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Converting to Parallel, boost creep Q's...

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Old Apr 20, 2005 | 07:11 PM
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Fatty_FC3S's Avatar
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Converting to Parallel, boost creep Q's...

Im considering doing a full sequential on friends FD. It has a really nice street ported motor, upgraded fuel pump, injectors, IC, dowpipe, exhaust etc.....

After many hours of fighting with the sequential system, parrallel would be much easier. I already ported the new '99 turbos on the car, but i wonder if this will be sufficient to control boost creep at 14psi (the max we want to run) on the car. I remmeber some people saying that they went parallel, but could never control the creep issue. Should the porting be ok? Or do i need to port really big and change the flapper (i dont really want to, but whatever is necessary).

We plan on using the APEX PFC for boost control...

Any suggestions?
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Old Apr 20, 2005 | 07:23 PM
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You won't have a problem if you want to run more than about 10 psi.
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Old Apr 20, 2005 | 08:35 PM
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Originally Posted by Fatty_FC3S
Im considering doing a full sequential on friends FD. It has a really nice street ported motor, upgraded fuel pump, injectors, IC, dowpipe, exhaust etc.....

After many hours of fighting with the sequential system, parrallel would be much easier. I already ported the new '99 turbos on the car, but i wonder if this will be sufficient to control boost creep at 14psi (the max we want to run) on the car. I remmeber some people saying that they went parallel, but could never control the creep issue. Should the porting be ok? Or do i need to port really big and change the flapper (i dont really want to, but whatever is necessary).

We plan on using the APEX PFC for boost control...

Any suggestions?
If im not mistaken...I dont think the PFC controls boost....
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Old Apr 20, 2005 | 08:52 PM
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rynberg's Avatar
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Originally Posted by Cgotto6
If im not mistaken...I dont think the PFC controls boost....
The PFC controls boost using the stock solenoids.

Most likely, there won't be a creep problem, but some cars just seem to do it when others don't. If you have ported the wastegate as far as you can, that's all you can do. If the car still experiences creep, then a restrictor will have to be added to the exhaust.
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Old Apr 21, 2005 | 08:48 PM
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I was thinking of leaving the turbo control door in (not removing), but it says NOT to weld this or leave it in on the "http://www.scuderiaciriani.com/rx7/" site. Why would they say that ? heat issue maybe? Heres what i was thinking, id like some input:

Remove Actuator

Build "solid" rod that holds door open (one end on arm, one end bolted where acutator previously was)

I know some people have boost creep issues at 14psi when they remove the door assembly entirely. My thought was to use a mechanical means to keep the door open, yet still have some restriction so as not to get boost creep. The door opens and stays like that above 4500rpm stock anyways, i dont see why holding it open all the time would be any different.....
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Old Apr 22, 2005 | 01:14 AM
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Originally Posted by Cgotto6
If im not mistaken...I dont think the PFC controls boost....
There is a kit you have to buy...
http://www.apexi-usa.com/electronics_boost.asp

Last edited by cesarx7; Apr 22, 2005 at 01:18 AM.
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Old Apr 22, 2005 | 06:59 AM
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Those turbos typically wont see any boost creep until you get around the 17-18psi range, and thats with no porting. You should be good to go.
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Old Apr 22, 2005 | 07:28 AM
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You especially do not want to add to restriction before the turbos. I have BNR stage 3's with the ported waste gate and have never had a problem with boost creep. Greanted I am still running a cat(high flow) everything seems to work out ok
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Old Apr 22, 2005 | 08:07 AM
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no boost creep here and I don't have a ported wastegate.
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Old Apr 22, 2005 | 08:12 AM
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stock twins, parallel... the higher peak boost your running the *less* if any creep your going to get... since the turbos run out of air at higher rpms.
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Old Apr 22, 2005 | 08:26 AM
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Originally Posted by Fatty_FC3S
I was thinking of leaving the turbo control door in (not removing), but it says NOT to weld this or leave it in on the "http://www.scuderiaciriani.com/rx7/" site. Why would they say that ? heat issue maybe? Heres what i was thinking, id like some input:

Remove Actuator

Build "solid" rod that holds door open (one end on arm, one end bolted where acutator previously was)

I know some people have boost creep issues at 14psi when they remove the door assembly entirely. My thought was to use a mechanical means to keep the door open, yet still have some restriction so as not to get boost creep. The door opens and stays like that above 4500rpm stock anyways, i dont see why holding it open all the time would be any different.....
I have removed the turbo control door and had it welded closed using an iron disk to cover the hole. I have had the turbo off several times since and it's still there in perfect shape.
I ported my waste gate and have not had any issues of controlling boost, but I also have the stock cat.
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Old Apr 22, 2005 | 08:39 AM
  #12  
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with a 3" exhaust and a ported motor(no restriction) has caused significant boost creep for me, however, I had removed the 2ndary butterflies and gasket matched every manifold from the TB down. My creep was almost 7psi by 6500rpm. I would set my boost controller to Off in order to keep boost from creeping beyond 14psi on pump gas. I also had ported my wastegate to within .0025 of the steel flapper door but still had huge issues. I had to install a 2.5" restrictor gasket into my exhaust between the midpipe and catback for restriction to keep the boost rock steady. BTW, I had boost creep issues with sequential operation also.
Art
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Old Apr 22, 2005 | 10:38 AM
  #13  
rynberg's Avatar
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Originally Posted by cesarx7
There is a kit you have to buy...
http://www.apexi-usa.com/electronics_boost.asp
NO YOU DON'T.
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Old Apr 23, 2005 | 12:01 PM
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So basically i would be OK as long as still have Cat in place, but without it, boost creep would be a pretty "for sure" thing.....

Maybe a Pop off vavle would be good insurance in this situation....
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