RJM GTR Intake Lower Manifold...oh yes!

Alstann

Woah guys! This has blown up since I last checked it out, haha.

Firstly, I'm planning to install it later this week or next week, I want to run my custom return fuel setup with this, so I need some more time to get that together. Planning on buying an Aeromotive FPR and running a return under parallel the OEM lines, and back to the tank, set it to stock FP, and let her run. To be honest, work has been getting very busy, so it may be a while before I have time to really crack at it and get a dyno day together.

Whilst I think there is definitely gonna be an argument with smoothness of the runners, my first comment will be that it is smooth to the touch, and definitely way less rough than a cast manifold. I purposely chose very harsh lighting to show the end-milling, and it is more than acceptable for a manifold, or any intake part.

Secondly, whilst I don't claim to be a race engineer or anything of the sort, I am professionally a MechE and also did analysis for intakes for Formula SAE. If you wanna talk about flow patterns here, the flow on the surface layer of any tubing in a closed environment is zero. This is simple fluid mechanics, and the velocity increases non-linearly to it's fastest point, which is in the center of the runner.

What this means is that surface roughness, to a degree, has negligible effect on air turbulence and velocity. If you ask old V8 guys in the business, they'll all tell you that polishing a manifold to a mirror shine is little more than a "feel-good" mod. The main contributors to power and flow are the runner shape and diameter. Minor losses will always exist, and anyone who tries to chase perfection will spend thousands of dollars doing it, for diminishing returns.

Speaking of manufacturing methods - machine time is VERY expensive. My experience in creating pure CNC parts that have complex paths and require lots of machine time - things like this are hilariously cheap. And don't even get started on casting - that will be a heartache when you learn how much master molds cost to create.

I don't want to address any personal feelings on this thread - just wanted to share what I think is a fantastic part. Bobby and RJM delivered to me a fantastic product, and I have no complaints. I knew exactly what I was purchasing since the inception of the part, and I'm happy to have one. I think that everyone should be happy parts are being developed for the platform!

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juicinjake

i understand that... and your concerns with regards to testing pre-release are legitimate. i am willing to take the plunge to inform the masses. i also appreciate you understanding that im about facts and that im not here to argue. i have purchased this intake, the aam, and have several various modified stock intakes that i will all be testing back to back on my 13 370z as soon as the aam manifold is done. as for rjm dynos, we aren't far off on my end.

Elmo370z

Build me a cmc please?

370Z JT

Are you the one doing the NA testing for them?

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COSMO

Seems like a lot of trouble to produce a before and after results. Now we don't know who is biased and who isn't on any upcoming reviews. .

bullitt5897

Well Jake is doing a great job and will have some good comparisons for the n/a guys.

As for forced induction dynos I will be doing the stock GTR and then the Greddy intake manifold.

Maybe people can stop judging a product until the real world results come in... The bench test results showed great promise. The concept and design also shows great promise now it's just down to Jake and myself getting on the dyno.

Both Jake and I feel there are gains to be had based on our early experiences with the product.

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Shop Cars: 2013 318whp Nismo VspecII 370z *SOLD*, 2009 1000hp+ 93oct 4.0L TT 370z Fast Intentions STAGE 4 #054

juicinjake

yes

juicinjake

let me clear one thing up right now, there is absolutely no bias here at all whatsoever... remember i bought aam's manifold too (and am also sponsored by them for their TT kit)... and have a host of other modified stock manifolds to test. my interest is information/data generation and learning, not just for myself, but for all of us. my goal is to figure out what sort of applications each of these manifolds work better on. the vq web forums are polluted with negativity, misinformation and overall a terrible mindset with regards to mods in general, particularly with regards to intake manifolds. they expect parts to make power. thats just crazy to me, because thats not how it works. combinations of parts make power, when tuned properly. some combinations of parts are better than other combinations of parts, for a given goal. often times i see a question asked to the effect of "whats the best intake manifold for a vhr?" thats the kind of question that shouldnt ever be asked. the question people need to be asking is "what is the best intake manifold for my existing combination with respect to my goals?" a 10k rpm vq might win a lot of drag races, but will probably suck to drive around town and operate at low (engine) speeds. the intake manifold that belongs on the 10k motor would likely not make good power on a lower rpm street car, and vise versa. this is the seemingly chronic sickness that i am attempting to cure in this community... by teaching people to build effective combinations targeted at their intended use and performance goals. this is what the domestic guys do. now, the aam is a shorter runner manifold, much like the factory unit... whereas the stock gtr upper (not rjms product) combined with rjm's lower produces a MUCH longer runner. these should have VERY different performance characteristics. i tested long and short runner stuff on DE's for years before moving on to this platform. runner length has a very substantial effect on the powerband. i honestly believe runner length and plenum volume are going to be the big variables in these tests. with regards to my methods... i will test all these manifolds with stock cams, and then pull the motor, cam the car, and do it all again. i am also building a 4.2 for one of my customers currently that i will test both manifolds on. by changing displacement, rpm, cams, and things of that sort, many different combinations are developed... and i will present my data as such. there will be no "this manifold is better than this manifold period" sort of comments from me... thats pure ignorance. what you will see, however, is a comparison of powerbands and combinations. that might lead into some crude calculus being performed on the dyno curves with respect to gearing, ie tractives...

now, back to the bias thing... im biased towards the Z/G COMMUNITY. this is my fam. this is the people that are like me and get me. i am doing what im doing bc the community needs this knowledge, they need a new mindset... and need to get away from "how much power will this part give me?" sorta stuff... they need to get away from negativity and skepticism... two things that have never, ever won a race in all of automotive history...

Elmo370z

Preach

Boss_302

I just want to chime in here.
About negativity and skepticism.
How can one sell a product to any auto community with out proven dyno numbers or facts.
Any reputable manufacture of aftermarket equipment will provide you with some type performance data that they have gather from testing before putting it on the market.
The thing here is we are not talking 5-6 hundred dollars, where talking 2k of hard earned money, so of cause we going to criticize and voice our opinion.
As far as finish is concern, yes the intake ports seem a little on the rough side.
It wouldn't be the first time I'v had to fire up the die-grinder and fix something to my liking that the manufacture cheapened out on. But this is what we do, and that's what it's all about.

FPenvy

being in here is like sitting outside someone's window and touching myself inappropriately.......love it

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324whp/258wtq AAM Tuned |F.I. NonRes CF CBE/NonRes TestPipes #373|UpRev Tuner|Akuma Motorsports Intakes|Z1 34 Row Oil Cooler

COSMO

my god man Get Back To Work!!!!!

FPenvy

this is work. you ever try to balance on a tree limb with only one hand for support when I'm fondling my own balls and jackin it?

serious core strength needed.

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324whp/258wtq AAM Tuned |F.I. NonRes CF CBE/NonRes TestPipes #373|UpRev Tuner|Akuma Motorsports Intakes|Z1 34 Row Oil Cooler

juicinjake

intake ports on the rough side... have you ever seen/held/touched a CNC head?

like i said when cosmo said it, yall's concerns about selling he product untested is legitimate, but some of us (individuals) are stepping up to try to fill that need. please be patient with us, and understand that we are trying to help. i also feel like you guys are placing too much emphasis on the performance of the entire combination on the lower, particularly due to the price. it cant do the job on its own. ill reiterate, the runner length and plenum volume are going to be determined by the UPPER, not the lower. all rjm has done here is created a product that facilitated the use of any gtr compatible upper manifold onto the HR/VHR platform, with a much nicer transition between runner angles than anything else previously released...

VSS370z

This just kill me. Dude you need some therapy sessions