ludeowner

hi everybody,

I'm considering getting a new DP for my FD, but I had a few questions. Right now I have an Apexi N1 with HKS filters (stock intake pipes). I understand that putting a DP on at this stage will be pretty risky.

If I do get the DP, what I was planning on doing was to restrain myself, and not do any WOT runs and always make sure my boost reading stays below 10-11 PSI. I want to get a DP because with the coming summer, it's looking to get really hot under the hood.

Another question I had about DP brands: Are there any DP makers out there that have pre-welded WB O2 bungs? I want to get a DP with a pre-welded O2 bung so when I get around to getting an FJO I wont have to uninstall the DP to get a bung welded on. I figured I could just get a bolt put some anti-sieze on there and use it to plug up the bung until I get the FJO.

However, if I can't find a good quality DP with a pre-welded O2 bung, what size nut do I have to use for the WB O2 sensor?

thanks

ludeowner

I just found out that the O2 nut size for the FJO sensor is 18mm x 1.5 pitch (is that right?)

Also I was looking at the HKS downpipe, but from my understanding they are mild steel. Is there going to be a problem with welding a SS nut onto a mild steel pipe? (I'm not a welding expert)

thanks again

1st to 3rd

I know of no DP's that have an extra 02 bung. Do not get a mild steel DP as they are subjected to extreme heat and do not last that long. Spend the extra $$ for stainless if you can.
The HKS has an extra bend for righthand drive cars and is not considered he best for flow.
As far as being careful, my car went from running 11-9-11 (on the gauge, which reads 1psi high) with intake and CB to hitting fuel cut with the DP. Cars differ, but if you are running anything over a true 10psi then you need a boost controller.

BMike

You're pretty close to pushing your luck, you should really put it on a dyno with a wide band or use an EGT, but if you remove the restrictor pill from the wastegate line you should be able to keep the boost reasonable, but dont even think of removing the main cat without porting the wastegate or getting a better ecu.

ludeowner

hiya,

I had a question about the fuel cut, so FDs get fuel cut when you go above a certain RPM (7600), AND they also get fuel cut when the boost gets too high? How high does the boost get before fuel cut hits?

Also for EBCs I know for external WGs, you cannot set the boost lower then the WG spring. But is it different for internal WG's? for example would it be possible to use an EBC to lower boost to say from the stock 10 PSI to 8 PSI with an internal WG? I'm guessing its not possible, but I might be wrong.

thanks

BMike

I believe its right around 11, its not a very big jump over stock. Electronic boost controllers cant really lower it, though in an FD you can remove the restrictor pill in the waste gate line and lower the boost and then use a EBC to tune it back up, it should drop to about 8 psi with the restrictor removed on a stock car. Do a search for more info on the pills.

ludeowner

Ahhh, I see...that's comparable to swapping out a 10 PSI spring to a 8 PSI spring on an external WG, and using an EBC to raise the boost back up. Only difference is you use pills instead of springs on the internal WGs.

thanks a bunch

r0t0r-rooter

you'll be fine with intake, dp, & cb if all you see is ~11 psi (even @ transition). I have had an hks dp for a little over a yr, and haven't seen any probs.

rynberg

First of all, the stock ecu does not enact fuel-cut at 7600 rpm. The rev limiter is at 8300 rpm.

The stock ecu will enact fuel-cut to the rear rotor whenever boost exceeds a set limit for a couple of seconds, which is 10.7 psi above 6000 rpm.

Bmike, you will not be running close to the edge at 10 psi. The stock ecu is so rich, you are plenty safe, if you keep boost at 10 psi.

The stock wastegate spring is 7 psi. So, using an electronic boost controller DOES allow you to lower boost to 7 psi.

ludeowner: You will really need the downpipe mounted on the car and the wideband o2 sensor in hand in order to determine the best mounting point. There are rules for mounting the sensor and the geometry of the car restricts where you can put it. It will probably be better off to wait, despite the additional labor involved.

Also, if you can afford to get a wideband, you can afford a $300 boost controller. Just my 2 cents.

ludeowner

I thought that the RX7 turbos had internal WGs which are controlled by actuator arms like Mitsu turbos?

It looks like the M2 SS DP has a bung already welded on. I may get that one and have it thermo wrapped or jet-hot coated (hear there may be a waiting list though). I will probably be installing the DP myself since I have access to a hobby shop with lots of tools and a lift.

I like the idea of using pills and an EBC to control boost creep and spikes. I didn't like the idea of using a MBC and guesstimating. So I will be looking into how to control my boost with those mods using an EBC and the pills.

rynberg

If you use an EBC, you DON'T NEED to use pills, in fact you remove the wastegate line containing the pill to install the EBC.

ALL downpipes come with an O2 bung already welded in. You need this to hook your stock o2 sensor back up. I thought you were referring to a SECOND bung for just the wideband o2 (which is what most people do).

ludeowner

Yup, I was looking to have an O2 bung installed for the wideband O2. I thought that the stock O2 sensor went into the main cat? I may have misread that from another post.

rynberg

No, the stock o2 sensor goes to the pre-cat/downpipe. Depending on where the o2 sensor bung is placed, you may just be able to use that bung for your wideband for temporary tuning and then plug your stock o2 sensor back in for daily driving. The problem with this is most downpipe manfs place the bung too close to the turbos for good wideband sensor longevity. This is why it's perhaps better to wait until the pipe is actually installed and THEN figure out where you want to mount the sensor.

BTW, the successful installations I've seen have the wideband placed in the downpipe at the midpipe/main cat end of the pipe, after the pipe flattens out to horizontal.

GoodfellaFD3S

iTrader: (213)

You're correct, the stock twins have an actuator arm that controls the WG . There is no wastegate spring (although many use the term for ease of understanding), but when the arm is all the way forward and the flapper door is open, on an otherwise healthy system you will see 7 psi. Along the same lines, when I turn off my Greddy Profec B I see 7 psi or 0.49 kg/cm^2 on the power fc commander.

As a side note, a 5spd R1 is a redundant descriptive term .

take it easy--

GoodfellaFD3S

iTrader: (213)

More good info, Tyler. What the hell would the 3rd Gen section do without you ?

Also, what the hell are you doing up so early (or so late)?

rynberg

It's late, not early. Me and early mornings do not get along well together....

You need to get back here so I can buy you a beer...