The Ace

After recently rebuilding my turbo, and generally tuning up my engine (new flanges everywhere, replaced tension bolts, cleaned engine a bit), I am now boosting 0,75-0,75-0,8-0,9 in 2nd-3rd-4th-5th according to my newly acquired boost gauge

Dont know why, but I'm not hitting fuel-cut in the first 4 gears (havent really WOTed 4th anyway), but I am sure hitting it in 5th. This weekend, going to and coming from my summer house, I couldnt even go past half-throttle, without the stock boost gauge sky-rocketing and the aftermarket one immediately "flirting" with the "1 bar" mark

So, the BIG question is this: WHAT DO I NEED ? I was thinking about an S-AFC, but then I realized that this is a rather mediocre solution. FCD is right out the window with this boost pattern (I like my engine ). I dont really have the money to go HalTech or PowerFC, so I am thinking about this:

FD pump, 850cc secondaries, and reprogrammed ECU done with a wide-band O2 and a dyno. That should cover me up to 1,5bars (I think...)

What do you think guys ? I cannt really do anything until my mechanic comes back from his vacations, but I want to have as much info as possible until then (2 weeks from now).
Hit me with any ideas, combos or solutions you might have.

V8what?!

That's a lot of boost for no fuel mods. Definitely buy the injectors and definitely buy an s-afc and an egt gauge or head straight for the dyno, but if you're going to run anything over 10psi (and some what say even less than that) then you will undoubtedly need a front mount intercooler. If not, then you get to play Pop Goes the 7. Have fun.

V8what?!

don't forget:
1.0bar = 14.7psi

That means you're already over 10psi, and you will also need a front mount if you ever want to touch 1.5bar (~22psi). Front mounts look cool too...

The Ace

Remember, I didnt plan for this, the "0,9bar" boosting levels just came along with the rebuilt turbo Thats why I'm taking it reaaallllyyyyy easy on the gas pedal

0,9bar is actually 13,5psi , so I'm WAY past the "no fuel mods needed" sign, or even the "stock system can support up to 250WHP" billboard back there I'm guessing I'll be putting down around 250RWHP with the proper tuning, so I really need some nice fuel mods (pump, injectors) and the proper management.

BUT, since S-AFC is just a piggyback, and I will dyno-tune with a wide-band, I really think that the reprogrammed ECU will be the fix-all-end-all solution. Dont have the money (or the time) to go Haltech, so....

The Ace

Oopss, and something else: I'm thinking 850cc just for secondaries, and keep the 550cc for primaries. Can I get away with 720cc ?

What's better ? 720cc all around, or 2x550cc + 2x850cc ? The 4x720cc have a little bigger overall flow, but the 850cc can provide even more flow when needed...

I am looking at 100EUR for a pump, 100EUR for two 850cc, and around 300EUR for the reprogramming....Will these mods suffice ?

Barwick

silly Europeans.. putting the comma where the decimal point goes, and the decimal point where the comma goes..

The Ace

Same thing can be said about you

The Ace

Nobody wants to help me tune (and save ) my Rex ???

How about if I just get the S-AFC ? Will that suffice ? (highly doubt it...)

chatch

I hope somebody will help you out. Im kinda in the same boat(except my motor is dead) and wondering what I should do about fuel. Already got a pump but I'm wonderin bout the rest of my soon-to-be setup.

`Matt

BlackRx7

I was not aware that you could tune a stock ECU without lots of trouble.......................

The Ace

If the ECU has EPROMS to store the maps, its a piece of cake. You just calculate the new maps. remove any fuel-cuts, rpms limiters etc etc, and then load the new software onto the ECU.

If the ECU cannot be reprogrammed, then you can get a "clean" one, and you just download all the software/data there.

What "troubles" are you refering to ?

jspecracer7

If you do use the Fd pump, you'll be fine because of the higher fuel pressure. Be sure to "tune" it though, either with an S-AFC or remapped ECU.

You CAN run to 300~rwhp with the fuel pressure turned up and the injectors at 85% injector duty.

Gecko_7

A S-AFC is fine for what you have done.

The Ace

OK, so a S-AFC will do for up to 1 bar (as I am seeing from the boost gauge). An FD pump -and FD secondaries probably- will also need to be installed.

But, how about the fuel-cut ? I know that the S-AFC modifies the AFM readings in order to achieve the enrichment of the A/F mixture, so does this mean that the fuel-cut will no longer be a problem ?

hIGGI

iTrader: (7)

Ace

If u`ll need S-AFC / S-ITC, let me know, i`m willing to sell my set coz i`m gettin E6K. Might want to deliver personally to Greece ;o)

The Ace

Hey, cool

Hit me with an offer for the S-AFC, and we'll see what we can arrange "for delivery in Greece"

soul assassin

theres no way in hell you are going to pull 1.5 bar with a stock "rebuilt" turbine. you will be fine with the FD pump and 850 cc secondarys. that should be good for 1.2 max but with out a front mount you are shooting your self in the foot.

The Ace

No, I didnt mean that I want to aim for 1,5bar. I said that reprogramming the ECU will cover me with fuel maps good for up to 1,5 bar of boost.

I'm very happy with my 0,9bar. I think that even going above 1bar requires a FMIC and probably water-injection in the IC surface.

I just want to make sure that FD pump, 850cc (or 720cc ?) secondaries, and -most importantly- the S-AFC will be enough. I suppose that I'll have to wait until my mechanic gets back....dont want to do anything hasty

soul assassin

well you wil not be "set" to run 1.5 bar boost with a FD pump and 850 cc injectors, that combo will be no good after 1.2bar. So for right now to be safe up too 1.2bar i would go with your FD pump or a GTR pump or any 215-255lph pump and 850 cc secondarys

The Ace

Seeing the other threads about fuel requirements, I am getting the feeling that I wont even need the 850cc, right ? Just the FD pump (or a Walbro, if I can find one), and the S-AFC to lean out (because I'll be running rich, even with 0,9bar), am I correct ? The stock injectors will be working a bit overtime, but that shouldnt be a problem, as long as I keep the boost under/around 1 bar....

Gecko_7

If ur running .9bar and not hittin boost cut then I guess u dont need a FCD but just to be safe I would buy a fcd and then get the S-AFC Tuned at a dyno would be ur best bet.

I basically have the same set up as u but I got a walbro 255 and a S-AFC should be good for up 12-14psi without leaning out. I dont plan on running anything over 12psi anyway.

The Ace

Yeah, but you see that's the problem. Lets say that FD pump and S-AFC are enough (after tuning) to provide the necessary fuel for my 0,9bar (13,5psi) boost levels. However I have the feeling that I've hit fuel-cut 4-5 times on the highway when going past half-throttle in 5th. It was not like everyone says "like hitting a brick wall". It was more like a hickup, a momentarily hesitation.

If this is indeed fuel-cut, then a) I'm hitting fuel-cut WAAAAYYYYYY later than usual (at 0,9bar), and b) my FCD (which I built myself) is set to clamp at 3,7V, which correspond to 8.2psi (according to Paul Stokes and the various info around for the stock boost sensor).

So if my ECU has a fuel-cut at 13.5 psi (which should be a voltage of about 4,4-4,5V) and I'm clamping the sensor output at 8.6psi to avoid fuel-cut, then I'm just making it worse. Unless having S-AFC negates the whole issue (because you are using just the AFM signal, and not the boost sensor's).

This is really confusing....

SaabGuy

Is your wastegate ported??? It may be a good idea. Its easier to raise boost than to lower boost.

The Ace

No. I was thinking about it, but I didnt think it was necessary at the time

Anyway, I dont want to lower the boost, since this seems to be the "normal" performance of the car as it is right now, I just want to make sure that I'm able to keep my A/F mixture correct.....

Well, if all else fails, I'll just connect a DMM to the O2 sensor, and try to find at what voltage/pressure comes the fuel-cut. I'll then set the FCD to clamp at that voltage, and I'm set (after having installed and tuned the S-AFC of course )

Josepi

Be careful, that COULD (i stress could) have been detonation. Atleast in the mild form of it. Mine seemed like it had a few small hiccups before it started sounding like someone was beating on the motor with a hammer (gee the sound of the rotor trying to reverse itself isn't the most pretty thing in the world...).