JIMMY54

iTrader: (2)

Im dropping in a J-Spec S4 T2 into my 84',Its going to be running on a microtech with 3" Exhaust and Intake. Going to be using 680cc Secondary injectors and a good fuel pump (haven't decided which yet). I've been trying to read up as much as i can, what levels will occur if i don't port the WG? Would it be ok to let it creep since my fuel system should be up to par?

This is a little off topic but does any one know what Boost levels a NPR (small or large) intercooler is good for? Also wheres the Best place to Hook up an aftermarket Boost gauge?

Thanks for all the help

RylAssassin

I was hitting 15psi on my s4 turbo with an open exaust like yours. My wastegate wasent ported at all either so thats how it was hitting that high of boost. From what ive read 15psi is the max these turbos can go, i guess its ok if the fuel is there, but you also should worry about the IC temps, and the fact that the turbo wont last for **** at 15psi of boost. There designed for what 8 max?? So anyways if its all you have for now then **** it, use it as much as you can but id suggest upgrading that turbo real soon.

RylAssassin

damn double posts
websight acting up again

gsracer

I have a 2.5''TID/filter with 3'' turbo back into a single n1. Let me tell you fighting boost creep has been a bitch. I have ported the wastegate to the edge of the stock flap and tried to backcut it as much as I can. In the first 3 gears I get very little creep. I have my boost controller set to .7 bar. Here's how the boost stacks per gear:

1. .7 bar
2. .75 bar
3. .8 bar
4. .8 creeps towards .9 bar
5. I don't want to go to jail

My biggest worry now is just that the IC isn't sufficient enough for nearly 13 pounds of boost. As a result the intake temp is rising and detonation becomes that much easier. I should be getting my 720's in any day, and have the safc wired via the pressure sensor so the plan is to go just a little rich above 9-10 pounds.. I'll shoot for a 11:1 a/f ratio. Basically I'm smothering the air with fuel to prevent detonation, crude, but it'll do until I can get a s5 turbo and a nice front mount.

Anyways....boost creep is a bitch.

Jaared

ok so a s4 Tii with 3"dp.. 3"midpipe... back to the stock "Y" and stock catback.
stock s4 turbo with no port on the WG
hks Fcon and walbro will have hella problems or what?

creep is bad..

Jaared

i shoulda added the actual question... will the fuel mods actually support the thing up to 13lbs of temp boost while creepin?

I mean the Fcon thing said it can support up to 14lbs. I need to know if my injectors will be maxed out at that amount of boost. I know the IC will be strugglin but i plan on getting a FMIC soon. And water injection is in the works too. So i want to be able to drive the car daily and not have to hold my breath everytime i go through the gears.

With 720cc injectors i will have to buy a GCC(like a afc, lets you adjust the fuel curve at 5 points) for the Fcon and get it dyno tuned.

I may get a boost activated switch and hook it to a light.. alot like a shift light but for boost. I need to aim it at my eye.. at 10 or 11 psi im gonna have to get used to backing off it.

PS i do have a boost gauge. so im gonna be watching it too.

gsracer

do you still have the stock intake and TID? If they stock TID is kept creep won't be bad at all.

walbro, 720's, and the fconn can easily support whatever the stock turbo can throw at you. Especially iwth a front mount or water injection it shouldn't be a problem. The stock turbo starts losing it's effeciency past 12-13 pounds anyways.

JIMMY54

iTrader: (2)

I don't have stock intake box or TID, as everything will have to be custom since its a J-spec motor (didn't come with any of that included). So If i port the wastegate and add in a Cat....Do you guys think that would help alot?

gsracer

a highflow cat would help boost creep a good bit, yes. If you really want to eliminate all boost creep on a s4 I believe you would need a bigger flap for the wastegate door. However if you do plenty of backcutting and enlarge the wastegate hole size to the edge of the stock flap you can eliminate most of the creep and could run .7-.8 bar.

That being said, before winter I want to find a s5 tubro/manifold or weld on a bigger flap.

Jaared

cold makes it boost more right?

and will i be ok without the 720s... is there any easy method to tell if your running lean... i mean i dont have a egt or A/F..

I dont want to join the club of people that blow a motor first week.

gsracer

cold air is denser and as a result can make boost creep even more of a bitch.

In my experience with just a walbro I was just fine at 11 pounds of boost. My a/f were actually in the mid 11's from 4k on.

Unfortunately there is no easy way to tell whether you are running rich or lean. The best and only true way to get specific numbers is with a wideband o2 sesnor. You can probably find a local club going to the dyno gor a group session and get a couple pulls with the wideband for 25-30 bucks.

madaz07

yeah i just gutted my cat it used to run 7psi in first and 10psi in second now its 10psi and 14 psi on my low setting. it goes a hell of a lot better without the cat. an electroni boost controler would help that??

Jaared

no... you could make it higher if you wanted with a boost controller...

all controllers are the same as long as you have the normale style wastegate.