Spool so fast that the turbo SURGES
Aug 20, 2010, 09:56 AM
#1
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Spool so fast that the turbo SURGES
Besides getting the anti surge housings, how might one tune to keep a turbo from surging ? ?
Here is why I ask...
I have the mods in my sig. Just changed over to e85. Upon doing so my turbo now spools insanely fast. If I do a pull starting at anything below 3500 rpm I get compressor surge big time (Thanks DB for making that suggestion). If I do a pull after 3500, it is clean and boost builds from 0 at 3500 to 30 psi at 3900 peaking at 33 at 4050. It holds 27psi to redline.
I use an AVC-R to control the boost. The car has an 18psi WGA and an original green turbo with revolver cams. The block is 2.0. The turbo hot side, exhaust mani and o2 housing are heavily ported. The head is port matched on the exhaust side.
Suggestions ? ? ?
Here is why I ask...
I have the mods in my sig. Just changed over to e85. Upon doing so my turbo now spools insanely fast. If I do a pull starting at anything below 3500 rpm I get compressor surge big time (Thanks DB for making that suggestion). If I do a pull after 3500, it is clean and boost builds from 0 at 3500 to 30 psi at 3900 peaking at 33 at 4050. It holds 27psi to redline.
I use an AVC-R to control the boost. The car has an 18psi WGA and an original green turbo with revolver cams. The block is 2.0. The turbo hot side, exhaust mani and o2 housing are heavily ported. The head is port matched on the exhaust side.
Suggestions ? ? ?
Aug 20, 2010, 10:01 AM
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Thanks for the fast response. I am running an APS dual vent. It does not leak for my boost leak test at 40psi. It holds rock steady.
I too am thinking that the boost controller will resolve the issue. HA how often do you hear of someone complaining of "too fast" of spool?
I too am thinking that the boost controller will resolve the issue. HA how often do you hear of someone complaining of "too fast" of spool?
Aug 20, 2010, 10:11 AM
#4
Only when the reason is the line to the wastegate blew off 
The APS is usually pretty solid. It could be possible that you need to back the screw out a bit more than normal, but i think the EBC is your issue. Start with your gain down to around 10% or so and your start boost about 5 to 10 psi before your desired and adjust tighter until the problem comes back.
The APS is usually pretty solid. It could be possible that you need to back the screw out a bit more than normal, but i think the EBC is your issue. Start with your gain down to around 10% or so and your start boost about 5 to 10 psi before your desired and adjust tighter until the problem comes back.
Aug 20, 2010, 10:13 AM
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Only when the reason is the line to the wastegate blew off
The APS is usually pretty solid. It could be possible that you need to back the screw out a bit more than normal, but i think the EBC is your issue. Start with your gain down to around 10% or so and your start boost about 5 to 10 psi before your desired and adjust tighter until the problem comes back.
The APS is usually pretty solid. It could be possible that you need to back the screw out a bit more than normal, but i think the EBC is your issue. Start with your gain down to around 10% or so and your start boost about 5 to 10 psi before your desired and adjust tighter until the problem comes back.
Oh the joys of pushing the limits of a turbo.
Aug 20, 2010, 10:44 AM
#6
i try to as well... I think you will find the sweet spot to be roughly 3 to 4 psi before desired, however its easier to build up to it instead of fighting the issue on the way down. On my personal car, right now im running only 28psi and i think my start boost is 24.5 and my gain is around 30%. On the previous turbo setup, same boost, start was only set to 21 and gain around 15%... otherwise it would surge. Seems like their should be an exact science with this instead of the trial and error, we need to employ myth busters.
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Aug 20, 2010, 07:21 PM
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Well, I lowered the duty for areas below 3500. It seems to have helped, but not solved the issue. I am thinking that I may add some timing to try to get the power back up as the loss of boost has made the car feel a little sluggish. It was very snappy before. I found that lower timing and more fuel really decreased spool time.
The surge is still there, but not as bad as it was. It always seems to happen at around 3100 rpm and about 18psi to 20psi boost. At this point I am stuck though. I have an 18psi WGA so the ability to lower boost below this point isn't happening. I do have the ability to adjust the WGA arm a little looser. It is cranked full tight now. I may go to as loose as it can go but maintain a fully close WG. I fear that I may get more boost taper up top though.
I realize I am on an old turbo with old technology and that I am pushing it's limits on e85. I only have about a month left before I deploy for the land of sand. Maybe I will be blessed by the turbo gods and a new turbo will be home waiting for me upon my return.
The surge is still there, but not as bad as it was. It always seems to happen at around 3100 rpm and about 18psi to 20psi boost. At this point I am stuck though. I have an 18psi WGA so the ability to lower boost below this point isn't happening. I do have the ability to adjust the WGA arm a little looser. It is cranked full tight now. I may go to as loose as it can go but maintain a fully close WG. I fear that I may get more boost taper up top though.
I realize I am on an old turbo with old technology and that I am pushing it's limits on e85. I only have about a month left before I deploy for the land of sand. Maybe I will be blessed by the turbo gods and a new turbo will be home waiting for me upon my return.
Aug 20, 2010, 08:30 PM
#10
Well, I lowered the duty for areas below 3500. It seems to have helped, but not solved the issue. I am thinking that I may add some timing to try to get the power back up as the loss of boost has made the car feel a little sluggish. It was very snappy before. I found that lower timing and more fuel really decreased spool time.
The surge is still there, but not as bad as it was. It always seems to happen at around 3100 rpm and about 18psi to 20psi boost. At this point I am stuck though. I have an 18psi WGA so the ability to lower boost below this point isn't happening. I do have the ability to adjust the WGA arm a little looser. It is cranked full tight now. I may go to as loose as it can go but maintain a fully close WG. I fear that I may get more boost taper up top though.
I realize I am on an old turbo with old technology and that I am pushing it's limits on e85. I only have about a month left before I deploy for the land of sand. Maybe I will be blessed by the turbo gods and a new turbo will be home waiting for me upon my return.
The surge is still there, but not as bad as it was. It always seems to happen at around 3100 rpm and about 18psi to 20psi boost. At this point I am stuck though. I have an 18psi WGA so the ability to lower boost below this point isn't happening. I do have the ability to adjust the WGA arm a little looser. It is cranked full tight now. I may go to as loose as it can go but maintain a fully close WG. I fear that I may get more boost taper up top though.
I realize I am on an old turbo with old technology and that I am pushing it's limits on e85. I only have about a month left before I deploy for the land of sand. Maybe I will be blessed by the turbo gods and a new turbo will be home waiting for me upon my return.
I have the APS as well (but didnt help w/ the issue, and reason for purchasing it) Ive thought I had a boost leak for a long time, but maybe Im/were just pushing TOO much airflow, too early and causes some sort of turbulence/reversion/surge...
I have the hotside coated/ported / int mani. inlet ported w/ a 65mm TB, and was thinking, maybe I need to port the stock ex. mani., get a better LICP, 3" DP, and a TP, as I have 2.75" DP and an Injen LICP (which isnt the largest Dia.) combined w/ a 100 cell HFC...
Edit: I was seeing 24-26 psi by 3375, in 3rd. starting fro 2000 - 2300.
just a thought...
Last edited by nonschlont; Aug 20, 2010 at 08:33 PM.
Aug 20, 2010, 08:38 PM
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I am beginning to wonder if it has something to do with the high/low fuel pump operation. Maybe the fuel pump crossover point can be adjusted so that it crosses over to the higher voltage sooner, thus eliminating the issue.
The "Boost Control High/Low Gear Range RPM/MPH Crossover" is set to 2900 rpm. Could this, by some grace of god, be the switching point for the fuel pump relay #3 that flips to bypass the resistor and allow more voltage to the fuel pump??? If so, I think all we would have to do is lower this value to like 2000 and is should solve our problem. MAYBE.
The "Boost Control High/Low Gear Range RPM/MPH Crossover" is set to 2900 rpm. Could this, by some grace of god, be the switching point for the fuel pump relay #3 that flips to bypass the resistor and allow more voltage to the fuel pump??? If so, I think all we would have to do is lower this value to like 2000 and is should solve our problem. MAYBE.
Aug 20, 2010, 08:49 PM
#12
I am beginning to wonder if it has something to do with the high/low fuel pump operation. Maybe the fuel pump crossover point can be adjusted so that it crosses over to the higher voltage sooner, thus eliminating the issue.
The "Boost Control High/Low Gear Range RPM/MPH Crossover" is set to 2900 rpm. Could this, by some grace of god, be the switching point for the fuel pump relay #3 that flips to bypass the resistor and allow more voltage to the fuel pump??? If so, I think all we would have to do is lower this value to like 2000 and is should solve our problem. MAYBE.
The "Boost Control High/Low Gear Range RPM/MPH Crossover" is set to 2900 rpm. Could this, by some grace of god, be the switching point for the fuel pump relay #3 that flips to bypass the resistor and allow more voltage to the fuel pump??? If so, I think all we would have to do is lower this value to like 2000 and is should solve our problem. MAYBE.