whitet777

I have been searching the archives for hours now, so I thought I would just give up and post.

I just put on my homemade cat-back with no muffler and am now getting boost spikes. My only other mod is the stock CAI air box mod w/ K&N drop in. My boost pattern for the 3rd gear pull is 13-14.5-9 to redline. It is similar in 2nd gear pulls also. Luckily it has been cold out, so my stock IC was hopefully enough to prevent engine damage.

I plan on autocrossing in the hot summer and will do some track days too. I need a rock-solid car for these events.

Here is my question that I have yet to find an answer. Will the Profec B solve both continuous boost and boost spikes? It looks like you only tap into the wastegate vacuum line and not the pre-control vacuum line w/ the Profec installation. For people with the Home Depot mod, they tap into both. So how could the Profec B fix both of my problems?

Will putting another stock BOV in parallel to my existing BOV also help? My local RX-7 expert gave me that advise. I am looking to stay inexpensive so a stock BOV in parallel and Home Depot solution would be ideal if it worked.

Oh, also, any idea what HP I could have been running with that boost pattern and the mods in my sig? Just curious. I know any boost control I do will just seem to make the car slower, but is better than a blown motor

whitet777

Oops, I guess my sig didn't show. I only have the cat-back and CAI I made as my power mods.

radkins

Yes the profec B should do the job well.

93BlackFD

the POWERFC would do better

especially if you plan to keep the car

Rx-7$4$me

The Profec B and the power FC would both do a good job untill u get a midpipe, then u might run into problems, also, the FC would help for future mods.

However The new Blitz SBC-ID boost controller walks all over the profec B and Power FC when it comes to controlling boost. Im currently running that, and used to run a Profec B. I think it was mentioned somewhere that the Profec was a bit better at controlling spikes, but not anything else.

Rx-7$4$me

You are VERY VERY lucky your engine didnt go kaboom, or hit fuel cut. Fuel cut pre 6k rpms is 11.7 and u surpassed that by a ton, affter 6k rpms its 10.7 jeebus!!!!

rynberg

The Profec will open your wastegate to alleviate any boost over what you set it too. It will therefore remove spiking and control boost once the secondary kicks in.

Your local "expert" is an idiot. Don't listen to anything he says. A BOV relieves boost pressure when the throttle is closed to prevent it from surging back into the turbines. It will NOT control boost at all. A Pop-off valve will bleed off extra boost but should not be used as boost control, but an emergency release. I don't consider a pop-off valve a desirable purchase unless you are running a big single that can very quickly generate WAY too much boost (if your wastegate fails).

The Blitz may be better but it's a lot more money if you are in a crunch. The Profec B works fine for me and many others on the forum.

whitet777

Thanks for the advise guys. I take it most of you are against the manual controllers. What about the more expensive manual controllers?

Before my exhaust, I was running 12-12-10 all season with no ill effects. I guess 13-14.5-9 didn't sound that bad to me. I can thank the cold Milwaukee air for saving my engine.

Rynberg, thanks for putting me straight with my "expert".

Is there really any advantage to the fuzzy logic with some boost controllers? Can they really anticipate the wastegate delays?

Finally, when installing the Profec B, do you remove the secondary pre-spool pill?

rynberg

You do NOT want a boost controller with fuzzy logic for running with the sequential twins. The sequential operation confuses the fuzzy logic.

If you are referring to the pre-control pill, you leave that and it's vacuum hose alone. The only hose you remove is the turbo to wastegate actuator hose. You will then plug the hose that ran from the wastegate actuator to the wastegate control solenoid and plug the opening on the wastegate actuator.

particleeffect

I'm no expert, but I must agree here, I don't think that stock ECU can ajust to feed you the fuel you really need at those boost lvls. And as we all know, lean=bad. That's if you don't hit fuel cut-off. So unless the stock ECU can automatically give you the fuel you need, don't boost that high.

I bet you're engine does give off a nice note now though.

whitet777

I am about ready to buy a Profec B. Thanks for the advise everyone.

And yes, my new exhaust sounds awesome. The slight backfire at shifts and throttle let-up make me feel like a Lemans racer. I am sure I will be dissapointed in the lower boost now.

ech

One thing - I bet you anything that in the hot weather you will not have any boost spike.

The cold air is the trouble. The thin hot air will probably not overwhelm the wastegate the same way.

apneablue

That's what I was thinking...The cold air won't save you, it will kill you if you are already on the edge. A cooler engine will produce more HP and cause you to boost higher so possibly your boost probs wont be as drastic in warmer temps...

As for the manual boost controler, don't bother. If you are really broke then go for it but if you can afford the Profec B then go for it...It's a real PIA to tune those things. Even if they get bumped in the engine bay 1/8th of a turn you are looking at a couple psi higher or lower. I am just saying this because I was messing with mine truing to iron out my boost from 10-8-10 with a small spike to 12. Now it's all over the place and I can't find exactly where I had it....Such is life I guess. I think I may end up going with the Blitz controler.

Good luck

whitet777

I bought the Profec B last night.

I was just thinking that the cold air kept the intercooler cooler and that is what prevented the detonation. I guess you guys may be right in thinking the other way in that the cold air is what created the problem in the first place.

What came first, the chicken or the egg?