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only MIVEC?

Posted: Sat Jul 20, 2013 8:10 am
by cranswick
Would it be possible to run ONLY in MIVEC? or "how low can you go"? since the 4g69 is not DOHC, valve timing can't be adjusted both sides, both ways, so when does MIVEC become useless, or could it be made to work effectively all the time, and what would be the pros and cons?

just thinking out loud here...also i was thinking about how throttle limit by rpm could greatly augment the effectiveness of daily driving traction/control, and launch control at the track...mmm....dual maps

Re: only MIVEC?

Posted: Mon Jul 22, 2013 7:09 am
by darewood
that is something I'm really interested in. Was always curious as to how long it could be driven with it "activated"

Re: only MIVEC?

Posted: Mon Jul 22, 2013 8:20 am
by hackish
You need a certain amount of oil pressure to activate it and the mivec cam lobes and valve timing are optimized for high rpms. So basically your non-mivec cam profile produces more power at low rpms but when it starts to fall off mivec kicks in with the lobes optimized for high rpm and thus go on to produce more power up high. In short, nothing to be gained, everything to be lost by doing this.

-Michael

Re: only MIVEC?

Posted: Thu Aug 08, 2013 8:33 am
by cranswick
where's the sweet spot? some earlier models had mivec come on at 3500 from the factory, and later models mivec kicks in a fair bit later

Re: only MIVEC?

Posted: Fri Aug 16, 2013 8:36 am
by darewood
I still havent found my sweetspot. I'm thinking it might be 4,500 with this new cam. I tried 3,500 but it seemed too low, and the stock 4,000 works, but seems to die out fast. I'm running 5,000 but seems too late. So 4,500 might be the sweet spot.

Re: only MIVEC?

Posted: Sat Aug 17, 2013 9:52 am
by hackish
First set it really high, tune the low cam maps. Then set it really low, tune the mivec maps. Finally pick a point that gives you a smooth transition without any lurching. It's best to find it on a dyno but you can get it pretty close by the seat of your pants.

-Michael

Re: only MIVEC?

Posted: Wed Aug 21, 2013 1:39 am
by cranswick
you set mine at 6-8psi on the dyno, now that I got the tune pretty solid for 94 at 11.8psi i'm scared to touch mivec, lol

just wondering if changing it will throw my AFR out to lunch and harm the motor more so than I already am :?

Re: only MIVEC?

Posted: Mon Aug 26, 2013 12:35 pm
by hackish
Since it was set on the dyno there probably isn't a lot of value in changing it. You can try moving it around but you will need to pay attention to the switchover fuel and timing.

-Michael

Re: only MIVEC?

Posted: Sat Sep 14, 2013 7:20 am
by cranswick
yeah, i'm really happy with the tune right now, I feel like that would be stepping backwards...thanks for the info