I decided to take off the Crawford plenum recently and go back to stock for a while before I decide on another plenum. Strange enough my car feels much much quicker. I didn't know what to make of this honestly, so I let a good buddy of mine (who has enough experience in my car) take it for a spin to get his opinion. Never the less he agreed with me! Im sitting there wonndering what could possibly have happened. Install and uninstall went perfectly normal for all I remember. I casually glance down at the odometer and it said 5030..thats when I remembered someone saying the car gets quicker after 5000 miles. Anyone know what happened here.....Is the 5k theory true? I thought typical break in was around 1200miles max...Your thoughts please bc im really impressed with the cars power afterwards? The only other mod I have is the Greddy Evo exhaust......

 

thats frikkin weird, could it be ....uhh...i dunno!

 

see this thread:

https://my350z.com/forum/tuning/119243-any-current-ts-reflash-experiences.html


we're discusing a theory about the ECU degrading performance for the sake of emissions.

Maybe when you added the crawford plenum, it added power at first, but later stole it back from you via pulling timing. Once you removed it, maybe the ECU determined it could add the timing back?

 

Very possible... ECU is the Brain of your car it is constantly changing mixture etc. The break in period will be different depending on the driver.

 

Maybe a leak in the install process of the plenum? This is the first time I've read of someone having even a remote loss in power b/c of the plenum. Oh well, more power the better! I have mine on the way, I'll post my findings.

ravi

 

The install process was great and I checked for leaks on multiple occasions...once again I dont think I lost any power...if anything it felt about the same with the plenum on. No real differences...but after taking it off it felt soo much better and smoother. Its got me beat?

 

give me a break...

you are relying on your butt dyno and how the car feels to determine if it is quicker w/o the plenum? you cannot be serious?

the only way to be sure is to have gotten the car dyno'd. anything is pure speculation and a waste of time.

plenums have proven to increase horsepower.

 

Chill out man....I know they are proven. Thats what has me stunned. I wouldnt be wasting my time typing if I felt it was a small difference. I also have another source who drives my car often and thought the same thing. Yeah its definitely something you wouldnt see everyday... Im just seeing if anyone else has had the same issue or a possible reason for this. I thought it was an interesting note so I mentioned it.....

 

True..but what good is a dyno if the car feels slower? Isn't that the end result? To make the car feel faster?

 

sorry if i came off wrong.

but i don't believe you can feel your car going faster, unless there was a huge change in power when the crawford was removed.

the reason for dyno is hard numbers, or the best you can get given the science of dyno testing.

did the car feel faster in the low rpm's or high rpm's? maybe he re-gained some low-end torque.

nevermind....maybe the car does feel faster w/o the plenum. since feeling is objective, i'll leave it at that.

 

I thought about the fact that I will regain torque down low once removed....but even on the highway in 5th the car pulls really well. I was easily at 110mph. Before, it felt like it would take forever. Im actually kinda worried that there is such a difference....oh well I guess I'll just enjoy it and leave it at that.

 

when i first put my crawford V5 plenum on, I noticed the sound difference and I *think* I noticed more power up top, but wasn't at all like "holy crap!!!!!" like some of the early adopters have written. I kinda felt cheesed out with how overhyped MANY of these products are.

Maybe I'm just expecting too much from parts to make me say "holy crap!!!!"

 

+1...thats why im ending it and going straight to FI

 

I'd love to go FI, but engine reliability becomes a problem. Oh, and I'm going to upgrade the suspension/wheels/tires before anything else.

 

Yup, it sure is a risk but I'll have faith in it. There are plenty with reliable FI kits. Plus Tuan is gonna tune mine...

 

I agree w/some that the only single "holy crap!!!!" mod is a FI kit; probably a TT that will get you over 500 at the rear wheels. Unfortunately, you also go "holy crap!!!!" 20-30k mi. later when your engine/tranny blows up.

If you plan to also invest in forged internals, add a tranny cooler, a power steering fluid cooler, a larger radiator, and a new thermostat, you might do OK if you only plan to drive your car 10k mi./yr., sell it in several yrs, and don't drive it like a mutt all the time.

OTOH, why not just buy a new C6 ZO6 'Vette (500 hp) if you're a raw power junkie? It won't cost much if any more than a Z w/all the above, even a base level if you add all the "typical" mods of sound system, rims, intake, exhaust, body kit, etc., and the ZO6 will still be more exotic, even if your blown Z could outrun it, which is possible but unlikely.

For many of us who HATE taking our cars in for repairs, who put 25k mi./yr. on our Z as a primary daily driver, and plan to have the car for possibly 100k mi. or more, it ISN'T worth the risk. That's the great thing about a free country, though; to each his own.

 

Very sorry but what is a Plenum? IS that what oyu guys call an intake?

 

Its the intake manifold which consists of an upper and lower plenum. Plenums direct airflow to your cylinders. Aftermarket plenums for the Z are said to allow a more even distribution of air flow particularly to the 5th and 6th cylinders...at least thats my understanding of it...

 

zman1910's exactly right: the problem with the stock upper plenum is that it is designed as a "wedge," which robs cyl. 5 & 6 (the two "front" ones) of air for a faster intake needed to keep a proper F/A mix, esp. above 5krpm. Sad thing is, the only apparent reason for it was to get it under the stock strut bar on the vert., and to accomodate that lovely, tasteful, plastic gladiator shield over the front of the plenum.

And I'm also happy you got a helpful response to your question. One of my partners is a certified car nut and drives a Boxster S; one of my neighbors mods American muscle cars; and neither one had any idea what a "plenum" was until I said the magic words, "intake manifold." But when most of the people on here talk about the plenum, they mean "upper plenum," which is the top part of the intake manifold.

 

+1 on the VETTE

I plan on having my 350 way beyond 150k, especially with the miles I put on each year. It's why I will never go FI, besides being way to expensive to maintain. But if you have plenty of dough, I say do it, FI is always fun

I have 1500 miles on my AAM spacer and it still pulls hard. It was instant gratification...imo, BBB for the butt dyno!

Zquicksilver