I promise you...I've spent hours researching. Now I just have one simple/maybe not so simple question:

For those of you who remember, my previous FD was totalled by an 89 year old lady in a Cadillac flying through a red light.

I salvaged most of my performance parts....what I'm interested in knowing right now is about the exhuast. I'm in the process of buying a 94 FD totally stock with 33K miles on it...I'd like to make use of the exhuast I saved from my previous car (downpipe, resonated midpipe, Racing Beat Dual tip). Now, understanding that the wastgate is obviously not ported and I'd rather not go that route to prevent boost creep, can upgrading to a properly tuned Power FC prevent the problem?

I'm getting mixed info...some say I can use "pills" to reduce creep. I don't really understand what those are. Others say I just need a Power FC.

I'm looking for the safest way to increase power, but not being comfortable removing the turbos to port the WG, I'd like to go another route if it's possible.

Thanks for the info.

-Ian

 

no, pfc can't relieve creep. Creep is due to physics...WG can't bypass enough exhaust around the turbine wheel, so the twins keep building boost.

put in a hi-flow cat and that should yield enough back pressure to prevent creep.

or you can put some other form of restriction in the exhaust, restrictor plate (waste IMO), or change your cat back and use super traps or similar.




**edit**not recommended but, set the car up for 14-15psi and tune for that and you won't have creep your twins might not last as long...but what a ride it will be!!

*reason for no creep at higher boost levels: not as much exhaust needs to be "wasted" more is required through the turbines to create such levels.

 

You're looking at two different ways to address this issue. The PFC will handle fuel and ignition for the higher boost, but it has it's limits. The pills come stock with earlier twins, but can't control boost creep. I would recomend a boost controler, you can get a manual one for pretty cheap.

 

Even a boost controller won't help you contain creep. The boost controller controls the wastegate operation.

As stated above, creep is due to physics. The WG can't bypass enough exhaust around the turbine wheel, so the twins keep building boost. In order to alleviate that you need to allow more exhaust flow through the WG (hence the porting).

Since you don't want to do that, I HIGHLY recommend getting a high-flow cat. That will add enough pressure to keep your twins from creeping.

HOWEVER, once you install the exhaust w/ DP, HFC, and CB you will see significantly higher boost levels (NOT creep, just overboosting) due to increased flow. Once installed you will need a boost controller (I recommend the Greddy Profec Type S - just put it in to control overboosting from DP, Stock Cat, & RB Dual, and its awesome).

With a DP, Stock Cat & RB Duals I was hitting 12 or 13 PSI if I tried. The boost controller fixed that for good! Now I'm tuned for 9-7-9 on low and 11-9-11 on high!

Good luck and glad to hear your getting back in the game!

Steve

 

But, a boost controller (either manuel or electronic) cannot control boost creep.

Dubulup makes a good post, it is all correct. Running a high flow cat is probably your best option.

 

Also, if you buy a PowerFC you don't need to waste money on a boost controller. The PFC will control boost (not creep) on the stock twins just fine.

 

Ok...it seems that since I already have a resonated midpipe, it would be silly to chuck it, spend the money for a high flow cat, and sacrifice a little power. I think I'm convinced that the best direction to go is to port the WG...If I were to do this, what do you all think a typical cost for this should be at an experienced rotary mechanic? Is it really complicated to remove the turbos to port the WG? Is there a good chance that even with porting it, I can experience creep? Is there a specific amount of porting that needs to be done or is it kind of apparant once you have access?

P.S. Does anyone have a picture of the WG (maybe even before & after porting) to give me an idea of what exactly we're talking about needs to be done?

Thanks a lot

-Ian

 

yeah i would like to see a pic of the porting also.

 

There's a good link in the FAQ about wastegate porting. It does reliably solve the problem.

 

anyone know approximately the cost for someone to port mine. i have Dp, Smic, m2 airbox soon RB dual tip cat, and manual boost controller. think i need porting.

 

You don't need to port the wastegate unless you have creep, which won't happen without a full exhaust and intake setup.

 

awsome

 

I have a 50mm Apexi external wastgate and i get creep with my 4in exhaust. I have a 14psi spring in the wastgate but sometimes it will creep to 21psi if the boost controller is not set up. I can control it with my boost controller though.

 

21 PSi !!!!!!!!!

 

then its not creep...its called operator error

 

all I can say is, WOW!

 

Jyro can make you restrictor plates for $80 shipped. No need to get new components. But frankly Id port the wastegate. Maximum power and reliability.

 

It's simple physics, air will travel the path of least resistance. A 4in exhaust pipe is gonna flow better than a 2in dump tube. I have to turn the boost controller down to 3 or 4 pounds to actually make 15psi. It's weird but it works. I will actually make 4 or 5lbs of boost with the wastgate wide open(no spring at all)

 

High flow cat - 325$
Porting your wastegate - ~350$.

Take your pic.

Also you'll get some money back from selling the resonated midpipe.

My setup is heatsheilded intakes, HKS D/P, HFC (from rx7store I love it), Apexi n1 and my boost is dead on 0.89bar. As it was set.

 

adding exhaust, intake, smic, etc and then a boost controller to limit the boost to stock levels?

I'm sure this is a silly question, but seems to me that the boost controller reverses the benefits of all the other mods, no?

Is the only way to retain the benefit of the mods while retaining motor longevity to add a FC to ensure A/F is sufficient for greater airflow?

 

You need to spend some time researching please. You can make a lot more power still running at 10 psi (stock boost). With the mods in my sig, I put down about 308 rwhp at 10 psi. That's about 90 rwhp higher than stock at the same boost level.

Sounds more like poor manifold design/wastegate placement to me.

 

Sure I guess uncontrolled boost would produce the maximum power but the stock wastegate opens at 7psi assuming no pills or boost controller. You need a controller to get the power. What youre thinking of is welding the wastegate closed which is just a really bad idea. I dont even feel like explaining. It should be apparent.

 

It's the manifold that comes with the Apexi RX-6 kit. It's a 50mm wastgate. It shouldn't creep. It's just that my exhaust is so damn big. It never creeped when I had my old 70mm exhaust.

 

instead of porting the wastegate cant we jsut buy a bigger one?


EDit! just looked around at how much a wastegate would cost...nm the dumb question.

 

The turbos have an INTERNAL wastegate....