If I had to take a guess, I'd say it has to do with the necessity for keeping things a bolt-on affair. Most aftermarket upper intake manifold replacements have to work in conjunction with the OEM lower manifold. Whatever shortcoming the OEM lower has is still present if the upper is replaced with a better design.

TK

 

From the tests that some of the shops have done on the Cosworth...50-60 whp gains in the mid to top have been proven on FI'ed cars...I would not consider that "minimal"

 

yours


any max effort setup that has deep pockets would benefit.i am not a big fan of itb's considering a thoughtfull sheetmetal intake can see the same results with far less moving parts.but in a space confined platform like the z/g,you could invest in itb's and not chop holes in your hood.the beauty of them is you can model them in any way you desire,they are applicable for any setup provided you build single minded(not a do everything motor).although they can be used in this way just know that you pissed away money for bling.

 

Who makes sheet metal intake manifolds for the G/Z?

I talked to several manifold companies at PRI a few weeks ago and most only fabricated manifolds for SBC and Mustangs. One company said they would port an OEM VQ plenum, but had no experience with a completely fabricated sheet metal designs.

 

with 4 grand in your pocket,i can think of a few....cfe and wilson are two quality shops.there are plenty of smaller shops who offer similiar services,turbo tim is one that has the skills and knowledge of vq.
my point was that few would be willing to "ugly" up their car for function.
even tim's had to fit within the confines of the stock hood for it to be marketable,forcing comprimise.if you where unfettered by space limitation wicked things could happen.the knowlege base is there,it just hasn't been applied to the vq.

 

not to get OT, but how much was the cosworth, $1K, and 50-60 hp. thats minimal to me, considering it isnt a bolt on, you have to get retuned if youre FI. and after all the hype and wait for the cosworth, ive missed the threads where results on hi hp FI cars are .

 

the cosworth is a compromised design,their r&d was broader than performance.they are also restrained by marketablity,and must conform to a "general" design to fit the masses.which turned it into a lump of bling with carbon end caps.

EDIT: 60hp is not to be discounted,people spend far more for less gain.but with their hands tied behind their backs it has it's limits.i actually like cosworth(you wouldn't know from my posts),i just think their vq plenum missed the mark.

 

I'm not so sure that the Cosworth provides 50-60 hp... I ran 550 something hp actual (584 adjusted for temp/humidity) with a stock plenum and Motordyne 5/16" spacer at 13.5 psi. With the Cosworth, I ran 609 actual (603 adjusted for temp/humidity), but that was at 17.5 psi of boost.

It's tough to compare the numbers because the temp/humidity corrections don't take into consideration the timing adjustments on the different days, and the temp/humidity on the two days were significantly different. Nonetheless, for actually measured hp, I gained roughly 50 hp, but I added 4 psi of boost and it was a much cooler day. As far as weather corrected hp, I only gained 19 hp, again with 4 psi of extra boost. I'm guessing that with the stock plenum and 5/16" spacer, we would have gotton within 10 hp of the Cosworth, although the hp may not have started dropping off at a lower RPM.

 

thats the problem with "claimed" gains.....to many variables.but just showing more hp doesn't mean you moved in the right direction.your torque curve is far more important.

 

My torque curve looks good. It's not as smooth as my run at 13.5 psi, but at 13.5 psi we weren't too concerned with blowing the motor. At 17.5 psi, Roger left a little rich and pulled back the timing at the torque peak to give us a pretty good margin of safety for my next track event, although we will be going back and doing some clean up of the tune, as well as tune it for meth.

 

this is the true value of itb's,they allow you to fine tune your curve.most are obsessed with hp but the reality is,how you build your tq curve determines what your car feels like.
i always say that hp is just math,but tq is how the car feels.

 

I talked to Wilson at PRI. They were the shop that recommended porting an existing manifold.

Usually any product that proves to make serious horsepower gains starts to look beautiful...

I am not a serious racer anymore either. If I was, I would immediately purchase a set of independent throttle bodies. I think they would really help my NA engine... but, I don't want to fool with the throttle cable... hood clearance... or air cleaner issues either.

 

wilson will make you one,seems they didn't take you serious.i'm sure they get alot of "i wanna" at shows.if you started the conversation asking if you could send them the longblock it was going on they would have been all ears.high end intake builders insist on having the actual motor it will be installed on.for them basic questions imply this service is not for you,that's why they told you to port.

 

Possibly. I would not be willing to send my longblock to them or finance their development of a sheet metal intake manifold... so that assessment would have been correct.

The fellow I talked to mentioned other Nissan inquiries, but said the projected volume was too low. That's all I know...

Ever notice that the Cosworth plenum is very much like independent throttle bodies with a carbon fiber air-box built in...

 

your misunderstanding me,it would be a one off for you motor only,thats why you build on the actual motor.variance in deck height,port match ect.the devil is in the details and this is what makes one off intakes exceed expectations.

 

CJM has made a couple and offers custom models built to order. look at the sound performance Z running one. that model was an attempt at getting the job done with a stock throttle location. there is a new model too, for race builds, front mounted throttle body (fits under the hood, fits over the timing chain, but requires slim fan/shroud setup to clear intake tubes). both currently very expensive, but after some comparison tests and updates, casting is in the future for greater cost effectiveness.

 

my take on the cosworth plenum... a massive step up with OEM style. its hardly a race inspired manifold... its more like something you would see OEM. the runners are long, the displacement is nothing major... it really just looks like a vastly improved oem model.. am i wrong?

 

I've seen a few sheet metal versions on the forum when I was exploring ITBs. Gotta a lot of trash talk from a bunch of idiots telling me it wasn't worth it but I posted a thread asking who would make them and got a few replies. SFR makes a pretty mean version but I haven't seen too many test and it was all surrounded by skepticism like the Cosworths. But I'd trust Tim or phunk to do any of this work. Other stuff was JDM but I seen one that basically had to large rectangles on each side and was supposedly equal volume on each side. I'd feel way safer with this than ITB in a box...

Would love to see a shop step up and make these but in the market now for the VQ35DE I'm not sure there would be enough purchases to pay for the R&D.

 

When you first came out with an example of the twin pump...I told you that if you made it work I would buy it....and I did buy one.....I am telling you the samething that if you make a plenum that blows the cosworth out of the water.....I WILL BUY IT !! Let me even go further...If its a one off and it the next best thing to slice bread!!!! I will pay the "One off fee"

 

youre in the power range, it could probably aid you, how high do you rev? got any links to dyno sheets i can see?

i think the g35 has more space for the front throttle intake than the Z, you may not have to change a whole lot other than extended throttle wiring and a new intake pipe from the IC.

as for one off fee... its up there man... the new front throttle one in full billet trim costs about $1000 just in material! so its pricey, definatly will need to cast it if we expect to move more than a few. one thing id like to add... it just looks SICK! makes the VQ finally look a little exotic.