moneyj51

Hi, firstly I have searched! I think there's almost too much information on this subject, making it hard to find my answer! Just want to be safe...

Anyway, my car's just had an HKS downpipe installed and I'm getting about 11.6psi solid boost on primary (I've not ventured into secondary because of just this!).

I have a 3" catback Magnaflow titanium exhaust, the HKS downpipe as mentioned, and apexi power intakes, otherwise standard.

NO power FC, or boost controller so standard injectors/fuel pump/ecu etc!

Is 11.6psi too high for a stock set up?

Thanks in advance

moconnor

iTrader: (14)

There is a lot information but it is pretty much all consistent: do not run over 10 psi on the stock ECU. Period.

DaveW

Fuel-cut boost levels for stock ECU:

moneyj51

I've also read people saying up to 2psi over the standard shouldn't really matter!

And from the info I've read I shouldn't be having this problem anyway! I've still got the standard cat... maybe my boost gauge isn't accurate... maybe it is... *sigh*

1993FDR1

2nd.

moconnor

iTrader: (14)

Ignore them.

You are not getting creep. You stock boost has increased because of a flow modification, which is to be expected.

You need to spend some more time reading. And get a boost controller.

moneyj51

Thanks for all the replies everyone!

moconnor - I have read and read and read! So much to learn! Not done much else for the past few weeks, I'm doing my best It's difficult when there's also a fair amount of contradictory info out there! Time to do MORE reading on boost controllers then! And a Power FC I'm thinking??

I have read everywhere that people shouldn't have problems overboosting with a downpipe and catback... I suppose it's just that every car is different then...!

moconnor

iTrader: (14)

It is confusing.

Every flow mod has the potential to increase maximum boost if the is no boost control mechanism in place. The stock control mechanism does not compensate for modifications so a catback and a downpipe can easily add 1.5 psi. (At a rough guess the downpipe may have added close to 1 psi and 0.5 psi from the exhaust.)

During warm summer weather running 1.5 psi over stock on the stock ECU is unlikely to cause harm because the stock ECU runs very rich, but do the same on a cold winter's night and the story may be different. I would not take the risk.

MrNizzles

iTrader: (5)

Not sure how much this will help, but I recently installed the stock factory pills onto my BNR's which previously were running solid at 7psi.

I have the following mods for my fresh rebuild now about 3k mileage:

- BNR's -- which "supposedly" have the wastegate ported to a nice proper size.
- downipe
- RB catback
- other reliability mods: rad, ast, fc thermoswitch, water temp gauge, boost gauge.

What's stock:

- airbox & hoses
- intercooler
- main cat
- ecu

BUT .. at wot in 5th gear, I see about 13 psi, which I thought was impossible and I have no fuel cut happening. In 4th gear at wot, I hit maybe 11 psi, but I'm starting to think I have a faulty boost gauge? How can I be getting boost creep in 5th gear only with these mods? I thought the stock airbox, intercooler and main cat would be enough air-flow-restriction, along with the ported wastegate on the BNR's ... huh.

One last note, my little afr meter ( http://www.3barracing.com/product_3.htm ) which has LED's (blue, green, yellow, red) instead of numbers, always shows blue or green (rich) at wot, never yellow or red (lean)

DaveW

At what RPM are you seeing 13 psi? If it's around 4000-4500 RPM, you are not much above the fuel cut level, and it would only take about a 1 psi error in the gauge to cause that. Plus, remember, the ECU boost cut levels I posted are actually in psia (absolute pressure) - anywhere at higher altitude you can run more boost (gauge pressure) if the atmospheric pressure is lower than the 14.7 psi that is normal at sea level.

Dave

MrNizzles

iTrader: (5)

rpm ranges were between 4k and 5k. Above 5k and I'm getting past 120 mph, so it's a little harder to monitor gauges at that point.

Elevation was maybe about 200 ft. ?

I'm going to hook up a 2nd boost gauge and see if they both read the same.

moneyj51

Well I think I'm right in saying that the Apexi pfc can cope with the higher boost anyway as it can provide the extra fuel needed, so it seems that would be the way to go? All be it a rather pricey way... I was always planning to get one in the future anyway though!

Maybe porting the wastegate would be a cheaper way to bring boost down to a lower level until I can afford the pfc? Am I right in saying this would lower boost?

dgeesaman

iTrader: (7)

This is a subjective issue.

The car has enough fuel to handle 12psi, which is why fuel cut is set about that mark.

HOWEVER, there are reasons why I wouldn't do it.
1) Manual boost controllers are cheap and very effective
2) Your boost right now is not stable and may increase further with cool weather
3) Your injectors might not (probably are not) running at 100% flow with a perfect spray pattern
4) You may get a bad tank of gas
5) You don't have wideband O2 sensors or tuning to know how much margin you have against being dangerously lean.

That's just five reasons to dial back to 10psi and have some cushion in things.

Dave

moneyj51

Sorry Dave, that post's confused me again... was that refering to the pfc or the wastegate porting? I thought the whole point in porting the wastegate is to reduce the boost??

Am I getting confused because what I have is not actually boost "creep" but just the increased boost due to the free flow?
I've done so much searching but just seem to be going round in circles!

Are you suggesting that I just get a boost controller for now then?

RLaoFD

iTrader: (6)

Porting your wastegate would be the most effective route.

sip

That is exactly what he is saying. Because your boost issue is due to an increase in flow (via your I/DP/E) rather than due to creep, then porting your waste gate will not help . You need to limit the boost via a boost controller. If you set your new boost controller at 10psi, and then you still see the needle slowly creep to 11PSI, then you have creep my friend (and this is when you would consider porting your waste gate.

How that clarifies things for you.

RLaoFD

iTrader: (6)

Uhh??? Increasing flow inevitably means that the wastegate cannot compensate for the air moving in and out of the system. This means that when the wastegateopens, air flows to capacity and the wastegate opening does not purge enough air, and pressure stays in the system. By porting the wastegate, more air is allowed to move into the exhaust and out of pressurized areas. This will stop the overboost.

dgeesaman

iTrader: (7)

I do not think that porting the wastegate is your next step. You do not have boost creep. While porting the wastegate will also lower the boost setting, all other things left alone, that's not how to adjust boost. Boost creep is when the boost climbs above maximum and keeps going. You have a maximum boost - your problem is that it's not set to the right level.

Since you have a PFC I suggest trying to adjust the wastegate and precontrol solenoid settings (sorry I don't know the details) and dial the boost back down. If you had a stock ECU you'd need a boost controller to do the same thing, and it may be necessary if the PFC settings adjustment aren't enough to control it.

Again, a PFC can be tuned to handle any boost at all. The limitation is the fuel system right now and maybe other supporting systems. So it's best to keep the boost at 10 or maybe 11 psi.

Dave

PandazRx-7

iTrader: (18)

You're saying that you have a stock ECU right now with stock pills in the precontrol and wastegate lines. Are you using the stock solenoids too? Why were you only getting 7psi before? That is a cause of only wastegate spring pressure which happens when you diconnect the solenoids?

Maybe you had the solenoids diconnected before (and seeing 7psi), but after the mods, you connected the solenoids and you're creeping...

nimrodroller

Hey sorry to bring this post back up, but I have a boost issue also.

When I'm boosting hard and the secondary turbo kicks in, it goes to 15psi then goes down to about 11ish.

I have apexi filters, and just an exhaust muffler, everything else is standard.

Ive noticed in 3rd gear at around 5000 - 6000rpm the car like almost dies (I think boost cut), Would getting a boost controller and winding it right down fix this?

dgeesaman

iTrader: (7)

Yes. You are at extreme risk of blowing your motor now.

nimrodroller

ohh man! Would a Boost Tap fix this over boosting?

dgeesaman

iTrader: (7)

I don't know what you mean by the term "boost tap".

For now, unplug your wastegate and precontrol solenoid electrical connectors. That should disable them and put you down to 8psi. If it does get about 8psi, then a boost controller will solve your problem. Keep them unplugged until you install the boost controller.

Dave

nimrodroller

Cheers man, Are they very easy to unplug? (rx7 noob)
Also untill I get a chance to unplug them, Would it still be safe to drive it but just nana it? or is that going to do damage?

MrNizzles

iTrader: (5)

I was getting 7 psi before (during break in of fresh rebuild) because I did not have the stock pill restrictors installed in the hoses for the turbo and pre-control actuators, so it was going based on the wastegate spring which can only produce 7 psi. Btw, my mechanic said this setup would "last forever"

I did nothing with the solenoids, they were always connected from the get go of the fresh rebuild my mechanic did.

However, I have hooked up a 2nd boost gauge (for comparison) and now I only see 11 psi max in all gears at wot, so I guess my first boost gauge was a little "off" by more than 1 psi. Also, BNR's do flow better than stockers, so that's prolly why I see a little more than 10 psi with the stock pills.

Any one else running the stock pills and/or ecu with BNR's ?

Maybe Santa will bring me a PFC and HKS boost controller