Single Turbo RX-7's Questions about all aspects of single turbo setups.

28 psi in 2nd gear, WG too small?

Thread Tools
 
Search this Thread
 
Old 06-12-05, 01:31 PM
  #1  
Mad Man

Thread Starter
 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 2 Likes on 2 Posts
28 psi in 2nd gear, WG too small?

I have a street ported FC with a PT67 .81 p Trim, this turbo wants too spool like crazy, which is good, it is doing so in 2nd gear on a 1 bar spring which is a little scary. For those of you who have either a T66, PT67, or a TO4R, what wastegate are you running, and what is your minimum boost you can attain. I am running an HKS cast, w/a HKS standard, I think it may be too small, but I know Kabooski had the identical set-up, what I do not know is wha his minimum boost was. The car is holding this boost level half way throgh second, and lighting up my 13" slicks, Be afraid, very afraid Comments... Yes the WG is connected properly, timing is retarded a bit, and fuel is pig rich. luckily I am running 111 octane, and have 11.5 plugs, or who knows. Carl
Old 06-12-05, 01:32 PM
  #2  
Mad Man

Thread Starter
 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 2 Likes on 2 Posts
BTW I have an open WG, it is open from the top of first, and from the upshift to second on. Carl
Old 06-12-05, 01:53 PM
  #3  
Rotary Enthusiast

 
Crusader_9x's Avatar
 
Join Date: Sep 2001
Location: Woodstock, GA
Posts: 1,384
Received 0 Likes on 0 Posts
My setup is pretty close to yours. When i had my old 3" to 2.5" exhaust it would hold boost all day long. When i switched over to the 4" after about 5krpms the boost guage would just start running laps.

When i first asked about my boost creep issue someone mentioned that they had a similar problem with the standard hks wastegate and when they removed and measured it, it only came out to like 36-37mm or so and not the 40mm that they advertise. He also mentioned that by getting the racing wastegate solved his problem.
Old 06-12-05, 01:59 PM
  #4  
Mad Man

Thread Starter
 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 2 Likes on 2 Posts
Perish the thought, I think I am going to buy one of those SSautochrome 50MM WGs, it comes with 6 springs, dump tube, and all hardware. My buddy got one, and we took it apart. It is visually the same as my HKS. It measures over 50mm on both the valve, and the dump. My HKS standard has a 32mm dump WTF... Well, maybe Roger(Kabooski) will let us know wha min. boost he can run. I think he runs it high all the time though. Carl
Old 06-12-05, 02:09 PM
  #5  
Mad Man

Thread Starter
 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 2 Likes on 2 Posts
Originally Posted by Crusader_9x
My setup is pretty close to yours. When i had my old 3" to 2.5" exhaust it would hold boost all day long. When i switched over to the 4" after about 5krpms the boost guage would just start running laps.

When i first asked about my boost creep issue someone mentioned that they had a similar problem with the standard hks wastegate and when they removed and measured it, it only came out to like 36-37mm or so and not the 40mm that they advertise. He also mentioned that by getting the racing wastegate solved his problem.
Did you ever solve your problem? What is the min. boost you can run?
Old 06-12-05, 02:21 PM
  #6  
nyt
Rotary Enthusiast

iTrader: (1)
 
nyt's Avatar
 
Join Date: Feb 2001
Location: long island
Posts: 1,259
Received 4 Likes on 4 Posts
crazy. i have a pt61 on an hks cast manifold with the hks standard wastegate with big street port. I'm usin the RB exhaust and I get no boost creep at all. you might try to run a new line to the actuator port (Side) on the wastegate. Also make sure there are no leaks in the wastegate itself. Sometimes the diaphram inside can tear or the little screws can come loose and cause boost creep issues.

with my setup the hks standard wastegate has controlled boost from 7 to 25 psi without problems (obviously i have a selection of springs, but ive never seen creep. only seen boost drop off when the spring was too soft)
Old 06-12-05, 06:46 PM
  #7  
Rotary Enthusiast

 
Crusader_9x's Avatar
 
Join Date: Sep 2001
Location: Woodstock, GA
Posts: 1,384
Received 0 Likes on 0 Posts
No i havent gotten that far yet, still savin before i get started on it. Im just about ready to pull the motor and get to work on it as well as new ems, extra guages, and other stuff.

As far as the boost issue goes if kept the rpms under 5 then i could hold whatever i wanted. Under 6 then i could hold anything under a bar, but after that it just jumped.
Old 06-12-05, 06:50 PM
  #8  
Yes its slow

iTrader: (7)
 
Slammedblk7's Avatar
 
Join Date: Jan 2002
Location: usa
Posts: 2,455
Likes: 0
Received 0 Likes on 0 Posts
im running the t70(pt70) using the standard 40mm wg, no creeping here. im also using the 10psi spring and holding 11psi. with the EBC turned off.
Old 06-12-05, 07:15 PM
  #9  
Rotary Freak
 
alberto_mg's Avatar
 
Join Date: Aug 2002
Location: nyc+li, ny
Posts: 2,690
Likes: 0
Received 0 Likes on 0 Posts
r1dreamer had what sounds like a similar problem in his FD. the bigger wastegate he got seems to be doing the trick now. he's running one of those types of manifolds with some kind of t04 iirc
Old 06-12-05, 08:42 PM
  #10  
Rotary Freak

 
c00lduke's Avatar
 
Join Date: Jan 2002
Location: Overland Park, KS
Posts: 2,360
Likes: 0
Received 0 Likes on 0 Posts
I'm running a T67-1 with a divided SS manifold and a 3 inch exhuast. My HKS racing wastegate was set at about .5 bar for a bit and never had any issues.
Old 06-12-05, 10:24 PM
  #11  
Need more sleep

iTrader: (1)
 
twokrx7's Avatar
 
Join Date: Nov 2001
Location: Woodlands TX
Posts: 1,690
Likes: 0
Received 2 Likes on 1 Post
When I ran the SR stage II turbo on the HKS cast mani I had creep issues with the standard wg, installed the HKS race wg and creep solved. Never could get very good control with the race wg but had no creep, that thing was huge compared to the standard wg.
Old 06-12-05, 11:18 PM
  #12  
Pineapple Racer

iTrader: (1)
 
pp13bnos's Avatar
 
Join Date: May 2001
Location: Oregon
Posts: 2,687
Likes: 0
Received 4 Likes on 4 Posts
I'm running a SR stage II with a 50mm HKS/10lb spring, and still have boost issues when I don't have the silencers installed in my N1 dual tip. While they realy aren't that bad....it still creeps to 13psi.

After talking to Ralph Friend (Groundzero) he says its a because of the XS cast manifold, and a to free flow of a exhaust on my car. From what he says, that he and Ari have seen in on more than one car in the past. CJ
Old 06-13-05, 03:58 AM
  #13  
Senior Member

iTrader: (1)
 
chohakai's Avatar
 
Join Date: Sep 2001
Location: San Francisco
Posts: 321
Likes: 0
Received 0 Likes on 0 Posts
something is definitely wrong

28 psi in 2nd is not boost creep, it's probably the wg not opening at all. Boost creep is something much more gradual, usually in higher gears.

Even silicone vacuum lines can crack, please double check your vacuum connections ,hoses, wg, and everything else before you run the car. When in doubt, disconnect boost controller, and just run straight from vaccum source to side port of the wg.

Fred
Old 06-13-05, 03:58 AM
  #14  
Banned. I got OWNED!!!
 
88fc3sw/HX83's Avatar
 
Join Date: Jul 2002
Location: Oregon
Posts: 930
Likes: 0
Received 1 Like on 1 Post
Guys, the boost creep issue is attributed to the free flowing exhaust. I'm running 4" and I get CREEP all day on a 10psi spring with a 50mm HKS racing wg. If I was running a 3" exhaust with some silencers in the mid pipe, my creep wouldn't be as bad. My solution is to buy a drum of VP "import" and put in about 5 gal for every tank
Old 06-13-05, 04:37 AM
  #15  
Full Member

 
Wankelboble's Avatar
 
Join Date: May 2005
Location: Norway
Posts: 50
Likes: 0
Received 0 Likes on 0 Posts
This is maybe a stupid question ... Is u WG working like it shud? My friends did have same prob .. when he opend it it whas burned . So it whas stock so it dident work Like i say maybe a stubid question :P
Old 06-13-05, 05:08 AM
  #16  
Laying Down Rotary Law

 
kabooski's Avatar
 
Join Date: Mar 2001
Location: central florida
Posts: 2,075
Likes: 0
Received 1 Like on 1 Post
Originally Posted by 88fc3sw/HX83
Guys, the boost creep issue is attributed to the free flowing exhaust. I'm running 4" and I get CREEP all day on a 10psi spring with a 50mm HKS racing wg. If I was running a 3" exhaust with some silencers in the mid pipe, my creep wouldn't be as bad. My solution is to buy a drum of VP "import" and put in about 5 gal for every tank

3" DP
3" Magnaflow Mid-Muffler
duel 3" Y Pipe
3" Apex N1's

Low boost= 15 PSI (15PSI spring)
Rock steady Boost

High Boost setting= 20PSI
did some test WOT's Saturday
for this same reason
testing to see if I had any creep issues
at higher RPM's it would hit 23 PSI
but never above that even in 4rth
Old 06-13-05, 12:59 PM
  #17  
Mad Man

Thread Starter
 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 2 Likes on 2 Posts
Thanks guys, seems like a fifty fifty split. I am going to redo each line just for fun. Fred, long time no hear, my WG is Def opening, its ~125Db under my car. WG is fully open from the top of first on. I am going to try the Ebay WG, I have a buddy with a Supra, and he is controlling his 42R with it, so far without issue. I have at least one, possibly two HKS Standard WGs for sale Carl
Old 06-13-05, 05:16 PM
  #18  
Senior Member

 
gfelber's Avatar
 
Join Date: Apr 2001
Location: Seattle, WA
Posts: 528
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Carl Byck
Thanks guys, seems like a fifty fifty split. I am going to redo each line just for fun. Fred, long time no hear, my WG is Def opening, its ~125Db under my car. WG is fully open from the top of first on. I am going to try the Ebay WG, I have a buddy with a Supra, and he is controlling his 42R with it, so far without issue. I have at least one, possibly two HKS Standard WGs for sale Carl
Carl,

What exhaust manifold are you using? WG may not be the problem.

Gene
Old 06-13-05, 06:38 PM
  #19  
Mad Man

Thread Starter
 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 2 Likes on 2 Posts
Originally Posted by gfelber
Carl,

What exhaust manifold are you using? WG may not be the problem.

Gene
HKS cast, a little more than half of the guys running my exact same set-up can run ~15 psi no problem, the other half switched to a larger wastegate fom what I can gather(like I posted earlier the standard measures 32mm at the outlet). I am going to datalog the WG behavior/boost on my AVCR, and see if it is spiking/creeping, or steady, that will go a long way towards solving this. My neighbors are getting a little tired of the open WG though LOL.
Old 06-13-05, 06:59 PM
  #20  
Ee / Cpe

 
XSTransAm's Avatar
 
Join Date: Jan 2003
Location: Gaithersburg, MD / WVU
Posts: 2,843
Likes: 0
Received 2 Likes on 2 Posts
im using the hks cast with the standard gate. i was able to keep my boost as low as 6 psi. the turbo is a t61 with a 1.0 exhaust side though.

what are you using to control boost? have you tried running a straight line from the gate to the uim to see what it does?

i would be very suprised if that gate wasent adequate for your setup
Old 06-13-05, 07:00 PM
  #21  
Ee / Cpe

 
XSTransAm's Avatar
 
Join Date: Jan 2003
Location: Gaithersburg, MD / WVU
Posts: 2,843
Likes: 0
Received 2 Likes on 2 Posts
Originally Posted by XSTransAm
im using the hks cast with the standard gate. i was able to keep my boost as low as 6 psi. the turbo is a t61 with a 1.0 exhaust side though.

what are you using to control boost? have you tried running a straight line from the gate to the uim to see what it does?

i would be very suprised if that gate wasent adequate for your setup
also maybe you just need a less stiff spring, 1 bar is pretty high imo
Old 06-13-05, 07:25 PM
  #22  
multipersonality disorder

 
GUITARJUNKIE28's Avatar
 
Join Date: Feb 2002
Location: so. cal
Posts: 5,656
Likes: 0
Received 0 Likes on 0 Posts
it was holding about 15 psi when i saw it.
what's different between then and now?
Old 06-13-05, 07:38 PM
  #23  
off camber

iTrader: (1)
 
855m0n0's Avatar
 
Join Date: Dec 2004
Location: atl, ga
Posts: 482
Likes: 0
Received 0 Likes on 0 Posts
I had a similar issue. i have a 46mm greddy wastegate with a .8bar spring. It ended up being a restriction on the pipe from my wastegate to my exhaust. You might try dumping to the atmosphere and see if that fixes it.
If that does then your wastegate is fine and you need a bigger pipe from the bottom of the WG back to your exhaust. If not, then get a bigger WG. Hope that helps!
Old 06-13-05, 07:43 PM
  #24  
Senior Member

iTrader: (4)
 
r1dreamer's Avatar
 
Join Date: Feb 2003
Location: Long Island NY
Posts: 728
Likes: 0
Received 0 Likes on 0 Posts
yes i have a t04s,hks cast manifold, full 3in exhaust now, and the standard 40mm hks wastegate couldnt hold the air flow.

i bought a hks 50mm wastegate adn it holds it. sometimes i still get some boost creep but nothing to worry about. if i did it again id go 60mm like steve kan told me.

brandon
Old 06-13-05, 08:06 PM
  #25  
Open up! Search Warrant!

 
Project84's Avatar
 
Join Date: May 2002
Location: Kicking down doors in a neighborhood near you
Posts: 3,838
Likes: 0
Received 2 Likes on 2 Posts
nevermind.

Last edited by Project84; 06-13-05 at 08:21 PM.


Quick Reply: 28 psi in 2nd gear, WG too small?



All times are GMT -5. The time now is 05:57 PM.