1994 RX-7: Xcessive LIM & Fuel Rail install (in progress)

[scotty305]

Getting dangerously close to being finished now... first post has been updated and the "to do" list finally feels like it is getting shorter. If I can get the blasted wiring harness through the firewall and the fuel system holds pressure without any leaks it may fire up next weekend.

Thanks to Nathan and Casey (not RCC members but good guys just the same) for stopping by and lending a hand this weekend.

[speeddemon32]

oh man, this thread is SOOO much better when you log in. I can see the pictures!

he he . anyways, your welcome! It was fun working on a rotary car again. makes me want one again. :-(

I am looking forward to seeing your car back on the road again. you know I want a ride right?

[speeddemon32]

soooooo????? :-)

[MaczPayne]

Hey Casey!

[scotty305]

Posted a couple more photos and updated first post to show what I've been up to in the past couple of months... lots of wiring, a couple of modifications to the fuel rail (one of the mounting holes in my original flange was acting as a huge leak because it was inside where the welds sealed the rail to the flange). Also ran a lot of vacuum lines the past week or two, that's nearly done now.
Have let a lot of things get in the way the past few months but it's starting to feel like the project is nearly finished.

[scotty305]

It's alive!!!

Got it fired up this week... spent about an hour idling in the garage today... adjusting fuel pressure, burning off lots of PB Blaster that had been used to break the exhaust studs loose, adjusting idle and low RPM settings...

So far there aren't any leaks, although the drain plug from my CSF aluminum radiator stripped the first time I removed it... I burned at least a day getting the tools to drill and tap a larger hole and then trimming a very large bolt shorter so it would work as the new drain plug.

I started the new fuel map from scratch because I wanted to try a few different things, but so far so good... it idles smoothly at 800-850RPM and throttle response seems just as good as it always was now that I've got the fuel map somewhat dialed in (running 50 psi fuel pressure for now, may turn it up eventually depending on duty cycles at high RPM). Idle seems to want a slightly richer AFR (12.5-13.0 compared to about 13.0-13.5 before), but I did find a pretty major exhaust leak at the flange where the downpipe meets the catalytic converter (one of the two bolts was missing!) so it's possible that may have been skewing the readings in the past. It's much quieter at idle without the exhaust leak.

I'll post photos soon, the engine bay looks very OEM with the UIM installed... still need to reinstall the hood, undertray(s), airbox, IC and charge piping before getting back on the road.

[ehron]

Any updates? I am interested to see how your gas mileage turned out after moving the primaries upstream. I would imagine your car likes the richer idle for the same reason.

[scotty305]

Not sure about gas mileage yet... have only gone through one tank of gas since getting the car back on the road. It was slightly better economy than the previous few tanks but I've moved recently so the car is seeing different driving patterns than before.

I've tried to adjust injector phasing and ignition timing in an attempt to get the idle smoother with less fuel but haven't been successful yet: leaner than 12.0 and the car tends to hiccup and misfire at idle. Next on the to-do list is adjusting fuel pressure, currently set to about 50psi with the engine off.

I don't think the injectors are to blame, pulsewidths are pretty reasonable at idle (around 2.4ms) and the charts provided by Injector Dynamics show their flow is linear well below 2.0 ms. At 11.5-12.0 it will idle smoothly down to 700RPM, and throttle response seems just as good as it was before changing the setup.



Almost forgot to mention: I originally had the Turbo Control solenoid vacuum lines swapped... pressure went to the vacuum port and vacuum went to the pressure port. Needless to say the car didnt transition properly until that was fixed; boost was normal below the transition RPM but dropped quickly above it.

[dudemaaan]

Nice work, Look forward to seeing the power difference with the new LIM.

[scotty305]

Got on a dyno last weekend. This is the first time the car has been on a dyno so unfortunately I don't have other numbers to compare against.

AFR's were about 10.0-11.0 according to the AEM wideband in the downpipe, and about 10.5-11.5 according to the dyno's Motec wideband mounted in a pipe and stuck in the end of the muffler (after the stock cat, stock muffler).
Ignition timing was about 3-11 degrees leading advance depending on RPM, with 15 degrees trailing split. Boost was about 10psi (165-173kPa), dropping to 7psi at the transition.

Didn't spend too much time making adjustments... it was late at night and the dyno owner was doing me a favor letting me use the machine. Boost wasn't as smooth as I'd like it to be (especially on the blue squiggly run), and I suspect there may be more power at different AFRs or ignition timing.

[TitaniumTT]

Scotty, I'm quite impressed with your build, I must say. You did a fine job with the fuel system. I was hoping to be the first one here to comment on the ID injectors. Which are you using? the ID 750, or the 1000 or a combination. I believe I'll be stuck with 4 1000's or two 750's and 2 2000's. We'll see, I still need to call Paul. Loving the FPR setup though. Very awesome.

Rotaries love the fat dumb and happy idle. It keeps the flame front slow and steady. My car loves the .85-.87 range for idle as do just about all the other rotaries that I have seen. IGN timing is around 5* @ idle. Holds really nicely for me.

Fuel pressure. I would run it as low as possible. It's my opinion that 50psi is just too high (unless Paul disagrees) however, I know a gent at MoTeC that is running his S5 @ 39psi static with 4 ID1000's. He sees 82% duty @ 15psi with .8L at redline.

Lambda's - there is alot more power, response and believe it or not, boost stability to be picked up by leaning at the fuel map. What I found with excessivly rich AFR's is the unburnt fuel increases EGT's as it burns in the manifold. This extra energy spools the turbo's harder for that split second. It's exponentially worse on a misfire.... tons of raw fuel expanding in the mani makes for unhappy turbo's, stockers anyway.

If you would like, I'd be more than happy to send you my timing map to compare with yours.

Why did you choose the AEM over the PFC. For your setup it would seem that the PFC would be the way to go (I honestly don't know anything about the AEM) or did you just want to experiment?

[TitaniumTT]

Something else to consider RE:High rail pressures. What fuel pump are you using? I can tell you from personal experience that the Desno fuel pumps are not very effiecent at all. The are hungry for amps. The more amps, the hotter they get, the hotter the get, the less effiecent they are, to the point where rail pressure starts to fall off. I know this from personal experience. 50psi plus boost puts you into the 60psi range, mine has trouble keeping up with 56psi on repeated dyno runs. Granted I'm using more fuel than you, so more flow at the same pressure means more load on my pump, but it's something that I would be concerned about. Proper wiring is the best place to start.

[scotty305]

Thanks, TitaniumTT.

All four injectors are ID1000's, I like them so far. One of the guys from Yawpower suggested the fuel dispersion/atomization is better at higher pressure (up to a point, of course). Stock fuel pump and wiring so far; I know it's not ideal for pump voltage but the fuel pressure sensor says that's not a problem yet. The same guy from Yawpower suggested upgrading to a Bosch fuel pump if I want to increase fuel pressure above where it's currently at.

I saw a local RX7 guy using a PFC and wasn't too impressed with the interface or capabilities. I went with AEM because I know a few locals with AEM tuning experience (mostly piston engines though); it can do quite a bit including closed-loop boost and O2 feedback, factory oil metering pump control. Outputs aren't as flexible as the Motec from what I gather, I don't think there's a way to PWM the CCV and CRV like you've mentioned in your thread. I'm using a bit of a workaround to get PWM control of the prespool valve; the EMS has a couple of tables (MAP vs RPM) intended for variable cam control and I'm using one of those.

The car isn't happy idling at 0.85 lambda (12.5 AFR), it wants to see closer to 0.80-0.82 or it will misfire. I've made most of the changes to the primary injectors that should result in a poor idle (further from intake port, higher flow rate, lack of OEM 'fuel diffuser' insert), I'm not sure I'll be able to tune it out. I've been meaning to adjust fuel pressure and see if that makes a difference, might give that a shot this week.

[scotty305]

I recently cut up the the stock gauge cluster to install a wideband O2 gauge in place of the OEM coolant temp gauge. I first saw the idea on Max Cooper's page: http://www.maxcooper.com/rx7/how-to/...ges/index.html


I removed the coolant gauge because it's been non-functional for a few years. I made a digital gauge using the coolant sensor in the rear iron for an instrumentation class. It's mounted behind a smoked plastic lens covering the warning lights on the left side of the cluster.






The lighting on the O2 gauge is too bright at nighttime, I may adjust this eventually. Aside from that I'm pretty pleased with how it turned out.

[speeddemon32]

looks awesome man!