I'm not looking for "By putting on a cone filter and a downpipe." I want to know exactly why the wastegate does not properly operate when the intake/exhaust is freed up. Also, how does one fix it? Pop off valve? Ported stock wastegate? Boost controller? Just wonderin before I get a TII...

 

I am not a t2 owner, but this might help.

http://www.1300cc.com/howto/how2/creep.htm
http://rx7.freeservers.com/modhb/boostcontrol.htm

 

It is because the wastegate is not big enough. The wastegate is held shut until a predesignated boost is attained, then the wastegate flapper door opens. Problem is that when it opens, only a limited amount of exhaust gas can escape from the wastegate...the rest of it MUST exit via the exhaust housing...thus turning the turbo wheel MORE and giving you higher boost....boost creep...

 

deadRX7Conv, Great links.. thanks. good info.

 

Like Rico said, would a pop-off valve eliminate creep? basically the same as a wastegaste, would this be able to bleed off enough boost to prevent creep?

 

Thanks for the info, now what's Boost Spikes? and how do you control it?

Thanks,

Elio

 

no the pop off valve is a "safty fuse" not a controller. it lets all boost out when it goes off. but the turbo keeps spinign faster so it'll get ruined at the same time.

 

But a turbo is cheaper and easier to fix/replace/rebuild than a engine. How do you prevent creep? My eventual plans are no more than 300hp at the wheels. Thanks for the AWESOME help guys!!

 

Porting the wastegate or going with an external wastegate will help with creep, and a boost controller would be added security. I have a ported wastegate, and I never see over 6 psi with a full exhaust and intake.

 

what about boost spikes?

Please somebody educate my ignorant soul!!

 

How much hp do you have Unique? Here is what I am thinking. Drive it stock, learning how to drive it . Then get: RB downpipe, Apex dual N1s, FCD, Greddy Profec-B boost controller, FD fuel pump, K&N w/ TID and TB mod, B&R stage II w/ ported wastegate. Would that be a cool setup to still be able to control boost with?

 

oh I see, thanks. I guess I really didnt understand exactly what a pop-off valve did. I was under the assumption that it was set to a certain boost level, and kind of "bled off" any boost that was above that level, sort of like a wastegate I guess. So is it kind of like a one time thing, like if boost goes to high it "pops off" and lets all boost out?? Sorry for being turbo-retarded

 

that's funny!

 

This is an excerpt taken from www.dynamicracing.com:

Blitz Super Sound Blow Off Valve protects against compressor surge. With this you can expect quicker boost recovery and increased turbo protection. Depending on boost settings, the valve spring can be adjusted by a simple adjusting nut.

Compressor surge is the same thing as boost spike, if I'm not mistaken.

A blow-off valve protects against compressor surge/boost spike, which I would roughly define as too much backpressure that occurs during a spooling turbo.

 

So, would my set up work for safely going up to steady 10psi?

 

A blow off valve only opens when the TB is shut, keeping the air from hitting the turbo after bouncing off the TB. A pop off valve will bleed out excess pressure, but that won't keep the turbo from producing that boost.

Boost spikes are the levels of boost that result from creep.

Rico, I am not sure what my power output is, but 275 would be a pretty good guess, judging by my 1/4 mile times and speeds. My turbo was upgraded by Majestic, which is why I make decent power with only 6 psi. I'm not sure how well the setup you described would avoid creep...I think it depends on how much your wastegate is ported, and if you have a high-flow cat or a midpipe.

Speaking of that, I think a high-flow cat would kill creep when replacing a midpipe, because it reduces the exhaust flow at high RPMs. Anyone have any opinions on that matter?

 

get the walbro fuel pump not the fd!

 

I would upgrade the injectors and add a fuel controller for those levels with an upgraded turbo. I am hoping to get mine up to 10 to see what happens, but I have to change my pump and injectors first...it's going to be a busy winter.

 

How does a bigger turbo at 6psi add that much extra power? What is the difference between a smaller turbo pushing 6psi and a bigger turbo pushing 6psi? And if 275 is possible w/ 6psi, that is AWESOME w/ me!! What are your mods Unique? God, 3 months ago I was doggin Turbo, now I want one!! It's the end of the world as we now it.....

 

A bigger turbo moves more air than a smaller turbo, but there is a lot of argument about how much of a difference it makes in performance. A lot of guys say that boost is boost, because the TB and so on can only handle so much air, but they can't seem to explain why a different trim of turbo will produce more power at the same boost levels, so it's an argument I tend to stay out of.

My mods are: 2.5" DP and MP, 2" dual CB, Majestic Stage II turbo with clipped wheel and ported wastegate, Magnecor 10mm race wires, HKS intake adapter with riceboy filter.

My best 1/4 mile time was 14.12 @ 96.9xwith bald street tires, a stock clutch that feels weaker than the one in my Subaru wagon, and a bad 2nd gear synchro that makes shifting take a long time.

 

6psi through a drinking straw from mcdonalds is moving alot less air than 6psi through a 3in pipe. CFM is a more accurate scale. A larger turbo is making the same amount of pressure; it is just pushing alot more air to do so.

 

Good stuff. SO add 720cc secondaries and a S-AFC to my equation, as well as a ACT HD clutch, and I should be rollin pretty. I am getting $6k this semester to get the car, then next semester, I will have another $6k to play w/ on the car. GREAT info ya'll!! 5 stars for all of your info!!

 

I agree, but the naysayers say (besides nay) that the TB and other intake components can only move X amount of air, so the CFM of the turbo is bottlenecked by the TB.

 

That sounds about right. I agree with vmb on the Walbro pump, as well. I'll be ordering one of them rather soon. With $6K for mods and a strong engine, you are looking at a seriously fast car. Just don't forget brake and suspension mods.

 

Yeah, I was thinkin about $3k on engine, $3k on suspension.