Boost creep control?
10-17-01, 09:57 PM
#4
Rotary Enthusiast
The ECU alone cannot prevent boost creep. If the boost controller/ecu detects a boost level rising once the wastegate is 100% what else can it do? You need to port the wastegate, or add some restriction to the exhaust (hi flow cat, stock cat, restrictive cat-back, restrictor plates [i have a few]), otherwise you will get creep.
Mike
Mike
10-17-01, 10:35 PM
#6
Original Gangster/Rotary!
iTrader: (213)
I believe the XR-1 gives enough restriction to get rid of the creep. But then your buddies can't hear you coming a few miles away; where's the fun in that :p
Actually, the Saint being the great guy that he is, there are two restrictor plates in the mail to me as we speak
If I only need one, the other will be sent to the first palooka that claims it...
Actually, the Saint being the great guy that he is, there are two restrictor plates in the mail to me as we speak
If I only need one, the other will be sent to the first palooka that claims it...
10-17-01, 11:00 PM
#7
Rotary Enthusiast
The XR-1 did not affect my boosting pattern. It does not decrease the flow enough to reduce the boost you will see. It is still very very loud at WOT, but the cops bother me less, especially when cruising around (no droning), and at idle the pictures don't rattle in the house when I am in the garage. People can still hear me from quite a distance when I get on the throttle.
I had pretty good success with the restrictor plates in the exhaust, but ultimately ported the wastegates, and can reduce my boost down to 9-10 lbs, and do not get creep.
I have 2 plates left. 1 new and 2 1/4 ID (you can dremel it larger if you need), and 1 used 2 1/2 ID, perfectly fine other than carbon. I gave two to Rich, willing to part with another.
Mike
I had pretty good success with the restrictor plates in the exhaust, but ultimately ported the wastegates, and can reduce my boost down to 9-10 lbs, and do not get creep.
I have 2 plates left. 1 new and 2 1/4 ID (you can dremel it larger if you need), and 1 used 2 1/2 ID, perfectly fine other than carbon. I gave two to Rich, willing to part with another.
Mike
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10-18-01, 12:02 AM
#10
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Originally posted by GoodfellaFD3S
Actually, the Saint being the great guy that he is, there are two restrictor plates in the mail to me as we speak
If I only need one, the other will be sent to the first palooka that claims it...
Actually, the Saint being the great guy that he is, there are two restrictor plates in the mail to me as we speak
If I only need one, the other will be sent to the first palooka that claims it...
10-18-01, 03:41 AM
#11
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what exactly are thse plates? i'm not really sure what they are...where do they go? sorry for such ignorant question but then thats how we all learn =) and XR1= the restrictor plate? lemme know how these work...sounds interesting
10-18-01, 08:50 AM
#12
Rotary Enthusiast
The best way to deal with creep is to
1) port your wastegate
2) add some restriction to your exhaust.
The creep is present because of too much flow through the turbos despite the wastegate being told by the ECU/boost controller to be 100% open.
You will not have boost creep problems unless you are running a full 3 inch exhaust (DP/MP[with or without resonator]/CB). Adding some restriction such as a hi-flow cat, or a more restrictive catback exhaust, or a restrictor plate in the exhaust flow can help.
A restrictor plate is just a gasket (made of metal) that has a hole that is smaller than the internal diameter of the exhaust piping. For example, having a hole of only 2 inches.
You can place it between the DP/MP, or between the MP/CB. I am not sure of the best location. I ran a plate between the DP and MP. As the gases get further from the exhaust manifold they will cool and become denser. You can also run silencers in your exhaust if you have for example the Apex'i GT or N1, or N1 Duals.
The plates are easy to make if you have the right tools, or you can have them machined by a shop. I had a bunch made up when I just wanted one, but now they are all accounted for.
Hope that helps.
Ulimately, the best thing is to port the wastegates. . But with the plates you can keep the boost down to a reasonable level, (depending on how free flowing your exhaust is, how good your turbos are, and the size of the hole, 10-14 psi [ I tried a bunch of different sizes] but you will need the fuel to compensate for the increased boost.) This is not an issue if you are tuned for 14 psi and run 14 psi max.
The Borla XR-1 is a silencer/resonator. I have it welded in the middle of my MP. It has 3 inch inlet and outlet, is a straight through design, with perforated core, and sound absorbing material inside that is apparently able to withstand the hi temps of rotaries. They are about $125 from summit racing, and my exhaust shop charged about $20 USD to weld it in.
Mike
1) port your wastegate
2) add some restriction to your exhaust.
The creep is present because of too much flow through the turbos despite the wastegate being told by the ECU/boost controller to be 100% open.
You will not have boost creep problems unless you are running a full 3 inch exhaust (DP/MP[with or without resonator]/CB). Adding some restriction such as a hi-flow cat, or a more restrictive catback exhaust, or a restrictor plate in the exhaust flow can help.
A restrictor plate is just a gasket (made of metal) that has a hole that is smaller than the internal diameter of the exhaust piping. For example, having a hole of only 2 inches.
You can place it between the DP/MP, or between the MP/CB. I am not sure of the best location. I ran a plate between the DP and MP. As the gases get further from the exhaust manifold they will cool and become denser. You can also run silencers in your exhaust if you have for example the Apex'i GT or N1, or N1 Duals.
The plates are easy to make if you have the right tools, or you can have them machined by a shop. I had a bunch made up when I just wanted one, but now they are all accounted for.
Hope that helps.
Ulimately, the best thing is to port the wastegates. . But with the plates you can keep the boost down to a reasonable level, (depending on how free flowing your exhaust is, how good your turbos are, and the size of the hole, 10-14 psi [ I tried a bunch of different sizes] but you will need the fuel to compensate for the increased boost.) This is not an issue if you are tuned for 14 psi and run 14 psi max.
The Borla XR-1 is a silencer/resonator. I have it welded in the middle of my MP. It has 3 inch inlet and outlet, is a straight through design, with perforated core, and sound absorbing material inside that is apparently able to withstand the hi temps of rotaries. They are about $125 from summit racing, and my exhaust shop charged about $20 USD to weld it in.
Mike
Last edited by the_saint; 10-18-01 at 08:52 AM.
10-20-04, 03:35 PM
#15
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Don't mean to change the discussion, but I'm having a boost problem also. My setup is a stock motor and turbos with the only thing changed is the removal of the first cat. But at 2800-3000 RPMs in 5th gear when I hit the gas, it goes up to 14 PSI for a few seconds and then makes a noise like a truck's Jake brake and I lose power.
The rebuilt turbo were put on by the previous owner two month ago, but he had said that he didn't know what length to make the rods going from the actuators to the two wastegate controls. I have a feeling that has something to do with it as I don't think the gates are opening up all the way.
Does anyone have a spec for the length of those rods? They are treaded on the gate side and look like they could be adjusted.
Thanks -
The rebuilt turbo were put on by the previous owner two month ago, but he had said that he didn't know what length to make the rods going from the actuators to the two wastegate controls. I have a feeling that has something to do with it as I don't think the gates are opening up all the way.
Does anyone have a spec for the length of those rods? They are treaded on the gate side and look like they could be adjusted.
Thanks -
10-21-04, 12:01 AM
#18
Original Gangster/Rotary!
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Originally Posted by pincusa
I have the stock ECU on the car. I'm trying to figure out what's letting it go to 14psi as the car is totally stock.
https://www.rx7club.com/ne-rx-7-forum-30/rx7club-com-north-east-rotary-meet-359784/
10-21-04, 12:49 AM
#19
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Everybody talks about porting their wastegate. Is it not possible to install an aftermarket WG with the stock twins? From what I'm reading I'm pretty sure I'll have boost creep when I get my setup installed.
10-21-04, 01:49 AM
#20
Original Gangster/Rotary!
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Originally Posted by americansoldier
Everybody talks about porting their wastegate. Is it not possible to install an aftermarket WG with the stock twins? From what I'm reading I'm pretty sure I'll have boost creep when I get my setup installed.
The stock twins already have an internal WG, that is actually part of the stock twin turbo assy. Can't really have one without the other, kinda like siamese twins
11-14-04, 08:29 AM
#22
Mr. Goodwrench
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FDeez, I installed a blow off valve to try to control the boost somewhat. I know it is not designed for that, but it was a temporary solution. I was still hitting fuel cut, but less often. Since I refuse to put any restriction in my exhaust, I was waiting to pull my turbos and port the wastegate, when all the sudden the fuel cut disappeared!!! Can anybody tell me what happened? Right now I actually beleive that the ECU "learned" the setup. The car runs perfect, 15 psi with 3" mandrel bent exhaust, no cats, K&N cones and stock ECU. Is the computer capable of "learning" to run better? In the beginning I was hitting fuel cut consistently in the top of second and transition in 3rd (the car is automatic), but as soon as I hit 15,000 original miles, it disappeared. Could there be a protection program in the first 15000 miles? I have never heard of such a thing. I also don't think the stock ECU can "adjust" itself to run 15 psi unrestricted without any knock or fuel cut. But after hitting fuel cut more than 50 times, the car runs smooth and very stong, no more hesitation. I didn't change anything, can anybody tell me what happened???
11-14-04, 08:36 PM
#23
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fwiw the mileage switch cuts out at 20,000 original miles. outkast you got a 15,000 mile fd? even if you run a pop off valve set at say 10 psi you will be overspinning the turbos which will shorten their life. some cars get by with a profec others dont and need a ported gate.
11-16-04, 10:34 PM
#25
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I bought it with 11,500 miles.... 
Yeah never mind it's still hitting cut, I have Profec but not hooked up right now, much better results plugging the WG actuator. I plan on porting the WG soon. I am also swapping to a manual rear end because right now my boost pattern is 7 and 15 !!!! Hopefully I can get an even 10 with no cut and a quick spool. I know I have an unusual setup.....
Yeah never mind it's still hitting cut, I have Profec but not hooked up right now, much better results plugging the WG actuator. I plan on porting the WG soon. I am also swapping to a manual rear end because right now my boost pattern is 7 and 15 !!!! Hopefully I can get an even 10 with no cut and a quick spool. I know I have an unusual setup.....