Boost Creep: Need Input
 

Hey Guys,

Since having my car built..I've had a slight battle with boost creep. I'm creeping pretty routinely above .90 bar which is where my boost control is set. My understanding is all cars are different, but the creep is caused by full exhaust and porting of the engine.

I'm able to hold boost through 6100-6600 RPMS (pending temperatures), then things start to get out of hand.

The way I see it, I have a couple options:

1. Remove my existing Turbos and port the wastegate. This isn't a small job. My turbos were rebuilt about 17,000 miles ago and I am leaking some oil from the second turbo. They still spool very quick, and I am able to sustain > .90 on the second turbo. My concern is: I have almost 100,000 miles on the same core..is it worth the cost to do this, or should I keep my foot out of the gas?

2. Leave it as is, I'm tuned rich for the creep by Steve Kan. We are coming into the warmer months and I tuned in cold. While I'm probably not optimized, I'm safe. I could leave it as is, until my turbos degrade and I am forced to make a decision on what to do (BNR, Single, used stockers).

3. Bite the bullet, preserve the engine, upgrade to single or upgraded twins.



I have also heard a boost controller (other than the PFC) MAY help pending where the "creeping" problem resides. I could get a boost controller, test it out, then make my decision. Would the $300'ish be worth it? Would I use this with my other turbos when I have to change out my existing? Again, I'm currently using the PFC.

Mods in signature..thanks for thoughts.

Worth a try, this will cost less than half of an electronic controller, easy to install and tune and holds rock solid boost.

https://www.rx7club.com/attachment.p...postid=2764921

https://www.rx7club.com/attachment.p...postid=2764932

oh it's a Hallman's RX-Pro controller and comes with a ceramic ball and two springs...you'll want the heavier one.

You get all those other parts installed yet?

*edit* you could get two of these bad boys and tune out the transistion (or make it VERY small), by opening the precontrol door more...

I'm pretty sure the Stage II's have a ported WG

Its pretty clear that you understand about boost creep and your options. .9 bar is 12.6psi. What do you rev your car to and what boost has it crept up to by then? Is the oil leak bad where you dont want to park in certain areas? If I were you I would turn up the boost to whatever it is creeping to (probably 13.5 will do) and get it tuned for the higher psi. This way it wont creep past that point, and you will wear your turbos out a little sooner so you dont have to deal with the oil leak for so long. Then you can get upgraded twins with a ported wastegate or come over to the dark side of single Mmwahaha! I would also try a ball and spring manual boost controller first like was mentioned above. You can make one for 15 dollars and it works incredible. My car would only creep to 12.5 at the end of third with full exhaust, non seq, and streetport. 4th and 5th were scary in cold weather though.

good luck

Catz XLD's installed. SS clutchline installed in 2 weeks. The guy that was going to help is up in VIR road racing, so I have to hold off (unless I can coerse you and 93blackfd to help this week/weekend). Pulleys, hoping to get it done this week..I need to borrow an impact wrench, but the job should be straight forward.

OEM polished scuff plates are installed, Ray delivers quickly.

MBC is a great idea, how long does this job take?

The highest I have seen is 1.0 mmHg. This was at about 7700 RPM in third gear. My understanding is I am tuned for 14.5 lbs, if I go over this, WI should help supress any det conditions.

How about you? Wheels on? Let's hope you stayed silver!

get a real boost controller

job took about 45min...

disconnect WG solenoid (and cap vac lines, would be the easiest since you are seq.), pull intake, connect a vac line to boost nipple on pri-housing, connect line on WG act, connect MBC (after installing heavy spring), cap other nipple on WG act, mount MBC. Put back together, go make adjustments. The kit comes with everything you need.

boost is measured in PSI, not mmHg ;)

Wheels are on and are staying silver...that pic was my car.

*edit...sorry for anyone who saw that.

that's not nice :(

You've said this before. How/why would it work? Is it worth the $$ for when I replace the turbos (regardless of which way setup I choose)?

Oh, I thought he was directing that at me...touchy mornings, hahaha.

I'd get a different boost controller too rather than the PFC using the stock stuff to "try" and control it.

How would it work? it would be totally separate for the PFC, the PFC doesn't car if it is controlling boost or not, just as long as the boost is controlled it will supply the fuel.

I say it's worth the money (and peace of mind), because the stock stuff is good for a stock set-up/boost levels, and the PFC is known for not controlling boost well, especially with a unrestricted exhaust.

if you are tuned for 14.5psi and creep to 14.7psi...that's not terrible but...it is fun to run thru redline without worring, that's where these motors shine.

profec B the weapon of choice? I've seen AVC-R's around, but am scared of all the settings!:confused:

I wouldn't use AVC-R for seq.

I see turbo spoolage as a total mechanical process, exhaust flow, spring in actuators, etc...why throw electronics into controlling it? Sure you can have cool lights and things in the cockpit...if that what you want??? the Hallman's has a cockpit adjuster add on too ;) hahaha, I'll get off my Hallman's kick now...

https://www.rx7club.com/showthread.p...hlight=perfect

Thanks Mahjik and all.

I've read a lot about boost creep. I've also spoken to several rotory specialists, including the one that built my engine. Reputable people have conflicting opinions. For instance, (such as that thread), some say the ONLY way to effectively eliminate/deal with boost creep is by porting the wastegate. Others say boost controllers may help because they are much more accurate (dual solenoids) than the stock set up.

My guess (I'm a newb) is that porting the wastegate can eliminate creep, while other methods effectively "deal" with creep.

I'm wondering if an aftermarket boost controller, other than the PFC, can give more accurate control and better timing, minimizing or eliminating the boost creep.

Creep is MUCH less noticable in warmer weather. In some cases, non existent. However, as dubulup said, I want the ability to have my pedal through the floor, through redline.

So I can remove my turbos and port the wastegate. I can't do this myself. I think it is a 5-6 RandR job at a shop with 1-2 hours for porting. Then, my turbos may only last 10K miles and I have to do this again.

Or, I can get a boost controller, which may help for both old and new turbos.

Or, I can continue to use the PFC with upgraded turbos that already have the WG ported.

Like I said, I'm tuned safe, but want peace of mind.

The problem is people confuse "boost creep" with "boost spikes".

Boost creep is that the wastegate is overloaded. If the wastegate is already at 100%, what else can a boost controller do? Nothing. Therefore, you have to port the wastegate.

Boost spikes however can be controlled by boost contollers as the wastegate is just not operating "efficiently" (where an aftermarket boost controller can do the job better).

for example, when i run 17psi, the wastegate stays closed shut....completely, so if i am not holding it to redline, its because of my solenoids cyling the wastegate too slow

when you try to hold 12psi to redline, you need a solenoid that can cycle your wastegate quickly enough and accurately enough to maintain that 12psi, when you run the stock setup (one denso solenoid) as opposed to an aftermarket (usually two really nice bosch solenoids) with its own integrated circuitry and what not, it works great for me, and i should have crazy boost creep

i just hear a lot of these guys bitching about enlarging their wastegates ($50 approx cost) and not getting a decent boost controller that they will need down the road anyways

the benefit to an electronic boost controller is that it is more accurate when you try to put down more power, it is also consistant and corrects for outside air temperature...no manual boost controller can do that

Aren't you running BNR's? I think they had ported wastegates, even their rebuilds. I'm not sure though.

The electronic ones also slam the wastegate shut, when they fail electronically or the pressure sensor fails, which means, a massive spike of 20 psi ??? Or whenever you take your foot off the gas, my guess is when you hear the engine blow...

Manual = Spring actuated, if the spring sticks, or something fails mechanically, the system goes back to stock 7-8-7 or non seq. 7psi... then when you check you replace a $30-$50 part the controller, and go on with life... the alternative, pay 300+ for an electronic controller, that even if you have the Blitz Dual, there is a chance (small as it is) for both sensors to fail, you get to buy a new engine, and depending on how pissed you are at your boost controller for blowing your motor, a new controller ! :rolleyes:
From what I've heard from AutoX'ers that have a controller, they swear by manual...
-DC

If it is truly boost creep, no controller will help. If it's a case of a bad controller, as it might be with the PFC, get something simple and proven, either an MBC or a Profec.

actually no, i thought i had a good understanding of how to use my boost controller until steve kan got in the car with me

the mild/sharp setting can be your best friend when you have creep...just learn to use it, and don't be afraid to try ALL ranges, i read the how-to on the newbie site and they said to leave it basically full sharp (or two clicks back)

that is wrong, now mine is at about 11 oclock

I agree with GT911 if it's truely exceeding the wastegate's potential nothing will help short of a new wastegate (bigger) or porting it to allow for more flow, it's a mechanical restriction, and if what you described helped, you don't have creep, you have (had) a poorly adjusted Boost controller...

What's interesting is 93blackfd has a half bridgeport (maybe full), and I have a stage 2 street port (both from Gotham). I have full exhaust, GR dp, SR res MP, RB dual. I'm not sure on his setup, but I believe it is similar other than the CB..which is very free flowing. we both live in ATL, we both run stock turbos. He runs his parallel, I run mine seq.

He's not getting any creep (or spike) and I am. He's running a profec B, I'm running PFC.

I'm assuming mine is creep, not spike. Not because I don't know any better, but because Steve kan told me when tuning:)

Steve definately says the ONLY way to cure creep is to port the WG, or get a new one. Charlie @ Mazcare says it's not required.

I think I need a boost controller of sorts anyway. When my turbos go bad, I will upgrade or go single. In either case I could use a boost controller also.

Will the Boost readings from the boost controller be different from the PFC? I have heard the PFC makes a horrible boost gauge.

I belive the PFC takes it's cues from the map sensor, which is somewhat inaccuarte, I'd say replace it with a GM 3 bar sensor, and then that would be better, the thing is I know I could do that with the AEM, no Prob, I'd just tell it I replaced the stock one and go, but with the PFC, I'm not certain it's that easy...