Yeah, I remember watching a documentary on F1 car design, and they did talk about the normal shape of the airbox (sloping downwards to the rear) causing the most air to reach the rearmost cylinders and starving the front cylinders.

 

I live in Virignia and have the plenum spacer (motordyne). I highly recommend the product and can truly feel the power from the mod. Def. the best bang for the buck and dyno tests have been performed showing the increase in HP.

 

ChicagoX: I would agree that the slope makes sense ASA LONG AS there is enough space to move the air. If it creates restriction, it is unlikely velocity will overcome it. I think this is why the 'enlarged' plenum solutions work so well. It also would indicate whay a spacer is a good solution, as it increases the area, improving flow/reducing restriction while still maintaining the slope.

 

Neff,
Haha... Just because I didn't post the results doesn't mean it didn't happen. I flow tested the plenum and spacers several months ago. You've seen that I posted pics of a stand alone upper,lower some time ago. I used that plenum for flow testing and development.

Not only did the spacer greatly equalize the flow, it increased flow to all the intake runners. All of them. 1 & 2 went up significantly. 3 & 4 went up modestly. 5 & 6 increased only slightly.

I know how you hammer just about every vendor except Crawford so I won't take it personally. At least you have been somewhat consistent in your hammer style... But man you were over the top on that one guy who came out with that chip/ECU mod. All he did was say he was developing a new chip mod and you pounded him ruthlessly. And then you "Demanded" that he send you one for free.

I thought what he said was interesting, I wanted to find out more if possible. Hope you didn't scare him away. It looked like he was fairly new to the board but now he probably thinks we're all a bunch of G35 jerks.

This is true. It is not 100% equalized. But it is also true that the flow is greatly equalized and much closer to an ideal level. Pressure drop varies inversely with the square of the flow area. Increasing flow area above all intake runner by the same amount will have the greatest effect on the runners starting with the least flow area. IE the pressure drop at intake runners 1 & 2 is greatly decreased while the pressure drop at intake runners 5 & 6 is nearly unchanged. This is the equalizing effect.

The greatest benefit comes within the first 1/4" of additional space. Raising it by 1/2" doesn't really change the pressure drop above the intake runners much, but the added internal volume decreases the intensity of the internal pressure pulses. Lowering the pressure pulsing intensity lowers the dynamic losses and wasted energy in starting/stopping the air flow. The incoming flow upstream of the plenum inlet will be more constant as opposed to pulsed. If you are familiar with hydraulic accumulators or snubbers, you would see the plenums added internal volume works the same way.

It is also true that the lower plenum has its own pressure drop imbalances precluding a 100% balanced flow. No plenum mod can fix this without intentionally causing a restriction to other runner inlets. Doing this would only counter the whole point of doing a mod in the first place. More HP....
I'll bet you a dollar flow bench testing of all the mods on the market (Crawford, Kinetix or any plenum spacer) will produce fairly similar results.

If I really must give an opinion on which would probably have the highest overall pressure drop, I would say it would probably be the Crawford due to its flat/angular corners immediately adjacent to the runner inlets. Without rounded contours like a stock plenum or Kinetix, the sharp angular corners will create stagnation points and recirculation zones. ...Stagnation and recirculation creates pressure drop... These same areas are also where flow rate is highest inside the upper plenum. The performance penalty will have the most effect there.

A linear manifold feeding a row or intake runners should be tapered with area decreasing as each additional intake is fed. This will maintain a constant flow velocity with constant dynamic pressure.

Eliminating the internal plenum posts will have little to no measurable effect on the flow bench or dyno. I haven't measured it, but I am comfortable saying this because I know the flow rate in that area is far too low for any significant pressure drop to occur. So how can I say this sort of thing without having measured it you may ask. The answer is I have a very good understanding of flow systems. In fact, I've designed supersonic inlets for ramjet engines. Flame holders for high subsonic combustion chambers, rocket engines and rocket engine injectors. Once you do it enough times you gain a basic understanding of fluid dynamics and how flow systems work.

All I can say plenum spacers do indeed balance the flow. This much has been validated by flow bench testing. And like Sickone said, "the slope makes sense AS LONG AS there is enough space to move the air."

Tony

 

Tony,

Dont take it personal, neffster seems to hammer just about everyone's posts.

 

I have doubts that Crawford makes the best mods for our cars..... their old plenum solution was to cut a stock plenum and weld a toaster looking box to the front of the plenum. It was the most expensive plenum solution available and required the sacrifice of the stock plenum all together.

I don't know why some people have things against the spacer (ie. Doug, Neff) - it's an effective mod at a very reasonable price, and can be installed 'stealth' on the G35.

 

I have read that some mods (e.g., Z-Tube, which I have) lower low-end performance.

Would the plenum spacer reduce low-end performance? You know....when you hit the throttle, will you feel more or less power? I saw the dyno results and the HP increases seem to be on the high-end, that's why I was asking. I don't want to sacrifice my hole-shot anymore.

Oh....by the way, why I am so paranoid/concerned is because I do feel that my car's low-end from a hole-shot has decreased doing the z-tube mod. However, the rolling start is impressive (more than likely due to the higher RPM's at a rolling start than 0 from a hole-shot).

Thanks!

 

I have never seen any reliable data suggesting a low-end loss of power associated with a correct z-tube installation.
There is also no info indicating anything but an increase in power throughout the curve after the spacer install.
I seem to remember a mag article indicating the G35's 5-60 was equal to or better than the 0-60.....could this be contributing to your 'feeling?'

 

Err I have to ask Tony, please post pics of your flow bench or flowbench testing. Or are you talking about a flow bench in your computer?

Concerning that ECU thread you mention, I have to support him and the others.

 

All I know is that the car used to shoot out like a bat outta heck when I mashed the throttle down. Now, it seems/feels/sounds (meaning less tire noise-same environmental conditions, but more noise from the engine bay) as if my car has less power from a hole-shot. The roling start has always been impressive and still is. It just feels slower-maybe it isn't.

Now, if there is no low-end power loss with the plenum spacer, then I know what my next purchase is!!!!

THANKS!

 

Gsedan35,
I don't have any pictures of it, but I can tell you it was a leaf blower connected to dryer ducting and a myriad of manometers all over the plenum. The overall accuracy was good to about 0.005 PSI. (Which is more than adequate for the application.)

The ECU thread?.. Are you supporting the guy who proposed the ECU mod or Neff?

Don't get me wrong...I'm not taking sides on it. I don't know anything about the proposed ECU mod or the company he was with so I am not supporting him (or them) I just wanted to hear more of the proposal.
Poor guy got pounded into a pile of hamburger meat.

 

LOL, I remember that thread. I'm pretty sure that dude is long gone never to return. Oh well, if the **** works then we'll find out sooner or later anyway I guess, just not from him

 

In all fairness (plenum spacer aside for now) the old thread where the guy was "hammered" was far from that. I was simply privy to some information that others, such as you, were not privy to. Six-five, myself and Kevin Pierson had several side bar conversations and realized that this person was a rip off artist in sheep’s clothing.

This individual had prior business dealings with other product manufacturers, such as you, and he tried to rip them off, he broke contractual agreements, he LIED ABOUT product abilities and performance, etc... He was an individual who would sell anything if he could make a HUGE PROFIT and had no problem with lying about any product if he could profit from his lies. Remember how he posted the product would provide a horsepower gain of 5-15%, then he went on to say that “no gains could be seen on a dyno”?

For more info about this scammer, send a PM to KPtech...

One more thing about this previous post... I never requested a FREE PRODUCT from ANYONE. Reading this statement only PROVES TO ME that you are putting your "slant" on what happened. After reading your above statements, how am I to know that you are not putting this same "slant" on your own product?

What I requested (not demanded) was that the guy give me a discount (he had over a 100% mark up on this Uni-chip). I then offered to do pre and post dynos on my own time and at my own financial loss. I also agreed to then spend several hours doing an independent write up posting my findings. My time and my money would have offset any "savings" I would have received. The only caveat was that the guy had to let me post the results of the dyno runs REGARDLESS of whether or not there were gains found.

Go back and re-read the entire post. Your "slant" and made up stories I find VERY insulting. Here’s the link for simplicity… Unichip discussion

Now, addressing the plenum spacer:

I have been very careful not to say anything negative about the spacer. I have not seen, nor have I been presented information until now that any flow bench testing has been performed. I have asked in previous posts (and have read where others have asked as well) whether or not this type of testing was performed and I've yet to see the answer prior to your post above in this thread. I have only heard claims by Copbait on my350z.com where he personally went toe-to-toe with the "Crawford Cronies" and I've read many claims by Dizz (on every flippin’ G35 message board there is ) about the benefits of this spacer. It is difficult for me to be 100% impartial since Crawford is a MAJOR SPONSOR to the FGC. It is true that I have been leaning toward Crawford’s side of the argument since the spacer has been developed, yet it is untrue that I’ve been anything other than impartial regarding the spacer.

The reason for me leaning toward Crawford is simple. Doug’s products have been independently dynoed by many different people all over the United States over the last few years. The Crawford products have held their own very well and have proved that Crawford is a manufacturer who does not "inflate" horsepower and torque claims on their products. Doug also happens to be a great person to do business with, he stands behind his products, and he offers free technical support. Heck, he even likes to talk car stuff for fun over the phone and is working very hard to come up with a 300rwhp NA solution for us VQ35DE guys. So when he gives technical information about plenum spacers that is not disputed by the manufacturer, I tend to believe him.

I'd love for you to present your flow bench test results and spend a few minutes helping everyone understand the fruits of your labor.

Some things you may not realize:
I do want the plenum spacer to work.
I have previously suggested that you patent the spacer idea.
I do want a solution for half the price of a Crawford Plenum that gives equal or better gains.
I do not mean to be “so harsh” on others in my posts.
I am a person who likes to be presented the raw data so that I can draw my own conclusions and not have to go by what others say. (For the record, I’ve had Fluid Mechanics I and Fluid Mechanics II in college so the data would be meaningful to me).

I just want independent testing and impartial results to be brought forth. So far all I've seen is people from California who either know you personally or have driven to meet you (or even had you install their spacer) give reviews and post dyno charts. (Dizz and Copbait are the two that immediately come to mind.)

In closing, I did not ask for a free product with the Unichip distributor from V6P.net. The statement you made about that is a LIE! I do not feel that I “hammer just about every vendor except Crawford” since I speak highly of quality products made by companies like KP Technologies and Blue Batmobile because I know first hand that these products work as advertised. These are products that either I myself or my close friends have paid full price for and have tested (before these suppliers were ever FGC Sponsors). For the record, I also openly promote the aftermarket manufacturers like TEIN, Nismo, JIC, Nissan, Borla and stores like Performance Nissan, Lokey Infiniti, Racing Zone, etc… All of these are companies that I’ve personally had good experiences with.

On the other hand I’ve bad mouthed Avalon Racing (maybe unfairly) due to a very bad experience I had with Paul. I’ve also bad mouthed Random Technologies for not standing behind their products and I’ve questioned several other manufacturers who have made claims and not stood behind them like Alphaworks/Nexus. I’ve said negative things about Injen and the fiberglass blowout from their exhausts, and I’m sure there are a few other manufacturers I’m forgetting. Heck with 3000+ posts, it’s hard for someone to be brutally honest and not say some things that aren’t all peachy. (I don’t know how gsedanman does it ).

I have tried to be very open minded about the spacer, and I’ve never said it didn’t work. Please re-read my previous posts if you think this is an inaccurate statement. A simple “Advanced Search” with limits of “find only posts by Neffster” and the words “plenum spacer” will help you to see that I’m not making this up.

Thanks for reading, yet another chapter of my novel. Good luck with your company and your product.

 

I have a great question that I do not think anybody can answer. IM trying to figure out how this spacer can balance out the flow in the 2004 VQ. Its safe to say that the front cylinders do not flow as well as the back four. Lets say its 28% less flow in the front. Now you put a spacer on top and you raise the whole top plenum. OK so you enshrouded the fronts and now they flow better. But at the same time the back four has more flow now. No, its more volume. Now the front flows right and now the back is lazy. Now flow in the back has not improved at all because there really is no improvement in flow. Flow would only improve if there were more stroke in the VQ or more cam timing. I do not care what anybody says when you add more volume you raise the power curve. when you add more cam timing you raise the power curve, Only more stroke will need the added volume. Cam timing will also play a big part here. Now understand this spacer does not make the intake flow any better at all. Flow would be based on port size and angles of the ports. I can understand how the spacer may help the front cylinders but in no way could it balance all six. I would love to see some flow testing here. Big flow numbers only give you the possibilities of higher Hp. The true question is what did it do to the torque curve. torque wins races. Now with that said lets put the new 2005 lower plenum on with more volume (SPACER) and shorter runners. You will kill the torque curve and the drivability of this VQ. Short runners are for high rpms, Drag racing, long road courses, long are for low end power. Here is the deal you want the same flow and the same volume to all cylinders and because of the design of the 2003-2004 intake with a spacer there is no such thing as a balanced intake. The jury is still out on the 2005 lower plenum. I see a disaster with a spacer and a 2005 6mt intake. I would like to see some flow numbers on each port with a spacer. I bet its all over the board and not one flows the same. We all need to see facts. Trust me I know how to build cars. There is so much to be said here. The point is the G35 3.5 liter VQ is very well designed. The best mod so far has been the "Gords grounds.
Everything else has killed the drivability. And with more HP.
Its like boob jobs they look good. but are they sensitive?

 

Excellent post Gee Pasta. I too would love to see a flow bench of a stock intake manifold with and without the spacer and then one with just a Crawford plenum. It's a pipe dream, but it would answer all our questions to what's best for volumetric effiency and ultimately the performance. I'm still tetering on the spacer or a plenum.