Just curious what is the lowest you lowered your VTEC engagement point using Apexi VAFC on a ITR ?

Whats recommended and whats low within being safe?

Thanks for replies ahead of time

 

When I dynoed my car yesterday, the tuner there said that they had another Type R in there before that had a V-AFC. They set it to 3500 and there wasn't enough oil pressure to engage it.

 

You can go as low as you want, it's always safe. The motor won't blow up for sure.

 

So at what engine rpm was there enough oil pressure to engage it?

 

how come people want to set it THAT low is what I want to know......?

 

I see...but what is recommended? I've heard if you go lower than 4500 RPM you actually LOSE power. Can someone enlighten the rest of us on this subject?

 

He never told me. Basically, he wanted to move the increase in the torque curve which happens at the vtec engagement point. So they moved it as far back as 3500rpms and move it up incrementally. I don't know how familiar they are with honda's since the cars I saw a at their lot were M3s, and porsches, and a nice ferrari testarosa. Plus they said that the best performing header they've seen on an ITR is the one made by JUN. I then asked him if he's heard of Spoon and he had no idea what I was talking about.

 

Wow 3500 sounds real low


like yakkosmurf i am wondering at what rpm does it have enough oil pressure

Anyone have any other input I heard that there is a point where you lose something but what is it?

 

Doesn't the Mugen ECU have the VTEC cross-over at 4600 rpm?

Mattj

 

Ragin - This is the explanation I got from the tuner.

I got this image from S&M Racing because it is similar to the dynoplot that I only have a hard copy of. Hope Aleph doesn't mind.



Beginning at the vtec engagement point, the torque curve starts rising and it starts to plateau at a little over 6k rpms. He explained to me that by moving vtec down, we can see the increase in torque sooner as well as increase the range of the plateau. So instead of consistent increased torque from 6K to 7100 rpms, it will start sooner but still fall off at 7100rpms. Was this guy blowing smoke up my ***?!


[Modified by CPR, 5:48 PM 10/31/2001]

 

yea i think mugen's is at that point but there ecu might have some other programing that a VAFC dont have to make that happen effectively....i dont no for sure but i doubt the Mugen ECU does the same thing as the VAFC

Does anyone know for sure ??

 

Yeah, the guy said some low number like that, which sounded ridiculous at the time, but I'm having some second thoughts right now.

 

i dunno i think 4600 sounds alot better then 3500

from what i heard the lowest you should go is 4000 but i dunno for sure and its all hearsay so thats sorta why i am trying to ask guys in here if they have any suggestions from experience

 

A friend of mine had his vtec setting on his type-r at 4800rpm, that was only his "Seat of the Pants" impression, he thought it felt like a good engagement point. But when he brought it to the dyno he lost a lot of horsepower and torque when he hit vtec. So when he raised the vtec point to 5500 it was "optimal" point for his set up. He gained back like 13lbs of torque and 15whp between 4800rpms and 5500rpm that was lost for setting his vtec too early. His car only had dc 4-2-1, dc cat back, AEM CAI, AEM pulleys, and Mugen headgasket. Goes to show once again that the dyno is best place to tune your car.

Cheers

 

umm...your mid lobe on your cam..doesnt get to use all its power..when vtec is that low...

 

I have my V-tec set @ 5100,what is the stock vtec engagement

 

I hear the best point for VTEC activation is 1200 rpm. That's what my dyno operator said. He said that that way I'll almost always be in VTEC, except when I'm idling. Don't try and arbitrarily set your VTEC point without tuning on a dyno. One good method is:

- do one pull with VTEC set for 9000rpm
- cool off engine
- do one pull with VTEC set for 4000rpm or something else ridiculously low
- superimpose both charts
- find the RPM where they intersect
- set VTEC for 100-200rpm lower than the intersection point to compensate for activation time
- enjoy your properly tuned VTEC activation point

any other way is a complete waste of time. If any tuner tried to tell me to set it for 3500rpm I'd get a new tuner.

 

Tune it on a dyno.

Don't "trial & error" your VTEC engagement. With a V-AFC, you should be able to optimize fuel, spark, and cam switchover... there is no silver bullet. You should be able to tune it using the scientific method.

FWIW - I have seen V-AFC reprogrammed VTEC switchovers at 5300. However, this is just a astarting point, your mods (such as they are) might respond differently.

To sum up ...tune it on a dyno...

 

can anyone confirm this is a good way of finding the ideal vtec crossover

 

id rather have the vtec come on around 5500 or 6000 rpm....my .02

 

no lower then 4600 but keep it above 4800 to be safe

 

Lowering it does absolutlly nothing unless you have the vtec fuel curve come on at the same time...if you lower it 4500 you will be in vtec at 85mph on the highway which can fry your valves...go no lower than 5,000 and go to a dyno...don't touch the fuel unless you are on a dyno...everyone gave me the advice I just gave you

 

So I guess if I trip VTEC on the highway it'll fry my valves? What?? When did hitting VTEC even at a lower RPM point cause it to fry valves?

Like seriously...I'm wondering here.....

 

Hey guys I am new to this board but I know what up with the V-AFC from tuning it on my 00SI.... Just to let you know I could tune this thing like nothing now that I have being messing with it since march. Stock VTEC point on my car is 5400 RPM according to when the VAFC gets the signal from the ECU. You gotta understand that if you lower it it will affect how much fuel you need because VTEC will obvisously need more right, well then you have to go into the screen where it lets you adjust the % between where the STOCK(5400rpm) and where you set it.EXAMPLE-5200rpm. Besides adjusting the amount of fuel from a few different options you have, with the VAFC you can't adjust the MAP control for example the igtion timing which also effects VTEC. I have mine set right below 5400 rpm most of the time but on the highway a couple of times racing a TYPE-R swap I raise to 5500rpm and have had a better top end since I never went down to 5300. Anyhow I have played with it like at 4500rpm and it didn't help and instead lost some HP. It just rode around on VTEC all the time and it wasn't even as loud when it engaged. Just my 3 cents...

 

Would you like ketchup with those valve fries... heh heh


Seriously though, the valves would be fine, but cam wear would be heavier ( pretty steep ramps, not meant for constant engagement at low oil pressure... you know, less lubricant and all that rot ) but the fuel economy... YIKES!!