supergoat

So what am I getting myself into?

I am good with cars so it's not a first time thing.......just on a rotary. I've gotten really good at removing the manifold from a Probe GT....can have it off in about 20min. The RX-7 looks a little harder though.

Is there a good detailed write-up for removing the intake manifold? I really don't want to go in unprepared and remove stuff I don't need, or not do something I should.

I will have a month off from school and work and since I can't drive the rx-7 in the snow much anyway, I decided to remove the manifold and port it. But I have never gotten that deep into a rotary before.

Thanks guys.

supergoat

BoostedRotors

its a snap. i know on my turbo ll its very simple, i remove the intercooler and there it sits...5 bolts and a few hoses...now the lower is a bit more involved. get yourself a haynes or chiltomn...they give you a step by step

niner

you should be able to do it without any problems if your pretty handy w/ cars. be sure to label everthing real well!!!
take your time. its pretty straightforward, just one intake piece after another

supergoat

thanks guys!

My only real concern is the throttle body. It has a mild port right now but I did it while still on the car.....I'm just that good.

The TB seems to have quite a few cables on it. All I need to disconnect is the throttle cable right?

One more question, to remove the upper intake manifold, will I need to disconnect the fuel lines or are they on the lower.

I don't plan on removing the lower manifold unless I feel like it. I will probably port the "exposed area" while still on the car. Anyone have suggestions to catch the pieces of alluminum from falling into the intake? I usually use greasy or wet rags. No problems so far.

Thanks again guys.

BoostedRotors

you can pull the upper intake manifold and the throttle body off all in one piece. its really simple and makes lfe a lot easier. just remember to label as you go, there should only be 5 or 6 hoses, a couple plugs, the oil metering switch, and the accelerator cable. you dont have to mess with any fuel lines or anything of that nature...good luck and let us know how it comes out!

supergoat

hey thanks! I really appreciate this help. One last question and I'm done. Where is the oil metering switch at? What's it look like. Or will I know it when I see it.

BoostedRotors

is right front of the throtle body...its held on by a cotter pin. youll see it. it may have a little protector on it covering the cotter pin. good luck

supergoat

THANKS!

Silkworm

Sticky parts while removing manifold:

You'll need to remove the two 10mm nuts holding brackets on to each side of the upper manifold where it bolts to the lower manifold. Tricky placement, but if you pull before those are disconnected you could bend a vacuum hardline.

at least one of the fuel lines to the secondary fuel rail will need to come off, but the other can stay.

G'luck.

PaulC

turboren

It makes sense if you have enlarged ports, but not otherwise.

Unless your actual intake ports are enlarged, you will see little if any gain by porting the manifold. In fact, low-speed torque, drivability, and fuel economy will all suffer.

If the runners are made too large, without corresponding increases in the port sizes, the engine will actually choke itself and produce less power. This happens for two reasons. One is that the relatively large runners are trying to flow more air than the ports will allow. The other (main) reason is that the runners, which were previously designed for optimal velocity with the stock-size ports, will now be experiencing loss of laminar flow, with corresponding turbelence forming in the runners.

In actuality, the intake runners don't really need to be enlarged until you start getting into bridge ports. The stock manifold can usually be made to flow better (read: produce more power) by filling in"dead spots" with epoxy than by porting, for stock or street ports.

In short, unless you have the ports to support it, I wouldn't mess with the intake manifold.

BTW, while you have the manifold off, replace the coolant hoses to and from the intake. The one from the rear housing to the IAC motor is a real pain to get off otherwise, and WILL eventually fail if it hasn't been replaced within about the last 6 years.

Ren

mazdaspeed7

You are wrong about the intake manifold. It flows barely enough for a stock engine. Once the mods start stacking up, it starts robbing more and more power. I gained more seat of the pants acceleration feel from porting my intake manifold that I did with the true dual exhaust.

Now, the restriction is not in the runners within the manifold, its in the flanges where the manifold pieces bolt together. For some reason, Mazda narrowed all of the runners just before the flanges. Just porting the flanges out to the size of the runners makes the manifold flow like it should have fromt he factory.

Turboren, no offense, but what experience do you have with ported intake manifolds? I will go ahead and say that my knowledge is limiter to n/a manifolds. It probably applies to turbo manifolds too, but I have no expecience with those.

I understand your reasoning, but that is for a perfect intake manifold, and face it, out manifolds are far from perfect.

The n/a manifolds simply narrow down too much to make them decent for even a highly modded stock port engine(mine) or a street port engine. From the gains I got on a stock port engine with the ported manifold, I would say street ported n/a's are losing a good percentage of their gains from the intake manifolds poor design from the factory.

pp13bnos

iTrader: (1)

Mazdaspeed7 is correct. I got more butt dyno hp, by porting the intake, than i did with the exaust. On the 89+ cars, the 2ndary injector bumps are something that should be rounded off. This will help bottom end (and top end) because the intake charge comes back up the intake manifold, once the rotor closes the ports off. The smoother the intake, the faster the intake charge (fuel and air) will travel, thus creating more hp.

Super goat, do youself a favor and dont port it on the car All those little filings, will go right into your engine....mabye causing your motor to go. I know that one of Robs customers had a intake extrude honed, and they did'nt clean it. The motor lasted about 2 mins, from what i was told. CJ

pp13bnos

iTrader: (1)

I was talking about the VDI system.

ItsNiceToBurnRice

yo, I just did this 4 days ago to replace the gasket. whith ****** around alot and talin to all my friends that were here, I got my intake off in 6 hours. the next day it took 3 to get it all back together. Just be VERY VERY VERY careful with the metering lines and the oil nozzles. the lines are very brittle and break too easy, heres a tip, when taking them off and puttin them back on use a hair dryer and get them nice and hot so they get somewhat soft and flexible. Good Luck

Felix Wankel

Pulling the lower intake is a cakewalk if you don't have the smog pump on.

The upper is pretty easy, just be careful to unhook everything, and don't go jerking on it. I always forget the damn little coolant hoses when dealing with a car I just bought, because I mod my TB's and do away with it.

tesla042

What's the best way to clean the metal shavings out? I blasted water thru all the runners, both directions, for a few minutes, while routing my finger around in there... Is there anything else I can do?

-Tesla

LoSRx7

Can someone post a link showing how to do the TB porting proberly
??? Like how much should be done, and some before and after images??? Thanks

SpeedRacer

Taking of the upper intake is a cinch for the most part. First depressurize the fuel system by disconnecting the fuel pump with your engine running. 2 12mm bolts will pop off the intake elbow from the throttle body. 2 10mm bolts will get the throttle cable bracket off the TB so you can disconnect the cable. There are 4 12mm bolts connecting the TB to the expansion chamber. You don't have to remove the coolant lines from TB. There is no need to remove it from the engine bay really. You can just ubolt it and and move it out of the way. There are 4 12mm bolts and 2 12mm nuts holding the expansion chamber to the upper intake. Remove these (which will release the vaccum spider thingy. There are a couple of vac lines connected to the expansion chamber that you will have to remove. There are a bunch of 12mm bolts holding the upper intake to the lower intake, remove these. Remove the 2 12mm bolts holding the secondary fuel rail down. Be careful lifting the rail so as to not damage the fuel injectors. Thats pretty much it. Make sure you label your vac lines or at least remember where they go. It is best to order all the gaskets you need before doing this, because they will probably need replacing. You will need the expansion chamber to extension chamber gasket, as well as the extension chamber to lower manifold gasket. Also you should replace the fuel injector o-rings and grommets.

tesla042

And, for the love of god, keep your bolts seperate! I didn't, and i'm dreading the day I put mine back together.. I'm going to have to use speedracer's writeup above to figure out which goes where.. bleh!

-Tesla

SpeedRacer

hehe...the funny part is, that whole writeup is based off memory. I have done that whole routine 10+ times in the last 2 years. Most of the bolts are the same size, so its not too hard to remember. The bolts that hold the fuel rail on are a little different. And there is on 12mm that is REALLY long, that goes into the middle of the lower part of the VDI/extension manifold, right by the fuel rail. Then there are 2 12mm bolts shorter than the rest that hold the bottom, driver side of the expansion chamber onto the bracket thingy. I forgot to mention that in my writeup. Hope that helps Tesla.

tesla042

Whoops...didn't notice that writeup is for a series 5... This is on my 87... ehehe

-Tesla

pp13bnos

iTrader: (1)

To clean the intake, i had taken a small peice of a shop towel, put it in the intake runner, (with the vdi out.) then push it with a peice of semi bendable rod (like a brazing rod) far as i can. Then take pressurized air, and blow it the rest of the way. Make shure the intake is spotless...you don't want metal going through the engine. CJ

supergoat

Whenever i port manifolds I take them to the local "self-wash" car wash where they have the pressurized water hose and just give it hell. Gets all the metal shavings out almost instantly. Than I spray in wheel cleaner then rinse that out to make sure I get out as much gunk as I can also.

Works terrific.

BiG WaNkLeR

I have a lot of other mods to do before I do anything like this one but am interested in the possible gains I can get. What kind of tool do you use to make those flanges wider inside where they get smaller?