TD04 Hard Pipe and/or FMIC Surge Issue Thread

[Bleu]

Did anyone figure out a good answer to fixing surge? Yes I realize I'm necroing a thread.

[fastfalcon94]

Subscribing. I too have the surge and have a ton of things I'm going to try this summer once my tranny is back in.

But I have a custom front mount intercooler (28" wide core, 11" high, 3" thick), 3" cold side piping to throttle body, 2" 'piping off the turbos to a Y into 3" piping for hot side. I have ran this intercooler for probably 7-8 years but my hot side piping was a modified Y pipe that went into stock piping that I rerouted. But I had 9b turbos at 14 psi, and 19t turbos at 19 psi without surge before. Also have ips pre turbo intake pipes. I was running gm maf in blow thru, safc, and Tial bov

Flash forward and now I have dr750s, 2" cold side intercooler piping, aem v2, speed density, same bov, same ips intake pipes, and I surge like crazy. Stock heads/cams/camgears

in this video I slow down, then pull through 2nd, 3rd, and 4th and I get the surge in every gear



and heres a video of my car at work. If I rev the engine you can actually hear it through the filters. I also show how my vacuum lines are plummed.




Things I've tried
----------------
-boost leak tested to 30 psi
-unhooked blitz boost controlle and ran on wg boost
-bought a hand vacuum/boost pump and made sure my wastegates open at the same time
-Ran new vacuum line with equal length hose to wastegates
-made sure my tial bov hose was right diamete, aligned the banjo bolt on the tial with the hose (if you have a Tial you know what I mean)
-tried a 3psi Tial spring, this helped. Hardly surges in 2nd gear but easily surges in 3-6. But then my bov is open at idle


Things I'm going to try this summer
-----------------
-increasing timing in low rpms
-Maybe pull fuel like J_fast recommended
-installing bungs in my IC piping right after the turbo. I'm going to try running my boost source for my EBC as close to the turbo as possible. May not help, but my friend said
it did on his dsm when he was experiencing this with his fast spooling ball bearing turbo. I actually ordered all the nipples/bungs last night.
-removing preturbo intake pipes and filters and doing a quick spin
-removing my hood and using my gopro to film my bov and turbos with intakes off
-I wasn't going to try balance tubes because a few people on 3si tried it without success, but maybe as a last option I will.
-I would like to try the divider plate. I may even cut open my intercooler endtank and run it right to the core. But getting the divider plate to flow through my intercooler L bend will be tricky.


I also searched google for "twin turbo pressure surge" and read a bunch of stuff. There are a lot of theories from exhaust firing order, exhaust being too restrictive, too small of vacuum line, balance tube, turbos being wrong size for car etc.. It's nice to see that we aren't the only platform experiencing this.

I believe supras have some special reed valve and a few air sensors so during partial throttle only 1 turbo is spooling and the reed valve prevents air from flowing into the other compressor.

SupraTT - sequential turbo operation

Also some of the custom turbo motorcycles see this and add surge tanks built into the piping. I think this would be equivalent of using a bigger core. More space to pressurize equals a little longer for air to stall turbo.


and heres my IC setup





And this is the only shot of my piping that I have. You can see the Y and why it would be a real pain to try to split it from there to the intercooler.

[TurboSinceBirth]

That sounds really weird and annoying at the same time. I'm glad I don't have a problem because that would drive me crazy. How many of you guys have a rebuilt tb? I doubt it would make much of a difference just curious since my shaft seals were leaking badly before I upgraded turbos.

[KeithMac]

I had horrible surge with my tdo4-16gs and fmic, turns out there was a clump of kitchen roll stuck in the end tank of the ic!. It would still hit 26psi most of the time too..

Maybe if surge is that bad you may need to try a less restrictive ic?, it sesms the bigger the compressor wheel the worse it gets for people?.

My ic pipes are quite large from ic to throttle body and I have no surge issues at all now..

[J. Fast]

Quick qualifying question guys... What type of boost gauge behavior are you seeing when you hear surge? Is the boost gauge bouncing?

[KeithMac]

Mine would, it was only at low boost though. Are people getting surge at WOT?. There was a thread on the UK site where somekne fitted a valve that vented the boost pipe between 30% to 60% TPS and that sorted his issue out..

[CoopKill]

Gauge bounces under low load/cruise conditions, yes.

[TurboSinceBirth]

I wish we had some compressor flow maps for these quick spooling TD04s. I was looking at some other TD04 maps trying to figure out if I pushed my turbos to too high of a PR thus running it outside of the map resulting it surge and snapping my shaft. It seems like at lower rpms when the turbos spool so quickly the demand lines are shifted to the left on the compressor map extending into the surge portion. Reading up on other platforms they faced the same issue and it was only solved by running a bigger hotside, some sort of TPS run bypass valve, or giving the car more throttle to get back onto a good section of the compressor map.

This is on a stock motor granted but I chose this for illustrative purposes so you get the idea.


You can see the left hand side of the compressor flow map. At 2k rpms you're barely spooling. At 3k rpms you can probably hit mid teens or more boost with 13Gs since they spool quick which 15-20 psi at the assumed VE will surge real bad. We don't have a compressor map for DR-750s but taking into account how quickly they spool high boost at lower rpms will more than likely push it off the compressor map resulting in surge. I realize most of the issue is around the transition from vacuum to boost but there are some generating boost at lower rpm part throttle conditions having issues. I'm curious if you were able to increase the VE of the motor if it would shift the demand enough to the right to get rid of the pulsing kind of like how Matt ran the opposite settings on cam gears +3/-1 to get rid of it. He may have increased the VE enough at that particular spot to be ok.

I don't know how many issues Ray would have with pulsing if he installed a FMIC. With a built lower end, Stage III heads, cams, cam gears, and other possible VE improvements he could install it could potentially get rid of the pulsing. If this is more related to the difference in hotside intercooler pipe length between the front and rear turbos or the inability of the hard pipes to expand, then none of this really applies I'm sure.

[mb3000]

I wish we had some compressor flow maps for these quick spooling TD04s. I was looking at some other TD04 maps trying to figure out if I pushed my turbos to too high of a PR thus running it outside of the map resulting it surge and snapping my shaft. It seems like at lower rpms when the turbos spool so quickly the demand lines are shifted to the left on the compressor map extending into the surge portion. Reading up on other platforms they faced the same issue and it was only solved by running a bigger hotside, some sort of TPS run bypass valve, or giving the car more throttle to get back onto a good section of the compressor map.

This is on a stock motor granted but I chose this for illustrative purposes so you get the idea.


You can see the left hand side of the compressor flow map. At 2k rpms you're barely spooling. At 3k rpms you can probably hit mid teens or more boost with 13Gs since they spool quick which 15-20 psi at the assumed VE will surge real bad. We don't have a compressor map for DR-750s but taking into account how quickly they spool high boost at lower rpms will more than likely push it off the compressor map resulting in surge. I realize most of the issue is around the transition from vacuum to boost but there are some generating boost at lower rpm part throttle conditions having issues. I'm curious if you were able to increase the VE of the motor if it would shift the demand enough to the right to get rid of the pulsing kind of like how Matt ran the opposite settings on cam gears +3/-1 to get rid of it. He may have increased the VE enough at that particular spot to be ok.

I don't know how many issues Ray would have with pulsing if he installed a FMIC. With a built lower end, Stage III heads, cams, cam gears, and other possible VE improvements he could install it could potentially get rid of the pulsing. If this is more related to the difference in hotside intercooler pipe length between the front and rear turbos or the inability of the hard pipes to expand, then none of this really applies I'm sure.

That's why I've always been uncomfortable buying a turbo without a compressor map.

[KeithMac]

Would be worth running a pressure sensor / gauge pre throttle body to see what kind of pressure there is in the ic pipes in surge conditions.

A valve to vent pre throttlebody boost driven from a TPS vs RPM map would get the job done, or opening the BOV artificially between 20% to 60% tps..