Plenum spacer
Originally Posted by bsgoren
Sometimes ppl do tend to over-analyze things...ya' think? 
The bottom line is both mods increase HP/torque; how does each one accomplish this and which one has greater gains? Who really cares? Yes, it would seem the best mods for our cars are ones which much time is devoted to R&D (e.g. - Gordgee, Tony, etc.)...this is why we should just say "thank you" (which we also do this by buying their stuff of course!!! 
) to guys like Doug @ Crawford and Tony @ Motordyne (and Gordgee for his GG System). They have the interest in, the knowledge, and the determination to to improve our cars; it's great that they take the time to figure out ways to do so.
I don't think most of us need to get into the middle of a pissing contest or between two 'competitors' -- these are 2 different mods which take 2 different approaches to a similar problem. Both make improvements to the stock setup; one happens to be more than double the price of the other and may or may not have better HP/torque gains. Which one is the most efficient solution and which one is better for you? I think that all depends on what's important to you and which one you perceive to be a better 'bang for your buck.'
With all that said, I've read many threads and posts on both plenum mods -- the Crawford plenum and now, the MD Plenum Spacer. Personally, I am hesistant to change out my car's plenum; it's a "big hunk of metal" - a very important piece of the engine and it just doesn't sit right with me to replace it (even if its design is inheritantly flawed). Not to mention, it's rather expensive. However, adding a 3/8" plenum spacer for $225 to the stock plenum, which by all accounts thus far seems to add noticeable HP and torque gains, I think it may be a worthwhile and "safer" mod. So I ordered the 3/8" MD Plenum Spacer and I'm expecting it this week. I have no interest in dyno'ing my car just to see how much more HP the 3/8" plenum spacer adds; just as long as I can feel and possibly hear a difference, I will be happy. Some may be in the same camp with me while others "must know" exactly "if, why, how, and just how much." Personally, I don't care about the minute details of how & why it works and eactly how much it works; I just want to be assured it works and I'm not wasting my $$...period! From the several dyno's done (however they were done) and many testimonials posted, it appears that it works and would be a nice mod for the money, adding some extra HP and torque...provided it doesn't blow up my engine, of course.
The bottom line is both mods increase HP/torque; how does each one accomplish this and which one has greater gains? Who really cares? Yes, it would seem the best mods for our cars are ones which much time is devoted to R&D (e.g. - Gordgee, Tony, etc.)...this is why we should just say "thank you" (which we also do this by buying their stuff of course!!! ) to guys like Doug @ Crawford and Tony @ Motordyne (and Gordgee for his GG System). They have the interest in, the knowledge, and the determination to to improve our cars; it's great that they take the time to figure out ways to do so. I don't think most of us need to get into the middle of a pissing contest or between two 'competitors' -- these are 2 different mods which take 2 different approaches to a similar problem. Both make improvements to the stock setup; one happens to be more than double the price of the other and may or may not have better HP/torque gains. Which one is the most efficient solution and which one is better for you? I think that all depends on what's important to you and which one you perceive to be a better 'bang for your buck.'
With all that said, I've read many threads and posts on both plenum mods -- the Crawford plenum and now, the MD Plenum Spacer. Personally, I am hesistant to change out my car's plenum; it's a "big hunk of metal" - a very important piece of the engine and it just doesn't sit right with me to replace it (even if its design is inheritantly flawed). Not to mention, it's rather expensive. However, adding a 3/8" plenum spacer for $225 to the stock plenum, which by all accounts thus far seems to add noticeable HP and torque gains, I think it may be a worthwhile and "safer" mod. So I ordered the 3/8" MD Plenum Spacer and I'm expecting it this week. I have no interest in dyno'ing my car just to see how much more HP the 3/8" plenum spacer adds; just as long as I can feel and possibly hear a difference, I will be happy. Some may be in the same camp with me while others "must know" exactly "if, why, how, and just how much." Personally, I don't care about the minute details of how & why it works and eactly how much it works; I just want to be assured it works and I'm not wasting my $$...period! From the several dyno's done (however they were done) and many testimonials posted, it appears that it works and would be a nice mod for the money, adding some extra HP and torque...provided it doesn't blow up my engine, of course.
For the winner. Plus what I offered. Dennis
Registered User
Joined: Oct 2004
Posts: 539
Likes: 0
From: San Diego, CA
Originally Posted by Gee3Five
You didn't answer the mans question...so I will repeat it for you.
Is it proper for a mod to act as the voice of a vendor? Especially in a thread like this?
A good question that needs an answer, I think.
Is it proper for a mod to act as the voice of a vendor? Especially in a thread like this?
A good question that needs an answer, I think.
I have the MD spacer. I DO feel a difference. I am happy with the mod.
No, I will not be dynoing the car. I don't feel the cost of the dyno is worth finding out if in fact it made more hp. I'm content with knowing what I know. Some people, including myself, are not going to pay more money for the crawford because they can't justify it in their minds. I know I can't. Therefore, for the group buy price of $175 or whatever it was for the 3/8" spacer, I couldn't be happier.
No, I will not be dynoing the car. I don't feel the cost of the dyno is worth finding out if in fact it made more hp. I'm content with knowing what I know. Some people, including myself, are not going to pay more money for the crawford because they can't justify it in their minds. I know I can't. Therefore, for the group buy price of $175 or whatever it was for the 3/8" spacer, I couldn't be happier.
Registered User
Joined: Dec 2004
Posts: 65
Likes: 0
From: Stevenson Ranch, CA
Originally Posted by bsgoren
I have no interest in dyno'ing my car just to see how much more HP the 3/8" plenum spacer adds; just as long as I can feel and possibly hear a difference, I will be happy.
I'm glad someone has alluded to why we REALLY mod our cars. I modify mine because of how the mods change how the car FEELS!!. Looking at dyno plots of what my 1/2" spacer does to my car isn't NEARLY as satisfying as how the spacer makes my car FEEL when I throttle it.
Sometimes I think that some guys rather hang framed dyno plots in their dens and living rooms than take the car out and spank it!
Whats the fuss? There are dynos that prove that both mods make power. Go out and FEEL it baby!!!!
Originally Posted by Gee3Five
You didn't answer the mans question...so I will repeat it for you.
Is it proper for a mod to act as the voice of a vendor? Especially in a thread like this?
A good question that needs an answer, I think.
Is it proper for a mod to act as the voice of a vendor? Especially in a thread like this?
A good question that needs an answer, I think.
This spacer in no way makes sence's there is no way it can balance the flow.
I understand all you people out there belive in it and thats fine with me.
I do not know many people here but what I can say is that Neffster HAS" Always giving time to the newbes and he wants the the best for his car and shares what he knows with what you self centered people out there think what you know. You better pick a fight with a dum ***. Then you can win.
Neffster Do you think you could be nice so the thin skins and the belivers
of nothing will not pay you much time.
Originally Posted by copbait
My thoughts exactly. Thank you for clarifying.
What do you have to add to g35 driver. What the heck do you know.
Bring it on. Im all grown up here and my quess my oldest boy is your age.
Maybe you could ask him a few questions about what the truth is.
Copbait How much time did you spend on your name. Grow up.
You have no clue what true power to the ground is. No dyno will show you how little your fingers are . Just keep hitting the keyboard with the biggest thing you have.
Your new buddy
Registered User
Joined: Oct 2004
Posts: 539
Likes: 0
From: San Diego, CA
Originally Posted by GEE PASTA
buddy!! What is your point here but to ask stupid questions.
What do you have to add to g35 driver. What the heck do you know.
Bring it on. Im all grown up here and my quess my oldest boy is your age.
Maybe you could ask him a few questions about what the truth is.
Copbait How much time did you spend on your name. Grow up.
You have no clue what true power to the ground is. No dyno will show you how little your fingers are . Just keep hitting the keyboard with the biggest thing you have. Your new buddy
What do you have to add to g35 driver. What the heck do you know.
Bring it on. Im all grown up here and my quess my oldest boy is your age.
Maybe you could ask him a few questions about what the truth is.
Copbait How much time did you spend on your name. Grow up.
You have no clue what true power to the ground is. No dyno will show you how little your fingers are . Just keep hitting the keyboard with the biggest thing you have.
Your new buddy 
What the hell are people fighting about anyways!?1) Both mods work great - Awesome!
2) One is half the price as the other and allows stock engine cover - Awesome
3) Both have many proven dyno to back them up - Awesome
4) They are not exactly the same engineering wise - Well yeah.
5) One balances flow better than the other - Frankly 90% of us don't give a hoot as flow dynamic is too geeky for us butt dyno people.
All these plenum threads are filled with people who are happy with their spacers and some Crawford owners who would argue Crawford is superior. Okay~ I don't think anybody with a spacer would care if that were true. The problem being that there is a possibility that plenum spacers might actually make more power than the 'perfected' Crawford plenum.
I think many would agree with me that Neff is a great contributor on the board and an upstanding guy. I feel that Neffster is being used by Crawford to sell products on these boards. It would only make sense someone at Crawford to chime in instead of using Neffster as their human shield.
My problem with Crawford - 1) Price, 2) Continuous updates in plenums, 3) Anti-spacer and some false claims. By #3 I refer to the thread on My350Z where they first claimed the spacer would not work! Newsflash - it works, and it works very well! In the beginning Crawford chose to cut out a stock plenum and fuse a toaster shell to the front half of the plenum, and it costs $500+ and sacrifices the stock plenum. That doesn't sound like smart engineering to me, unless even the V1 Crawford plenum makes significant more power than a simple spacer.
I am tired of this anti-spacer argument on this forum. If Crawford has solid research data that shows the spacer is crap and their cast plenum is the best - then someone at Crawford should post here instead of using a well respected forum member here as their messenger.
Registered User
Joined: Feb 2004
Posts: 8,269
Likes: 0
Originally Posted by copbait
Who is a mod? I don't believe a mod has even posted in this thread yet. Yet
Secondly, there are several different types of people posting in this thread.
(1) There are the "I bought a spacer and I feel the gains" people. These are the people who are not reading my posts for content and feel as if I'm putting them down for not buying Crawford's products. Nothing could be further from the truth.
(2) There are those (who I feel are ignorant) who are claiming that the spacer "balances air flow" and negates all pressure drops from the front to the rear cyllinders without really understanding what they're saying.
Let me ask you this... WHICH SIZE SPACER BALANCES AIR FLOW? The 1/4", the 3/8", the 1/2"? Not all of them can possibly yield a ZERO PRESSURE DROP! Why did Doug have to raise the front of his plenum 1.0" and not only 1/4 or 1/2 to get his results? It is my understanding that all of the spacers have the same design, they just have varying thicknesses. One of these designs MUST be better than the others, and since Tony has already said that the 1/2" spacer performs best on the dyno, I can only imagine that this design lowers the pressure drop the most.
(3) There are the people who've read my posts and realize that I've said the spacer makes gains on the dyno (and the butt dyno). This is good IMO. However, many people will be modding more in the future. My original point (which has been lost on most people replying in this thread) is that if you plan on spending a lot of money on EQUAL LENGTH HEADERS and high flow cats in the future, you may not want to save ~$100 or so and buy the plenum spacer over the Crawford Plenum. You may want to buy a product that negates the pressure drop problems inherent in the stock design of the VQ35DE intake manifold.
It is true that I've based the above statement on what Doug's told me, but hopefully this afternoon I'll be able to post the flow bench results and settle my side of the argument.
Also, why do you think that the 2005 G35's now have a new part number for the lower manifold? Could it be because there really is a problem with its flow design and they've improved upon it?
Finally... for the square corner argument.
Originally Posted by anonymous
…I am an engineer by degree and have dealt with some flow phenomenon but not to the extent that I can definitively explain why the spacer or Crawford Plenum would work better than the other. However I do know that when fluids flow into a "right angle" area like in the spacer, some of the fluid will remain in that area and circulate causing a 'bubble' which prevents more fluid from entering the space and this allows the remainder of the fluid mass to 'freely flow' over the top of this bubble.....effectively making the right angle area a non-factor. A real world instance of this is the bed's of pick up trucks.....a bubble of air will form in the bed when the tail gate is up and the air traveling over the cab will freely flow over this bubble and over the tailgate and then into eddy's that disturb the vacuum that forms behind the truck.....allowing for better mpg than opening the tail gate, which doesn't disturb the vacuum and thus reduces the mpg of the truck. I thought I'd pitch this idea your way....it might help explain why Doug's Plenum, which has these areas but also far more headspace than a factory plenum and/or a factory plenum with a spacer, balances flow.
Btw, you made an excellent point on the fact that some people may not care about balancing but if they are interested in using equal length headers, they will care.
Keep up the good work.....as I've said before I find you posts informative and appreciate your quest for what is best for our cars.
Btw, you made an excellent point on the fact that some people may not care about balancing but if they are interested in using equal length headers, they will care.
Keep up the good work.....as I've said before I find you posts informative and appreciate your quest for what is best for our cars.
Bottom line: I’ll post the data as soon as it is available to me. Until then, let’s hope that Tony has a change of heart and shares his data with us as well. That is if he even has any data to share.
Also, if you own a 350z and want to get a 1/2" plenum spacer, no problem. Just make sure to get the Crawford Strut Bar since you'll have to scrap your stock one.
Registered User
Joined: Aug 2004
Posts: 694
Likes: 1
From: SOCAL
Originally Posted by GEE PASTA
Many years in school for me and you know what. The spacer should not work. What the hell do I know.
From what I can tell from your posts, you seem to be stuck on volume. Particularly for the 1st 2 cylinders. I think what you are seeing is a lower volume over the 1st 2 cylinders so your assumption is that the 1st 2 cylinders can't possibly flow the same, or enough. But keep in mind, the the amount of volume needed there only needs to be enough to provide enough air to those cylinders. The volume needed over cylinders 3 & 4 need to be enough to provide those cylinders with air as well as flow the air that is going to the 1st 2 cylinders. And the volume of air needed over the last 2 cylinders needs to be enough to provide flow to all the cylinders. This is a fairly simplified way of looking at this, but it is true.
You also seem to have some hang ups on flow to the rear cylinders increasing since you are also increasing the volume in the plenum over these cylinders. But consider a cylinder can only take in a certain volume of air. Short of pulse tuning, each cylinder can not fill more than it's displacement in volume. If the rear cylinders are closer to 100%, then it would make sense that they would see little gain. Since the biggest problem with the stock plenum seems to be with getting sufficient flow to the front cylinders. It would seem to me the front cylinders will see a bigger improvement in flow than any of the other cylinders anytime you are adding volume to all parts of the plenum. And this also seems to be consistent with the increases in flow to each pair of cylinders that hydrazine claims to have obvserved.
Frankly, I doubt we would actually find a large difference in flow improvement to each cylinder, between the spacers and the crawford plenum. While from a fluid dynamics standpoint, a well designed taper would be ideal, its not going to make a very significant difference. I doubt the taper of the stock plenum can be the ideal match for each of the spacers as well. It seems to me that both add volume to the plenum to aid in additional flow, especially to the front cylinders. This being the case, personally, I'd opt for the spacer from a cost and OEM look standpoint.
In any case, I would like to hear your technical argument that backs your opinion that the spacer should not work. Otherwise, I think you may wasted many years in school.
Sorry but I couldnt resist posting again. If I designed a mod for a car and people were skeptical or saying one is better than the other Id come on and back up my own product. I dont understand why people are arguing about the plenum, there are 10 different exhausts for the coupe all w/ different gains why arent we arguing about that?? Our plenum mod's include 2 options: a spacer, or a new plenum alltogether. THATS IT, some choose the spacer, others choose the new plenum. It's as if I purchase a Fuji exhaust and I have people breathing down my neck about how its got a restricted angle in it and it doesnt provide power. Well perhaps I WANT a restricted angle on my car, perhaps I WANT to have a ****ty exhaust. Why does that bother everyone else???? Perhaps I enjoy driving around w/ a hood spoiler, but thats just my decision!! This is the US and people can do whatever to their cars that they like, why are people arguing over mods that BOTH produce gains?? The bottom line is one vendor doesnt like that its product (which had the largest share of the market) suddenly noticed a drop in sales and is now trying to knock another product. If the crawford guys are so worried or concerned about the spacer and its 'inner workings' they should come and post about it themselves. People, IF you dont like the spacer or the crawford/kinetix plenum than thats too bad!!
Last edited by pdjafari; Mar 22, 2005 at 08:55 AM.
Originally Posted by g35audioman
I have the MD spacer. I DO feel a difference. I am happy with the mod.
No, I will not be dynoing the car. I don't feel the cost of the dyno is worth finding out if in fact it made more hp. I'm content with knowing what I know. Some people, including myself, are not going to pay more money for the crawford because they can't justify it in their minds. I know I can't. Therefore, for the group buy price of $175 or whatever it was for the 3/8" spacer, I couldn't be happier.
No, I will not be dynoing the car. I don't feel the cost of the dyno is worth finding out if in fact it made more hp. I'm content with knowing what I know. Some people, including myself, are not going to pay more money for the crawford because they can't justify it in their minds. I know I can't. Therefore, for the group buy price of $175 or whatever it was for the 3/8" spacer, I couldn't be happier.
Don't drink and Mag Race
Joined: Mar 2004
Posts: 2,065
Likes: 3
Since my response to the original poster is in question here, I feel compelled to comment:
Neffster, you have seemingly made a career out of being abrasive and insulting of late...why? If you re-read my original post, it was simply a quick summary of how plenums/spacers work.
The direct quote was: "The plenum spacer is designed to add volume to the intake plenum. There is a proven restriction to the front cylinders in the OEM configuration, probably due to component sharing with the 350Z. Increasing the volume balances the flow and adds HP. This is the theory behind the Crawford, Kinetix, and soon-to-be-released APS plenums."
Correct 'balances' with 'aids in balancing' and we no longer have controversy...that was the intent.
Nowhere, I repeat NOWHERE did I say that any spacer solution "negates all pressure drop from the front to the rear cyllinders (sic)"
Nobody claimed zero pressure drop save you.
(2) There are those (who I feel are ignorant) who are claiming that the spacer "balances air flow" and negates all pressure drops from the front to the rear cyllinders without really understanding what they're saying.
Now you've managed to personally insult me. I have more than a few years of education under my belt. If you need metrics, let's compare SAT and IQ tests. I'm more than happy to continue this thought via PM.
Fantastic. The President of Mars has sent me a congratulatory hologram pledging his undying support in my fight against the rampant spread of pigheadedness on this board. It's also nice to hear.
And in what format would it be acceptable? Anything penned by hand would be inherently circumspect. Computer print-outs? UNFAKEABLE! No, wait...those could be 'massaged' as well......... I give up. In what form is the Crawford data going to be produced? If it's not forensically certified by the accounting firm Neffster&Neffster, it is invalid.
Tony has shared more data to date than I've seen on your benefactor's website. Your calling him out on this is plain wrong, IMO.
Why did you feel it necessary to get that last sales pitch/dig at the competition in? This is a G35 board......who are you trying to sway to the CZ camp? It is a doubly poor argument, seeing as the Crawford plenum requires purchase of the same item.....Wasted ammo, IMO...
Neff, you used to be a respected, opinionated (which is a good thing, IMHO), FAIR contributor to this board. Now it is nothing but Crawford rhetoric and negative jabs here and there.
I don't feel that you are the only driving force behind all of this vitriolic discourse. I believe that sponsorship is affecting your once courteous and equitable stance.
W.
Neffster, you have seemingly made a career out of being abrasive and insulting of late...why? If you re-read my original post, it was simply a quick summary of how plenums/spacers work.
The direct quote was: "The plenum spacer is designed to add volume to the intake plenum. There is a proven restriction to the front cylinders in the OEM configuration, probably due to component sharing with the 350Z. Increasing the volume balances the flow and adds HP. This is the theory behind the Crawford, Kinetix, and soon-to-be-released APS plenums."
Correct 'balances' with 'aids in balancing' and we no longer have controversy...that was the intent.
Nowhere, I repeat NOWHERE did I say that any spacer solution "negates all pressure drop from the front to the rear cyllinders (sic)"
Nobody claimed zero pressure drop save you.
Originally Posted by neffster
(2) There are those (who I feel are ignorant) who are claiming that the spacer "balances air flow" and negates all pressure drops from the front to the rear cyllinders without really understanding what they're saying.
Originally Posted by neffster
There are 12 people sending me e-mails, PM’s and AIM’s in support of my statements. Not everyone feels as if I’m “hammering” in tone which is nice to hear.
Originally Posted by neffster
Bottom line: I’ll post the data as soon as it is available to me. Until then, let’s hope that Tony has a change of heart and shares his data with us as well. That is if he even has any data to share.
Tony has shared more data to date than I've seen on your benefactor's website. Your calling him out on this is plain wrong, IMO.
Originally Posted by neffster
Also, if you own a 350z and want to get a 1/2" plenum spacer, no problem. Just make sure to get the Crawford Strut Bar since you'll have to scrap your stock one.
Neff, you used to be a respected, opinionated (which is a good thing, IMHO), FAIR contributor to this board. Now it is nothing but Crawford rhetoric and negative jabs here and there.
I don't feel that you are the only driving force behind all of this vitriolic discourse. I believe that sponsorship is affecting your once courteous and equitable stance.
W.
Last edited by ChicagoX; Mar 22, 2005 at 01:30 PM.
