but i got a quick question... ultra, i remember you telling me that it would be a bad idea to change the timing of the vtec because it would mess up the timing or do some damage. i don't remember exactly what you said, but given that... wouldn't it be a BAD idea to use one of these to change vtec engagement? all comments welcome... no flaming plz :akuma
so basically you want to increase the engagement point to higher rpm's? i don't understand why... i just thought that since when the vtec kicks in that it increases the efficiency of the motor and allows more air in (am i right about that?) that it would be better to open vtec sooner.(move engagement to lower rpm in theory)
you want to increase the point when and only when you have aftermarket cams that are usually much more aggressive than the stock pieces and require the extra air/fuel. engaging too soon and you wont have enough airflow and you'll bog down. too late and your mid range sucks. different cams like different x-over points.
regular engines can either work well in the higher rpms or the lower rpms. this is because of how the cams are setup (also bore vs stroke, but that's irrelevant for this discussion). a motor that is purely high end sucks in the low end and vice versa. the beauty of any variable valve control is that you can have both kinds of profiles in one motor. but if you set the crossover too low, then you basically have the hot lobe at too low of an rpm to be effective. now if you've tuned the motor, a higher x-over point would be ideal in some cases because of the camshaft profile. some camshafts are made to make power between 6k and 10k, so why would you need to hit vtec any lower than 5.8k? you'll just be wasting gas and bogging down. that's why people who lower their vtec x-over say it hits harder because you're actually bogging down first, then hitting the sweet spot for those (usually stock) cams.
cool, so raise the vtec engagement up when you've got aftermarket cams so that you get the vtec at the higher rpms, where you'll need the extra kick...
so, what about this... is this a smart idea? say you have a vtec and a turbo, right? is it a good idea to control the vtec to come in at... say 5k and then the turbo to come in at 6.5k to add 3 stages of powerflow? ya know, normal then vtec then turbo... it's just a theory i got... or is it better to have vtec and turbo at the same time? or maybe turbo, then vtec... i dunno
you always want vtec to be where there is maximum amount of air flow. that is when it is efficient. anything before that is just going to bog down the motor. also, w/ turbo, vtec in it's stock form is bad. vtec will increase duration and there will be valve overlap which is bad for a turbo setup. which is why you need turbo camshafts in a turbo motor. and usually turbo camshafts have their profile in a way where the hot lobe is good for boosting in the high rpms. well guess where vtec would have to be.
A forum community dedicated to Honda and Acura owners and enthusiasts. Come join the discussion about performance, modifications, concepts, reviews, classifieds, troubleshooting, maintenance, and more!