That would be hard to do since you would need the upper plenum, the lower plenum and the actual intake manifold that attaches to the head. would be interesting though.

 

Thanks for the offer. I am game, but the only drawback is that flow bench testing is somewhat limited in what it can tell us about plenum performance.

Flow bench will make a great measurement of relative static flow charecteristics and pressure drop, but real world use is pulsed flow. There won't necessarily be a linear correlation between the two. And it won't necessarily indicate which will prevail on the dyno.

 

i'm in a retarded phase right now, where is the increase in air volume coming from on the lower plenum?

thanks

 

I've got all three available for testing.

 

It looks more like the runners are re-tuned to a higher quarter wavelength for more flow at higher RPM.

My guess is it will take out a little low end and put it up high. If they also increase the flow area between the top of the intake runner and the bottom inside of the upper plenum they may also increase the low end at the same time.

We'll see.

 

gotcha thanks

 

I too want to use this in conjunction with the Crawford plenum. Is there really such a thing as too much volume? Would it lean out the mix or something?

 

I just got back from dynoing my car... Well about a half hour ago... Had to do some paperwork when I got back :-/

Current performance mods on my car...

JWT Pop Charger (Stock Z Tube)
DC Sports Ceramic Headers (Stock Cats)
NISMO Cat Back Exhaust
UR Crank Pulley (blue)
TILTON Full Street Clutch

Also... 18x10.5" ENKEI NT03+M w/ Kumho Ecsta MX 295/35/18 Tires at 32PSI Cold (makes a difference on the dyno)


I compared it with a couple of other 350Z's dynos with simlar mods... I must say, I am impressed with my torque curve (if there is really much of one)...

I am a bit lean up to 4200... If I fix that my lower torque would be better as well as HP... I am very happy with where my car is now with my amount of performance mods...

I asked, the vinyl didnt help my HP

RWHP - 258.2
RWTQ - 237.4

And I drove WOT 32 miles under the CA sun. Put it on and did the pulls... So my car was pretty hot...

 

Looks like Nissan retuned the lower plenum with shorter runners. Isn't that supposed to give higher peak HP with lower low end torque?

Jason, when are you guys going back to R&D? I'm sure a few of us would like to check out the dyno runs. Also, how much were the runs? I've been wanting to get my car on a dynojet.

 

Wednesday it looks like...

$100 with AF
$75 without AF

 

From what I have dynoed so far, I haven't seen anything indicating there can be too much volume.

I've dynoed 1/4", 1/2" and 3/4" plenum spacers all on the same engine and the power curve area only went up with increasing volume. In fact I don't think we will ever see an upper volume limit on the Z. The 3/4" spacer is so large you can even close the hood. The 3/4" spacer barely fits in the G35 Sedan but will fit no problem on the FX.

For purposes of thoroughness, I will be mapping out how much plenum potential is available. I will dyno a range of ridiculously large plenum spacers on an FX. At some point there will be diminishing returns but at least enough data will be available to make a plot of power Vs plenum volume.

This curve will make it easy to locate the optimum trade between volume and power.

Tony Colette
Motordyne Engineering

 

this thread is very promising. thanx to all you motorgeeks who are willing to figure this stuff out for us.

 

roark, like I said on the other forum, I might be willing to loan an AAM spacer.

 

What we should do is take every one of these plenum mods and slam them all onto one car without taking the car off the dyno. Now that would be something to see.

 

I would love to be able to side by side dyno all these parts on the same car... but that means atlesat 30 mins down time per run to install the other part...

not sure how much per hour they are going to charge to rent the dyno

 

Shawn at Church Automotive charges $50/Hr. He's located in Torrance. I've been able to test baseline, and three different plenum mods at three pulls each in 2 hours. With A/F included.

It's the best deal for doing large volumes of dynos. For doing a large number of dynos it could save a ton of $$$.

What would be the availability of the other mods? Got mods?

Ive got plenum spacers ready to donate to the test! Heck, I'll even pay my share of the dyno bill.

It would make the ultimate mapping of available plenum mods. I like it!

 

well.. basline was already done at R&D...

so the new plenum will be done there as well on wednesday / thursday

 

That's good. You could continue with that as part of the plan. It would make a good reference point bridging the gap between Dynajet and Dynapac.

For a full mapping of all available plenum mods to the VQ owner, it would require testing both the standard lower plenum against the new 05 lower plenum. And then testing every plenum mod on each. This would flush out which combination offers the most area under the curve, which is best for daily driving and which would be better for tracking.

Changing out the lower plenum isn't hard to do either. I've done it. It sure would make a great research project that nearly every 350Z and VQ freak could benefit from.

 

maybe after we do the new plenum run...

we can have a day where we test it with other plenums / spacers...

would have to bring the tools etc needed for the install and pound it out between runs...

it would be better if it was done on a dyno day so other runs can be done in between...

when is the next dyno day?

 

I've been asking that same question myself. How about we set one up? I'm sure a lot of people would be interested.