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-   -   Rev limiter at lower RPMs (https://www.rx8club.com/canada-forum-35/rev-limiter-lower-rpms-13358/)

Jasper_the_2nd 10-24-2003 03:12 PM

Rev limiter at lower RPMs
 
I'd read about the variable rev limiters in other cars, but I didn't think the 8 actually did that, until today.
Hopped in the car after work (a balmy 5 degrees), a didn't give it very long to warm up, since I was in a hurry. I didn't have to wait the normal minute and a half to pull out of the driveway. The on ramp to the highway is right across from the driveway at work, so normally I just pull out and go straight onto the on ramp.
I got about half way across the road, and the car hit the rev limiter, at 6500 rpm. Not expecting it, it bounced a few times before I even realized what was going on.
Once I got up on the highway I dropped down to third to see if it was still doiing it, but it was back to normal by then.
Is this something normal, and I've just managed to never get out of work that quickly, or what?

ZoomZoom 10-24-2003 03:28 PM

The rev limiter on the RX-8 is set to kick in at 9,500 rpm. However it sounds like the ECU is programmed to lower the rev limiter to 6,500 rpm until the engine is fully warmed up. I know that this technique is used in the Honda S2K, the engine in the S2K will not V-Tech until the engine is warm.

Sounds like your engine was not fully warmed up when you got to the ramp that day.

Wing 10-24-2003 03:33 PM

That happened to me once leaving work, I was just exiting the my spot and punched it a bit and I really didn't expect it! But then I tried it again about 10 seconds later and it didn't do it.

I think it's smart to have but it will only happen when the car is frozen. Come winter I'm sure more will notice it.

lurcher 10-24-2003 03:39 PM

It's normal and is mentioned in the manual; which BTW also recommends a long idle warmup only in very cold conditions - less than -18C/0F - or when the car has sat idle for several days.

Redshift 10-24-2003 05:02 PM


Originally posted by ZoomZoom
the engine in the S2K will not V-Tech until the engine is warm.
The engine in the S2K will never V-Tech, since that is a brand of cordless phones.

VTEC, however, is a totally different technology... :)

Jasper_the_2nd 10-24-2003 05:21 PM


Originally posted by Redshift
The engine in the S2K will never V-Tech, since that is a brand of cordless phones.

VTEC, however, is a totally different technology... :)

Fun, I had a conversation about that the other day.
I friend (and Honda owner) noticed I had V-tech in the kitchen.
:)

f1michel 10-26-2003 10:07 PM

never idle for 90 sec it's a waste a very valuable fuel, by the time you have your seat belt buckled you're ready to drive away, although not at 9 K .

5Gen_Prelude 10-27-2003 01:44 AM

Not sure if this is also true with the 8, but VTEC also won't engage unless you're at WOT. It will allow you to rev to redline as normal though - just the 2nd lobes don't engage

Redshift 10-27-2003 07:43 AM


Originally posted by 5Gen_Prelude
Not sure if this is also true with the 8, but VTEC also won't engage unless you're at WOT. It will allow you to rev to redline as normal though - just the 2nd lobes don't engage
Not sure I understand what you mean, but either way, I think it's wrong.

If you mean that the computer will not let VTEC engage until the engine has warmed up, that is true. Regardless of WOT or not. (Since VTEC actuation is controlled by oil pressure, it can't/won't engage until proper oil temperature is reached.)

If you mean that the computer won't let VTEC engage unless you are at WOT at any time, well, that's not true. I drove an SiR (and by drove, I mean thrased) and VTEC engages at a set RPM point, not a set throttle position. Trust me.

takahashi 10-27-2003 07:53 AM


Originally posted by ZoomZoom
The rev limiter on the RX-8 is set to kick in at 9,500 rpm. However it sounds like the ECU is programmed to lower the rev limiter to 6,500 rpm until the engine is fully warmed up. I know that this technique is used in the Honda S2K, the engine in the S2K will not V-Tech until the engine is warm.

Sounds like your engine was not fully warmed up when you got to the ramp that day.

Not just the S2K... my B17C Integra Type R (DC2) has no Vtec when the engine is cool

5Gen_Prelude 11-01-2003 02:32 AM


Originally posted by Redshift
If you mean that the computer won't let VTEC engage unless you are at WOT at any time, well, that's not true. I drove an SiR (and by drove, I mean thrased) and VTEC engages at a set RPM point, not a set throttle position. Trust me.
Sorry, I don't trust you. There's actually 10 VTEC points depending on the TP which can increase the cross over point and at very low TP, eliminate it all together. Saying you can't engage it at WOT wasn't quite correct, but saying there's a fixed point isn't either.

Anyway, my point was simply that there are a number of factors (including speed) that decide when VTEC and the secondaries engage, not unlike the 8's

Redshift 11-01-2003 03:10 PM

Well, we both oversymplified to some extent, seeing as how this isn't a Honda discussion board, I didn't feel like getting into it any deeper. I guess you do for some reason. I just wanted to point out that WOT had nothing to do with it.

*shrug*
Regardless, my SiRs cam profile would change over at 5500rpm whether I was at WOT or barely giving it enough throttle to accelerate... assuming the car was warmed up, had consistent oil pressure etc.

Same story on the 2 'Lude SHs, the 3rd Gen GS-R, the 3rd Gen GS-R w/ Type R cams and Hondata computer, 2nd Gen GS-R, 2nd Gen LS/VTEC Hydbrid and the RSX-S owned by my friends.

I'm not saying that the activation point can't vary a little bit, but in the 4 years I was into Honda's I never heard of these 10 specific activation points.

5Gen_Prelude 11-01-2003 06:02 PM

I send you the link if you care.

Redshift 11-01-2003 06:58 PM

Actually, I would like to see it, if you wouldn't mind.
Not that I don't believe you, so don't think that. I'm just surprised I've never heard of it before, and would like to learn more about it.

5Gen_Prelude 11-04-2003 01:40 AM

There's another link I can't find right now but here's one: http://www.hondata.com/techecuanatomy.html


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