Posted: Aug 14 2007 at 4:32pm | IP Logged

I dont have the TBS not sure my self how... IMPRESSIVE.... the gains will be, but headers are a must for any tuning... remove all posible restrictions before things like... cams, porting or reflashes/ chips... because you need a healthy base line for proper dirrection.

Going with that, i just drove to plymoth ma, a good 100 miles each way, all high way and i averaged 23.7 after the trip with some city in side that 200 miles with k&n and headers... i can only immagine what a cat back will do... i might get the stillin kit just because its compleatly pre made, you just un bolt and rebolt. all polished stainless. i think its like 500-600... torque will be sacrificed slightly by this upgrade unless you keep some back presure... for the 4 liter, i dont see any gains of a 2.25 pipe... thats almost stock. 2.5 at least to 3" would be an actual gain, just with 3" it needs to be mandrel bent or it will be kinked, or egg shaped.  Just because it sounds hi flow doenst mean it is, just has less baffels.

Posted: Aug 16 2007 at 10:41am | IP Logged

what y'all should keep in mind is what the throttle body spacer is supposed to do, it's supposed to in most case increase the length of the intake route to increase velocity and volume of air going through the intake manifold as well in a lot of the models they are "rifled" to cause turbulence of the inflow to better atomize fuel/air mixture. i've heard a lot of people say that on newer MPI (multiport injection) motors that this is useless or doesn't justify the use of these devices because the injection point is moved further down the causeway so to speak. and if you take a good look at the intake manifold on the 3.3 or i would imagine the 4.0 as well (haven't had a chance to really study that engine) you can see how the manifold is not a straight line into the combustion chambers. it is curved and also they get smaller, so any turbulence of the air would probably be canceled for the most part prior to getting to where the fuel is injected. so in essensce canceling anything the TBS did before the air got there. I am by no means an expert mechanic, hell i wouldn't even really call myself a good mechanic lol...just a weekend wrench turner at best, but i do enjoy learning about my truck and how to improve performance.  i have thought tho, and posed this question in a previous post i believe: what if, to provide that "turbulence" closer to the injection point, you could rifle or groove the individual outlets on the intake manifold to cause the air to spin or a mini vortex so it could effectively do what a TBS is supposed to do. would you see gains on this, don't know...i for one...am not ready to yank my manifold off and try it on  my truck as it's my daily driver.  i would love to know definitively if TBS's work on our engines because everything i've said above is anecdotal because that's how i've seen it explained. the only true way to know for sure would be for someone to take their truck, run a dyno pre-TBS and then post install and see if there were any diff obviously, if i find any information to substantiate this either way, i'll be sure and let pass it on.

Posted: Aug 16 2007 at 3:26pm | IP Logged

actualy grouving the end of the intake runners would actualy create quite the disturbance in air flow. there are already several other options that correct this issue. Some to mention are ceramic coated cylindar heads, back cut valves and even the whole 4 valves per cyl helps since the two intake valves open sequentialy, this already starts a vortex inside the cyl to aid in atomization.  Of Coarse this is all alittle over the top, i dont plan on drag racing my Frontier into any 10 second brackets.  I Dont know alot about the Air flow of the 3.3 with the eaton charger on it, but i know even it cant push more than 9 psi, the Vg motor lacks at the top end from suffacation, patialy from a few issues. on NA from intake manifold the Runners are a great design for torque, but dont have the ability for high rpm asparation, so yes as you mentioned the TBS is usless, just makes more whissle. Correct me if im wrong but isnt that still a 54mm tb? or is it a 60mm? 2nd Get headers, part of the problem on the Vg is its cast manifolds. Most headers have equal legnth runners so they hit the collector at the same time, causing vaccum on unfired cylendars helping scavenge the exhaust.

My point is , why bother modifying things that arnt the issue..