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Discussion Starter #1
(mods please move this if you need to, but don't delete)

As you all well know in the process of getting parts for my LS/VTEC project I got a stripped down b16 cylinder head. luckily it came with an intake manifold and a throttle body (no TPS though) It has some casting numbers which lead me to believe it is a 1st generation JDM b16a. now comes the questions
- what difference (if any) is there between the IM and a type-R IM
- What should the throttle body's Internal Diameter be? it seems to be the same as my b18a's T.B.
- on that note what are the I.D's for the different b-series T.B's
more questions to follow...
 

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Discussion Starter #3
Mike Thanks! I guess I'll have to save up for ANOTHER part. (ITR TB) hmmm... I wonder how much I can get the b18a one bored out, which would save some green.
Mike? back to you in the studio!
 

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Discussion Starter #6
true, but If I can bore out the TB I have, then busting out the blue ink on the TB, marking the IM plenum entrance with that and then using the trusty DREMEL tool to taper/match the plenum entrance effectivly portmatching the IM plenum entrance to the TB. the money saved COULD go to an extrude hone job. honestly would that be a reasonable cost alternative? If I broke down to buy the Type-r IM then I would also need a new fuel rail, if the fuel injector ports don't align. (b16a and b18c5)

btw I will make an article for the site!
 

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the gains aren't going to be at the TB.

you can go too big on a TB bore and really kill your flow velocity at the upper rpms.

When I refer to the plenum, I don't mean the plenum port size. I am referring to the plenum port volume. The entire plenum (or "log" as it's called) itself. This is what turns the incoming flow down the runners, creates a high pressure area entering the runner, and also reflects the rarefaction wave coming back from the closed intake valve to give your resonance frequency.

Large volume or big plenums like smaller TB diameters (62-64mm ) and smaller volume plenums prefer larger Tb diameters (65-68 mm). The former provides enough flow capacity feeding the plenum for upper rpm power and the latter provides enough flow velocity to maintain velocity down the runner for low end power.

The 2 biggest problems with TB: not portmatching the plenum port (having a port smaller than the TB diameter) and going too large resulting in a power loss in the upper rpms.

Extrude honing removes and equal amount of material out of the runner. You actually want to shape the runner with an asymmetric diameter. If you want to spend the money, send it to Joe Alaniz or Endyn to have them port the plenum internally and the runners.
 

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remember a lot of people get fooled by placing a huge TB on their package and feeling an improved low end throttle response on the butt dyno but if they bothered to check their actual power or timeslip, they lot flow velocity in the upper rpm and upper rpm power...the net result is like the AEM hump in intakes...your butt dyno feels the gain but the where it matters, on the track, sees a loss in performance....
 

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In a single plenum IM, the theory is that the plenum is used to create resonance to generate a high pressure zone from multiple reflected intake pulses just before the intake valve opens. The speed at which the pulse enters and fills the cylinder will dictate where along the powerband the greatest torque will occur. The intake/TB unit in a single plenum IM system serves as a ram feeder to the plenum. It provides the necessary initial pressure, flow velocity, and flow capacity. Short intake tubes generate high initial velocities later in the powerband. Long intakes like a CAI will create a double hump in which there is an initial brief increase in torque from a faster initial velocity. This is known as the "AEM hump" (usually from 4000-5500 rpm) where it was first observed and labelled as such. So when people say my CAI felt like it made more power, this is what the butt dyno senses. For upper rpm power the limiting factor on the CAI or long intakes becomes the diameter. So where a CAI can hurt you is in the upper rpms, IF THE DIAMETER IS TOO SMALL FOR THE RAM EFFECT NEEDED. Cam spec, headporting, CR, R/S, and displacement will dictate how much resonance you need. Those (cam, CR, R/S, displacement) in turn were dictated by your power goal and powerband location. There is a logical stepwise unifying process to this. They all interconnect.
 

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Discussion Starter #11
kelly, mike thanks for your input!
with this in mind these are my goals, b18a block resleeved at golden eagle and bored to 84mm, b16a head spotfaced and ported. type-r valves and springs, ctr cams
compression ratio goal is 11:1, but depends on how good the porter is. r/s will still be the ls standard, unless anyone out there has some longer rods and a shorter stroke crankshaft for me

from the intake- diy cai through to the Throttle body. each segment of the piping will slightly step down in size, and the ends will be taperd (ala- dremel) to meet up with the one before it. hopefully this will increase the velocity as the air rushes along the pipe to the TB, but also reduces the pumping required due to a larger diameter entrance(velocity stack??). this will carry through to the TB. now if i go with king motorsports and understand/follow mike's advice, I will most likely keep the B16A IM since my redline will be around 6.5-7k not to exceed 8k.
after the air exits the TB it enters the IM plenum. now I will use inida ink to put an outline of the TB and use the dremel to grind away the metal in the way. this will taper smoothly to the plenum's diameter. if I can afford extrude honing, this step would take place afterwards. once the TB and plenum port are matched up then I will concentrate on the IM's runners matching the intake ports. I have a feeling that if the intake ports on the head are slightly larger than the runners, it may reduce reversion of exhaust gasses back into the IM during overlap. I don't anticipate a lot of this, but I'm not sure because of the cams (JDM CTR). I can't afford HYTECH or SMSP custom exhausts, but I have a Shipmate in Japan right now that could get me a JDM type-r header (98 is the best right?) I will also sweet talk some folks into hooking up a 2.5 inch exhaust setup, carsound cat of course.
Does this sound like a semi-well thought out package?
critcism is welcome as long as it is constructive, advice is alway wanted.
 

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I suggest you get the Skunk2 IM for the LS.

I suggest a 62mm TB.

there are several good places who can do a very competent excellent job at boring your TB: RC Engineering and Leitner & Bush are 2 I can think of in the US and Canada respectively off the top of my head....excellent workmanship/fit and no sticking throttle plates.

you don't need to Extrude Hone. Just get the IM ported and shaped...Extrude Hone cannot shape the runners..it just takes out material evenly throughout and it's advantage is that it gets into hard to get at areas a grinder cannot.


The DC JDM 4-1 is as good as the JDM ITR 4-1. Have you looked at the Type one Header?
 
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