Nismo Convert86

iTrader: (7)

Yup, looks a lot like the 13BRE Upper Intake Manifold, first thing I noticed when I looked at the pictures.

Here is my 13BRE:

rotarygod

iTrader: (1)

These tech discussions always crack me up as the people that usually ask the most questions about plenum size, runner diameter, length, tuning, etc are typically the most ignorant people when it comes to technical design. These same people will usually fire back that something may work on paper but not the real world, or say other things like X person makes XX hp with a different setup so you aren't going to do any better. All of these things are complete and utter ignorance talking. Then you have the generally intelligent people like Howard who know from experience that some things work and others don't.

I'll throw out these 2 general statements and they will both be absolutely correct.
1: His manifold works better than stock.
2: His manifold isn't as good as stock.

Confused yet? Every manifold design, regardless of approach, amount of money spent on it, or who built it will do certain things well and other things not so well. If this manifold made 40 hp more than a stock manifold does on a 700 hp car, people would proclaim it superior. However what if spool was slower and part throttle response was terrible? Would it still be better?

All anyone should be asking him is, "Did you see any performance benefit from it?" If he says yes then the next question should be "Where you did see benefits and where did you see negatives?"

2a+RoN

^Couldn't agree more...

t-von

iTrader: (8)

I'm not LOL! I know exactly what your talking about. When I 1st saw the manifold I thought wow it's gonna have improved top end but the sacrifice will be partial throttle and low end with no secondary throttle controls.

SENZA PARI

rotarygod, I think this is the most intelligent thing ever written about intake manifolds I laughed out loud when I read it. Everything you said is so true and I have see comments like the ones you talk about on every car forum I have been on about nearly every manifold we have made. Except for supraforums, those guys love to try anything new to get a leg up.

Howard Coleman

iTrader: (6)

Rotarygod's comments .

that's why manifolding is so complex. generally it envolves tradeoffs. do you want top tick hp or do you want max hp under the curve? but if you want hp under the curve... where do you want the curve along the rpm band?

porting is very similar in concept. my GT3 race engines were restricted to two 38 mm venturies... so we moved the curve up the rpm band. to the point where they ran only between 7000 and 10,000. it was great for Tq/HP given the rules. but totally sucked below 7000. of course being truly race engines it made no difference as they never were near the street.

most of us however do the dual purpose thing and want to have it all.

tradeoff decisions are often butchered.

you can get what you want but you can't get ALL of what you want.

it would be interesting to find out where the strengths and weaknesses of the manifold are.

hc

madbouncy

How did you actually make the manifold and do you have any pictures of what the inside looks like where the runners meet the plenum? Look forward to seeing the results.

Real manifolds are rapid prototyped? We had ours done that way at school and even though we got it through a sponsership, they quoted it at 6400 dollars and it was about the same size as the manifold posted. I don't see a lot of people being able to do that with multiple manifolds to find out the perfect one. I would consider what people like Howard do to be a lot more real than the unlimited budget race teams. As what he does and actually puts out to the public is usable and recreatable by normal people on normal budgets.

SENZA PARI

The manifold is based off the factory upper, which has been cut down. All material is .22" thk. The welds have been removed and transitions radiused, other than TB weld.
The insides are no different, see below.

rx72c

iTrader: (8)

Fastest and Quicket 20b in the world uses FACTORY inlet manifolds.

Some of the fastest 13bs are also using Cosmo re manifolds and are right up their with e&J intake. Tells you something.

SENZA PARI

It tells me that the fastest rotary in the world (fastest what, quarter mile? I could care less about drag times personally) is using a manifold that was not designed with that goal as the determining factor for its design. If you honestly believe that the stock manifold is the optimum piece for that, then i'll stop posting and leave the forum. It works, and does the job, but like everything, it can be improved upon, or tailored to better reach a certain goal, and thats the bottom line.
Making the assumption that something is "ideal" or can't be improved upon because it "works" is the best way to keep from progressing...

BigTurbo74

iTrader: (4)

Looks great inside.

got_hp

subscribing........keep up the good work!

i'm very interested to see the results.

it would be neat if you could vary the plenum volume between testing runs to find the sweet spot in plenum size.

Maxstyle

iTrader: (3)

Spec, feed me specs please!

SENZA PARI

Runner lengths are now at 16.5" vs. stock length of 25". Plenum volume is an oz. shy of 2 litres.

haydenw

Tells you what?

That you cant improve on the factory manifolds

arghx

iTrader: (3)

One of the points people are trying to make here is that no one can easily point to a power level where OEM 13B-REW or 13B-RE manifolds/throttlebodies hit a "brick wall" where they stop making power. I'm not even sure we've found the limits of the REW manifold even though it's the only turbo 13B manifold to have basically zero plenum.

The other point is that when you "improve" on a factory manifold you may be giving up something else. So you have to decide whether or not you want the tradeoff. A big bore single blade throttlebody (Q45 or Rotaryworks) for example loses the the two-stage design of the factory ones. That hurts low throttle driveability. Every single rotary I can think of, including the 12A and the 13B-MSP Renesis, uses a staged opening of the intake ports either through the TB design or some other means (shutter valve on Renesis). With a Q45 TB you also give up cruise control and fast idle if you care about those, unless you do something custom I guess.

It doesn't mean that you shouldn't get an aftermarket manifold or TB... it's just that an aftermarket manifold and TB isn't a "no brainer" mod

SENZA PARI

Which is exactly the point I'm trying to make. Factory manifolds and throttle body setups were desgined to capture torque (as rotary's by mechanical design are not going to make huge torque numbers), and maintain the drivability required and expected from a mass produced automobile... Hence the 25" intake runners, staged throttle bodies, etc. It makes sense.
Now you put that same motor and intake setup in a drag car making upwards of 1100 hp... a 750 rpm idle is not important, drivability around town is not important, cruise control is not important... see where this is going? In this case, the factory plenum is a restriction. There are different "ideals" (although we'll never find a true ideal, there's always trade-offs, we can only get close) for different needs.
Sure you can squeeze 45 psi through a factory manifold and make big numbers, but due to the restrictive Tb's, lack of volume, and spaghetti string runners, you're creating more work for your motor than necessary. Why? More stress, more heat? Are these good things?
Yes, you can do it, people do it all the time, it works. That does not make it ideal, nor does it mean it can not be improved upon.
I just don't understand...
Nowhere in this thread has anyone said any one manifold, the one pictured or otherwise, was the "best". Not myself, not Howard, no one. Yet people continue to comment on how such and such isn't necessary, the stock manifold works, and so on. If that is so, what is your interest in this thread, other than to stir things up? If there is no need or desire to progress, or to better figure out how to tailor specific part of a system (an intake, like anything else on a car, is just one small part of an entire equation. What that equation is to you, be it drag racing, road racing, drifting... they all have there own set of parameters), why comment?
As stated more than once in this thread, this manifold was designed - conservatively - to increase flow in the upper rpm range. Also stated more than once in this thread is that low end torque will more than likely be the sacrifice. We will just have to sit tight, and wait and see what we find out. Until then, I'd appreciate if all those unwilling to grasp the idea that there are better ways of doing things, or with the lack desire to better understand what does and doesn't work, to please refrain from posting.
Or continue to, as it does make for some fun...:-)

D Walker

iTrader: (1)

For the race car I am building an equal pressure manifold like those pictured in my post. In my application I am doing road racing and hillclimbs, and midrange power IS something I am very interested in. I also am not sure that a rotary, regardless of powerband, will benefit in the same way a piston engine would from simply lopping off the OEM runners and welding on a plenum tank and TB flange. My biggest concern here is the chance of reversion and bad harmonics back through the intake. These can be a PITA to figure out and then fix.

SENZA PARI

What makes you say that? (not starting trouble, just looking for detail. Always willing to learn).

the_glass_man

iTrader: (2)

How much does it weigh compared to stock cast unit?

D Walker

iTrader: (1)

Generally its bad form to quote ones self but:

Other concerns would be the internal airflow through the manifold, but on a turbo car you can get away with a lot through simple brute force- the blower tells the air where to go. Shortening the runners while keeping them the same diameter might save a bit though and keep some intake velocity going. Another concern is equal flow to all runners. I have seen several manifolds (including the FD) whose flow characteristics will run one runner or another leaner or richer than its mates, causing tunibg issues that will be hard to track. It is well documented(to me at least) that the FD manifold is subject to this phenomenon, which has been proven to be solved by changing the lower runners or having them ported and balanced.
Changing the upper plenum and runners may actually exacerbate this issue and could lead to other expensive issues.

KNONFS

iTrader: (14)

Out of all of the 13Bs running 7.1 or less, use an aftermarket intake manifold. The closest one is Pica Racing using a modified RE manifold.

I have yet to see a 13B using an OEM manifold and be among the "fastest" drag cars in the world.

BTW - E&J does not make any intakes, they make TB.

haydenw

I am very well aware of VE gains and losses through manifold design but thanks,

You wont ever hit a " Brick wall " in manifold design.

My point was, it tells you nothing that the fastest rotary runs factory manifolds. Where in drag racing its not all about horsepower, all it tells you is that the team (pac performance) are happy with the power band that the factory intake does for them at this point in time.

got_hp

everyone understands that.........what hes trying to say is that just because they use a stock-style manifold, that does not mean there aren't gains to be found.

davyv 123

Any news yet.