PnP ? group buy on extrude hone
 

I recall seeing a story in honda tuning couple years ago where a guy with a D16Z6 had his IM extruded and he got a little increase in mpg along with a bump in trq/hp as this smoothed the airflow alot. anybody interested in having their VX Intake Manifold extrude honed? Their site says 15-20% discount on group buys of at least 4 same parts(time saved for them to change their equipment).

Maybe having it port matched first will help ? let me know what u guys think. ive mostly though along the lines of PnP for hp/trq but now im thinking along power/fuel efficiency*spell check*. Last time i checked they charged $395 to extrude Intake/Exhaust manifolds.

I'm not sure why you are trying to increase your fuel economy, but if it is for economical reasons then it will take an extremely long time to break even. $395 can be spent much more wisely in other proven modifications or towards fuel.

Changing the length of the intake runners will probably be detrimental. Intake runners are sized based on Helmhotz resonance. By timing intake pulses (caused by valve closure) to valve overlap, cylinder scavenging is improved. The runners should already be sized to either remove an inconsistency in torque (usually ~3000rpm) or to improve low-end torque (<3000rpm).

Porting and polishing are generally undesirable in the hypermiling field. It has a tendency to increase hp by raising peak torque - the opposite of what is generally desired.

Additionally, the VTEC-E motor is set up excellent from the factory for fuel economy. When you are only developing ~12hp at cruise, you don't need large pipes or high flow rates. The major constriction, the throttle plate, is already taken care of through lean burn.

Lastly, modifying your vehicle permanently will adversely affect your car's resale value. Once you customize an automobile, you make it much less desirable for the common man...who will probably not appreciate your taste. Your car has inherent worth. By maximizing its resale value, you'll save money. If you are concerned about costs, focusing on the whole picture will see you furthest ahead.

- LostCause

:confused: sorry u got me with the holzman thing. :confused: i was under the impression that improving airflow efficiency would be a good thing. yes my goal is improving fuel economy. so sounds like porting is not best for mpg. that guys ex increased mpg :) more likely from the polishing since it reduced restriction on air flow.
I didn't say anything about changing runner length.I'll be using the stock VX intake manifold. and from that EX's results he got an extra 15-30miles on a full tank.damn wish i could find that article! maybe i can search honda-tuning. As for resale value LOL It's already been improved with the shiesty-earl-schieb paint job alone; not to mention all the upgrades i've done myself on it;suspension,motor,ect.
I plan on keeping this :turtle: much longer, thats why i'm swapping the stock VX back in and selling the 130hp D15B sohc vtec i've had in it past 4yrs or so.
Another possible upgrade is with a Crane Hi-6 hi capacity ignition i used to have but traded for some work done on a Camry i used to own :o. That helped idle and smoothed combustion, dont recall how much i gained mpg from it tho. I think i spent $200 for that with msg cap from summit racing. Appreciate the feedback tho!

Porting and polishing improves efficiency by smoothing flow, unless I'm missing something.

A rough texturing on the intake side of the engine is a good thing. It helps create a thicker boundry layer at low intake air velocities. This ends up speeding up the air flowing directly through the center of the intake. We should all know fast flowing intake air is a very good thing as it increases in cylinder turbulence and increase torque. As the mass of air flow increases the boundry layer gets thinner to accomodate the increased volume. At some point this will create a restriction, but for us this should never be a problem since we don't use anywhere near peak horsepower. Polishing the intake will reduce the boundry later and therefore decrease low rpm torque. As LostCause mentioned, this is generally bad for mpg.

by doing this work you would also be enlarging the intake, because you are removing metal from the intake until you get to the "even" part of it.
I've also read that the air intake is intentionally left with the rough texture, both to help with air flow like was already stated, and to help with fuel mixing, that it wouldn't have been that costly to do this kind of work at the factory when you have 10,000 intake manifolds that are being built, if it really did help, and that an easy way to do that would be to build a welded intake, instead of a cast intake.

ok so it sounds like PnP is a good thing for increasing hp/tq towards performance, but too much increased airflow = ecu compensating by increasing gas, which decreases mpg improvement . thanks for the input hombres. i may just get a throttle-body spacer/vortex thingy which is only about $100 and NOT do the EXTRUSION $369(+-).

If you think it will help, (I don't know) use a flap sander and a drill inside your intake, I've done a few intakes that way, none turned out as well as the 504 we had extrude honed for a Boat, but for about $40 (probably much less) in flap sanders, and a few hours you have a result similar to Extrude Hone.

My procedure goes something like

2.5" 40 grit everyplace it will fit, do the big spaces first, because the wheel will wear down and end up smaller.
1" 40 Grit everyplace else, again do the larger spaces first, the wheel will shrink with use

2.5" 120 grit to smooth it out
1" 120 to smooth it out

If you want to go all out grab a sheet of 300 grit and wet sand everyplace you can get at in a direction along with the airflow, not really necessary, the 120 leaves a very nice/ smooth finnish in Aluminum.

Drill works well for 2.5" Drill press is best, a die grinder works extremely well with the 1"

lol i busted out the dremmel just to clean out the exhaust ports. and wire brush. then brake cleaner. hope that stuff didnt kill my o2 =(