Here's the situation:
'90 TurboII
Stock intake
Full turbo-back 2.5" non-mandrel exhaust, no cats

The DSV (or wiring) is acting up so the car is only running on 5.5lbs of boost (where the WG is mechanically sprung) RIGHT NOW it doesn't boost creep all too bad (although I can get it to hit about 7 if I put it in 5th and climb a hill from 70 to 100)

Now I run 14.1 @ 100mph with this current setup (not bad I guess for low boost).

However, Z28's and Trans Am's still beat me. I don't like that.

The car is in storage right now, and in the spring I'm going to fire her up and bring it right on over to a guy in the area to do some work. However, I'm still undecided on what exactly to do.

I want to install a cheap mechanical boost controller so that I don't have to worry about that crappy DSV problem and bring it up to about 7.5 lbs boost (I want to stay within stock limits). Now I'd ALSO like to get a Chris Sanders TID & intake setup. So basically here's what I'm looking at:

7.5lbs boost (manual boost controller)
Full turbo-back 2.5" non-mandrel exhaust (no cats)
3" TID & cone intake (airbox optional)

I'm 99.9% sure the stock wastegate won't keep up, and it'll creep like a biotch when those are done.

So, my question to you guys is this: If I port the wastegate (both holes), will they be large enough to prevent boost creep with this setup?

 

Check the Archive for Boostedmotorsport's post regardin this:

His is with a S4, but it would seem logical that you could get the same or better results.

"I have done this procces and can hold 5.5lbs(If I wanted to!) with 3" turbo back, TID, intake, ported TB, and 11-13 lbs"

 

a MBC will make a hudge diff. even if you only set it to 7. it just spools so much faster and sooner.

a TID and cone will probably put you up to 9-10 which is still probbaly ok. just get a fuel pump. and set the MBC to 9 and you'll fly

 

sounds like a strong car...nice time for a low boost

91 T2
previous owner of my car ported the S5 wastgate...my mods are similar to yours:
Cone intake
Bonez 2.5 DP, MP, no cats
RP 50mm catback

1st gear 5psi, 2nd gear 6, 3rd gear 7, (never went WOT in 4th or 5th)

dunno what I'd run in the 1/4...but its much quicker than stock with what i believe is a lower boost. mine is probably restricted by the small catback, but its in storage for the winter also... so in spring i'll open it up more...

just out of curiosity do you get a code for this dsv?

 

Its funny. Everyone is always talking about boost creep, but I never get any. I wonder if its because my car is so light.

 

I ported my wastegate and so far boost has been pretty solid. My mods: FCD, TID mod, TB mod, Bonez DP, stock main cat and stock exhaust. My car is a 1988 TII.

I get .5 bar in all gears.

 

well this is good news.. there's a guy in Michigan around here that knows a ton about RX-7's and he swore that it'd still creep no matter what. Now, of course it'll creep a LITTLE bit I'd imagine no matter what, unless you had a massive wastegate, but I think I'll port the sucker when I get some time and a place to work on it and see what happens.

 

Man... Mine creeps like a bastard.
I get 7 psi in 1st and 2nd, 9-10 is third, and 13+ in fourth.
That's with a ported wastegate too...
I'd like to keep in to 10-11 psi in fourth, without sacrificing lower gear performance... oh well. I might try and port it a little more.

 

thread = back from the dead

Sorry, I still need a little more information on it. It appears that the higher you go on your boost setting (if you set it to like 9 or 10) then it'll creep a whole lot easier. At least that's what I get from reading what you guys say.

 

wait a minute.. bambam.. you're running an S4 turbo on your S5 car? Then you only have one hole for the wastegate.. no wonder you creep like a biotch.

 

*sigh* bump

 

I just finished porting my s5 wastegate.

About 2-3 weeks ago I hit 15 psi in 4th gear. Luckly my BOV broke open and let the 15+ out. it probably would have gone to 20+ psi. ANyways...

I took the s5 turbo off and began thinking. The flapper only opens up about 1/3 of an inch. Take your flashlight and take a look for yourself. What I did was I ground the backplage of the turbo and parts of the flapper. Now the flapper opens much further than stock. More than 1/2 an inch.

Next step is to grind out the w/g holes. The larger hole really wont help all that much when ported as the whole passage is very difficult to port. But you can knock out a lot of the stuff BETWEEN the two holes. This will allow the exhaust from the larger hole to escape more quickly.

The smaller hole you can bore out with a drill bit or dremel until you are satisfied. Then what I did was grind just a bit from the lip on the smaller hole, allowing exhaust to freely flow away.

Last think I did was polish the turbine housing. Specifically the area where the wheel comes close in contact. I posted this a while ago, if you grind out enough its just about like clipping the turbine.
*Hint* If you look carefully you can grind a small groove and I think this actually raises your a/r. Increases lag, but makes top end more happy. If you need more information on this I will try and explaine better.

Results: So far I havnt gone all crazy with flooring the car yet. Its about 40 degrees F here. I hit about 7-8 psi in 3rd gear, 6 in 2nd, a little less in first (like 4) but that has more to do with my huge intercooler, pressure drop, and tires slipping causing the rpms to redline in 1/2 a second.

 

OH I also did this porting on my friends turbo and he didnt like the results. Mainly the trimming of the lips is what screwed him up. Turbo lag was a lot more, but he still hit 12psi in forth gear.

Dont trim the smaller hole's lip too much, maybe only 2mm.

 

sweet.. that's some more useful information.. if you could, please let me know what a 4th and 5th gear pull does on the freeway from like 65 or 70.

 

on another note how hard is it to remove the turbo/manifold on an S4, I rarely have boost creep, the highest I've seen is 15psi, and that was in 4th on a cold cold day, is 12psi too much for the stock S4 turbo?

 

I've removed an s4 turbo. Hardest part is probably the heat shield.

Take off the avc thing right above the turbo. Its 3 10mm nuts and really makes room for removal much easier.

 

Oh I have an upgraded compressor and some fuel mods so number might be different. I'll let you know tho, weather up here sux for the next 5 years.