Hi,
I no this topic comes up alot, and I have read all the past articles...But there is still one thing that hasnt been mentioned. Y is boost creep bad? I no if the car leans out its bad....but if you can get ur car to add enough fuel...isnt higher boost better? I think I read that the stock computer can,t compensate for the additional boost....But couldnt an aftermarket one?

The reason Im asking all this is b.c I just put a dp,mp on a 93 rx7 and its boosting at about 13 or soo with the stock catback still on there. I treid doing as much research before doing this....so i used a smaller gasket between the mid and catback so that it didnt boost to high, but i would still like to go with a hole 3inch system.

Also how involved is it to take off the waste gate?

Any advise would be much appreciated!
Thanks! Dan

 

Take the restrictor pills out of the wastegate and prespool lines. they're located directly below your airbox. That should help quite a bit. Do that before you go boosting 13 anymore, or else you are really really takin a chance at blowin the motor.

About your other questions...boost creep wouldnt be as bad if you tuned for it...but if you're going to go that far, you might as well get a boost controller and keep the boost somewhere constant.

 

I agree about getting the boost controller. I have an AVC-R and it regulates boost from the pressure sensor to the selenoid like a champ!

 

I have herd that a boost controller cant regulate that much boost tho. I was told that the waste gate hole is not big enough...so even if the boost contoller opened the waste gate all the way...still not enough air can escape, wich means air backs up causeing higher boost. I no porting the waste gate helps...but i dont no if I really wanna go that far.

 

If you have an upgraded fuel system and have an ecu tuned to handle it, there is nothing really dangerous about boost creep (to a point). However, it's better to have control of your boost IMO.

A boost controller will not stop boost creep.

BTW, follow racerfoo's advice and remove the wastegate pill to keep your boost down for now. You should not have put a midpipe on while still running the stock ecu.

 

As much as I agree with rynberg's suggestion about not installing a midpipe without an aftermarket ecu, I must disagree with his suggestion that a boost controller will not stop boost creep.
Maybe if you're running sequential, it might not help eliminate boost spike. However, if you're running non-sequential, a greddy tvvc mbc or an apex-i avc-r ebc works perfectly because they both bypass the stock boost duty selenoid. The avc-r is especially great at regulating boost creep for us non-sequential guys because it works off a boost sensor feedback system. I would also like to point out that that pos selenoid is a good percentage of the boost issues people have in the first place.

 

You're wrong.

Either you are switching the definitions of spike and creep in your mind or you have no idea what you are talking about.

Boost spike is caused by the wastegate not opening fast enough/early enough and the boost overshoots the intended mark. This is certainly correctable with a boost controller.

Boost creep is when the wastegate is fully open and cannot divert enough exhaust flow to keep the boost at the target level. For example, you set the controller to 12 psi and under WOT, the wastegate is fully open but does not flow enough air and your boost starts to rise (creep) above 12. This is why a lot of people running midpipes port (make larger) their wastegate opening to flow more exhaust air.

 

BINGO!

 

So at this point what would be the best thing....just add the restriction plates in the exhaust , or just take the mid pipe back off for now? And what is safe to boost at ......12psi?

Also how hard is it to port the waste gate?

Thanks for all the advise, keep it coming!

 

I'm running non-sequential so boost spiking does not pertain to me. As far as boost creep is concerned, my avc-r boost control selenoid piggybacks off my only remaining wastegate, which is (avc-r) directly fed boost feedback from the pressure sensor to regulate 10lbs. of boost like a champ. So either I have not come across this particular problem or I really have no idea what I'm talking about. Prolly the latter.

 

I'd recommend taking off the MP, especially if you're still using the stock ECU and fuel system. Best to stay below 10 psi to keep from popping your motor.

Porting the wastegate is a major PITA, because you have to remove the turbos to do it.

 

take out your pills, like i said. that will take you down to 10 or under and you'll be fine.

 

Take the midpipe off for now dude. You will probably pop the engine ******* around one night in this weather. I'm in the NY/NJ area so I know that the climactic conditions (cooler weather) around here are making me spike to about 13-14psi before my PowerFC takes over and brings me down to 10psi. If my PowerFc wasn't keeping my boost in check, god only knows how much boost I'd be running.

Rynberg (and others) - will the boost controller, really control the spike? I've heard contrary, but am really not sure overall. It looks like my Power FC is working well on controlling overall boost levels, just the spiking is making me worried. Please advise.

Thanks.

 

MY power FC did a shitty job controlling my boost. A friend suggested a man boost controller and it has boosted like a champ not one spike ever. I would not count on the PFC to control boost.

 

If you adjusted the duty cycle on the primary (PFC), you could probably eliminate your spiking. And yes, an electronic boost controller will work very well to prevent spiking. I don't have a midpipe, but with my mods, the car spools very quickly to whatever level the Profec is set to and stays there. No spiking but with quick spool. The solenoid that an EBC uses will likely work far better than the stock solenoid, especially an 8-10 year old one.

Note that it IS possible to spike with the Profec, if you have it set wrong. Properly set-up, it won't happen.

 

Anyone have opinions on ECU's? Which one did you like/dislike. I see the range in price from about 600 to 1200....Is there a hudge difference in them?
I forget who make the 1200 dollar one, but it has many more options and power levels, and you can control it inside the car....but 1200 is a lot for a computer. Im use to spending 100-200 for just a chip....these things get expensive!

 

Take a read here:

https://www.rx7club.com/forum/showth...hreadid=116858

 

Again, thanks for all your info...all this is really helpful.

IS THE PETTIT CHIP WORK WITH THE STOCK COMPUTER OR DO YOU HAVE TO BUY THE HOLE COMPUTER? AND WHATS THE DIFFERENCE IN BUYING THE HOLE COMPUTER OR JUST THE CHIP? THANKS, DAN

 

I believe the chip will work with a stock computer but, Im not too sure

 

You either have to send them your stock ECU, or order one directly and get charged for a core; I don't think you can just order the "chip" from them. I believe they modify the board so that the ROM chip can changed if desired.

 

A blow off valve with a trip valve or a "Trip" Valve by itself will aslo prevent you from spiking / boost creep... what this does is you set the pressure on the valve that you want to start releasing excess pressure to the atmosphere, and once you creep or spike beyond that point the valve opens and bleeds off extra turbo pressure without removing pills or porting wastegate...

 

Thanks so much for everything. I took out the boost pills and its back down to 10psi and wont go above. Its actually boosting alittle below 10...i was wondering if you drilled out the holes in the pills....would that also work, so that the boost will be a tiny bit higher? If I understand the purpose of the pills, they just dont let as much vacume to the waste gate with means the waste gates open later = more boost. With the pills out they waste gates are opening much sooner so pressure doesnt build up...so if you just make the holes bigger....it would be a happy median?