I want to know if any one has done this with the VG maxima IM and Heads.

i want to open up or fill in the areas around the injector in the IM and head to attempt better air flow



i have seen some examples of filling it in a little to reduce vacuum loss and fuel sticking to the walls in Z31 NA builds. im almost ready to attack my heads and Intake to maximize flow and fuel atomization so i wanted to get some ideas or opinions before a go shooting my self in the foot.

i am adding Stage 1 JWT cams to the heads so i can utilize the flow.


thank you for the comments and ideas, its greatly appreciated.

 

Lots of fuel consumption threads here on the forum - what is yours with your particular driving habits/style in comparison to the best reported in these threads?

Personally - I wouldn't bother if my own experience with the VG is anything to go by (std everything on the motor gets me around 8.5km/l in town and 11km/l open road at 120km/h)

 

My recent best at 75mph (120km/h) on an 8 hour highway drive was pushing around 27 mpg (11.5 km/l) which was not bad but i average daily drive 26 mpg at 75 to 80 mph. but the main concept of my post is the modding of the head. i dont know exactly what my results will be. if i get improved power with out much loss in MPG or any loss i will be happy. but mostly im just doing minor porting on the IM and intake ports with more major porting on the exhaust side. i have a make shift flow testing rig to get some numbers with. when im done with the heads i will post the numbers i get. but this is on a spare set of heads so im not killing my daily driver if i F* up. i done 302 and honda heads before so im confident in my ability to not screw up horribly.

 

I'm pretty sure porting the heads and manifold would make more top end and less low end and mileage. If you really want good gas mileage get a Civic I don't know why anyone wastes their time trying to make a car with a heavy cast iron V6 get good gas mileage when you could easily double your gas mileage by buying a cheaper car from the same time period. Hell put a D16 in the Maxima if you can't deal without the body and interior of one.

 

If it is done correctly it should improve both hp and tq

 

well as i thought i mentioned im not aiming for awesome full economy, im looking for anyone that has modded the heads and IM in the fashion that i am discussing. if this still remains unclear then i apologize.

 

Port Matching and minor clean up in the bowl area only increases velocity do not touch the floor or hog out the port just mildly clean & blend transitions and you'll be good...

 

You could polish the intake runners to a very smooth (mirror-like) surface upstream of the injectors.

You might be best off not polishing the runners around and downstream of the fuel injectors, as some surface roughness there is theorized to aid in air-fuel mixing.

 

a rough surface cause a thin layer of air to stick to it acting as lubricant for the air fuel charge. the surface is consistant with 120 grit sand paper if i remember correct.

 

to answer you question i'm in the process of the same project. I had a local shop port and polish my heads and the intake to match the gaskets. Currently the heads and intake are complete. I also put JWT stage 1 cams in the heads. I replaced all the valve springs lifters basicly replaced all parts in the heads. the car is being put back together and should be complete in a week or so. I'll post some updates on how the car runs, keep in mind the car needs to be driven for about 1000 miles to break in the new cams and parts so i won't be beating the hell out of the car to see exactly how big an improvement there is until i hit that 1000 mile mark. I'll keep you posted. If you want pm me and i'll send you picks of the heads and intake.

 

i really hope you did a before and after dyno...so you can see how much you paid and what you got for it...

 

Yes yes yes, right on the money, 120grit flapwheel is where I leave manifolds for customers because it gives it a nicer & smoother look, but on my own personal stuff I leave it even rougher. Thing of it is though, it isn't a noticable difference by any means, but why do extra work in a situation where if there was a noticable difference it would be the other way around.

Also, not sure what you guys have for possibilities here- but on the 3.5 manifolds when I port match them a good portion of the improvement comes from marking each individual bolt and giving it a specific hole, then I wrap tape around each bolt one by one until it is a snug fit. On the 3.5 mani's all of the mating surfaces (except lower to head) can literally be misaligned up to a 1/4"!! and adding spacers to the mix (which you should be! nwp ftw) makes this even more prevelant since it doubles the mating surfaces. Lots of room for gains by getting rid of these production tolerences for sure.

NOW, personally, if I had a cammed out VG, what I would do is figure out one way or the other how to stick a villager manifold on there, even if I had to cut the damn hood and put a scoop on it. It's real similiar to the pathy in design, and adding a pathy manifold w/the bigger throttle body & all onto my z31 gave some pretty unbelievable butt dyno gains. Not sure if anyone has looked into the villager manifold, I don't know if the TB is still bigger or not either, but I'm thinking it might be easier since it's off a fwd.

 

WTF! @ edit

 

you do realize that stock for stock the maxima had the best intake.
both the quest and the pathfinder had lower HP numbers, only the Z31 equaled it without the VI. That could very well be because the Z31 possibly used different cams? I don't know for sure, it may be because of the Z31s exhaust as well.