Controlling boost spike?
01-25-05, 03:29 PM
#1
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Controlling boost spike?
Anyone have a good idea of where to place pellets to help reduce the spike after transition? And dont say to just buy a controller cuz that will not solve the spike... Thanks for any help...
01-25-05, 05:05 PM
#2
RX-7 Bad Ass
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Pellets are basically a VERY simple boost controller.
Many times a lot of the spiking problems is letting the factory boost controller run the boost, which it has no idea that that the whole system flows a LOT more. It simply runs away with the boost. Disabling it gets you way too little boost, which isn't acceptable either.
You really need to look into a good electronic boost controller. They're not that pricey, and can be found used for really good prices. Heck, a new Profec B is just over $300.
Dale
Many times a lot of the spiking problems is letting the factory boost controller run the boost, which it has no idea that that the whole system flows a LOT more. It simply runs away with the boost. Disabling it gets you way too little boost, which isn't acceptable either.
You really need to look into a good electronic boost controller. They're not that pricey, and can be found used for really good prices. Heck, a new Profec B is just over $300.
Dale
01-25-05, 05:09 PM
#3
The Laser Man
or you can just get a manual boost controller... if your not into changing your boost levels everytime... for example set boost for normal driving day... and race day.... then the manual boost controller is all you really need and it works good too~~
my 2 cents.
my 2 cents.
01-25-05, 08:33 PM
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OK, I'd like a little more discussion on this. As hard as it may be to believe, there is discordant information on the subject on this forum and elsewhere <<shock>><<gasp>>.
Some say boost controllers (whether manual or electronic) are really only for increasing boost above stock levels, and do nothing to control the boost spike during transition.
Others say that the boost spike with the "pills" is due to the wastegate not reacting quickly enough because the pills take a while to transmit the increased pressure to the wastegate, and that manual or electronic boost controllers are either "on" or "off" and higher flow, so they work more quickly than the pills and therefore help eliminate the boost spike.
Others simply say boost controllers have eliminated their boost spikes during transition, without attempting an explanation.
Anyone running stock boost levels (10-8-10) having trouble with transitional boost spike that fixed that problem with a boost controller without changing anything else?
Thanks.
Some say boost controllers (whether manual or electronic) are really only for increasing boost above stock levels, and do nothing to control the boost spike during transition.
Others say that the boost spike with the "pills" is due to the wastegate not reacting quickly enough because the pills take a while to transmit the increased pressure to the wastegate, and that manual or electronic boost controllers are either "on" or "off" and higher flow, so they work more quickly than the pills and therefore help eliminate the boost spike.
Others simply say boost controllers have eliminated their boost spikes during transition, without attempting an explanation.
Anyone running stock boost levels (10-8-10) having trouble with transitional boost spike that fixed that problem with a boost controller without changing anything else?
Thanks.
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01-26-05, 12:20 AM
#9
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I have a manual controller on the car now and it does not help with the spike. I am able to tune the primary fine, but cannot tame the spike after transition...
01-26-05, 07:32 AM
#11
Racecar - Formula 2000
1) Porting is not usually necessary to control a "spike." Porting is necessary to control boost "creep." A spike is a momentary over-boost, usually at transition to the 2nd turbo. Creep is too much boost caused by the WG being too small to control it.
2) What kind of manual controller do you have?
If you just have a needle valve, that is essentially just an adjustable pill, and still relies on the ECU to control timing and value of pressure that the wastegate actuator sees. This is pre-programmed OPEN LOOP (the ECU does not rely on the actual boost pressure to control boost) and has a lot of delay built in due to the long small vacuum lines to the control solenoid. What the ECU is doing is balancing the pill flow area with the duty cycle of the WG control solenoid to control the actual pressure that the WG actuator sees.
A ball & spring controller in place of the pill with the line on the other side of the WG actuator blocked will do a much better job of controlling boost at the level you set with the spring tension.
If that doesn't control the spike, then you may need a second ball & spring controller on the pre-control actuator with the line on the other side of the PC actuator blocked similar to what Damian dela Huerta did - there is a good thread on this.
2) What kind of manual controller do you have?
If you just have a needle valve, that is essentially just an adjustable pill, and still relies on the ECU to control timing and value of pressure that the wastegate actuator sees. This is pre-programmed OPEN LOOP (the ECU does not rely on the actual boost pressure to control boost) and has a lot of delay built in due to the long small vacuum lines to the control solenoid. What the ECU is doing is balancing the pill flow area with the duty cycle of the WG control solenoid to control the actual pressure that the WG actuator sees.
A ball & spring controller in place of the pill with the line on the other side of the WG actuator blocked will do a much better job of controlling boost at the level you set with the spring tension.
If that doesn't control the spike, then you may need a second ball & spring controller on the pre-control actuator with the line on the other side of the PC actuator blocked similar to what Damian dela Huerta did - there is a good thread on this.
Last edited by DaveW; 01-26-05 at 07:46 AM.
01-26-05, 08:31 AM
#12
Originally Posted by DaveW
1) If you just have a needle valve, that is essentially just an adjustable pill, and still relies on the ECU to control timing and value of pressure that the wastegate actuator sees. This is pre-programmed OPEN LOOP (the ECU does not rely on the actual boost pressure to control boost) and has a lot of delay built in due to the long small vacuum lines to the control solenoid. What the ECU is doing is balancing the pill flow area with the duty cycle of the WG control solenoid to control the actual pressure that the WG actuator sees.
Dave,
Thanks for you input which clarified a question I had (creep vs. spike), but I'm back to the question posed by mcdaddy... is an electronic BC generally adequate to control spiking @ transition on cars running stock boost (like mine)? And note that I said "generally", as nothing on these cars seems totally universal.
Jim
01-26-05, 08:43 AM
#13
Rotary Freak
Originally Posted by macdaddy
OK, I'd like a little more discussion on this. As hard as it may be to believe, there is discordant information on the subject on this forum and elsewhere <<shock>><<gasp>>.
Some say boost controllers (whether manual or electronic) are really only for increasing boost above stock levels, and do nothing to control the boost spike during transition.
Others say that the boost spike with the "pills" is due to the wastegate not reacting quickly enough because the pills take a while to transmit the increased pressure to the wastegate, and that manual or electronic boost controllers are either "on" or "off" and higher flow, so they work more quickly than the pills and therefore help eliminate the boost spike.
Others simply say boost controllers have eliminated their boost spikes during transition, without attempting an explanation.
Anyone running stock boost levels (10-8-10) having trouble with transitional boost spike that fixed that problem with a boost controller without changing anything else?
Thanks.
Some say boost controllers (whether manual or electronic) are really only for increasing boost above stock levels, and do nothing to control the boost spike during transition.
Others say that the boost spike with the "pills" is due to the wastegate not reacting quickly enough because the pills take a while to transmit the increased pressure to the wastegate, and that manual or electronic boost controllers are either "on" or "off" and higher flow, so they work more quickly than the pills and therefore help eliminate the boost spike.
Others simply say boost controllers have eliminated their boost spikes during transition, without attempting an explanation.
Anyone running stock boost levels (10-8-10) having trouble with transitional boost spike that fixed that problem with a boost controller without changing anything else?
Thanks.
Check your hoses and valves before you go buying other controllers.
01-26-05, 09:39 AM
#14
Racecar - Formula 2000
BLKTOPTRVL,
Excellent point!
Sgtblue,
A ball & spring controller in place of the pill with the other WG nipple blocked will react much faster than a pill or needle-valve (which still rely on the stock WG solenoid for control) to control boost-level and spiking. Reaction time also depends heavily on the length and ID of the pressure line to and from the controller, since the air flow rate and its compressibility can create a significant lag in a long/small line. The same line-related lag factors also apply to electronic controllers.
I am not familiar with the software and (multiple?) inputs used in electronic controllers, so whether they would work better/faster/worse, I don't know, so I'll leave the electronic controller discussion to others.
Excellent point!
Sgtblue,
A ball & spring controller in place of the pill with the other WG nipple blocked will react much faster than a pill or needle-valve (which still rely on the stock WG solenoid for control) to control boost-level and spiking. Reaction time also depends heavily on the length and ID of the pressure line to and from the controller, since the air flow rate and its compressibility can create a significant lag in a long/small line. The same line-related lag factors also apply to electronic controllers.
I am not familiar with the software and (multiple?) inputs used in electronic controllers, so whether they would work better/faster/worse, I don't know, so I'll leave the electronic controller discussion to others.
Last edited by DaveW; 01-26-05 at 09:45 AM.
01-26-05, 10:54 AM
#15
Originally Posted by BLKTOPTRVL
Everyone is always looking for outside cures... If your car is relatively stock and had been controlling boost well for years, then suddenly getting spikes and creep is not a sign that you need some new controller. It is simply a sign that something (stock) that was working, is no longer working.
Check your hoses and valves before you go buying other controllers.
Check your hoses and valves before you go buying other controllers.
BTW DVSeven, apologies if I'm whoring. I just thought my questions went with yours and mcdaddy's and wanted to avoid a seperate thread.
Last edited by Sgtblue; 01-26-05 at 10:58 AM.
01-26-05, 11:51 AM
#16
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DaveW,
So it sounds like you're saying that a boost controller (probably either a mechanical ball & spring device or an electronic device) that uses the boost pressure directly to turn the wastegate actuator on or off should control the boost spike (with the caveat that you might need 2, not just 1).Since the stock set-up is "open loop", rather than "closed loop" or "feedback," then I take it that the ECU doesn't know or care that it is no longer controlling boost, and won't throw error codes or go into a "safe" mode?
So it sounds like you're saying that a boost controller (probably either a mechanical ball & spring device or an electronic device) that uses the boost pressure directly to turn the wastegate actuator on or off should control the boost spike (with the caveat that you might need 2, not just 1).Since the stock set-up is "open loop", rather than "closed loop" or "feedback," then I take it that the ECU doesn't know or care that it is no longer controlling boost, and won't throw error codes or go into a "safe" mode?
01-26-05, 12:09 PM
#17
Racecar - Formula 2000
macdaddy,
You're getting out of my range of knowledge here, but, at the risk of saying something wrong (which I'm sure will not go uncorrected :-)):
1) the stock ecu does know what the boost is, through the MAP sensor,
2) the ECU will fuel-cut if the boost gets too high (~13 psi at transition, and 10 to 11 psi otherwise, but
3) the ECU, however, does not use boost data to actually control the boost.
Additionally, since the stock ECU uses RPM, the intake air temperature, and the MAP data for fuel supply enrichment through open-loop mapping, it doesn't know how much additional air is going into the engine due to intake and exhaust modifications. This can cause the engine to run too lean and detonate (deadly for rotaries) under high load, especially if the fuel is not the best (high-octane).
You're getting out of my range of knowledge here, but, at the risk of saying something wrong (which I'm sure will not go uncorrected :-)):
1) the stock ecu does know what the boost is, through the MAP sensor,
2) the ECU will fuel-cut if the boost gets too high (~13 psi at transition, and 10 to 11 psi otherwise, but
3) the ECU, however, does not use boost data to actually control the boost.
Additionally, since the stock ECU uses RPM, the intake air temperature, and the MAP data for fuel supply enrichment through open-loop mapping, it doesn't know how much additional air is going into the engine due to intake and exhaust modifications. This can cause the engine to run too lean and detonate (deadly for rotaries) under high load, especially if the fuel is not the best (high-octane).
01-26-05, 01:11 PM
#18
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Eek, a few things need to be cleared up here....
1. An electronic boost controller will most certainly control boost levels and spikes -- if it didn't, it wouldn't be of much use!
2. You can use a boost controller to lower boost levels below the stock 10 psi, because the stock boost level is above the "spring" pressure of the actuator (7 psi).
3. Electronic boost controllers are much easier to set and live with than manual controllers, even if you are not constantly fiddling with them. You can't just flip between two settings with a manual controller, as someone suggested. It's a hell of a lot easier to tune your boost by turning a dial in your car than opening the hood and futzing with a super-sensitive valve after each run until you get it dialed in.
4. A boost spike does not require a ported wastegate! It requires better wastegate control.
5. The stock ecu does not have closed-loop control as someone already stated. By installing an electronic boost controller, you are ceasing to use the stock wastegate solenoid. This has no effect on the ECU -- no codes or other issues.
1. An electronic boost controller will most certainly control boost levels and spikes -- if it didn't, it wouldn't be of much use!
2. You can use a boost controller to lower boost levels below the stock 10 psi, because the stock boost level is above the "spring" pressure of the actuator (7 psi).
3. Electronic boost controllers are much easier to set and live with than manual controllers, even if you are not constantly fiddling with them. You can't just flip between two settings with a manual controller, as someone suggested. It's a hell of a lot easier to tune your boost by turning a dial in your car than opening the hood and futzing with a super-sensitive valve after each run until you get it dialed in.
4. A boost spike does not require a ported wastegate! It requires better wastegate control.
5. The stock ecu does not have closed-loop control as someone already stated. By installing an electronic boost controller, you are ceasing to use the stock wastegate solenoid. This has no effect on the ECU -- no codes or other issues.
01-26-05, 01:26 PM
#19
Racecar - Formula 2000
Rynberg, thanks for the additional clarifications!
On your item 5 - Although this is pretty obvious, that also applies to a manual ball & spring type controller, as long as the second WG actuator nipple and the line to it are plugged.
On your item 5 - Although this is pretty obvious, that also applies to a manual ball & spring type controller, as long as the second WG actuator nipple and the line to it are plugged.
01-26-05, 01:57 PM
#20
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My 2 cents... About a month ago on a really cold day I noticed spiking up to 13psi on my stock car with an adam_c style intake. I installed a damian style boost controller using joe-p mbc's and the spike is gone, I get a perfect 10-8-10 pattern. I couldn't explain why the mbc works better than the stock pills, but from my own experience I'm sure it does. Since then I've installed a cat-back and still get perfect boost.
01-27-05, 10:45 AM
#22
Originally Posted by DVSseven
Sounds like I should not even bother with pills, maybe ill just purchase a Profec-b II and cross my fingers...
Read the instructions on the profec when you get it. It will make you feel better as you understand how the controller works.
01-27-05, 12:51 PM
#23
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Thanks everyone, I might try and play with the pellets this weekend but will probably end up ordering a Profec beginning of next week or so. I will keep everyone posted if I have any questions....
01-28-05, 04:11 PM
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Originally Posted by DVSseven
I have a manual controller on the car now and it does not help with the spike. I am able to tune the primary fine, but cannot tame the spike after transition...
https://www.rx7club.com/forum/showth...ost+controller
01-29-05, 12:12 AM
#25
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Originally Posted by rynberg
5. The stock ecu does not have closed-loop control as someone already stated. By installing an electronic boost controller, you are ceasing to use the stock wastegate solenoid. This has no effect on the ECU -- no codes or other issues.