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I just got a VTEC controller made by A'pexi about 2 days ago. it is awsome, but i need some help with it. i know how to raise and lower VTEC engagement, and mess with the fuel in the wide throttle and narrow throttle. does anyone know what is the best air to fuel ratio to imput in the wide throttle section? the place i bought it from told me to mess around with it untill i found the best results and then bring it in to get it on the dyno. i dont have any money to dyno it so i wanted to know if anyone had the info to imput in the vtec controler. i have a 2000 GSR.
Thanks alot
SKYY55
 

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the torque curve should tell you how far to go. the air fuel just tells you the direction to go and serves as a warning limit indicator to tell you you may be approaching lean areas that may be dangerous. Most people stay around 13.5:1 as a limit but each engine is different. Some people go leaner as long as their engine temps don't spike up on them. I've seen 14.0:1-14.2:1 but not any leaner . Other people tell me they push even past that. They have more kahonas than I do...
 

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this is not a answer to your question, but i was wondering i have a gsr turbo what would be the best rpm to engage the vtec or should i just leave it alone
 

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MD, I was under the impression that you should leave the VTEC engagement point where it is if you have stock cams cause the boys at Honda already figured out the best point for it to engage with those cams. Since Skyy55 doesn't mention having aftermarket cams, shouldn't he leave the engagement point alone?
 

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I just dyno tuned last nite and corrected the huge dip I had in my torque/hp. I gained back the 60hp I had lost in that dip. (check my dyno graph posted here) I now have my VTEC engaging at 4500rpm and the power and engagement is soooo much smoother and pulls very nice. I will be at the track tommorow for Import Wars here in New Hampshire so I will let you all know if I beat my current best of a 13.8 !!
 

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Good luck ati2ude...I hope get into the low 13's....Your car is my favorite on this whole site....besides mine of course
 

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I always thought that it wasnt good practice to mess with stock settings unless the car was on a dyno and showed where and where not to set A/F points/settings.

I have an R-Spec vtec controller (i really only bought it to get rid of the speed limiter on my jdm teg) but found by messing with the settings that 4700rpm seemed to give a greater lift than any other vtec engagement point. there is absolutely no gains at all setting it lower tha 4400rpm, and there is a huge kick if i set it at 5800rpm, it really pushes you back into the seatbut its slower getting there!
 

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usually the vtec controller is used on new cams or a new induction system (IM and/or headporting) to allow you to tune for a broader flatter torque curve, using the air fuel ratios as your compass. Each engine will breathe uniquely, as it is modified..not all b18's will breathe the exact same way even though they may have exactly identical parts. The air fuel ratios will vary slightly at each rpm. This can be related to miniscule variations the way the engine was assembled at the factory and how the engine was broken in and maintained.

if you have modified the volumetric efficiency, then the stock settings are no longer the ideal settings. you are correct in saying that moving vtec earlier with stock cams ,IM , head, and exhaust system will generally not improve performance. it just makes the car run richer. you are also correct in stating that the best way to mess with the settings is by dynoing her using the air:fuel ratios as a compass to help guide your settings (which rpms to change, in what direction [more fuel or less fuel] , and by how much ).

If you have a GSR with stock cams and headwork, then moving the vtec to 5800 rpm when the IM secondary butterflies open will feel laggy since you are on the nonVTEC lobes at their plateaued peak power for too long. If you go to a dyno, try setting the VTEC at say 7500 rpm (i.e. most of the dyno pull is on the nonVTEC lobe), you will see when the nonVTEC lobe peaks out. You should set your vtec about 300 rpm before that plateau point. As I said each engine will breathe a little differently and have slightly different max out rpms for the nonVTEC lobe.

The reason you get sudden surge is because you just opened all 8 runners (max flow capacity) in the GSR IM and you are running on the big cam lobe simultaneously.
 

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I had a nice discussion on the benefits of having staggered primary nonVTEC lobes over at hondavision.com with a member there. As you know, when you look at a VTEC camshaft, there are 3 lobes per cylinder. The huge vtec lobe at the center of the 3 lobes are flanked by 2 nonVTEC primary lobes. These 2 primary nonVTEC lobes do not have the same lift on the stock cams and on most aftermarket VTEC cams. They are staggered to induce swirl filling at low to mid rpms.

The only aftermarket cams that don't have this primary staggered lift are the Toda cams. They decided not to stagger theirs but instead they both have the same lift. This begs the question as to how important is it to induce swirl early since the Todas are notorious for having a very strong midrange for a road racing cam.

Here is the thread on primary lobes:

Primary NonVTEC Cam Lobes
 
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MichaelDelaney
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