How much boost is too much?
 

Now that I found the cracked Y-Pipe coupler and replaced it, this thing boosts like a mo-fo. It hit 15 psi quick, and beyond. I drove it around a bit today, and thought that 10 psi was safe, so I had to back out of it to try to only get about 10 psi.

But it was hard to watch the boost gage that close with the rpms climbing so quick. How much boost is safe? I think it actually de-fueled ... or whatever its called, when it went beyone 15 psi. I can't be sure but it seems like it cut fuel at about 17 psi or so. And it seemed like it would've pulled more boost if it hadn't cut fuel.

So, I'm not sure what's bad, but I would think it would be safe to keep the boost down to maybe 12 psi or so.

Any advice you can give me on how much boost is safe, and how I could control the boost lower if that the safest direction, would be appreciated. Or anything else I need to know. Thanks.

- JyRO

Stop boosting and start reading. Running all that boost has the potential to blow your engine.

-Max

pleaseeeeeeeeeeee dont tell me your running stock ecu. If you are, anything over 10 is too much boost

14 psi = Max efficiency of Stock Turbo's
10 psi = Stock Boost
12 psi = JDM Turbo Spec

12 psi is not JayDeeeMmMM turbo spec for every model or year.

Also, "max efficiency" and "the point at which the efficiency drops so steeply that more boost doesn't make more power" are not the same thing.

-Max

read the stickies... they are your friends :)

Hahaha

Buy a boost contoller and read the FAQs

By boosting too much on a stock system you're risking your engine. Too much and you'll probably hit the fuel cut off, which it sounds like you have done. If you're on the stock ECU not enough fuel will be delivered and you'll lean out which is to coin a phrase..."not good".

1) List your mods - if that's a stock ECU like I think it is, you were damn lucky to have any compression today. 11psi is as high as I would tune a stock ECU.

2) Unplug your wastegate and precontrol solenoids, and make sure the hoses running from those solenoids all the way to the primary compressor housing are intact and not leaking. That should regulate you to 8psi.

Dave

Is it not possible to just buy a fuel-cut defender for an FD, so that you don't hit fuel cut at 12psi on stock ECU?

Unplug the wastegate and you'll never stop boosting. Putting on a straight line with no pill will "regulate" the boost to the wastegate spring level of 7 lbs (per square inch). :bj:

Am no expert on this but from what I've read with regard to my own situation it's mainly down to the factory ECU being locked down. If you want to start messing with more and more boost you need to get a programmable ECU so the maps can be adjusted, that's the best way to make sure the engine doesn't lean out.

Disclaimer: As I said, this is my understanding, experts feel free to correct me...please be gentle however... ;)

<Duplicate>

Guys - Before you beat me up too bad, understand that this is a project car I bought as is.

From what I know about the car, I would guess that the ECU is the stock one. I would like to effectively limit the boost to 10 psi ... 12 at the most. I went above this only about 3 times yesterday, and only for a second or two. And when I did, it didn't seem to make any more power (at least not by seat of the pants), but did have a bit of a different sound to it. I honestly believe it was a combustion sound difference, as it was too lean.

The mods are:

Positives:

Other notes:

It is a 93 model.
It is silver with the rear wing.
I bought this car from my cousin, who knew how to drive it (sort of) but I don't think he knew much or anything about what's under the hood. Originally he had a blue '93 with a rebuilt engine, with only a down-pipe. He totalled that car all to he11, and bought this silver one with lots of pettit racing stuff on a sour motor. He had his blue crashed car's motor put into the silver car and kept all the pettit racing stuff. Since then, he crashed the silver car into a telephone pole at slow speed. Then the car sat for maybe 4 years.

It is now mine to feed and care for. So I'm learning. I knew nothing about them before except that I had a 1st gen car and know how a NA 12-A works. That's about the limit of it.


Negatives:

The car was crashed into a telephone pole at ~15 mph.
The front bumper and hood are replaced with fiberglass units, but they are not fit well on the front end.
The fenders where they meet the bumper cover are slightly damaged.
The steering wheel airbag deployed and has since been removed. The steering wheel is now airbagless with the cover torn where the airbag came through

- JyRO

The mods are...?

Sorry, I was getting my old list / editing, check it out now.

Dude, if Pettit did the swap and everything my thought is that you have a Pettit ECU, however it would have come from your bro's previous FD from which the engine came right ?
Hard to say, get a boost controller or be extremely careful not to overboost. Fuel cut is bad.

Did I say bother? I meant cousin. The way I understand it from cuz is that the new car (which is the silver one that I have now) had a bunch of pettit stuff on it already, built and installed by pettit in FL (the sticker is still on the driver's door jam from Pettit). The motor was no good, so he pulled the NG motor out of the new silver pettit car, put his old crashed blue car's good motor into the silver car. Well I should say, he had this engine swap done for him, in Chattanooga somewhere I think (I can ask again).

Basically, he crashed his blue car, bought it back for the insurance company. Then found a Pettit car out of FL for cheap cause the engine was no good. Had his old car's motor put in the new one.

I would guess that whatever ECU was in the silver car (my car) it was left in there.

How can I document which ECU I have? Let me know and I'll check it out ASAP.

- JyRO

JyRO,

It sounds like you have one of two possible problems:

1. Wastegate isn't functioning properly
2. Uncontrollable boost due to unrestricted exhaust

Problem #1 could just be something you bumped off.

Problem #2 can't be solved by just hooking up a boost controller. Boost controllers only control the wastegate. If the wastegate is already working at 100%, there is nothing else a boost controller can do. Two ways to help this one out:

2a. Port the wastegate (requires turbo removal)
2b. Add restriction plates to the exhaust


I would also pull the ECU out just to see what the car has in it. Whatever ECU is in it, I'm sure it's not up for the task of regular street duty at 17 PSI.

Good luck!

Depending on what cat-back you have, My Apexi N1 came with a silencer that I actually ran before I had a PFC and it really helped. With that in I had no boost creep or spikes. Now my setup is much different but... There are other posts here about exhaust restrictions to help control boost, some people will use a smaller diameter gasket from DP to MP and so on...

No. Fuel-cut defenders do not work on FDs! (Well, they'll work, right up until you blow the motor.)

Nope. Unplugging the wastegate solenoid (at front of UIM) will let the wastegate open at "spring" pressure.

stock airbox?
 

I was thinking I may put the stock airbox back on. That would make it harder to get air, thus richening the mixture, and maybe lessening its ability to make boost. I guess I didn't mention it, but its running two K&N's. Let's see if I have a picture of the 2 cylinder K&N's. I'm not a big lover of K&N's anyway.

Any thoughts?

- JyRO

Fix your boost control issue before you start messing around with things you don't necessarily have to change. Have you verified proper connections to the wastegate?

And get that plastic AST out of there! :)

Basically you have no cats (DP/MP), catback and intake. That's disaster waiting to happen unless you control your fuel/boost.

Not sure about that Turbo timer either :)