm.

[ortedd]

I think that you can accelerate fastest shifting right before the fuel cut off, because while your car will not be producing peak hp, when you engage the next gear, your engine will already be up in the higher hp range. If you shift at the peak hp, your next gear will drop you further down in the curve. Compaired to the slope of the HP curve after the peak, the slope before is steeper. torque drops off, but being in a lower gear produces more torque to the wheels. People all have opinions on this and mine is to shift right around the cut off. It feels right if nothing else.

Ohh and i would tend to agree that it is possible that the tach is over shooting to some extent, because i definitely get a cut off around 7100-7200

[Surprise]

The ideal gearing/engine would be set up so that you shift at peak HP. Then the resulting rpm drop should be at the peak torque level.

So..
Max Hp @ 6500
Max torque @ 5250

so 1st gear shift at 6500 rpm the next gear if desighned correct should drop to 5250.

[chunky]

Originally posted by Nosjunke
My experience with the fuel cut is this;

Your driving your car in 1st gear away from a stop light, you want to bump it off the fuel cut, so you go for it. The motor starts pulling and revs up getting near 6500 rpm, tons of fuel is being crammed into your motor and it's using it almost just as fast as it's getting it. So when you hit 6800 the fuel cut comes in but the motor is already at 7100 or 7200 rpm and runs out of fuel. The split second it takes to cut the fuel off lets your motor go up a few more rpm.

I can gradually rev my engine to 7100-7100rpm.

redline and fuel cut are two different things. redline is where you should really start thinking about upshifting, fuel cut is honda slapping you on the hand for not shifting fast enough.

I usually try to shift JUST before the fuel cut. I did the same in my 2000 si. redline was at 8000rpm, fuel cut was about 8200rpm

[Surprise]

The real redline is actually above the fuel cutoff. Redline is a calculated/tested piont at which the rotational forces are strong enough to tear apart the engine (rods, spring, rockers, kingpin etc.). Honda and all other engine makers set the indicated redline lower to give the customer a safety margin, fuel cutoff is another physical method that prevents you from hitting the actual redline. It would be more accurate if Honda if honda put yellow ticks at 6800 to 7100 and red ticks at 7100-7200 and past.