SC12 with FMIC droping boost

[dave_101]

Just got a quick question about SC12's running FMIC's

I had a FMIC fitted to my AE101 Map gze, when I got the car back I noticed that in 2nd and 3rd gear I would get 13pound boost up around 4800 rpm, then it would suddenly drop back to 11pounds for the rest of the rpm like there was some kind of leak. This did not happen before I got the FMIC installed. It's running 2" pipe with a fairly large cooler.

I quizzed the mechanic about it thinking there might be some kind of leak in the pipes or seals, he said that it was most likely just the way the SC12 reacted to the extra length in pipe etc. Does not seem to do it in 1st or 4th gear which I found kinda strange. Will check tomorrow and edit my post with the exact rpm and gears it drops boost.

Has anyone else with a gze and fmic seen this as well?

[AE101LEV]

ur getting 13 pounds with fmic??? WTF on what size pulley?

factory pulley on 2"piping on 280x300 cooler i get 8-9 pounds
175 nevo i get 11 pounds 12 on a cold night

could be related to heat, velocity drop, the gay knock sensor retarding problem gze's have reducing the rotation of the crank :S what cooler u running have u altered the SC pulley as well "hmf" i want 13 pounds on fmic i got air pod in engine bay sukn up heat.. im guna see if the heat bandage stuff makes a difference as well cos the piping before the cooler gets very hot!. so prob half my problem... is this a rwd/fwd application.

[dave_101]

I have the Nevo 175 pulley, and the cooler is pretty big. Forget the size, will measure it tomorrow. Before I got the FMIC she would goto 14pounds. It's a FWD setup, an AE92 hatch.

13pounds is the best I get in 4th on the highway now with the FMIC, but I get like u said around 12 pounds in most gears, and then I get the drop to just above 10 after she hits 4800rpm mainly in 3rd I think it is. Will post tomorrow exactly what gears she is doing it in.

The motor seems to be really good, I bought the cut with 121,000 on her, and with the FMIC and stock ECU shes running 122.3KW atw.

I have a gay ass knock sensor too, thank god the FMIC seemed to make that a fair bit better. But now being summer shes back to being a bitch. Looking at playing with that tomorrow, might even try this 7mgte one and see how that goes.

[Hen]

Check for leaks. It doesn't really make sense that it'll do it just in particular gears. That more points to an intermittent leak I think. Especially since you've just had your intake piping played with.

Hen

[Ghetto-Spec .:bayka:.]

Hey man, 122kw with SC instant response must be incredible to drive, your lucky, just don't spin a bearing like me.

-- knock sensor issue --
Ive had "gay" knocking issues for over a year on my ae93 and finally solved it. For me using a FMIC actually made the power drop problem more acute. I switched the knock sensor out with a 7MGTE one and that almost fixed it, but now and again it would still be highly gay. Recently after my engine rebuild i replaced the knock sensor with a factory 100kw 4age knock sensor and havn't had a problem at all.

If you do manage to "fix" the knocking issue, i highly recommend getting a knock check next time your on the dyno in the heat...$5000 later after my rebuild, im beginning to think that my engine might in fact have been knocking and i simply bypassed the issue with a 7MGTE sensor

-- large FMIC --
I also was running a large FMIC running 13-14psi but didn't notice any effects as prominant as yours. For reference though, 4th gear for me always managed to reach an extra pound or two higher than 2nd & 3rd.

-- stall issues with large FMIC --
Didn't have any stall issues either, but i was running at smaller fixed SC pulley that always kept pressure in the FMIC. Are you still using a clutched SC?

Hope that helps
Daniel

[MWP]

This is my explanation... may not be the correct one though.

When using the FMIC, the air is cooled and becomes denser.
Because its denser the air also consumes less space and drops in pressure.

This effects superchargers because they pump a specific amount of air per rotation.
It doesnt effect turbos as they use the wastegate to control boost therefore always supplying the same pressure.

... that doesnt explain your weird different gear problem though.

[dave_101]

-- fmic & boost loss --
Ok I took her for a drive this morning to make proper note of exactly when I was loosing boost and in what gears.

1st seemed ok, with around 11 pounds to redline.
2nd would get 12pounds just before 4000rpm, then at about 4100rpm I would get a very sudden drop from 12 pounds down to 11 pounds and even 10.5 pounds.
3rd gear was exactly the same as 2nd, would loose about 1.5 pounds after she hit 4100rpm.
4th I am going to test this afternoon on the highway, I usually get 13 pounds in forth tho. Just like you said Ghetto, I get an extra pound in 4th compared to the other gears.

The drop is really sudden hey, soon as she hits 4100rpm, it drops right off. It does build back up a little around 6000rpm, but not more then 0.25 pounds.

After reading the above, do you guys reckon that sounds like some kind of leak in the system, or could it be what MWP was describing?
Checked the pipes this morning and could not notice any bad welds or anything, have yet to check the rubber seals around joining pipes and on the cooler itself. Anyone know a good way to test a system for leaks?

-- knock sensor --
As for the knock sensor, think I might not go with the 7MGTE one now. As the thought of her pinging and the ECU not knowing about it is worse then the problem itself. I did think about getting a microtech as posts on this forum said it fixed it in all cases. But it's a $1700 fix which is bit much. Ghetto, is your motor a MAP or AFM gze? Just wondered if I would be able to do the same thing on my MAP and use the 100kw 4AGE sensor.

-- stalling issues --
Yeah I am still using the clutch on the SC, was told by my guy it’s not the best idea to remove the clutch. Something about the life of the SC would be reduced, not 100% sure tho.

Ghetto, I love this motor. The torque in 1st and 2nd is just insane, on a cold night she really hammers. The FMIC was the best thing I did to this baby, aside from the fact I need to fix her idle issues, but Sprinter & AE101LEV have given me some ideas for that. Ended up with another 11kw because the timing was able to be moved forward just that bit more.

[Ghetto-Spec .:bayka:.]

Thats incredible power your making (for me anyway). I don't think i got close, but i was constantly plauged by ignition (knocking) retard timing, failed superchargers and intercooler pvc piping.

I run an ae101 MAP ZE same as yours mate. 4age 100kw knock sensor will screw straight in, you MAY need to cut the outside of the plug up to make it fit properly. (i had already done this to get the 7mgte one to fit) But the centre bit of the plug is exactly the same accross all models so this is all that counts.

The sudden boost loss you describe is odd. If its 100% systematic every time it sounds like it would have to be tuning somehow. Its not like the SC is slowing down or anything but i have heard of people loosing boost due to tuning issues. I also had weird anomolys with boost when my SC started to fail due to teflon coating breaking off and loosing the air seal. But i dont' think thats it. Also when i had ECU driven ignition retard it DID NOT affect my boost noticably.

-- idle prob --
if you havn't stuffed around with any vacuum lines since you switched to the FMIC i doubt its anything other than directly caused by the larger FMIC volume. As your running a nevo pulley your std SC electonic clutch remains, assuming you havn't hooked up a switch yet the ECU will be switching the charger off below 1500rpm and thats where your problem might lie. I recommend as a quick way to test this : locate your SC relay (small black box mared SC RELAY near your passenger side front strut in the engine bay.) There are 2 thin and 2 thick wires going into the relay. cut the thick two wires and simply join them together. This will ensure the SC stays ON always. see if the idle is affected.

Dont worry about the life of your SC, im sure your doing heaps more damage at 8250rpm 14psi

Another Q: have you removed the Air Bypass Valve on your SC setup? (ABV mod)

[dave_101]

Yeah I am pretty happy with it hey, just want to iron out the Knock bug and also the idle thing. Not to worried about the boost drop so much, as it does not seem to make a huge difference anyway. Just if it was a leaking pipe, was going to see if the guys that installed it could take a look etc. Might just leave it for now.

Not a bad idea to test the sc wired up as always on to see what happens, something I can do on the weekend. thanks man.

Thats really good news about the 4AGE knock sensor, will have my guys drop one in when I get a service in a couple of weeks. Will let everyone here know if it fixes the problem, as this is a crap load cheaper then going after market ECU.

Yep the ABV mod was done when I had the pulley fitted, with the stock cooler i was getting 14psi all day long. But that air temps were just insane, poor thing

Thanks everyone for taking the time to reply.

[AE101LEV]

i had the stalling issue for a bit.. basically the only way to stop it was to bring up the throttle stop a bit to stop the throttle closing as much to just keep the motor going when the clutch is pushed in and it drops to 500 and comes back up... then reset the throttle positioning sensor and its all good..

now i have heard that advancing the base timing to 15deg instead of 10 really helps against the knock sensor issue and feels faster. I havnt done it yet to lasy but soon i might try it.

[reecegze]

Not trying to hijack
my 4agze has a afm charger and my charger sees 12.5 psi from 3000rpm onwards on full booting
Its starts off at 10 then builds upto 12.5 ish. I run a 300 x 280 fmic intercooler with 175nevo and 2inch piping , and abv is still operational but the aftermarket ecu somehow lets the charger keep boosting

Question is i got a map sc12 charger sitting in my shed and wondering if its worth swapping my sc AFM > MAP to use that smaller pulley. Would this give me around 13+ u think ?

[Ghetto-Spec .:bayka:.]

For the effort mate, i wouldn't bother for slightly more boost. Its a bitch changing out the SC12's on a FWD configuration. (ive done it numerous times)

If you want to go crazy though, ive always wanted to know what you can get with the EA air con pulley -> SC12 + nevo pulley -> crank.

I rekon with an adequate FMIC and 3SGTE MAP sensor you could get 18psi

Sure a lot of ppl will say the SC12 will die and there is too much heat and bla bla...but someone has to fucking do it. I heard that some dude actually tested the failure point of the SC12's and he got a couple that could hold 18psi reliably

[Adsport]

FYI SC2 puts out 132 degrees air temp at 10psi..

spinning them to make 18psi is a deathwish ive seen many die just from 175mm pulleys installed

[AE101LEV]

i have a ea air con pulley at home but i dont know how to install it really cos it needs sleavn and shit to fit ont he shaft or somthn.. so havnt really bothered.. but yeh SC12 melts down at 18psi i might have a go if i got a week to play with it but cos its my everydayer i cant really spend time on fabrication like that unless i am certain i know what needs to be done to install it.

also.. a map sensored ECU limits and doesnt run to well to 14/15 pounds doesnt it??

[Ghetto-Spec .:bayka:.]

Thats correct. Mine had problems at around 14-15psi when running the EA falcon pulley.
I know exactly what needs to be done for the EA pulley mod and have written it up on the previous toymods forum, including sleeve specifications:

http://forums.toymods.org.au/index.p...art=0&count=60

If you cant afford a NEVO its cost me $30 and a bit of time to do the ea pulley mod. I machined the sleeve on a laithe at a friends place. The exact specs can be found on the above link.

Cheers
Daniel